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Museum of the Rockies • 2013 Docent Manual

EARLY EARTH HISTORY ANDTHE LANDFORMS/LIFEFORMS EXHIBIT

Rewritten Summer 2008/Updated in 2011 and 2012

The Landforms/Lifeforms exhibit begins with the Precambrian Eon and the earliest formation of Earth’s geologic, maritime and terrestrial features. Before focusing on exhibit information, this part summarizes the evolution of the universe from the “explosion” of space itself (the Big Bang) to the expanding universe that exists today. It is also important to understand Earth’s early formation which is covered in this part.

THE EVOLVING UNIVERSE

This summary describes various aspects of the evolution of the universe. The scientific evidence for this scenario is overwhelming, but it is the subject of intense ongoing research and will evolve as new knowledge is obtained.

The Big Bang: Nearly 14 billion years ago, the universe was compressed into a point infinitely small and dense and contained all mass and energy. An expanding superheated fireball called the Big Bang resulted and marked the beginning of space, time, and the physical laws which would govern the universe.

Elements Form: At first, the expanding universe consisted only of a hot, glowing “soup” of radiation and elementary particles like quarks, which combined to form protons (hydrogen nuclei) and neutrons. After 3 minutes, some protons and neutrons combined into helium nuclei. At this time, the universe was about three-fourths hydrogen and one-fourth helium.

Matter Dominates: After several hundred thousand years, the expanding universe had cooled to the point where electrons could join with atomic nuclei to form stable atoms. The universe cooled to a temperature near 3000 K. Hydrogen and helium began to clump into vast clouds. Radiation no longer interacted constantly with matter and became a background glow. This radiation is detected today as Cosmic Background Radiation (CBR). Today, the universe has expanded by a factor of a thousand. Wavelengths have stretched by a factor of a thousand, and the temperature has decreased by a factor of a thousand to the observed CBR temperature near 3 K.

Galaxies Form: Clouds of matter, collapsing under gravity, formed the first stars within huge gravitationally bound structures called galaxies. The galaxies themselves formed immense clusters. Many of the young galaxies possessed bright, active cores called quasars where gas falling into black holes released huge amounts of energy we see as x-rays.

Landforms/Lifeforms •

Galaxy Types: Some galaxies are elliptical (round or oval shapes) where stars are formed very early. Other galaxies are spirals, whose “arms” are sites of star birth. Still other galaxies are irregular in shape.

The Milky Way: About 4.6 billion years ago, in the disk of an average spiral galaxy, a contracting cloud of gas and dust formed an average star (the Sun) with a family of planets. It takes light about 100,000 years to cross the galaxy but only about 11 hours to cross the solar system.

The Universe Continues: The universe continues to expand, and its billions of galaxies are getting farther apart as the volume of space increases.

NOTE: Docents looking for an easy-to-read, superbly illustrated overview of the Big Bang should read Big Bang by Carolyn DeCristofano. This 31-page book was originally written for children but does an excellent job of explaining this complicated theory. Several copies are in the Volunteer Library.

HOW DO WE KNOW HOW OLD THE UNIVERSE IS?

The Wilkinson Microwave Anisotropy Probe (WMAP) observatory has produced a picture showing what the universe looked like when it was only 380,000 years old. The image shows the universe when the hot, dense, charged gas (plasma) that filled the early universe condensed into clouds of neutral hydrogen and helium gas. The image shows the outer layer of hot gas that defines the edge of the visible universe. This picture is produced by collecting light that has been traveling through space for the past 13.7 billion years. Using this picture, scientists have been able to establish the age, size, shape and composition of the universe.

According to WMAP data, the age of the universe is 13.7 billion years with an uncertainty of only 200,000 years. WMAP confirmed that we live in a universe in which normal matter (protons and neutrons) makes up 4.4% of the total density. Dark matter (nature unknown) makes up 22.6% of the total density, and dark energy (nature unknown) contributes the remaining 73%. In addition, the age of the universe when cosmic background radiation (CBR) was emitted was 380,000 years; and the first stars appeared 400 million years after the Big Bang.

It is tempting to think that the radius of the universe is 13.7 billion light years because light has been traveling for about 13.7 billion years. But that’s only part of the picture. During the 13.7 billion years of travel time, the universe has been expanding and the starting point of a photon reaching us today after traveling 13.7 billion years is now 78 billion light years away.

EARLY EARTH FORMATION

In the past, a series of wall panels at the entrance to the Landforms/Lifeforms exhibit described the Earth’s early formation and its three layers (core, mantle

• Landforms/Lifeforms


and crust). These panels were eliminated when the lobby was reconstructed in 2010. However, the information is still pertinent to the Landforms/Lifeforms exhibit and is provided below.

Dust and Gas: A vast, whirling disk of dust and gas provided the material that formed the sun and planets about five billion years ago. This debris began condensing into rocky bodies, a process that set the stage for the formation of Earth and the other planets.

Rocky Bodies: The rocky bodies grew as their gravity attracted more dust and rocks. They began to collide with each other, combining into ever larger bodies. One of these accumulations of space rubble would become Earth.

Half-Sized Earth: As Earth grew larger and more massive, its gravitational pull increased. Stronger gravity brought space rubble crashing in with greater speed. These high-impact collisions generated so much heat that surface rock on the planet began to melt.

The Layered Look: Activity in and between three layers makes Earth the dynamic place we know today. Those layers were created when heavier elements sank toward the center and lighter elements rose to the surface of the still-hot planet. This sorting created the core, mantle, and crust. Core: Comprising about 1/3 of Earth’s mass, the core has a solid inner part and liquid outer part – both made of an iron-nickel alloy. Pressure keeps the superhot inner core from melting.

Mantle: The mantle extends from the core almost to the planet’s surface; it is composed of hot, solid, and somewhat elastic basaltic rock.

Crust: Earth’s relatively thin, rocky surface layer is called the crust.

The crust and upper skin of the mantle form the lithosphere, which is broken into plates. The interaction of these plates causes the mountain building, volcanoes, and earthquakes evident on Earth’s surface.

The Young Earth: Earth’s early atmosphere was made of steamy water vapor, carbon dioxide, and other gases released by abundant volcanoes. As the atmosphere became saturated, water vapor condensed and began to fall as rain. Those first rains cooled the crust and formed the oceans.

LANDFORMS/LIFEFORMS EXHIBIT

BACKGROUND

The Landforms/Lifeforms exhibit opened in June 1996. Nearly two-thirds of the original exhibit remains. Some exhibit items were removed and others relocated to make room for the entrance to the Siebel Dinosaur Complex and the Fossil Viewing Laboratory. A new exhibit segment, Earliest Life: A Microbial World,


has been added to the Precambrian Room. Almost all Cenozoic Era items have been removed from the original Landforms/Lifeforms exhibit; however, a new Cenozoic exhibit segment is now located on the second-floor balcony overlooking the Hall of Giants. Information on the new Microbial World and Cenozoic Era segments has been included in this section of the docent manual.

The first part of the Landforms/Lifeforms section covers exhibit descriptions and corresponds to the sequence of exhibits within the hall. The second part contains broader background information for developing hall interpretations.

The Landforms/Lifeforms exhibit explores early earth history and the continuing process of change and its effect on the geology and life history of the northern Rocky Mountain region.

Visitors move through re-created environments of the Precambrian Eon and the Paleozoic Era. The dynamic planet and evolution of life within geologic time is the unifying theme of this exhibit. The regional geology of the Beartooth Mountains and Glacier National Park is used to exemplify the theme of geologic and biologic interaction through geologic time.

Exhibit Title Panel: LANDFORMS/LIFEFORMSRocks and fossils of the Northern Rocky Mountains are rich in stories about ancient landscapes and past lives. Geologic forces have transformed our region from volcanic caldron, to tropical sea, to the mountains of today. Across that changing landscape, a miraculous succession of life has left a tantalizing trail to ponder. Whether or not they were evolutionary successes, all lifeforms – from bacteria, to antlered fish, to dinosaurs, to humans – have left their mark on this Earth.

Science can be more fantastic than science fiction. Join us on a trip through Landforms/ Lifeforms, through the Rocky Mountains, through time.

“There is grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms, or into one . . . from so simple a beginning, endless forms most beautiful and most wonderful have been, and are being, evolved.”

-- Charles Darwin, Origin of Species



LANDFORMS/LIFEFORMS EXHIBIT MAP

Major Geologic Time Divisions:

Precambrian Eon 4.6 billion years ago - 540 million years ago

Paleozoic Era 540 million years ago - 245 million years ago

Mesozoic Era 245 million years ago - 65 million years ago

Cenozoic Era 65 million years ago - Present

THE TIME ROOM AND GEOLOGIC TIMELandforms/Lifeforms •

The Earth is 4.6 billion years old. Two eons comprise all of Earth history: the Precambrian Eon, 4.6 billion – 540 million years ago (mya), and the Phanerozoic Eon, 540 mya to present. Three-fourths of Earth’s history is contained in the Precambrian Eon. During the Precambrian Eon, simple lifeforms evolved and spread worldwide, dominating the oceans that covered the planet. During the Phanerozoic Eon, all of the more complex animals (living and extinct) evolved. The Phanerozoic Eon is divided into three eras: Paleozoic Era (540 – 245 mya); Mesozoic Era (245 – 65 mya); and Cenozoic Era (65 mya – present).

The purpose of the Time Room is to enable visitors to make the conceptual leap from life time to Earth time. The interactive exhibits are designed to challenge visitors to think about and imagine time in ways they may have never before contemplated by connecting geologic time with time in everyday life. Several devices introduce the basic measurement of a million. By thinking of one million, then one billion, then 4.6 billion, it is hoped visitors will begin to appreciate the immensity of time.

Million Machine: A machine that can hold one million dimes.

Time Links: Visitors can move a chain that represents all of Earth’s time. Here is a chance to turn back time. Each inch of chain represents 10 million years.

Precambrian Eon 406 inches (4.06 billion years) Paleozoic Era 30 inches (300 million years) Mesozoic Era 18 inches (180 million years) Cenozoic Era 6.5 inches (65 million years)

For comparison, early humans appeared on Earth around four million years ago, less than half an inch from the end of the chain.



EARTHWORKS: The highlight of the Time Room is Earthworks, a kinetic sculpture which illustrates four different natural cycles: Food Cycle, Water Cycle, Rock Cycle, and Earth or Plate Tectonics Cycle. Balls representing energy leave the “Sun” and “Earth’s Interior” (represented by two globes near the center) to trigger each cycle.

Panel: Earthworks is a model of the dynamic Earth. All of the planet’s natural processes are connected in a wondrous system. External energy from the Sun powers the Food and Water Cycles. Internal energy from the Earth’s center drives the Rock Cycle, which continuously recycles rocks, and the Earth Cycle, which builds landforms. Can you follow the energy balls as they move through the machine?

Food Cycle: Plants use energy from the Sun, and are primary producers. Herbivores eat plants and are in turn eaten by carnivoresWater Cycle: Energy from the Sun evaporates water. Evaporated water falls as rain and runs to the ocean in rivers and streams, where it once again evaporates.Rock Cycle: Rocks are recycled from one type to another. This process is triggered by energy from the Earth's interior. Earth Cycle (Plate Tectonics): Heat energy from Earth's interior drives the motion of plates.

Recycling: One of the fundamental physical truths about Earth is that matter, the stuff of the Earth, is neither created nor destroyed, but simply changes from matter to energy, or from one type of matter to another. Earth’s internal energy melts rock, which in turn erupts on the surface and is weathered by rain, which


was evaporated by the Sun's energy from the ocean. All of Earth's processes are connected in a beautiful, complex system.

TIME LINE: A time line is painted at the top of the Time Room curved wall. Photo/text panels describe each major geologic time division and an accompanying globe shows the formation and movement of landmasses through geologic time. Significant events in the history of Earth and the evolution of life are also displayed within each major geologic time division.

TIME LINE EXHIBIT ITEMS

DISPLAY CASE: METEORITESMeteorites are pieces of stony or metallic space debris left over from Earth’s formation 4.6 billion years ago. About 150 tons of meteorites hit our planet each day, mostly in the form of dust. However, some meteorites retain considerable size in their journey from space: Huckitta Meteorite, which landed in Australia, weighs more than a ton.

Gibeon iron meteorite, Namibia, Africa: This 7-pound metallic meteorite is made mostly of iron and nickel, the same materials that comprise the core of the Earth.

Esquel pallasite, Chubut, Argentina: Typically, stony-iron meteorites like this one are equal parts silicates and metal, usually iron-nickel alloy. In this rare specimen, the silicates are large crystals of the mineral olivine.

DISPLAY: PRECAMBRIAN ERA (4.6 billion – 540 million years ago)

Panel: Precambrian EonThis is when it began; Earth came into being during this time and primitive life forms took shape. The Precambrian Eon lasted four billion years and spanned the first 3/4 of our planet’s history. Colonies of cyanobacteria that lived in shallow ocean water were the dominant life forms. Precambrian-age rocks can be seen in the Beartooth Mountains, the Madison and Gallatin Ranges, and in the peaks of Glacier and Grand Teton National Parks.

Precambrian Globe, 3.8 billion years ago: Oceans have formed, but are occasionally vaporized by meteorite strikes. The planet’s basaltic crust is remelting to form granitic crust – the foundation of the new continents.

Precambrian Shelf DisplayQuartzite, Hellroaring Plateau, Beartooth Mountains, Montana: Look for the small, brownish red minerals in this quartzite. These zircons formed in this specimen 3.96 billion years ago, an indication that some of the oldest rock in North America can be found in the Beartooth Mountains.



Image, Beartooth Mountains: Rocks lying exposed in the Beartooth Mountains are among the oldest in North America. Some of the minerals in these rocks formed 4.02 billion years ago, when the Earth was young.

Banded Iron Formation, Boulder River, south of Big Timber, Montana: Banded iron formations formed over 2.2 billion years ago when oxygen released by cyanobacteria bound with iron dissolved in sea water. These formations record the respiration of organisms that lived before Earth had an oxygen atmosphere.

Raindrop Imprints, McNamara Formation, Little Blackfoot River, Montana: The small indentations in this rock are thought to have been left by raindrops falling on mud – a record of one rainy day, one billion years ago.

Salt Casts, Helena Formation, Glacier National Park, Montana: The cubes in this limestone formed when salt crystals grew in the mud of a lakeshore about one billion years ago, in what is now Glacier National Park. Salt crystals form in arid climates, indicating that today’s forested northwestern Montana was once desert-like.

Image, Glacier National Park: Some of the oldest sedimentary rocks in the entire Northern Rocky Mountain region are found in the Lewis Range of Glacier National Park. Fossils of some of Earth’s earliest life forms have been discovered here.

Precambrian Events 4.6 billion Earth forms 4.2 billion Oceans and primitive non-oxygen atmosphere form 3.96 billion Oldest rock in North America 3.5 billion Oldest known fossil; first direct evidence of life on Earth 2.2 billion Oxygen atmosphere develops 1.4 billion Sediments deposited in a large, shallow lake or sea in the area of Glacier National Park 600 million First multicelled organisms

DISPLAY: PALEOZOIC ERA (540 – 245 million years ago)

Panel: Paleozoic EraSeas covered the land for most of this time. The predecessors of all modern life forms evolved in the watery environments of the Paleozoic Era. Over the years sediments were deposited on the sea bottom, forming layers of sandstone, mudstone, and limestone thousands of feet thick. Paleozoic-age rocks can be found throughout the Rocky Mountains.

Paleozoic Globe, 450 million years ago: The future Northern Rocky Mountain region is situated a few degrees north of the equator. Most of what will become North America is covered by shallow seas.


Paleozoic Shelf DisplayWorm Burrows and Tracks, Wolsey Shale, Gallatin County, Montana: Worms and trilobites, some of the earliest animals to evolve, left tracks and burrows in this mud, 530 million years ago.

Lodgepole Limestone, Gallatin County, Montana: Brachiopods and other marine organisms lived 350 million years ago in the tropical waters that covered what is now the Gallatin Valley.

Image, Bridger Mountains: The Bridger Range is a typical example of ranges within the Northern Rocky Mountain region that formed from rock layers folding and pushing upward along large thrust faults.

Paleozoic Events 530 million Primitive ancestors of most modern animals lived in oceans worldwide 425 million The first land plants appear 375 million The earliest mountain-building event on west coast of North America 370 million Corals and stromatoporoids build reefs in tropical waters covering region

DISPLAY: MESOZOIC ERA (245 – 65 million years ago)

Panel: Mesozoic EraSome of the Rocky Mountain ranges began to uplift during this time. Mammals, dinosaurs, birds and flowering plants first appeared on the land. The collision of tectonic plates on the west coast of North America put tremendous stress on continental rock. This pressure folded and lifted the land to form many ranges of the Rocky Mountains. Mesozoic-age rocks can be seen throughout Montana and Wyoming.

Mesozoic Globe, 152 million years ago: North America continues to move north. The Rocky Mountains are forming and the Atlantic Ocean is widening.

Mesozoic Shelf DisplaysHadrosaur Tibia, Choteau, Montana: Touch the fossilized shin bone that belonged to a duckbilled dinosaur living 80 million years ago near what is now Choteau, Montana.

Folded Shale, Glacier National Park, Montana: Stress in the Earth’s crust deformed this rock during mountain-building activity about 70 million years ago.

Mesozoic Events 245 million All landmasses assemble into one supercontinent called Pangea. Earth’s most massive extinction occurs.



150-110 million Rocky Mountains begin to form along the west coast of North America. To the east, rising sea levels create the Cretaceous Interior Seaway. 110-50 million Mountain-building activity continues in the Northern Rockies 65 million Dinosaurs die out in yet another major extinction.

DISPLAY: CENOZOIC ERA (65 million years ago to present)

Panel: Cenozoic EraWe are living in the Cenozoic Era. The Northern Rockies continue to rise, and glaciers and volcanoes are still at work. The beginning of the Cenozoic Era was marked by the development of many new mammal species. The first horses appeared early during this time. Across the globe from the Northern Rocky Mountains, humans walked onto the scene early in the era.

Cenozoic Globe, Present: The world as we know it – at least for now. Continents continue to move at the rate of about one inch per year.

Cenozoic Shelf DisplaysMesa Falls Tuff, Ashton, Idaho: This tuff was formed 1.3 million years ago when hot gas exploded through silica-rich molten rock during an enormous volcanic eruption near what is now Yellowstone National Park.

Snake River Plain Basalt, Idaho Falls, Idaho: A massive eruption of iron-rich basalt lava onto the Snake River Plain formed this rock about six million years ago. The most recent Snake River Plain lava flow occurred only 2,100 years ago and can be seen at Idaho’s Crater of the Moon National Monument.

Projectile Point: Replica of 11,000-year-old Clovis projectile point made of chert. Humans first arrived in North America at least 11,000 years ago, and shaped local stone for use as tools.

Image, Yellowstone National Park: Yellowstone National Park’s unique features spring from volcanic activity that began 15 million years ago and continues today. Organisms living in Yellowstone’s hot pools may provide clues about early life.

Image, Grand Teton National Park: The Teton Range, centerpiece of Grand Teton National Park, rises along a fault line at the base of the mountains.

Cenozoic Events 55 million Mammals diversify after dinosaurs die off 15 million Migration of the North American plate over a fixed “hot spot” creates volcanic activity from western Idaho to Yellowstone. Prairie grasses evolve.


5 million Wyoming’s Teton Range – like many other ranges in the Northern Rockies is uplifted along a fault 2.5 million Glaciation begins in the Northern Rocky Mountains

PRECAMBRIAN EON: FOUNDATION FOR LANDSCAPE AND LIFE

(4.6 Billion to 540 Million Years Ago)

The purpose of the Precambrian exhibit is to introduce the theories of the origin of life and to use the principle of actualism (the present is the key to the past) to infer conditions in ancient environments.

Panel at Fissure Entrance: Precambrian Earth, Hardening Crust Step back in time 3.8 billion years. There is no oxygen. The sky grows red and is streaked with meteors. Small continents and oceans have formed. Today, rock from this time lies exposed in the Beartooth Mountains. Metamorphic rock from the Beartooth is among the oldest rock to be found in North America. Precambrian Globe, 3.8 billion years ago. Oceans have formed, but are occasionally vaporized by meteorite strikes. The planet’s basaltic crust is remelting to form granitic crust – the foundation of the new continents.

Earth Fissure: The purpose of the fissure exhibit is to provide visitors with a sensory experience of the Earth's early crust. As visitors leave the Time Room, they walk through double doors into a fissure in the Earth's crust. Overhead, an anoxic (lack of oxygen) environment casts a reddish hue through which occasional meteors (strobe lights) can be seen and the temperature is warm. Casts of metamorphic rock (Archean gneiss) from the Beartrap Canyon overhang the visitors and cover the walls. A text panel explains that some of the world's oldest rock can be found in the Beartrap Canyon and has been dated at 3.8 billion years old.

Fissure Label: Cast of Archean gneiss (continental basement rock) Beartrap Canyon, Gallatin County, Montana, 3.8-2.7 billion years old

EARLIEST LIFE: A MICROBIAL WORLD



“The role of the infinitely small in nature can be infinitely great” -- Louis Pasteur

INTRODUCTION

The Museum of the Rockies is less than 100 miles from one of the world’s natural treasures, Yellowstone National Park. The Greater Yellowstone Ecosystem extends beyond Park boundaries and encompasses much of southeastern Idaho, southwestern Montana and northwestern Wyoming. This area provides scientists an amazing array of research opportunities in geology, geoecology, environmental and earth sciences, biology, microbiology, thermal biology, chemistry, and other scientific disciplines.

The Microbial World display was developed by Dr David Ward, Professor, Montana State University, Land Resources and Environmental Sciences Department. Dr Ward is a nationally recognized microbial ecologist and thermophile researcher. MSU is a leader in researching the biology and interrelated physical and chemical processes of geothermal environments in the Greater Yellowstone Ecosystem. Dr Ward’s research team focuses on better understanding microbial diversity as it really occurs in nature as a consequence of ecological and evolutionary processes.

Anyone who has visited Yellowstone National Park’s famous thermal features remembers erupting geysers, billowing clouds of steam, the smell of sulfur, and dazzling arrays of color. Microbial mat communities are one of the primary sources of color in Yellowstone’s thermal waters. Scientists study microbial life to learn about the limits of life; to understand the Earth’s past and the evolution of early life; and to find clues about how to seek evidence of life beyond Earth.

This exhibit contains five parts: The Earliest Life video, the microbial life wall panels, the Touchable Timeline display, the center string-of-bead algae and stromatolite display cases, and the Tree of Life touchscreens.

VIDEO: EARLIEST LIFE, A MICROBIAL WORLDVisitors encounter the video as they emerge from the Earth Fissure into the Precambrian Room. The video provides an orientation to the idea of an Age of Microorganisms based on fossil and genetic evidence, and describes what these records tell us about how life evolved. The video is 5:40 minutes long and plays on a continuous loop.

Video’s Key Points:

- Life existed on Earth nearly 4 billion years ago. For 3 billion years, single-celled organisms were Earth’s only inhabitants.

- DNA evidence supports the dominance of microorganisms during an Age of Microorganisms (3.5 billion years ago to 600 million years ago). DNA was


also used to determine the relationship among all living organisms depicted in the Tree of Life.

- Ancient microbial mat communities left fossils called stromatolites that resemble modern microbial mats.

- Modern bacteria and archaea found in Yellowstone hot springs are the most genetically similar to Earth’s earliest life.

- Life is dynamic and adaptive. Early life used chemicals for energy (chemosynthesis). Later, life forms developed the capability to use light for energy (photosynthesis), a process which released oxygen as a waste.

- By 2 billion years ago, microbial life, using photosynthesis, helped create an oxygen-rich atmosphere which changed the chemistry of the entire planet.

- Once oxygen was available, aerobic life (oxygen-breathing animals) developed.

- Multicellular life developed. Predation became another source of energy to support life – by eating other life! Earth’s earliest predators ate microorganisms.

- 600 million years ago: Explosion of animal and plant diversity. Earliest animals may have grazed coastal microbial mats into extinction. Today, microbial mats are only found in extremely salty or high-temperature environments like Yellowstone hot springs.

- Scientists study microbial life to learn about the limits of life; to understand Earth’s past; and to find clues about how to seek evidence of life beyond Earth.

WALL PANELS: The exhibit wall panels emphasize the fossil evidence of an Age of Microorganisms and what this means for searching for life on other planets. The panels, from right to left, take visitors through Earth’s Past (represented by stromatolites and microfossils); to Earth’s Present (the study of current Yellowstone microbial mats as an analog for ancient stromatolites); to Other Microbial Worlds (studies of microorganisms in Earth’s extreme environments as insight into possibility of life on other planets). The center display cases provide excellent examples of fossil evidence described in the video and the wall panels.

PANEL: EARTH’S PASTMicroorganisms Dominated Early Life: Fossil evidence suggests that microorganisms were earth’s earliest organisms and earth’s only life forms during most of Precambrian time. Microorganisms are single-celled creatures, much smaller than the point of a pin. They built communities, called mats, which carpeted ancient coastlines and extreme environments like hot springs. Fossilized mat communities are called stromatolites. Stromatolites and the fossil microorganisms they contain are the dominant Precambrian fossils.

Tiny Microorganisms Can Create Large Landforms: The mat communities that microorganisms built were as extensive as modern coral reefs in the shallow seas that covered western Montana 1.1 billion years ago. Over time, the fossil remains of these microbial communities, called stromatolite beds, were uplifted by mountain building and eroded by glaciers. Today, they can be seen as large rock formations in Glacier National Park and many other places.



Images: Stromatolite Formation, Glacier National Park Microorganisms: Fossilized (left) and on a pinpoint (right) Artist’s concept of early Earth life.

PANEL: THE PRESENT, A KEY TO THE PASTScientists compare modern microbial mat communities to stromatolites (fossilized remains of ancient microbial mats) in order to better understand what life was like on early Earth. The thin layers in this 1.1 billion year old stromatolite from Glacier National Park are similar to the layers in a modern microbial mat from a Yellowstone National Park hot spring.

Images: Microbial Mat Stromatolite

PANEL: EARTH’S PRESENTMicrobial Diversity: Microorganisms live in diverse extreme environments, including places that are extremely cold, acidic, salty or dry. They can also use a diversity of energy sources. For example, microorganisms that form mats use light for energy in a process called photosynthesis. Other microorganisms can use an unusual variety of chemicals, like hydrogen, sulfur and iron, for energy in a process called chemosynthesis. Chemosynthetic bacteria living near hot spring sources form communities called “streamers,” which can also be fossilized.

Microbial Mats – Grazed to the Extreme? Living microbial mat communities exist today, but only in extreme environments like the hot springs in Yellowstone National Park. From the fossil record, we see that about 600 million years ago, animals evolved and stromatolites became rare. This suggests that animals may have eaten microbial mats. Mats could then only exist in places too extreme for their predators. Even in hot spring environments flies graze on mats growing in areas as hot as 108 degrees Fahrenheit. Most mats are found at even hotter temperatures.

Images: Yellowstone hot spring showing green microbial mat in foreground Chemosynthetic bacterial streamers Flies grazing mat

PANEL: MICROBIAL LIFE, A KEY TO FINDING LIFE BEYOND EARTHA long Age of Microorganisms occurred on Earth before the evolution of complex life forms like plants and animals. If life evolved elsewhere in the universe as it did on Earth, chances are greatest that it would have been microbial life. Microorganisms are simple life forms that can live in a great range of environments and can use a wide variety of energy sources. They have broadened our understanding of where we should search for evidence of past or present life on other worlds. Image: Mars and Earth


PANEL: OTHER MICROBIAL WORLDS?Past Life on Mars? Geologic evidence suggests that Mars once had large water bodies and hot springs that could have provided habitats for mat-formed and chemosynthetic microorganisms. Scientists are exploring these places for fossil evidence of microbial life.

Life on Europa Today? Europa, a moon of Jupiter, is covered by a liquid water ocean with a thick layer of ice. On Earth, chemosynthetic bacteria thrive in deep-sea hydrothermal vents. Scientists hypothesize that there may be similar deep-sea vents and chemosynthetic microbial life on Europa.

Images: Spirit rover explores Gusev Crater on Mars Artist’s concept of early Mars ocean Europa

TOUCHABLE TIMELINEThe Touchable Timeline display gives visitors the opportunity to examine and touch rocks containing the kind of fossil evidence supporting the existence of an Age of Microorganisms. Rocks are cut to a length that shows the relative length of geological time represented by each rock.

Touchable Timeline Panel: Stromatolite fossils formed in rocks dating from 3.5 billion years ago to 600 million years ago show the long period (about 3 billion years) when only microbial life was present on Earth. At that time, animals began to appear in the fossil record suggesting that early animals likely ate microbial mats.

Actual rock/fossil specimens that visitors can touch (right to left, oldest to youngest specimens): Touch one of Earth’s oldest rocks

Touch a 1.1 billion year old stromatolite from Glacier National Park Touch Paleozoic fossils of ancient life

CENTER DISPLAY CASE PANEL: COMING TO LIFEThe rock in the case contains some of the oldest fossils in North America. String-of-bead algae preserved in the rock were alive 1.4 billion years ago and are one of the first life forms that can be seen with the naked eye. Certain types of bacteria are even older than algae, and were probably the planet’s first living organisms. Earth came to life about 3.5 billion years ago – a full billion years after the planet formed. In a chain of



events we only partially understand, chemical elements present on the planet combined and gave rise to simple living organisms. The rock contains Eukaryotic algae (a string-of-bead algae) in argillite. It was found in the Appekumny Formation, Glacier National Park, Montana, and is 1.4 billion years old.

CENTER DISPLAY CASE PANEL: LIVING, BREATHING ROCKStromatolites are rock-like colonies of cyanobacteria that were Earth’s dominant life form for three billion years. Cyanobacteria, which live in shallow water, secrete slime to protect their cells. When mud sticks to the slime, a colony produces another layer of slime. This cycle of sliming and coating creates the stromatolite.

Like plants, stromatolites use energy from the sun and carbon dioxide from water to make their own food through photosynthesis. Also like plants, cyanobacteria give off oxygen. Respiration from countless stromatolites produced the atmosphere we breathe today. Fossil stromatolites can be seen in Glacier National Park.

With no predators around, stromatolites thrived for three billion years. Today, stromatolites live in only a few places, including Shark Bay, Australia. Snails and fish that would graze on cyanobacteria can’t survive in Shark Bay’s super-salty water.

Image: Stromatolites, Shark Bay, Australia Case: Model of Living Stromatolites Fossils: Nested Conophyton from Helene Formation, Glacier National Park, 775 million years old. Composite stromatolites from Snowslip Formation, Glacier National Park, 700 million years old.

TREE OF LIFE WALL DISPLAY: The Tree of Life display contains two interactive computer touchscreens. The left screen features how genetic evidence is used to construct a Tree of Life that supports fossil evidence of an Age of Microorganisms. The right screen focuses on what the Tree of Life says about the evolution of life on Earth. The touchscreens allow visitors to explore the development of the Tree of Life; its depiction of relationships among life forms; the evolution of energy sources for life; and the identification of life’s earliest common ancestor. Key concepts included in the Tree of Life display are summarized below.


What is the Tree of Life? The Tree of Life is a living record of life’s history. It depicts the relationships among life forms based on the similarity of their DNA. It shows how life diversified from an earliest common ancestor into three Domains called Bacteria, Archaea, and Eukarya. Domains Bacteria and Archaea are composed of microorganisms with simple cell structures. Domain Eukarya is comprised of organisms with complex cells, including plants and animals. The Tree of Life is consistent with the fossil record in supporting a long Age of Microorganisms preceding the relatively recent evolution of plants and animals.

Relationships and Ancestors: Most of the Tree of Life is comprised of microorganisms. Plants and animals make up a recent past of Domain Eukarya. Evidence from the fossil record suggests plants and animals evolved much later than microorganisms. Microbes are the most genetically diverse organisms and are still the dominant organisms on Earth.

Innovations in Life’s History: All life needs energy to survive. Microorganisms use photosynthesis (light for energy) and other unique methods to obtain energy using what is available in their environments. The closest descendants of life’s earliest common ancestor obtain energy from chemicals that are available in the hot water they inhabit. The process is called chemosynthesis. Earth’s earliest microorganisms used chemosynthesis to obtain energy. Photosynthetic microorganisms evolved later than chemosynthetic microorganisms. One type of photosynthetic bacteria called cyanobacteria evolved a means of producing oxygen during photosynthesis. By producing oxygen, billions of tiny cyanobacteria gradually rusted the Earth; the accumulation of oxygen began changing the Earth’s atmosphere; and aerobic (oxygen-breathing) organisms began to evolve.

Early Evolution: Scientists can infer properties of a common ancestor by studying the properties of its most closely related descendent. By studying genetic evidence, scientists have determined that the modern organisms that are the closest descendants of life’s earliest common ancestor are several types of Bacteria and Archaea that live in extremely hot environments. Life’s earliest common ancestor may have lived in extremely hot environments. The fossil record shows that multicellular life forms arose 600 million years ago. This is only about 15 percent of the total time that life has existed on Earth.

Explore the Tree of Life: Click on species icons to learn more about them.

“Microbes always have the last word.” -- Louis Pasteur

MOUNTAIN-BUILDING IN MONTANA



The Landforms/Lifeforms exhibit includes displays that follow two specific Montana landscapes through geologic history: The Beartooth Mountains and Glacier National Park. The displays combine photographs, models, rocks, and maps to create snapshots of what these places looked like in four different geological time divisions, from the Precambrian to the present.

PANEL: BEARTOOTH MOUNTAINS THROUGH TIMEThe landscape that is now the Beartooth Mountains evolved over time, from early continental crust, to sea floor, to lakes and rivers, to seething volcanoes. Glaciers carved the uplifted landscape into the final form we see today. Can you trace the evolution of the Beartooth Mountains landscape through time?

Image: The famous Bear’s Tooth, a pinnacle of rock for which the range is named, is located near the center of the Beartooth Mountain photomural.

The display includes four block models to show the development of the Beartooths from the Precambrian through the Cenozoic as described below.

Four Block Models of Beartooth MountainsPrecambrian Beartooth Mountains, 3 Billion Years Ago: Basement RockBeartooth rocks are among the oldest in the world. Rocks in the Beartooth Mountains are remnants of the original North American continent which formed through crustal collisions over 3 billion years ago. Display: Precambrian gneiss, Hellroaring Plateau, near Red Lodge, Montana 3.2 billion years old

Paleozoic Beartooth Mountains, 400 Million Years Ago: Seafloor and Estuary DepositsThe rising sea drowned a river valley to create an estuary long before the Beartooth Mountains were uplifted. For hundreds of millions of years, oceans covered much of the early continental crust. As the seas advanced and retreated, marine sediments were deposited on this crust. Such an advance of the sea created this estuary about 400 million years ago. Newly evolved, armored fish – such as the one in the siltstone on display – lived here, and simple plants grew in the shallows. Display: Paleozoic fish fossil in siltstone, Beartooth Butte Formation Park County, Montana, 400 million years old

Mesozoic Beartooth Mountains, 210 Million Years Ago: Lake and River DepositsAfter the sea receded, vast lakes and rivers covered the area of the present day Beartooths. About 210 million years ago, a lake half the size of Montana covered


the marine deposits that had been laid down earlier. Rivers delivered tons of sediments, forming a delta. Aquatic animals such as the crocodile-like Phytosaur lived in Lake Popo Agie while dinosaurs roamed the lake shore. Display: Mesozoic limestone, Popo Agie Formation, Dubois, Wyoming 210 million years old

Cenozoic Beartooth Mountains, 50 Million Years Ago: Mountains, Volcanoes, GlaciersAfter the Beartooths had been uplifted, tremendous volcanic explosions in the area covered the young mountains with lava and ash. The Beartooths were uplifted into mountains about 50 million years ago. Shortly after this uplift, massive volcanoes spewed out lava and ash, covering earlier lake and marine deposits. Two million years ago, glaciers began eroding the earlier deposits and carving the landscape we see today in the Beartooths. Display: Cenozoic lahar made by a volcanic mud slide Absaroka Volcanic Group, Park County, Montana, 45 million years old

PANEL: GLACIER NATIONAL PARK THROUGH TIMEThe landscape that is now Glacier National Park has changed over time from ancient lake, to sea floor, to the rising Rocky Mountains. Glaciers carved the landscape we see today, lending the park its name. Can you trace the evolution of the Glacier National Park landscape through time? Image: Lake McDonald glacial valley in Glacier National Park.

The display includes four block models to show the development of Glacier National Park from the Precambrian through the Cenozoic as described below.

Four Block Models of Glacier National ParkPrecambrian Glacier National Park, 1 Billion Years Ago: Shallow LakeAbout one billion years ago, the area that is now Glacier National Park was covered by a large shallow lake called the Belt Sea. Colonies of bacteria called stromatolites grew in shallow water near the lakeshore, as did simpler string-of-bead algae. The landscape around the lake was probably similar to today’s Death Valley National Monument in California. Display: Precambrian mud cracks, Snowslip Formation, Glacier National Park, Montana, 800 million years old

Paleozoic Glacier National Park, 530 Million Years Ago: Shallow Seas and HurricanesShallow seas flooded the continent, covering the earlier one billion year old lake deposits. Occasional hurricanes ripped up chunks of ocean sediment that had not yet turned to rock. These chunks became covered with particles of mud and sand and later hardened into rocks such as the one shown on display. Display: Paleozoic limestone pebble conglomerate Park Formation, Gallatin County, Montana, 530 million years old



Mesozoic Glacier National Park, 80 Million Years Ago: Rocky Mountains RisingThe Lewis thrust fault separates the mountains from the prairie on the east side of Glacier National Park. The Lewis thrust fault shoved very old Precambrian rocks over younger Mesozoic rocks, resulting in the uplift of mountains in what is now Glacier National Park. East of the fault, dinosaurs roamed between the rising mountains and the shore of the Cretaceous Interior Seaway. Display: Mesozoic shale, folded during thrust faulting Near Glacier National Park, Montana, 100 million years ago

Cenozoic Glacier National Park, 2.5 Million Years Ago: GlaciersAbout 2.5 million years ago, a cooler climate led to the onset of the Ice Age. The Ice Age was a long period of intermittent glaciation during which huge ice sheets moved south from Canada into what is now northern Montana. Glacier National Park’s spectacular scenery was carved by mountain glaciers about 200,000 years ago. Display: Precambrian boulder scratched by a glacier in the Cenozoic North Fork Flathead River, Flathead County, Montana, 200,000 years ago

PALEOZOIC ERA: A SEA OF TIME (540 to 245 Million Years Ago)

The purpose of the Paleozoic exhibit is to emphasize the concept of evolutionary change and diversity of life on the changing surface of the Northern Rocky Mountain region. Visitors learn about the environments present in this region during the Paleozoic Era and the life forms that lived in those environments. As visitors leave the Precambrian Room, they enter a re-created underwater environment. Note: Wavering light on the exhibit floor represents light on the ocean's surface shining on ripple marks on the sea floor during the Paleozoic Era.

PANEL: EARLY PALEOZOIC EARTH, SHIFTING SEASYou are in the water 450 million years ago. Seas come and go across the land. The predecessors of all modern animals are here in primitive, aquatic form. Today, we can read the record of these fluctuating sea levels in the rocks. Former beaches are sandstone; tide flats are mudstone; and limestone marks old ocean floor. Rocks that formed during the time of shifting seas can be seen in the Bridger Mountains. Early Paleozoic Globe, 450 million years ago: The future Rocky Mountain region is situated a few degrees north of the equator. Most of what will become North America is covered by shallow seas.

The Paleozoic exhibit features three dioramas, each representing marine ecosystems from three different Paleozoic periods of time: Cambrian Period (540 - 505 mya); Devonian Period (408 – 360 mya); and Mississippian Period (360 – 320 mya). Each display includes a text panel, the diorama, and a display case


containing fossils and models of life forms featured in the diorama. Panel texts and brief descriptions of each diorama are provided below. Additional background information on the dioramas including species information can be found in the second segment of the Landforms/Lifeforms section.

ALL THE ANCESTORS DIORAMA Panel: One day 530 million years ago, the primitive ancestors of nearly all modern animals lived in Earth’s waters. These creatures were buried in an underwater mud slide in what is now Yoho National Park in western Canada. Today, their fossils inform us about early life.Scientists determine the relationship between ancient and modern life forms by comparing the anatomy of living animals with fossils. All vertebrates, or animals with backbones, are thought to have descended from the tiny Pikaia and its relatives.

Image: Burgess Shale fossil quarry, Yoho National Park, British Columbia, Canada Image: Tiny Pikaia flees Anomalocaris. Wormlike Pikaia is the earliest known animal to have the special muscle characteristics of animals with backbones.

Diorama Summary: Visitors view a snapshot of the Northern Rocky Mountain region 530 million years ago during the Cambrian Period. A 30-inch Anomalocaris is cruising toward Pikaia, the world's first animal with a proto-backbone. Trilobites and other arthropods walk along the bottom. Aysheaia feed and crawl over sponges. Worms in their burrows can be seen where the glass cuts the muddy substrate. This community represents the early ancestors of several life forms alive today, as well as several life forms that are extinct. This time period represents the most diverse time for life forms with appearance of new designs in body type, locomotion and feeding strategies. One of the big changes was the development of an exoskeleton. This Cambrian fauna died in a catastrophic mudslide and is found today in the Burgess Shale of Yoho National Park, British Columbia, Canada.

Display Case Highlights: Eldonia ludwigi – related to sea cucumber Sanctacans uncata – an arthropod and ancestor of scorpions and spiders Olenoides serratus – a trilobite and an active predator and scavenger Canadaspis perfecta – an arthropod and ancestor of crustaceans Pikaia gracilens – known as the ancestor of all vertebrates, including humans Ottoia prolifica – ancestor of modern carnivorous worms Aysheaia pedunculata – may be the ancestor of all insects

WILD WEST REEF DIORAMA



Panel: One day 370 million years ago, the Northern Rocky Mountain region was a tropical place – perfect for reef and reef creatures. During this time, the region spanned the equator. Fish and mollusks lived near reefs in what is now the Northern Rocky Mountain region.Corals build most reefs today, but ancient reefs were built by Stromatoporoids: coral-like animals now extinct. Like modern reef-builders, stromatoporoids preferred warm, clear water. Fish of this time period had developed working jaws. This important new anatomical feature allowed them to begin preying on other animals. Image: Fossilized reef, Challis ID

Diorama Summary: This diorama depicts the Gallatin Valley in Montana, 370 million years ago during the Devonian Period, when it was a shallow marine environment near the equator. An off-reef community is featured with cephalopods and armored jawed fish (Dunkleosteus) swimming above brachiopods (animals with shells on both sides of soft body) burrowing among sponge thickets and corals. By squirting water out between their tentacles, cephalopods could move quickly, driving their shells ahead of their bodies. Cephalopods could be predator, prey or scavenger. In the diorama, one group flees the approaching predator Dunkleosteus, while another group scavenges a Dunkleosteus carcass. Devonian life forms are becoming specialized.

Display Case Highlights: Platyclymenia americana – a cephalopod related to modern nautilus. By filling empty chambers in its shell with water or gas, it could move up or down in the water. Stromatoporoids – thought to be related to sponges. Each individual secreted a skeleton; colonies of stromatoporoids built reefs. Loxonema – a snail. Snails have lived successfully for over 500 million years, adapting to life in the oceans, in fresh water, and on land. This snail grazed on algae. Michelinoceras montanense – a cephalopod. “Squid-in-a-cone” are related to modern squid. Arthroacantha carpenteri – Although they resemble flowers, these crinoids are animals related to sand dollars and starfish.

MIX AND MATCH DIORAMA Panel: One day 320 million years ago, male sharks used alluring head appendages made of bone or cartilage to attract females. Sharks once swam through a shallow bay in what is now central Montana. Three habitats are depicted in the diorama: a shallow, weedy area; a slightly deeper transition zone; and deep water. Like today’s animals, these fish were adapted to specific habitats. Small disk-shaped fish moved easily among the weeds. Sharks were streamlined for fast cruising in open water. Shrimp lived suspended from algae


mats to stay off the inhospitable muddy bottom. Image: Fossil fish quarry, Lewistown, Montana

Panel: Fish PreservesThis former marine bay in central Montana was a natural fossil factory 320 million years ago. Fossils from this site are remarkable in their detail. Specimens with internal organs have been discovered, and fossil fish have been found with fossil blood in their fossil veins. Black skin pigments have also been preserved, allowing scientists to reconstruct color patterns. What caught these ancient fish for us to find today? Occasional earthquakes caused mud slides which swept out across the bay in thick currents, quickly killing and burying any animals in the way.

Image: The bay before a mud slide Image: Many animals are quickly killed and buried during a mud slide Image: Skin pigment, fins, liver and veins can be seen in this photograph of a fossil fish

Diorama Summary: This diorama depicts life in the Bear Gulch area near present day Lewistown, Montana, 320 million years ago during the Mississippian Period. A wide variety of animals live in this sponge thicket including sharks, fish, coelacanths, shrimp, and cephalopods. Many of these animals are types of sharks. The 4-foot Stethacanthus sharks cruise toward open water while the flattened Squatinactis swims close to the bottom. The odd looking Falcatus or unicorn shark, with its strangely shaped dorsal fin that turns back toward its head, is probably a shrimp-eater. The Caridosuctor, a type of coelacanth, is also looking for shrimp. Although shrimp and brachiopods usually inhabit the sea floor bottom, these animals at Bear Gulch live attached to algae mats floating on the surface of the water or attached to sponges and floating logs. The disk-shaped Guildayicthys maneuver quickly through the weedy areas to avoid predators. Fish have adapted to fit the differing environments of open water, near shore, and shallow weedy areas. This Mississippian fauna may have been quickly buried by a mud slide caused by one of the area’s frequent earthquakes. The Bear Gulch area contains some of the world’s most important fossil fish.

Display Case Highlights: Echinochimaera meltoni – related to modern chimaeras and ratfish. Antler-like scales and large fins were used to attract females and impress other males. Caridosuctor populosum – related to modern coelacanths. It probably had electrical sensors in its snout with which to locate food in the muddy bottom. Guildayicthys carnegiei – This ray-finned fish lived in weedy shallows. Its disk-shaped body was well adapted for maneuvering among the shallow weeds and sponge thickets.



Euloxoceras angustius – This nautilus is related to modern nautiloids with coiled shells. It preyed on small fish and invertebrates, and in turn, was a favorite food of sharks. Apholidotus – This ray-finned fish lived in burrows on the bottom of the bay. Although it resembles modern eels, the two animals are unrelated.

As visitors exit the Paleozoic Room, they enter a transition area with a display case featuring land-based life forms near the end of the Paleozoic Era.

Display Case: One Day 270 Million Years AgoThe amphibian Diploceraspis rests beside a small pond after laying her eggs. Diploceraspis shared her swampy habitat with spiders, scorpions, cockroaches, giant dragonflies, and other insects. Plants like the horsetail were common and tall, club moss trees towered overhead.

PANGEA: THE SUPERCONTINENTThe Paleozoic Era ended with a massive extinction event. About 245 mya, seafloor spreading caused all the world’s landmasses to assemble into one continent, Pangea. This supercontinent had a dramatic effect on worldwide climate, causing severe droughts in the interior, stagnation of seas, and global warming. Because climates and habitats changed faster than most species could adapt, an estimated 96 percent of marine species and 75 percent of terrestrial species became extinct. Earth’s dynamic geological forces helped shape the course of biological evolution. Surviving terrestrial animals rapidly evolved into dinosaurs, mammals, and birds.

MESOZOIC ERA: AGE OF DINOSAURS(245 to 65 Million Years Ago)

The building of the Rocky Mountains marks the geologic high point of the Mesozoic Era. At the same time the Rocky Mountains were being folded and faulted, the Cretaceous Interior Seaway flooded the interior of the continent from the Gulf of Mexico to the Arctic Ocean. This shallow seaway was home to marine animals such as the swimming reptile plesiosaur, the diving bird Hesperornis, and the coiled, shelled cephalopods called ammonites. Dinosaurs roamed between the edge of the seaway and the rising Rocky Mountains, making Montana and Alberta some of the richest areas in the world for dinosaur fossils. Dinosaurs and other animals and plants suffered another extinction event at the end of the Mesozoic Era, 65 mya.

The Museum’s major Mesozoic Era exhibit is The Siebel Dinosaur Complex which is normally a separate tour. The transition area in front of the Fossil Viewing Lab contains three displays which highlight life forms, other than dinosaurs, that lived during the Mesozoic Era. Note: The two panels are mounted on the wall bordering the Dinosaur Play Area.


Display Case: One Day 70 Million Years AgoThe Hesperornis was a huge, toothed, flightless bird that specialized in swimming and diving. Hesperornis lived along the edge of the Cretaceous Interior Seaway, feeding on fish and nesting on protected barrier islands. The 6-foot long, 110-pound bird was an excellent diver, thanks in part to its heavy dense bones. Unlike birds of today, Hesperornis had teeth.

Panel: Returning to SeaAfter living on the land, some animals, including ancestors of the plesiosaur, returned to life at sea about 240 mya. Plesiosaurs descended from the class of land reptiles that included crocodiles and dinosaurs. Some land adaptations, such as the internally fertilized egg, were still useful, but legs were replaced by paddle-like limbs. All of today’s marine reptiles and marine mammals, even whales, have ancestors which once walked the Earth. Cast of plesiosaur fossil: This plesiosaur, a carnivorous marine reptile from the Thermopolis Shale, lived 140 mya. This specimen, found near Edgar, Montana, is probably a new species of plesiosaur.

Panel: Winging ItSome dinosaurs developed the ability to fly 150 mya, leading to a lineage we now call birds. Not all birds found flight to be advantageous. Some species settled in habitats that did not require birds to fly in order to survive. Eventually, those birds evolved into flightless species.Cast of an Archaeopteryx fossil: The oldest known bird which lived 150 mya. The original fossil is in the collection of the Berlin Museum of Natural History, Germany.

CENOZOIC ERA: THE RISE OF MAMMALS(65 Million Years Ago to the Present)

About 55 mya, another burst of mountain building continued to uplift the Beartooth and Bridger Mountains and other Rocky Mountain ranges. This was also a time of tremendous volcanic activity in the Northern Rockies. Great volcanic explosions occurred, spewing lava and ash across the entire Northern Rocky Mountain region. Rocks in Hyalite Peak and other parts of the Gallatin and Absaroka Ranges were formed as a result of this volcanic activity.

Mammals were living here 30 mya. Fossils of camels, dog-sized horses, saber-toothed cats, mammoths, and mastodons have all been found within a few miles of the west flank of the Bridger Mountain Range.

Less than 10 mya, another period of mountain building raised the Bridgers and other Rocky Mountain ranges to their present-day height. Even today, these mountains continue to rise and the valleys continue to settle. About 2.5 mya, a cooling climate led to the onset of the Ice Age, during which huge ice sheets moved south from Canada and mountain glaciers flowed down valleys. From then



until the ice retreated about 20,000 years ago, ice sheets and mountain glaciers carved some of the spectacular scenery we see today in Glacier National Park and the Beartooth Mountains. However, much of Montana, including the Gallatin Valley, was not covered by ice sheets during the Ice Age.

Visitors can learn more about Montana during the Cenozoic Era in the Cenozoic exhibit on the second-floor balcony overlooking the Hall of Giants. Exhibit panels describe geological, climatic, and biological changes during the Epochs of the Cenozoic Era. Fossils found in Montana from these Epochs are also on display.

EXHIBIT TITLE PANEL: THE CENOZOIC ERA, 65 Million Years Ago to the PresentThe Cenozoic Era represents all of geologic time between the end of the Cretaceous Period (end of the Mesozoic Era) until the present, and includes the Paleogene, Neogene and Holocene Periods. These Periods are broken down into Epochs, which include the Paleocene, Eocene, Oligocene, Miocene, Pliocene, Pleistocene, and Holocene. Rocks representing each of these Epochs are found in Montana, and each has produced a variety of fossils. Research at the Museum of the Rockies primarily concerns dinosaurs, and as a result we have few Cenozoic specimens. Most of our Cenozoic collections are from the Miocene Epoch.

Throughout the Cenozoic Era the area that is now Montana underwent major climatic and topographic changes that affected the organisms that lived here. The most significant alternation was the building of mountain ranges. Thrusting of the Rockies in western Montana, and block faulting of mountain ranges east of the Rockies, gave Montana the mountain and valley topography we see today. The valleys between the mountain ranges are called Intermontane Valleys, and these valleys are where we now find most of the Cenozoic rocks that produce fossils.

Map: The World and North America during the Tertiary, 20 million years ago

PANEL: PALEOCENE EPOCH (65 – 55 million years ago)Sixty-five million years ago there was an extinction that wiped out many species of animals and plants, including the non-avian dinosaurs. For the first 15 million years after the extinction there seems to have been little change in the climate. The North American climate remained similar to what it had been during the Cretaceous Period, with subtropical “greenhouse” conditions existing as far north as Alberta, Canada. A shallow marine seaway, called the Cannonball Sea, extending down from the Arctic Ocean, covered the easternmost part of Montana and the Dakotas. Near the end of the Paleocene Epoch there was a slight cooling.

The young Rocky Mountains, which had begun rising during the Late Cretaceous, continued to uplift the North American continent, pushing the seaway off the continent. As the mountains continued to rise, valleys formed adjacent to the mountains, and these valleys, known as intermontane valleys, provided the homelands for the newly evolving mammals.


During most of the Paleocene Epoch, eastern Montana was covered by swamps, some that now produce the coal mined around Roundup or strip-mined near Colstrip. These coal units come from rocks known as the Fort Union Group.

Common fossils from the Paleocene includes many varieties of fossil leaves, turtles, crocodiles, aquatic lizards called champsosaurs, primitive mammals, and birds. Fossils: Crocodile tooth and armor plate; maple leaf; turtle shell fragment; Champsosaur vertebra

PANEL: EOCENE EPOCH (55 – 33 million years ago)Eocene Epoch rocks are uncommon in Montana, having mostly eroded away in most of eastern Montana over the past few million years. Late Eocene rocks are either buried deep underground in many of the intermontane valleys of western Montana, or sparsely outcropping around the edges of some intermontane valleys. Uplift of the Rocky Mountains stopped by the end of the Eocene, and the mountains began to erode into the valleys.

Based on studies of paleoclimate in north-central Wyoming, it is evident that through the early part of the Eocene Epoch the climate warmed back up to the subtropical levels of the Cretaceous Period. During the middle Eocene, the climate began to deteriorate, and would do so for the rest of the Cenozoic Era. The entire world was beginning to cool off.

By late Eocene time the swampy forests that had dominated the landscapes of Montana during the Paleocene and earlier Eocene, changed to dry woodlands with open grasslands. These dry woodlands and grasslands were home to the primitive ancestors of many of our common plant-eating mammals of today, including horses, camels, deer, and rhinos. Many species that are now extinct also inhabited this environment. Fossils: Titanothere (Rhino-like mammal) tooth fragment; Merycoidodon (primitive deer) jaw; Mesohippus (primitive horse) upper jaws; Hyaenodon (carnivore) partial jaw; Titanotheriomys (primitive rodent) jaw; Carnivore coprolite (fossil dung)

PANEL: OLIGOCENE EPOCH (33 – 23 million years ago)Rocks of Oligocene age are uncommon, but do outcrop around the edges of most of Montana’s intermontane valleys. The most common Oligocene age rocks were deposited during the Late Oligocene, about 24 million years ago.

Erosion of the mountains continued through the Oligocene Epoch. In most of the intermontane valleys, shallow lakes formed near their centers; and these lakes hosted a few species of fishes and insects. Fine mud settled to the bottom of the lakes preserving any of the plants and animals that died in, or were washed into



the lakes. In some of these lake sediments, we find exquisitely preserved fossil impressions of insects, leaves, and rare birds.

Paleoclimate studies conducted in the Badlands of South Dakota reveal that the continental climate continued to cool and get dryer. Much of the dry woodland areas of the late Eocene were replaced by grasslands by the end of the Oligocene Epoch. This change from forests to grasslands marks one of the most important events of the Cenozoic, as it was the time many plant-eating mammals changed their diets from browsing on leaves to grazing on grasses. The teeth of many mammals underwent major evolutionary changes to allow for grinding the highly siliceous grasses (e.g. grasses containing tiny silica fragments that made them tough to chew). Fossils: Miohippus (primitive horse) jaw; Megoreodon (sheep-like mammal) skull Pogonodon (sabre-toothed tiger) skull Insectivore jaw; bird feather; leaf; bee; fly; May fly

PANEL: MIOCENE EPOCH (23 – 5 million years ago)Throughout the Miocene Epoch the mountains of Montana continued to erode, and by the end of the Epoch the Rocky Mountains were covered to their tops.

The climate warmed slightly during the early Miocene, but then continued its cooling and drying trend. Forests continued to be replaced by grasslands and savanna. Grasslands probably dominated most of the intermontane valleys of Montana.

Miocene rocks are now found in the middle of most of the intermontane valleys and yield a variety of mammal fossils including rodents, elephants, rhinos, camels, horses, cats, and many other animals. Fossils: Teleoceras (primitive rhinoceras) jaw; Amebelodon (primitive elephant) jaws

PANEL: PLIOCENE AND PLEISTOCENE EPOCHS (5 million years ago to the present)The Pliocene and Pleistocene Epochs are marked primarily by the Ice Age when the Earth had cooled off to the point where ice built up over much of the northern half of North America and Asia. Glacial movements and melt-water rivers began to erode the sediments away from the mountains reforming the valleys that we see here in Montana. Yes, thousands of feet of Cenozoic gravel and mud still fill most of these valleys.

The continued cooling that caused the Ice Age is thought to have been responsible for most of the earlier extinctions of the mastodons, rhinos, horses, peccaries, camels, and many more. The surviving species, such as the modern horse, camel, and mammoth elephants are thought to have gone extinct within the last 10,000 years, possibly killed off by humans.

Fossils: Mastodon upper jaws Mammoth tooth in jaw fragment; mammoth tooth



LANDFORMS/LIFEFORMS EXHIBITTHEMES AND KEY CONCEPTS

Updated 09/01/2012

THEMESAll life is interconnected. Tied to following areas of exhibit:

- Microbial evolution- Tree of Life: bacteria, archea, and eukaryotes- Microbial mats (stromatolites) and their role in providing oxygen- Dioramas- Coming ashore- What does the future hold?

Life is dynamic. Tied to following areas of exhibit:- Earthworks machine- Changing look of the Earth- Mountain building- Microbial mats (stromatolites)- Microbial evolution- Dioramas- Coming ashore- What does the future hold?

KEY CONCEPTS IN SPECIFIC EXHIBIT AREAS

Time Room: Earthworks machine demonstrates various Earth cycles: Food Cycle: Sun, plants, consumers, digester, fertilizers for plants Water Cycle: Sun, evaporation, precipitation, transportation Rock Cycle: Sedimentary, igneous, metamorphic rock and how they recycle into one another Earth Cycle: Plate tectonics, erosion, rock melting and recycling

The Earth’s history is divided into two eons: Precambrian and Cambrian Precambrian Eon: Before visible “life” – 4.6bya to 540mya (Huge amount of time!) Earth forms, cools, crust forms, water forms, early life develops from the “soup” Cambrian Eon: “life” – 540mya to present. We are currently in the Cambrian Era

Cambrian Eon is divided into three eras: Paleozoic Era (old life): 540 mya to 245mya Explosion of microbial life (All the Ancestors); Era ends in mass extinction (Pangea) Mesozoic Era (middle life): 245mya to 65mya Dinosaurs (K/T Boundary – mass extinction) Cenozoic Era (new life): 65mya to present


Changing look of the Earth (exhibit globes): The Earth has been and continues to undergo major changes in appearance. Internal and external forces create changes in the Earth.

Bear Trap Canyon Fissure: 3.8bya Earth’s early crust exposed right here in Montana

Mountain Building: Montana Mountains Beartooths and Glacier Park formed during Precambrian Eon (when the rock formed; the mountains appeared at different times) Bridger Mountains formed during Paleozoic Era Yellowstone Park and the Tetons formed most recently during the Cenozoic Era

Fossil Record: Stromatolites are fossils of ancient microbial mats: breathing “rocks” polluted the atmosphere with oxygen. For 3 billion years, microbial colonies converted our atmosphere from carbon dioxide to oxygen.

Microbial Evolution: Life on Earth existed from 4bya For 3 billion years, single cell life was the only inhabitant DNA evidence determines the relationship of all living organisms Stromatolites (which are fossils) resemble modern day microbial mats Modern bacteria and archaea of Yellowstone hot springs are most genetically similar to early life Life is dynamic and adaptive (innovations) By 2bya microbial life, using photosynthesis, helped create an oxygen-rich environment; Iron banding (rusting) When oxygen was available, oxygen-breathing life (multi-cellular life) developed Predation was a new energy source Big evolution picture: Chemosynthesis to photosynthesis to predation (life eats life) 600mya an explosion of plants and animal diversity occurred Scientists study microbial life: Learn about the limits of life; Understand Earth’s past; Seek evidence for life beyond Earth. Eukaryotes are the ancestors of both plants and animals

Evolution of Fauna in North America: All the Ancestors (Burgess Shale – fossils from Canada) Once oxygen was available, life forms exploded (pikaia, the first chordate) Wild West Reef (fossils from Idaho) Rocky Mountain region: a shallow marine environment near the equator Mix and Match (fossils from Lewistown, Montana) Sharks: not that much different from modern day sharks Ray-finned fish: trout to tuna ancestor



Lobe-finned fish: crawled out of the water to breathe

Coming Ashore: Changes necessary to live on land; non-permeable egg shell

Hesperonis: The flightless bird with teeth

GLOSSARY OF MICROBIAL WORLD TERMINOLOGYThe following definitions were extracted from Seen and Unseen, Discovering the Microbes of Yellowstone by Kathy B. Sheehan, David J. Patterson, Brett Leigh Dicks and Joan M. Henson, 2005, for internal use by docents in developing interpretations of the Microbial World exhibit.

Archaea: One of the three main groups of organisms. Archaea are genetically and chemically distinct from the two other groups, the Eukarya and Bacteria. Archaea cells lack nuclei and have unique membranes.

Bacteria: One of the three main groups of organisms. Bacteria lack nuclei and are genetically and chemically distinct from the Eukarya and Archaea, the other two groups.

Biofilm: A sticky coating formed by a single bacterial species or, more often, many species of bacteria, as well as fungi, algae, protozoa, debris, and corrosion products. Biofilms can form on any moist surface.

Biomass: The total weight of material produced by living organisms.

Caldera: A large, usually circular crater created when liquid rock erupts from a volcano.

Chemosynthesis: The breakdown of simple chemical compounds within a cell for the production of energy.

Chlorophyll: An energy-capturing substance used in the process of converting sunlight to energy.

Chloroplast: A compartment inside plant and algal cells where photosynthesis takes place.

Cyanobacteria: A large group of photosynthetic and aquatic bacteria, often referred to as blue-green algae.

Domain: A term used to describe one of the major branches of the tree of life. There are three domains: the Bacteria, Archaea, and Eukarya.

Endospore: A dormant structure inside bacterial cells that is highly resistant to heat, dryness, radiation, and disinfectants.


Eukarya: One of the three main branches of the tree of life. Eukarya are distinguished from both Archaea and Bacteria because they have membrane-bound compartments (such as nuclei, chloroplasts, and mitochondria) inside the cell. Plants and animals belong to the Eukarya.

Eukaryote: The common term for a member of the Eukarya.

Fumarole: A vent or crack in the ground from which volcanic gases or steam escape into the atmosphere.

Gradient: A change in an environmental condition (such as temperature or light) with distance from the source. Temperature gradients vary widely over the Earth, sometimes increasing dramatically around volcanic areas.

Habitat: The place or environment where an organism lives.

Halophile: An organism that lives in a very salty environment.

Hyperthermophile: An organism that lives in environments above 176 degrees Fahrenheit (80 deg C).

Magma plume: A column of liquid rock rising from Earth’s interior.

Mat: A thick, layered coating (biofilm) formed by communities of microbes.

Metabolism: The chemical processes within living cells.

Methanogen: A microbe that lives without oxygen and releases methane gas as a waste product of cellular metabolism.

Microbe: A microscopic organism such as a bacterium (Bacteria and Archaea), virus, alga, fungus, and protist.

Mineralization: A geological process that produces hard crystalline materials such as limestone, sulfur, or salt or soft materials like clay. Living organisms make mineral compounds in a process called biomineralization. Microbes secrete substances such as sulfur or iron that create surfaces favorable for crystal formation. Fossil stromatolites, teeth, bones, kidney stones, seashells, and coral also are examples of biominerals.

Mitochondria: Compartments inside eukaryotic cells where much of the energy for metabolism is produced. A single one of these compartments is called a mitochondrion.

Mutation: A genetic change or alteration that can be passed on to offspring.

Photosynthesis: A process by which organisms capture sunlight and transfer the energy into chemical compounds for use by the cell.



Polymerase chain reaction (PCR): A laboratory procedure for making copies of DNA or RNA, the genetic material present in all living organisms.

Prokaryote: Single-celled microorganisms without a membrane-bound nucleus; the Archaea and Bacteria.

Protist: A single-celled eukaryotic microbe such as an alga or amoeba.

Sinter: A mineral deposit from hot springs and geysers, occurring as an incrustation around the springs and sometimes forming conical mounds or terraces.

Solfatara: A volcanic area or steam vent with high levels of sulfur.

Streamer: Wispy, hair-like strands formed by colonies of Bacteria and Archaea.

Stromatolite: A layered, vertical column or domed structure formed by cyanobacteria.

Thermal feature: A geyser, fumarole, or spring heated by underlying molten rock in a volcanic region.

Thermoacidophile: An organism that lives in hot, acidic environments.

Thermophile: An organism that lives in hot environments.

Travertine: A calcium carbonate mineral deposit.


LANDFORMS/LIFEFORMS - BACKGROUND INFORMATION

This part of the Landforms/Lifeforms section of the docent manual contains background information useful in developing interpretations of the exhibit.

- A Brief Summary of the History of Earth

- The Geologic Time Scale

- Geology and Evolution of Life in The Northern Rocky Mountain Region (Precambrian Eon; Paleozoic, Mesozoic, and Cenozoic Eras)

- Brief Description of Ancient Life Forms (The Slime Makers; Bugs and Worms; The Shell Makers; The Backboned Ones)

- Background Information on the Three Paleozoic Dioramas: All The Ancestors; Wild West Reef; Mix and Match



A BRIEF SUMMARY OF THE HISTORY OF EARTH

Precambrian Eon (4.6 billion years ago - 540 million years ago)4.6 billion Earth forms4.2 billion Oceans and primitive non-oxygen atmosphere form3.96 billion Oldest rock in North America3.5 billion Oldest known fossil; first direct evidence of life on Earth2.2 billion Oxygen atmosphere develops1.4 billion Sediments deposited in a large, shallow lake or sea in the area

of Glacier National Park600 million First multicelled organisms

Paleozoic Era (540 million years ago - 245 million years ago)530 million Primitive ancestors of most modern animals lived in oceans

worldwide.425 million The first land plants appear.375 million The earliest mountain-building event on west coast of North

America happens.370 million Corals and stromatoporoids build reefs in the tropical waters

covering the region.360 million Pangea begins to assemble.360 million The first amphibians appear.245 million All landmasses assemble into one supercontinent called

Pangea. Earth's most massive extinction occurs.

Mesozoic Era (245 million years ago - 65 million years ago) 208 million Land accreting on west coast of North America.150-110 m. The Rocky Mountains begin to form along the west coast

of North America. To the east, rising sea levels create the Cretaceous Interior Seaway.

110-50 m. Mountain-building activity continues in the Northern Rockies.

65 million Dinosaurs die out in yet another major extinction.

Cenozoic Era (65 million years ago - Present)55 million Mammals diversify after dinosaurs die off.15 million Prairie grasses evolve.

Migration of the North American plate over a fixed "hot spot" creates volcanic activity from western Idaho to

Yellowstone.The Northern Rockies are uplifted along a fault as the crust

extends. 5 million Wyoming’s Teton Range, like many other ranges in the Northern Rockies is uplifted along a fault.

2.5 million Glaciation begins in the Northern Rocky Mountains.



GEOLOGY AND EVOLUTION OF LIFEIN THE NORTHERN ROCKY MOUNTAIN REGION

The landscapes of the Northern Rocky Mountain Region are exciting. Evidence of every geologic process on Earth can be read in these landscapes. Not in many other places on Earth can you see some of the Earth's oldest rocks, oldest fossil communities, and the bottom of an ancient ocean, not to mention volcanic calderas, glaciers, and newly formed mountains. Landscapes are exciting, but the interaction with evolving life is really a story. Have you considered that the landscape determines which life form will occupy it?

Why do we study geology and the earth sciences? Why do we recreate outside? Why do millions of people visit National Parks? The purpose of studying geology isn't to identify rocks, but to observe, experience, and interpret how a landscape came to be. It is the experience of understanding that is fulfilling, connecting. The land itself will reveal a story--a story as old as the planet with more action and adventure than any story from the Silver Screen--a story about home, about every living creature, about you. We need the landscape to deeply connect with ourselves.

Interpreting a landscape is not difficult. All natural features of a landscape are the result of processes operating through geologic time. Any landscape you observe and experience can be interpreted with a basic understanding of a few geologic processes and their products, keeping in mind the immensity of geologic time.

GEOLOGIC PROCESSES

Weathering process by which Earth materials are changed in response to atmospheric conditions

Erosion action of water, ice and wind to break rocks into smaller pieces

Transportation movement of sediments by water, ice, wind, or gravity

Deposition accumulation of sediments or rocks

Lithification compaction and cementation of sediments into rocks

Metamorphism action of heat and pressure to chemically change rocks into a new rock with different minerals and textures from the original rock

Melting solid rock becoming molten


Volcanism processes associated with eruption or intrusion of volcanic rocks

Precipitation reactions between dissolved molecules in water that results in deposition of a sediment

Landscape FeaturesGeologic processes produce landscape features such as: mountains, plateaus, mesas, buttes, canyons, gullies, arroyos, chasms, ravines, flats, plains, hills, tropical islands, beaches, coastlines, geysers, hot springs, fumaroles, bubbling mud, glacial lakes, mud flows, avalanches, etc. A set of features defines a landscape. Landscapes evolve through time. Mountains become plains and plains become canyons. A coastline becomes an arid dune field.

Rock CycleThe rock cycle is a graphic demonstration of the interaction between geologic processes and the landscape features, or products of those processes. The rock cycle contains the major geologic processes and all of the rock types. Any rock type can become any other rock type. For example, a sedimentary rock can melt to form an igneous rock, metamorphose into a metamorphic rock or erode and be deposited as another sedimentary rock. An understanding of the rock cycle will take you far in landscape interpretation.

THE LAWS: There are a few scientific laws to remember when interpreting landscapes.

Law of Uniformity: The present is the key to the past. This means geologic processes happening today also happened in the past. Processes occurring today such as erosion and deposition also happened in the past. Also, processes happening in the past are still occurring today, although the rates of processes may have changed. For example, the Earth underwent a period of intense bombardment by meteorites 4.6-3.8 billion years ago. The Earth is still bombarded by meteorites, although not as frequently as in the past.

Law of Conservation of Energy: The energy of the universe is constant. Energy can neither be created nor destroyed, although it can change form. For example, the energy of falling water erodes a rock at the base of the waterfall. The water is losing energy, but the rock is gaining energy. The energy is not lost, but transferred from the falling water to the rock. A corollary to the Law of Conservation of Energy is Gravity Works. In other words, water flows downhill, and so do rocks and sediments. In more technical terms, a system always tends toward lower potential energy, i.e. water flows downhill.

Law of Conservation of Matter: Matter is neither created nor destroyed. Everything is recycled. Every drop of water, every river rock, every speck of volcanic ash is recycled through the rock cycle or the hydrologic cycle. For example, a boulder in a river is eroded by the action of running water. Some



parts of the rock are dissolved, and some parts are broken into pieces of sand. The dissolved molecules are carried into an ocean where they precipitate as mud. The calcareous mud becomes compacted and lithified into a limestone. The ocean bottom is uplifted into a hill, and then a mountain. The river boulder is now part of a limestone cliff exposed in the Bridger Mountains. It hasn't disappeared, only changed form.

GEOLOGIC TIME

The Earth is 4.6 billion years old. Radiometric age dating is a process of determining when a specific rock or mineral was formed. Certain radioactive elements like uranium decay at a constant rate through time. Uranium decays to lead. By measuring the ratio of uranium to lead in a mineral or rock, the age of the rock can be determined. Another way of age dating rocks is to calculate the age of volcanic layers within a sedimentary fossil-bearing rock. The age of the fossils is then known to be between the ages of the two bounding volcanic layers. Rocks found in other parts of the world with the same fossil assemblage can then be assigned an absolute age. The geologic time scale uses both radiometric ages and biochrono- stratigraphic (fossil evidence) ages of rocks to delineate time.

Life forms evolve through time. We know this from the fossil record. Landscapes also evolve through time. We know this from the rock record. For example, at different points in time we know that Gallatin Valley was at the edge of one of the oldest continents, on a tropical ocean bottom, uplifted into mountains, covered by a shallow, muddy sea, and obscured by volcanic ash.

During the early Precambrian, Earth was a lava ocean. Meteorites were bombarding and cratering the newly forming thin crust. Tons of dust choked the atmosphere which was composed mostly of carbon dioxide (CO2). The sky, when it periodically cleared of dust, probably glowed pink or red and the temperature was very hot, certainly hot enough to boil water (212 degrees Fahrenheit), and probably much hotter. There was no free oxygen and no free water. Water vapor belched out of volcanoes, condensed and fell upon the cooling Earth as rain. The crust solidified and bodies of water formed. Life began in a soup of organic chemicals. Meteoroid bombardment periodically evaporated the oceans, repeatedly obliterating newly evolving life forms. Eventually, the meteoroid impacts decreased, the oceans stabilized, and the stage was set for the proliferation of life forms.

The following pages cover the development and changes in the Northern Rocky Mountain Region landforms and lifeforms during the Precambrian Eon and the Paleozoic, Mesozoic and Cenozoic Eras.

PRECAMBRIAN EON4.6 billion years ago - 540 million years ago

PRECAMBRIAN LANDFORMSLandforms/Lifeforms •

The BasementRocks comprising the Gallatin and Madison Ranges are among the oldest in the Northern Rocky Mountains at 3.3-2.7 billion years. These black and white banded metamorphic rocks are called gneiss (coarse-grained, banded rocks that formed during high-grade regional metamorphism) and can easily be viewed in Gallatin Canyon or Beartrap Canyon. Older gneiss crops out to the southwest in the Beartooth Mountains. These rocks are about 3.8 billion years old and represent the original continental crust. All of these Precambrian rocks originally formed on the continental shelf of the early North American continent and were subsequently buried and metamorphosed about 15 miles below the surface.

The Belt BasinThe oldest preserved sedimentary rocks in the region are lake sediments called the Belt Supergroup, or Belt rocks. These bright red, green, yellow, gray and purple rocks are visible in Wolf Creek Canyon north of Helena all the way to southern British Columbia and west to eastern Washington. The most famous Belt rocks are those comprising the peaks of Glacier National Park.

Most Belt rocks are alternating layers of mudstone, sandstone, and limestone deposited in a shallow lake that extended from LaHood, Montana, north through Manhattan, Logan, Helena, Glacier National Park, and British Columbia, and west to eastern Washington and northern Idaho. These rocks were deposited from about 1.4 billion years ago to about 1.2 billion years ago, when the lake dried up.

Earlier interpretations have suggested that the Belt basin was a shallow sea, but no evidence of marine structures has ever been found. There are no tidal channels, no tidal flats, and no evidence of marine currents, all of which we should expect to find in marine rocks. Instead, very detailed studies of the sedimentary structures in the rocks seems to indicate that they were deposited in a shallow playa lake. Studies of modern playa lakes show similar styles of deposition. [A playa is the lowest part of an intermontane basin which is frequently flooded by run-off from the adjacent highlands, or by local rainfall. Sediments consist largely of colloids, clays and evaporates (e.g. gypsum). The surface is generally flat, with mud flats and locally small dunes.]

About 1 billion years ago, this early continental crust was uplifted along a fault near LaHood, Montana, which marked the south shore of the ancient Belt lake. The Belt rocks in this vicinity are very different from other Belt rocks. Large clasts are incorporated into the rock. A clast is a particle of broken-down rock. These fragments may vary in size from boulders to "silt-sized" grains, and are invariably the products of erosion followed by deposition in a new setting. Rounded gray-and-white banded boulders from the uplifted crust can be seen incorporated into black sedimentary rocks along the Jefferson River at LaHood.

About 600 million years ago the Belt lake was flooded from the west by the sea. Over 3500 feet of marine sediments were deposited in what is now Gallatin Valley. These sedimentary rocks crop out near Three Forks, Logan, and Manhattan, and form the peaks of the Bridger Range.



Bridger MountainsThe Bridger Mountains dominate the Bozeman landscape. Trending north-south for over 27 miles and flanked on either side by large valleys, the Bridgers are a typical Northern Rocky Mountain range.

Remnants of early continental crust--banded gray-and-white metamorphic rock known as gneiss--can be found at the base of the Bridgers in Cottonwood and Sypes canyons. These rocks are metamorphosed sediments which were deposited about 3.8 billion years ago on the edge of the early continent. Gneiss can also be seen in Gallatin and Beartrap canyons.

PRECAMBRIAN LIFEFORMS

String of beadsString of beads are fossil algae and are found in 1.4 billion year old rocks in Glacier National Park. String of beads are the oldest macroscopic fossils in North America, but are not the oldest fossils in North America. The oldest fossils in North America are microscopic algae found in rocks of the Canadian shield (northern Minnesota and southern Ontario). String of beads are on exhibit in the Precambrian Room.

StromatolitesFossil stromatolites 3.5 billion years old are found in Australia. Glacier National Park has fossil stromatolites that are more than 700 million years old. Stromatolites are organo-sedimentary structures. This means the stromatolite is composed of both organic tissues and limestone, a type of sedimentary rock. Cyanobacteria comprise the organic part of the stromatolite. Cyanobacteria photosynthesize the Sun's energy and the surrounding sea water to create their life energy. As the colony grows, it secretes slime. Passing silt and calcium carbonate precipitating out of the sea water attach to the slime, giving the stromatolite its layered appearance.

Microbes in the second layer can also photosynthesize, however, if conditions prevent them from obtaining light, they switch into manufacturing their food without sunlight in an anaerobic process. The cyanobacteria generated oxygen as a waste product which, as it gradually accumulated in the atmosphere, changed the course of evolution for all subsequent life. Because life first evolved in an oxygen-free environment, oxygen was a poison to those life forms and they either died off as a viable life form or found ways to exist in the newly created environment (including hiding in places that were oxygen free, such as the bottom of the ocean near hot vents and inside of animals). Stromatolites are on exhibit in the Precambrian Room.

Ediacara FaunaEventually, simple microbes evolved into simple animals. These simple animals are called the Ediacara fauna, after the Ediacara Hills in Australia where their fossils were first found. These animals are very thin, jellyfish-like forms. Simple quilted bodies absorbed nutrients directly from sea water as the animals floated in the water column. Some of them may have been attached to the sea floor.


They probably did not swim, breathe, or eat, in the way we usually associate with animals. The Ediacara fauna are about 600 million years old.

PALEOZOIC ERA540 - 245 million years ago

PALEOZOIC LANDFORMS

During the Paleozoic, the seas came and went across the land, depositing different types of sedimentary rocks. In the Northern Rocky Mountains, virtually all of the rocks of Paleozoic age are marine sedimentary sandstone, shale and limestone. These rocks crop out in the Bridger Range, in the Horseshoe Hills, and in Rocky Canyon.

PALEOZOIC LIFEFORMS

Burgess Shale FaunaThe next major fauna in the fossil record is found in the Burgess Shale. The fauna is composed mostly of arthropods. All but one group (phylum) of animals alive today evolved from ancestors represented in the Burgess Shale. For example, Pikaia is ancestral to all vertebrates, Aysheaia is ancestral to all insects, Sanctacaris is ancestral to all spiders and scorpions, Canadaspis is ancestral to all crustaceans (crabs, lobsters), and Burgessochaeta is ancestral to earthworms. The only group not represented in the Burgess Shale is the Phylum Bryozoa, marine animals much like corals.

Evolution and Adaptation for Living on Land Early amphibians evolved from a group of fish about 360 million years ago, during the Devonian period. Amphibians had developed lungs and legs that allowed them to utilize the land.

LungsThe evolution of lungs from the stomach of a group of fishes in the Devonian period is fairly simple. We understand this change by studying the anatomy of fossil fish and living examples of their close relatives, the lungfish.

The swim bladder regulates a fish's vertical position in the water column, and is an outpocket of the stomach. Like the stomach, the swim bladder is composed of blood-rich tissue efficient in gas exchange. Early fish could gulp air which went into the swim bladder through a connecting tube. The oxygen was then absorbed by blood flowing through the swim bladder tissue. The ability to obtain oxygen from the swim bladder was an advantage for fish living in oxygen-poor environments. When a swim bladder is used to obtain oxygen, we call it a lung. Our lungs are simply sacs with blood-rich tissue that is efficient in the exchange of gases.



LegsThe fish Eusthenopteron may be a close ancestor of amphibians. This fish had bones in its fins that are the same bones found in other vertebrates. In fact, the same bones that you have in your arm: the radius, ulna and humerus, as well as some of the wrist bones. These bony fins allowed Eusthenopteron to drag itself from one pond to another. This behavior occurs today. Fishes in Borneo have been observed leaving their crowded ponds at night and dragging themselves over wet leaves in search of less crowded conditions.

Eventually, the fish pectoral girdle (in vertebrates, the skeletal structure that provides support for the fore limbs or fins) and pelvic girdle (in vertebrates, the skeletal structure that provides support for the hind limbs or fins) became fused to the backbone, providing strength and stability for proper walking. With lungs and legs the fish is now an amphibian.

Amphibians have moist, breathable skin. Their eggs are laid in water where the young hatchlings go through a tadpole or larval stage before becoming adults. Amphibians of the past, like amphibians today, could not live far from water. In order to truly exploit the land, animals had to adapt to drier conditions. The adaptation that made this possible was the amniotic, or closed egg.

Amniotic EggsThe amniotic egg is one of the greatest adaptations that land animals have achieved. It evolved about 320 million years ago. Unlike amphibian eggs, amniotic eggs have a hard or leathery shell that protects the egg from drying out. Amniotic eggs are laid in nests on land and the hatchlings do not go through a larval stage, but emerge as miniature versions of the adults. Also unlike amphibians, amniotic eggs are fertilized internally, increasing the breeding success rate.

MESOZOIC ERA245- 65 million years ago

MESOZOIC LANDFORMS

Mountain BuildingThe Mesozoic Era can be thought of as the Age of Mountain Building. The Rocky Mountains were formed by four major geologic processes which occurred primarily in Mesozoic and Cenozoic times. These processes are accretion, folding and thrusting, magmatism and normal faulting. All of the processes are the result of plate tectonics.

AccretionSmall microcontinents and island arcs collided with North America at present day western Idaho beginning about 150 million years ago. These small landmasses are called accreted terranes because they were accreted or attached to the edge


of the continent. You can see accreted terranes at Riggins, Idaho and the Blue and Wallowa Mountains of eastern Oregon.

Folding and ThrustingStresses from continental collision are transported through the rock layers, accumulating until a fault breaks the rock or the rock deforms into folds. Low angle thrust faults accommodate the stress by shoving slabs of rock up and over other slabs. Friction in the overriding plate is thought to be reduced by fluid pressure in the pores of the rocks, and by the differential heat within the rocks, much like a car tire hydroplanes when a thin layer of water reduces the friction between the tire and the road. Because of this thrust faulting one can find older rocks on top of younger ones. The Lewis thrust fault in Glacier National Park is an excellent example. This fault is visible right above the tree-line in the photomural in the exhibit. The more ductile rocks like limestone accommodate stress by deforming into folds. You can see folded rocks in the Bridger Range.

MagmatismAs continental collision progresses, deeper rocks are melted. The molten magma rises upward, and may bulge and deform the overlying rock. The Boulder batholith now exposed by 75 million years of erosion and over 130 years of mining is one such magma body, long cooled into solid rock. You can see the Boulder batholith from Interstate 90 near Butte. Another example is the Idaho batholith, the gray and white granite-like rock that crops out throughout central Idaho

Bridger MountainsContinental collisions off the west coast of North America about 150 million years ago transmitted tremendous stress to rocks in the Gallatin Valley. The rocks began to fold in response to this stress --- the beginning of the rise of the Bridgers. With continued stress, the rocks broke along large thrust faults which transported older Paleozoic and Mesozoic age rocks over the top of younger rocks. This episode of folding and faulting occurred throughout the Northern Rocky Mountains and into western Canada. These thrust faults are now exposed at the surface in the Bridger Range and near Three Forks, in the Horseshoe Hills. Folded rocks are visible throughout the Bridgers, especially at Fairy Lake.

Cretaceous Interior Seaway At the same time the Rocky Mountains were being folded and faulted, the Cretaceous Interior Seaway flooded the interior of the continent from the Gulf of Mexico to the Arctic Ocean. Rivers and streams were carrying sediment into the Seaway which covered central and eastern Montana. Do not confuse the Cretaceous Interior Seaway with the Paleozoic seas. The Cretaceous Interior Seaway covered the interior of the continent, advancing into Montana from the east, while the Paleozoic seas covered the western margin of the continent and advanced into Montana from the west. Also, these two seas are separated by hundreds of millions of years.



Mesozoic age sediments include marine sedimentary rocks of the Interior Cretaceous Seaway and terrestrial sedimentary rocks deposited by rivers and streams.

MESOZOIC LIFEFORMS

After the Permian extinction that wiped out most of the amphibians, the new amniotes rapidly radiated into these vacant niches, eventually diversifying into turtles, snakes, lizards, crocodiles, dinosaurs, birds and mammals. Mammals are also amniotes because their eggs have the amniote structure, they are carried inside the body until they "hatch" and are expelled during live birth, and the "hatchlings" are not larvae, but miniature versions of the adult.

Returning to the SeaAfter dominating the land for millions of years, some of the reptiles and later some mammals and birds, returned to a marine lifestyle. One such reptile is the Plesiosaur who returned to life at sea about 240 million years ago. Plesiosaurs retained the amniotic egg, although it is uncertain if they laid the eggs or bore live young, since no Plesiosaur eggs have been found. Other adaptations for marine life included limbs modifying into paddles, which enabled Plesiosaurs to be fast and efficient predators.

Winging ItEventually a group of dinosaurs developed feathers and wings, and learned to fly. We call them birds. Wings evolved from modified front limbs. Other adaptations included lighter bones. Eventually some birds returned to a marine lifestyle. Hesperornis was a large ocean-going bird. Its wings had modified into tiny useless nubs. It had powerful hind limbs for swimming and diving. Unlike other birds, it had heavy dense bones and teeth.

The Cretaceous Interior Seaway was home to marine animals such as the reptile Plesiosaurus, the diving bird Hesperornis, and all sizes and shapes of the coiled shelled cephalopods called ammonites. Dinosaurs roamed between the edge of the seaway and the rising Rocky Mountains. A nesting ground of the duck-billed dinosaur Maiasaura was uncovered near Choteau, Montana.

CENOZOIC ERA65 million years ago - Present

The geologic and fossil record provides us with an understanding of how changes in environments and prehistoric life over the last 65 million years created the present-day Rocky Mountain region. Through time, the Rocky Mountain region evolved from a place dominated first by forests filled with early mammals to grasslands filled with plant-eating and predatory animals. By three million years ago the region was part of the Ice Age world. Environmental changes and extinctions around 10,000 years ago left essentially the modern-day ecological communities of the Rockies. This background of changing life and landforms throughout the Cenozoic was greatly influenced by the processes of mountain


building as expressed in volcanic activity and earth movements, finally contributing to the Rocky Mountain region environments of today.

The Early and Middle CenozoicThe evolution of the present-day world of the Rockies began with the major extinction event that eliminated the dinosaurs. This extinction marks the beginning of the Cenozoic around 65 million years ago. Small, early forms of mammals inherited the environments abandoned by the dinosaurs. In Montana, the early part of the Cenozoic is marked by the presence of petrified forests in the Yellowstone area. These forests were preserved because they were buried by mudflows caused by local volcanoes, much like the eruption of Mt. St. Helens in 1980.

Continued mountain building throughout the early part of the Cenozoic helped to create an open grassland for the first time in the Rocky Mountain region. This early Cenozoic mountain building was the result of local volcanism and compressional types of faulting. During the Cenozoic, the response by prehistoric life to the newly formed valleys and plains and the rain shadow effect of the rising mountains was a change from the earlier forests to open grasslands. Animals adapted to this environmental change. The smaller mammals of the early part of the Cenozoic were replaced by plant eating animals with high crowned teeth and long legs and hooves. A second group of meat-eating animals evolved to prey on the plant-eating animals. The creation of this open grassland habitat provided the early basis for the present-day plant and animal communities.

Throughout the Cenozoic, mountain building processes played an important role in changing the environment of the Rockies. Volcanism buried the early Cenozoic forests. Isolated, "island mountains" of central Montana were created by igneous activity around 50 million years ago. By 18 million years ago faulting and earthquake activity associated with western continental hot spot had begun to help create the mountains and valley environments of today. The youngest of the mountain building events led to the formation of the Teton and Centennial Mountain ranges starting about 8 million years ago. Starting around 2 million years ago, three gigantic explosions formed the basic landscape of the Yellowstone region.

Late Cenozoic: The Great Ice AgeAlong with the continuing rise of the Rockies, the last 3 million years of Earth's history has seen the dynamic interaction between prehistoric life and the changing physical environments of the Ice Age. The Ice Age in the northern Rocky Mountain region is expressed in the eroded mountains of Glacier National Park and the Yellowstone region. Both mountain glaciers and huge ice sheets from Canada changed the landscape of Montana. Large glacial lakes were present along the western edge of the continental divide and also in eastern Montana along the present-day Missouri River valley. In the west, the melting glaciers caused a series of huge catastrophic outburst floods from Glacial Lake Missoula. In the east, the landscapes created by the ice margins and glacial lakes created a setting for Ice Age prehistoric life.



Fossils from caves and other settings provide a picture of the prehistoric life of the Ice Age world. In the valleys created by the uplifting of the mountains, mammoths, Ice Age horse, and camel lived in habitats shared with predators like saber-tooth cats. In caves, fossils show the presence of animals including horse, muskox, and Ice Age bear until 10,000 years ago. Around 10,000 years ago, the latest change in landforms and life occurred with the melting of the glaciers at the same time as the last major extinction event.

With the disappearance of the Ice Age world and the mammoths and other prehistoric animals that inhabited it, the essentially modern-character of the Rocky Mountain region had been formed.


BRIEF DESCRIPTION OF ANCIENT LIFE FORMS

THE SLIME MAKERS

Bacteria: Bacteria are the oldest lifeforms, dating back to 3.5 billion years ago. They may have first evolved in hot springs or deep ocean vents, but today they exist virtually everywhere, controlling most of the major chemical cycles on Earth.

Algae: Algae are the forerunners of plants. Algae evolved from the partnership of cyanobacteria and protozoa, both types of microbes. Chloroplasts within the algae cell manufacture food from the sun's energy. These chloroplasts were once free-living cells of cyanobacteria, now incorporated into the living algae cell.

Stromatolites: Stromatolites are colonies composed of layers of sediment and cyanobacteria. The outermost layers of cyanobacteria manufacture food for the colony by using the sun's energy and carbon dioxide in the water. Cyanobacteria in underlying layers can also photosynthesize food if there is enough light, but during periods of low light, they switch their metabolic machinery. This adaptive flexibility may have been these organisms' key to almost 4 billion years of success.

BUGS AND WORMS

Trilobites: Trilobites are a group of extinct marine arthropods that lived from 530 to 245 million years ago. Ranging in size from less than 1/4 inch to over 3 feet in length, these animals were among the first to develop hard external skeletons. Most trilobites had good vision with well-developed eyes sporting multiple lenses of the mineral calcite.

Spiders and Scorpions: Sanctacaris, nicknamed "Santa Claws" is the ancestor of the group of arthropods that includes spiders and scorpions. Unlike modern spiders and scorpions, Sanctacaris lived entirely in marine water. Fossils of Sanctacaris have been found in the 530 million year old Burgess shale of Yoho National Park, British Columbia, Canada.

Crabs and Lobsters: Canadaspis is the ancestor of the group of arthropods that includes crabs and lobsters. Like its modern descendants, Canadaspis lived in marine water. Its fossils are now found in the Burgess shale.

Worms: Ottoia is an extinct carnivorous worm that lived about 530 million years ago and is now fossilized in the Burgess shale. Like other worms of this kind, Ottoia was short and fat and spent most of its time in a burrow from which it could snake out its proboscis, or nose, and catch unsuspecting prey. Like Ottoia, modern short and fat (priapulid) worms still live in the oceans.



Segmented Worms: Burgessochaeta was a segmented bristle worm. A relative of modern earthworms, Burgessochaeta lived in burrows on the ocean bottom and used its tentacles to extract food from the mud.

Velvet Worms: Aysheaia was a marine worm and a relative of insects. Aysheaia lived in the ocean and fed on sponges 530 million years ago, unlike modern velvet worms which live under leaf litter in the Costa Rican rain forest. Modern velvet worms give live birth, but we don't know how Aysheaia gave birth.

Opabinia: With its five eyes and a spine-tipped proboscis, Opabinia seems unrelated to any modern animal. Opabinia was a swimmer and may have used the proboscis to reach into worm burrows for prey.

Anomalocaris: Anomalocaris was the largest predator of its day reaching up to 3 feet in length. Large grasping claws fed hard-bodied trilobites into a pineapple ring-shaped mouth where the ring would close upon the prey, crushing its shell. Fossil trilobites with healed wounds inflicted by Anomalocaris have been found. Anomalocaris is now extinct and seems to be unrelated to any living animal. Its fossils have been found in N. America, China, Greenland, and Australia.

Wiwaxia: Wiwaxia was protected by an armor of sclerites, tough scales made of chitin. Two rows of long spines along its back also served as protection from hungry predators. Although Wiwaxia resembles a slug, no slug, extinct or living, has ever had spines. Some scientists think Wiwaxia may be related to worms, others think it is unrelated to any group of animals alive today.

THE SHELL MAKERS

Brachiopods: Brachiopods are a type of shelled marine animal that flourished during the Paleozoic Era and still lives today. Brachiopod fossils are common in the Northern Rocky Mountains in a rock type called limestone from the Mississippian Period about 330 million years ago. Although they resemble clams, brachiopods and clams are not related.

Snails: There are about 67,000 species of snails and their cousins the slugs. Snails have adapted to live in the ocean, in fresh water and on land. Snails are the world's great waste recyclers. They feed upon almost everything, including algae that grows on reefs, and on the waste products of other animals, including crinoids. Clams: Clams and other ancient and living bivalves have played an important role in water purification. Clams pump water into their mantle, the outer part of their body next to the shell, and filter out organic particles, excreting the clean water.

Shelled Predators: Cephalopods are a group of hunting and scavenging mollusks that thrived during the Paleozoic and Mesozoic Eras and are still alive today as squid, octopi, and the chambered nautilus. Cephalopods have well


developed nervous systems with generally good eyesight, and are the most highly intelligent of the invertebrates (animals without backbones).

THE BACKBONED ONES

Grandmother Pikaia : Pikaia is the ancestor of vertebrates, animals with a backbone. Fossils show evidence of striated muscles running along the back and a primitive notochord, precursor to the vertebrate spinal column.

Armored Knights: Some early fish called placoderms were covered with hard plates rather than scales. These lunking fish could grow up to 30 feet in length and cruised the seas 400 million years ago in search of fish and other prey.

Lobe-fins: Lobe-fins are a group of fish that include lungfish and coelacanths, once thought extinct. They are named for their fleshy fins that evolved into the arms and legs of all other animals.

Ray-fins: Ray-finned fish are perhaps the most common fish. Named for the delicate webbing of their fins, ray-fins plied Montana seas 320 million years ago, and today you can still catch one in just about any lake or river.

Sharks and their Kin: Unlike other fish, sharks and their relatives have cartilage skeletons instead of bones. Ancient male sharks of the Bear Gulch bay used head appendages made of dentine, bone and cartilage to attract females and impress other males.

Amphibians: Amphibians evolved from a group of lobe-finned fishes about 360 million years ago. Adaptations for land included lungs and sturdy legs, both present in the fish, but modified and strengthened in the amphibians.

Amniotes: Amniotes are a group of animals that all have an amniotic or closed egg with a tough shell that resists drying. The amniotic egg was laid on the land and allowed amniotes to move away from wet habitats to fully colonize the land.

Dinosaurs: Hundreds of thousands of dinosaurs lived in the Northern Rocky Mountain region during the Mesozoic Era, making this region one of the richest in the world for dinosaur fossils.

Mammals: Mammals are a group of animals that, together with lizards, snakes, turtles, crocodiles, dinosaurs and birds evolved from a common lizard-like ancestor. During the reign of the dinosaurs, mammals lived furtive lives in underground burrows, using vegetation and the cover of night to avoid the fierce dinosaur predators. After the dinosaurs became extinct, mammals rapidly evolved into new forms and came to dominate the land.

Birds: Birds are descended from dinosaurs. The oldest fossil bird, Archaeopteryx, 150 million years old, lived during the dinosaur reign. Archaeopteryx fossils were misidentified as dinosaur fossils until a sharp-eyed scientist noticed feather imprints in the stone around the skeleton.



Lizards and other Reptiles: Lizards are the oldest amniotes, predating dinosaurs, crocodiles, snakes, turtles, mammals and birds. Early lizards were similar in shape and habits to modern lizards. Snakes, turtles and crocodiles evolved from an early amniote ancestor during the Mesozoic Era.

BACKGROUND INFORMATION ON THE THREE PALEOZOIC DIORAMAS

ALL THE ANCESTORS (Cambrian Period Diorama, 530 Million Years Ago)

Life in waters of the Burgess Shale is depicted in this diorama. This fossil site is located on the side of Mount Wapta, high in the Canadian Rockies, Yoho National Park, British Columbia. The animals were buried in a mudslide that swept them off a high reef into oxygen-poor water where they quickly died and were buried. Animals of the Burgess Shale have been found in China and other locations around the world, suggesting that these animals were widespread during early Paleozoic time. A strange thing about the Burgess Shale is how complex the life forms are at 530 million years compared with the simplicity of life forms only 70 million years earlier. This is a powerful demonstration that evolution can occur very quickly.

In the diorama, Anomalocaris is the center figure and is seen chasing Pikaia. This is a dramatic scene. Anomalocaris was the largest animal of its day and a predator. Note the mouth shaped like a pineapple ring--jaws had not yet evolved. Anomalocaris, like many of the arthropods, including trilobites, had gills on its legs through which it obtained oxygen. These combination gills/legs are called biramous appendages.

Pikaia is known only from about a dozen specimens, but in these specimens symmetrical back muscles can be seen. A notochord, or stiffening rod, extends down the center, dividing the animal into two symmetrical pieces. This arrangement of muscles and stiffening rod is present in all vertebrates. The primitive notochord evolved into the spinal column with which we are more familiar. Pikaia and its cousins (some of which are showing up in a Chinese site) are our direct ancestors. If delicate Pikaia had not survived extinction and lived to reproduce, we very well might not be here. So for us, it’s very lucky that Anomalocaris did not eat all of the Pikaia.

Ottoia is a carnivorous worm which lived in U-shaped burrows. It waited for other animals to come within reach, then would snake out its proboscis, snapping up the unfortunate prey and swallowing it whole. Hyoliths (conical shelled creatures of uncertain affinity) have been found inside the gut of Ottoia fossils. The jellyfish-like organisms in the upper left of the diorama are Eldonia. They absorbed food directly from the water, much like animals of the Ediacara fauna.


The Burgess Shale fauna represents an "explosion" in the diversity of life forms. If you look closely at these animals you will see a great diversity in body shape. Some are thin, delicate jellyfish-like forms. Others, like the arthropods have many biramous appendages and grasping claws near the mouth. Some animals have spines; some do not. Some, like the worms are elongated, others are more compact. Many have two eyes; Opabinia has five. Some are small; others large. Why do these animals appear so suddenly in the fossil record, and why are they so diverse in body shape and function? The answer to this question is thought to lie in part in the changing ocean chemistry of the early Paleozoic Era.

Prior to the early Paleozoic, life forms were small and simple. They did not hunt or engage in other complex behavior; in fact they didn't even self-propel. Geochemical evidence shows a marked increase in the amount of oxygen dissolved in sea water at about 540 million years ago. It's thought that the Burgess explosion in diversity was due to animals successfully adapting to the increase in oxygen. By using more oxygen, animals may have been able to evolve larger forms, and more complex behavior, like predation.

Remember also, at the start of the early Paleozoic, the ecospace was wide open. No one occupied the ocean's ecological niches, so the Burgess animals had a wide open frontier in which to live. Competition may have been very low so many strange mutants could survive and reproduce. Eventually, the ecospace filled up, competition increased, and unusual body designs were no longer viable. Chance also played a role. No one knows for example why Pikaia survived and Anomalocaris did not. Pikaia does not appear to be any better adapted.



Cambrian Period Diorama

All the AncestorsOne day 530 million years ago the primitive ancestors of nearly all modern animals lived in Earth's waters.Present site: Burgess Shale fossil quarry, Yoho National Park, British Columbia, Canada



ALL THE ANCESTORS CRITTER CARD LIFEFORMS INFORMATION

Anomalocaris was among the largest and first predators known in the Cambrian Period. Its body was designed for hunting with a segmented body, a jaw-like ring around the mouth and gills on its legs.

Aysheaia lived during the Cambrian Period and is thought to be the ancestor of insects because of its similarities to modern insects. It often lived and fed on sponges.

Canadaspis is the ancestor of crustaceans such as crabs and lobsters. It lived during the Cambrian Period and may have used its limbs to stir up the sediment in search of small animals and organic particles upon which to feed.

Eldonia was a member of the same family as sea cucumbers and looked much like a flying saucer or jellyfish floating in the water.

Hallucigenia lived 530 million years ago. It walked on the sea floor and had spines on its back for protection. It had seven pairs of legs.

Opabinia used its long nose to reach into burrows to grab worms and other prey. It had five eyes and a body that was divided into segments.

Ottoia was a type of carnivorous worm that lived in u-shaped burrows in the Cambrian Period. It burrowed in the ground, waiting for unsuspecting prey to come by. It would then snake out its long and flexible proboscis, or nose, to capture its favorite food. Fossils show some Ottoia parts found in the guts of other Ottoia, suggesting this was one of the first cannibalistic animals.

Pikaia was the ancestor of all vertebrates. A notochord, or stiffening rod, extends down the center of the body with muscles attached. The primitive notochord evolved into the spinal chord and backbone. Say hello to one of your earliest relatives.

Sanctacaris was the ancestor of spiders and scorpions. It was a predator that lived on and just above the ocean floor. Its first five pairs of spiny covered head appendages helped it capture prey.

Vauxia lived in the Cambrian Period and was the most common sponge in the Burgess Shale.

Wiwaxia used its many large, stiff spines to protect it from hungry predators. Wiwaxia roamed the Cambrian sea floor searching for food. The classification of Wiwaxia is still hotly debated by scientists.WILD WEST REEFDevonian Period Diorama (370 Million Years Ago)

This diorama depicts a tropical reef similar to those existing in Gallatin Valley at this time. A reef is a structure built by organisms with their bodies and secretions. The primary reef builders then are animals called stromatoporoids.


Modern reef builders are mostly corals. Stromatoporoids are tiny animals that lived in tubes composed of calcium carbonate. The hard tube serves as an exoskeleton. Stromatoporoids and other reef-builders such as corals are colonial animals, which means they only live in colonies. Ants are a modern example of colonial animals.

In this diorama, the primitive placoderm fish Dunkleosteous is chasing a group of orthocone cephalopods. Cephalopods are "squid in a cone". During evaluation, it became apparent that some visitors were confused by the cephalopods. They thought the cephalopods were chasing the fish. The answer to this confusion lies in the way cephalopods move. Do they pull their shell behind them, or do they drive the shell before them?

Cephalopods move by rapidly expelling water out of their bodies. When they do this, they move in the opposite direction. Remember Newton's law--for every action there is an equal and opposite reaction? Notice that the end of the shell is closed. The only way water can exit is between the tentacles, therefore cephalopods move in the direction the shell is pointing, driving the shell before them. In the diorama, they are fleeing the fish, and with good reason. Dunkleosteous was a fierce predator growing up to 30 feet in length. Throughout time cephalopods have been a favorite food for many life forms. Even today you can find them on menus around the world.

Another stunning life form is the large meadow of crinoids. Although attached to the sea floor, and shaped somewhat like flowers, crinoids are actually animals. They feed by arching their arms into the current and filtering out food particles as they drift by. Nutrient rich water is taken into the mouth and passed through the stem which is hollow inside. Wastes are then excreted out the anus located near the mouth in the calyx. Crinoid fossils are common in rocks in the Bridger Range and Horseshoe Hills. Whole specimens are rare, but pieces of the stems are fairly common. They look like a stack of small Lifesavers candy.



Devonian Period Diorama

Wild West ReefOne day 370 million years ago the Northern Rocky Mountain region was a tropical place--perfect for reefs and reef creatures. Present site: Fossiled reef, Challis, Idaho


WILD WEST REEF CRITTER CARD LIFEFORM INFORMATION

Charactophyllum was a type of coral that lived alone rather than in groups. Itgot its name of "horn coral" from its shape. It lived during the Devonian Period.

Dunkleosteus was a huge predatory fish that roamed Devonian seas. This placoderm, or armored fish, reached lengths of up to 30 feet and crushed prey with its teeth-like plates. In this scene, a young Dunkleosteus tries to make a meal out of cephalopods.

Melocrinites was a type of crinoid that looked very much like a plant. This animal used its tentacles to move tiny floating food particles into its mouth. Food passed through the length of its body before traveling back up the body to be expelled through the anus, which is located next to the mouth.

Michelinoceras was a type of cephalopod. These “squid-in-a-cone” used jet propulsion to move. By squirting water out between their tentacles, they could propel themselves quickly through the water, driving their conical shells before them. Modern day animals such as octopi, squid and nautilus are cephalopods too.

Platyclymenia was a type of cephalopod related to squid. It had an ornamented coiled shell up to two inches in length. It moved through the water column by filling chambers in its shell with water, or gas, so it could move up or down in search of prey.

Stromatoporoids were tiny animals that secreted a hard exoskeleton. These organisms lived in a colony and helped build the reefs during the Devonian Period. Many organisms together comprised a colony that could reach up to 2 feet in size. These colonies were built closely together in rounded, encrusted or branched shapes. Eventually, several colonies grew together to make a reef. The reef attracted other animals like fish and snails. Today, most reefs are built by corals.

Tropidocyclas was a type of snail that fed on corals and other animals. It moved along reefs by using its "stomach foot." It had two large tentacles with an eye attached to the end of each.



MIX AND MATCHMississippian Period Diorama (320 Million Years Ago)

This diorama depicts life 320 million years ago in a bay near present day Lewistown, Montana (Bear Gulch). The Bear Gulch fauna consist of some of the world’s most important fossil fish. Some specimens show internal organs such as the liver and veins. Blood in the arteries was not preserved, suggesting that the geochemistry of the basin was finely balanced.

Most of the Bear Gulch fish are sharks—cartilage fish. Sharks can be identified by their large, triangular pectoral fins. One type of shark is the chimaerid (Holocephalan). The evolutionary history of the Holocephalans was largely unknown until fossils of Bear Gulch were discovered and examined. The chimaerids can be identified by their long bodies and whip-like tails. The upper jaw is fused to the braincase, and a flap of skin covers the gill arches.

Many of the Bear Gulch male sharks and chimaeras, including Echinochimaera, sported spiny head appendages made of scales, cartilage, bone, or dentine and enamel. These head spines could be flashed to attract females and impress other males, much as antlered animals do today. No modern shark has this curious head gear.

The diorama depicts three environments—from left to right they are: the open water, near shore, and shallow weedy environments. Fish have adapted to fit these environments. Fish that live in the shallow weedy environment are small and disk-shaped. Their discoid (button-shaped) bodies allow them to move easily between the weeds. Their pectoral fins are placed to allow them maximum flexibility. In contrast, the large Stethacanthus has a fusiform (spindle-shaped; elongated with tapering end) body, with deeply forked tail. This body shape allows for fast cruising in open water for long distances. Modern sharks still employ the fusiform body shape, which makes them fast and efficient hunters. The Bear Gulch bay may have been a nursing ground for these large predators; they did not live full-time in the bay. The rays such as Squatinactis can be thought of as flattened sharks. They lived close to the bottom and swam by moving their large pectoral fins up and down.

The Bear Gulch fauna lacks a highly developed benthic community. The rocks show no evidence of burrowing, indicating that few if any animals lived on the bottom. Frequent mud slides may have prevented establishment of a benthic community. Shrimp and brachiopods usually inhabit the sea floor bottom. In the Bear Gulch bay, these animals lived attached to algae mats floating on the surface of the water, or attached to sponges and floating logs.

The exact cause of death for the Bear Gulch fauna is not precisely known, but the prevailing theory is that the animals died and were quickly buried by frequent mud slides. During the late Paleozoic Era, the Bear Gulch bay was part of the central Montana trough, an area frequently shaken by earthquakes. Underwater mud slides would sweep down, quickly burying the small fish. Large sharks are rarely preserved, perhaps because they could usually out swim the mud slides.


Mississippian Period Diorama



MIX AND MATCH CRITTER CARD LIFEFORM INFORMATION

Caridosuctor, or shrimp-eater, was a type of coelacanth that grew up to 12 inches in length. This fish used its tassel-tail to help it feed on the bottom. The electrical sensors in its snout helped it find food buried in the mud. The coelacanths are still alive today, living in deep ocean water off the coast of Africa.

Echinochimaera was a shark with a long, whip-like tail. It had a large head with very large eyes. The male’s head spines served as an attractant to the female Echinochimaera.

Falcatus, or unicorn shark, grew to about ten inches in length. Males had a strangely shaped dorsal fin that turned back toward the head. This small shark probably fed on shrimp.

Guildayicthys was a disk-shaped, brilliantly-colored fish. It used its narrow body and radial fins to maneuver quickly through the water to avoid predators. It lived in central Montana 320 million years ago.

Squatinactus was a shark that grew to three feet in length and fed on the sea floor. Its body shape and lifestyle suggest it was an ancestor to modern rays.

Stethacanthus was a shark that grew to four feet in length. Some species of this genus found in other parts of the world reached up to ten feet. Males had a bony, brush-life structure on the top of their dorsal fin to attract females. It lived in central Montana during the Mississippian Period, 320 million years ago.


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