earths historical highlights major stages in the history of earth major extinctions
TRANSCRIPT
Earth’s Historical Highlights•Major stages in the history of Earth •Major Extinctions
The Beginning• Earth is formed
from dust and debris orbiting the sun– A process named
Accretion• Like snowballing
– ~4.6 BYA (billions of years ago)
• Then the crust formed
The Eons of TimeMillions of Years Ago
PhanerozoicEon
Cenozoic era Quaternary, Tertiaray Mammals
200 Mesozoic era Cretaceous, Jurassic, Triassic Reptiles, birds
400 Paleozoic Permian, Carboniferous, Devonian Fish, amphibians
600 Silurian, Ordovician, Cambrian Invertebrates
800
ProterozoicEonSingle Cells & colonial
Neoproterozic Ediacaran, Cryogenian, Tonian
Stenian, Ectasian, Calymmian
1000 MYA (1 BYA) Mesoproterozic
1200 Colonial Organisms?
1400
1600
1800 Paleoproterozoic StatherianOrosirianRhyacianSiderian
2000 MYA (2 BYA)
2200
2400 Eukaryotes?
2600Archean EonBacteria only
Neoarchean (not yet divided into periods)
2800 Meoarchean
3000 MYA (3 BYA) Paleoarchean
3200 Eoarchean Bacteria?
3400
Hadean EonNo Life
Early Imbrian Bombardment ends
3600 Nectarian Era Earth cools, Oceans form
3800 Basin Group Era cometary bombardment!
4000 MYA (4 BYA) Cryptic Era Sun & Planets form
Eons divided into Eras divided into Periods (what was going on)
This scale of years is approximate, and may vary from other sources by a million years or so
NO
LIFEB
AC
TE
RIA
L LIFEC
OM
PLE
XLIFE
In Your TextbookThis whole time is simply called
Precambrian
MIC
RO
SC
OPIC
LIFE
Geological Timetable Era From/to events periods Ends with
Cenozoic“Age of Mammals”
Now Mammalsbirds
Quaternary
65mya Tertiary
Mesozoic(middle animals)“Age of Reptiles”
65 MYA DinosaursEarly mammals Reptiles
Cretaceous
Jurassic
250 MYATriassic
Paleozoic(ancient animals)“Age of Invertebrates”
250 MYA
540 MYA
Early reptilesAmphibiansInsects, molluskstrilobites
Permian
Carboniferous
Devonian
Silurian
Ordovician
Cambrian
Earlier Eras“Precambrian”
540 MYA
4 BYA
bacteria, etc First Life,. Earth cools
Pre-cambrianSee previous slide
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ERAS (simplified)• Cenozoic Era: Our era… lots of
mammals, birds, flowering plants• Mesozoic Era: Age of reptiles.
Dinosaurs and other large reptiles, gymnosperm plants
• Paleozoic Era: Age of invertebrates. Molluscs, insects, trilobites, worms etc. Algae and mosses.
• “Precambrian”: Age of microscopic life. Bacteria and some protozoans. Algae and cyanobacteria
The Major Eras• Life begins ~3.8bya• Beginning of
Precambrian Era– Bacteria and prokaryotes
appear
Palaeozoic Era“the age of invertebrates”
• paleo/old + zoic/animals = ancient life
• There was only one continent at the beginning– Rodinia (the mother continent)
• The land started off cold, but the seas warmed up quickly
• Life proliferates– Extensive variety of sea life– The predominant animal forms were
invertebrates (animals without backbones) like trilobites, insects, squids, snails etc.
• Then most life dies at the end of the Palaeozoic
The Paleozoic Era started about 543 million years ago, and lasted nearly 300 million years
(until 245 million years ago)
During the Paleozoic Era life proliferated. Many new and strange creatures populated earth’s oceans– sponges,
molluscs, trilobites, worms etc.
PALEOZOIC ERAThe “age of invertebrates”
Predominant life forms were invertebrates (no backbones)
The Paleozoic era is divided into six periods
PALEOZOIC ERA: Part I
• The Cambrian Period (540 MYA)– There was only one continent at the beginning– Rodinia: the first supercontinent (the mother
continent)
Most life was aquatic (ocean life)Sponges (formless animals)Jellyfish (soft aquatic animalsTiny molluscs (snails, clams)Marine Worms
Tiny mollusc shells from Cambrian Period (early Paleozoic)
PALEOZOIC ERA: Part II
• The Ordovician Period• The supercontinent began to break apart
– Into Gondwana ,Laurentia and Baltica
Africa, South AmericaAntarctica & India
North America Europe
Common life forms included:Trilobites (ancient arthropods)Jawless Fish (eels)Cartilage Fish (ancestors of sharks)
Plants and animals began to colonize the land
• Silurian Period (439-409 MYA): • Plants spread across the land
– Mostly mosses and primitive fern ancestors.– No really big trees yet
PALEOZOIC ERA: Part III
PALEOZOIC ERA: Part IV
• Devonian Period: (409-363 MYA)– First amphibians appeared– First insects appeared– Plants became larger and
more varied
• Underwater, fish were becoming larger and more diverse
PALEOZOIC ERA: Part V• The Carboniferous era (363-290 MYA)• AKA: Mississippian/Pennsylvanian Era
Great forests covered the land.
Much of our fossil fuel (coal and oil) comes from plants that died in the carboniferous period.
PALEOZOIC ERA: Part VI
The Permian period ended with the greatest of all mass extinctions.90% of aquatic life became extinct75% of terrestrial life
This also brought the paleozoic era to an end.
• Permian Period. (290-245 MYA)• By the end of the Paleozoic era, some of the
continents had rejoined, forming a new supercontinent called Pangea.
• More varied reptiles appeared.
Dimetrodon
The Palaeozoic Earth
End of the Palaeozoic
• Although the palaeozoic era is called the “age of invertebrates”, towards the end of the era some primitive fish, amphibians and reptiles had evolved.
• A mass extinction occurred to end the era.• We can identify mass extinctions in the fossil
record by finding a layer with very few fossils just above a layer with lots of fossils.
• This extinction was one of the biggest:– 95% of marine life and 75% of land life disappeared.
The Mesozoic Era: Age of Reptiles
• Meso/middle + zoic/animal = middle animals
• AKA the Dinosaurs’ era
• Albertosaurus
Mesozoic Earth
Periods of the Mesozoic Era
• Triassic Period:– Dinosaurs appeared
• Jurassic Period– Dinosaurs grew larger and more diverse. Small
mammals and primitive birds may have developed
• Cretaceous Period– Pangea broke up into the modern continents– The largest dinosaurs appeared
The End of the Mesozoic Era
• The Mesozoic era ended when a large asteroid smashed into Mexico, about 65 million year ago.
• The dinosaurs and many other life forms became extinct during the climate changes that followed.
• This was the 5th mass extinction
Cenozoic Era: The age of MammalsKnown for the
success and diversification of mammals
Periods of the Cenozoic Era
• Tertiary period: there were many large and unusual mammals
• Quaternary Period: primates and hominids evolved
The Quaternary Period• (Periods are smaller
divisions of Eras)• Known for global
glaciations– Ice ages
• Modern man has been evolving for– Over a million years
(perhaps as much as three million years)
– But has been sedentary for only ~10000 years• civilized
Chapter 17: Human Evolution
Hominid Fossils
• Humans and some of their extinct relatives belong to a family known as hominids.
• Hominids are classed within the order primates, along with apes and monkeys.
• The oldest hominid fossils have been found in Africa.
“Lucy” a hominid fossil from About 3 million years ago
• The complete classification of humans is:– Kingdom Animalia (animal kingdom)
– Phylum Chordata (chordates have a notochord)– Subphylum Vertebrata (with proper backbone)– Superclass Tetrapoda (decendants of four-limbed
vertebrates)
– Class Mammalia (the mammals)– Subclass Theria (live-birth mammals), – infraclass Eutheria (placental mammals)
– Order Primates (the primates: monkeys, apes, hominids)– Superfamily Hominoidae (anthropoids, greater apes)
– Family Hominidae (the hominids: humanlike. All other hominids except humans are now extinct)
– Genus Homo (Humans and early humans)
– Species sapiens (Modern “wise” humans)
This is presented for your information. You don’t need to copy or memorize it
The First Hominid?A newly discovered fossil
• Ardipithicus ramidus (Ardi): a chimpanzee sized hominid found in Africa and dated to about 4.4 million years, making it the oldest nearly intact hominid skeleton ever found.
On October 1, 2009, paleontologists formally announced the discovery of the relatively complete A. ramidus fossil skeleton first unearthed in 1994. The fossil is the remains of a small-brained 50-kilogram (110 lb) female, nicknamed "Ardi", and includes most of the skull and teeth, as well as the pelvis, hands, and feet
Some Other Identified Hominid Species
• Australopithicus afarensis “Lucy” is a species found in the Afar valley of Africa. They lived between 3 million and 4 million years ago
• Australopithicus africanus, Taller and heavier than “Lucy” lived in Africa between 2.3 and 3 million years ago
• Paranthropus* robustus and Paranthropus* boisei “nutcracker man” both lived between 1 and 2 million years ago in Africa* These two were formerly placed in genus Australopithicus
Australopithicus
Paranthropus
More Identified Hominid Species• Homo Habilis “Handy Man” lived in
Africa about 2.5 million years ago. This fossil used tools and may be the earliest representative of the human genus.
• Homo Erectus, “upright human” was first discovered in Java, and since then all over Asia, Africa and Europe. This may well be the ancestor of modern humans. They existed from 1.8 million years ago to as recently as 40,000 years.
Two Modern Human Species• Homo neanderthalensis (or possibly Homo
sapiens- neanderthalensis) lived in Europe from about 1.8 million years ago to as recently as 30,000 years ago. It has not been established if this was a separate species of human, or a “race” that would be capable of breeding with “modern” humans (hence the disputed classification)
The most recent evidence is that these two types of human were different species, so I will use the terms homo sapiens and homo neanderthalensis
• Homo sapiens (or perhaps Homo sapiens sapiens) is the designation of modern humans. The first fossils of modern humans were found in the Cro-magnon caves in southern France.
Because of where they were first found, early homo sapiens are occasionally referred to as “Cro-magnon man”. This is not an official designation, as they were undoubtedly the same species as modern man.
Some lesser-known and disputed hominid fossils
• Homo Floresiensis? “hobbit”: a very small hominid fossil recently found in Malasia dating to about 13000 years ago. Its authenticity is still under dispute. It may be a malformed human.
• Homo Heidelburgensis “Goliath” is a large fossil homind found in Germany. It may be a separate species or a variety of Neanderthal, Homo Erectus or Antecessor
• Homo Antecessor is a fossil found in Spain which may be an ancestor of both Neanderthals and modern humans, or it may simply be a variety of Neanderthal or Homo Erectus
Hominids (Human Ancestors)
Ardipithicus sp.
Australopithicus sp.
Paranthropus sp.
Homo Habilis
Homo Ergaster
Homo Erectus
H. Heidelbergensis
Homo antecessor
Neanderthal
? H. Floresiensis ?
H.sapiens
1 millionYears ago
2 millionYears ago
3 millionYears ago
4 millionYears ago
Now|A
rdi
Lucy
“Nut
crac
ker”
man
Ancestral Tree of Humans
Homo Sapiens Homo Erectus (Homo Heidelbergensis)
Homo Habilis (Homo Floresiensis) Paranthropus Boisei Neanderthal
Probable Brain Sizes 500 cm3 700 cm3 1000 cm3 1450 cm3 1400 cm3
He thinksHe’s so Smart!
Homo neanderthalensis
30000 to 1.8 million years ago
Homo sapiensHomo erectus40000 to 1
millionyears ago.
Homo habilis1-2 million years ago
Paranthropus robustus
1-2 million years ago
Geological Timetable: Extinctions Era From/to events periods Ends with
Cenozoic“Age of Mammals”
Now Mammalsbirds
Quaternary Extinction?
65mya Tertiary
Mesozoic(middle animals)“Age of Reptiles”
65 MYA DinosaursEarly mammals Reptiles
Cretaceous Extinction!
Jurassic
250 MYATriassic Extinction.
Paleozoic(ancient animals)“Age of Invertebrates”
250 MYA
540 MYA
Early reptilesAmphibiansInsects, molluskstrilobites
Permian Extinction!!
Carboniferous
Devonian Extinction.
Silurian
Ordovician Extinction.
Cambrian
Earlier Eras“Precambrian”
540 MYA
4 BYA
bacteria, etc First Life,. Earth cools
Pre-cambrianSee previous slide
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Assignment
• Read through chapter 10 in your text book, and answer the questions on pages 325 to page 329. – There are 20 questions in all .– See blackboard for due date.
Answers to Questions Page 325
• 1. a) The matter that formed our planet came from a great cloud of dust and gas that orbited our sun after it first formed.– B) The earth formed about 4.6 billion years ago (but it
took about a billion years for it to cool off and form oceans).
– C) The moon may have formed when a large celestial body collided with Earth with such force that it broke off a piece of the planet. The debris from the impact condensed, eventually forming the moon
• 2 A) The photo illustrates the presence of liquid water.
– B) The photo illustrates lightning, a source of energy for the formation of life.
– C) Other conditions not illustrated are:• Presence of elements necessary for life.• A long period of time.
• 3. A) The elements most needed for life include carbon, hydrogen, oxygen, nitrogen and sulfur.– B) Scientists believe that these elements
came from the atmosphere of earth.– C) It took a long time to form cells because
the probability of them forming was low– D) Life appeared between 3.5 and 3.8 billion
years ago.– E) The earliest forms of life resembled
bacteria • (your textbook mentions cyanobacteria, but I think
they more closely resembled archaebacteria)
• 4 A) the slow process that brings about modification of living beings is evolution
• B) Natural Selection gradually results in organisms better adapted to their environment.
• 5– A) Cenozoic is the era we live in– B) The Mesozoic era is when the dinosaurs
lived and became extinct– C) The “Precambrian” Era was the longest era– D) The Cenozoic era is when most of the
mammals appeared.– E) The Paleozoic era ended with the largest
mass extintion
• 6.
Event Era Period
Appearance of our species Cenozoic Quaternary
Extinction of dinosaurs Mesozoic Cretaceous
Appearance of dinosaurs Mesozoic Triassic
Extinction of 90% marine life Paleozoic Permian
Appearance of amphibians, insects Paleozoic Devonian
Appearance of fish Paleozoic Ordovician
Appearance of vertebrates Paleozoic Ordovician
Appearance of soft invertebrates Precambrian Precambrian
First evidence of life Precambrian* Precambrian*
• 7. The 380 million year old fish lived in the Paleozoic era and the Devonian period.
• 8. Jurassic Park was an appropriate name for a movie about dinosaurs, because many types of dinosaur existed in the Jurassic period
• I personally think a better name would have been Cretaceous Park, because the two “Star” dinosaurs (T-Rex and velociraptor) were more common in the Cretaceous Period.
• 9. – A) The chimpanzee is our closest “cousin”– B) The main feature used to distinguish between
humans and apes is bipedalism (the ability to walk upright)
• 10.– A) Three human genera are Australopithicus,
Paranthropus, and Homo– B) the scientific name of humans is homo sapiens.a– C) Two other human species were Homo floresiensis,
and Homo neanderthalensis..
• 11. Adaptations include:– A) Bipedalism, allowed us to use our hands to
carry things and use tools– B) Our brain allowed us to reason, become
inventive, develop tools, and communicate using complex languages.
– C) Our fine hair allowed us to keep cool– D) Our sweat glands also allowed us to cool
off during hot African days.
• 12. It is difficult to establish exactly how humans evolved because there is not as much fossil evidence as we would like.
• 13. Fossils are usually found in sedimentary rock.
14.
Fossil Type Formation
Footprints Trace The traces left in soil hardened
Bones Petrified The bones hardened and mineralized
Trilobite Cast Impression of trilobyte filled in with minerals
15. a) a body fossil is not shownb) A mammoth frozen in ice or an insect preserved in amber are examples of body fossils
• 16– A. False a palaeontologist studies fossils
– B. True there are petrified trees
– C. False most fossils come from sedimentary rocks
– D. False most organisms just decay
– E. True some fossils show both bones and impressions
(like archaeopteryx, the first bird, on page 322)
– F. False relative dating is less accurate
– G. True The carbon 14 gradually disappears
17.
• The law of continuity says that all sedimentary rock in a single layer formed at the same time. The law of superposition says that the deeper a layer is, the older it is
• 18 – A) If you think a tree is older because it is
larger, you are using relative dating– B) If you count the tree rings it is absolute
dating
• 19– A. Carbon-14 dating is based on the decay of
radioactive isotopes (radiometric dating)– B. The older the fossil, the less radioactive
carbon-14 it will have in it
• 20.– A. The orange layer is the oldest, since by the law of
superposition the oldest layer is the deepest– B. Species “B” probably appeared first, since its
fossils appear in an older layer– C. Species “B” probably disappeared last, since its
fossils are also found in a higher layer– D. Yes, they both existed during the time the middle
layer was deposited.– E. Relative dating helps us establish the dates of the
stratigraphic layers– F. Elements like uranium would be better than carbon
14 for determining the age of these fossils.