paleozoic era. continents in late proterozoic eon
TRANSCRIPT
Paleozoic Era
Continents in late Proterozoic Eon
Rodinia began breaking apart sometime during the late Proterozoic
By the beginning of the Paleozoic Era, six major continents were present
Each continent can be divided into two major components a craton and one or more mobile belts
Cratons and Mobile Belts
Transgressing and regressing shallow seas called epeiric seas Common feature of most Paleozoic cratonic
histories Cause unconformities
Continental glaciation as well as plate movement caused changes in sea level
Epeiric Seas
Four mobile belts formed around the margin of the North American craton during the Paleozoic
Franklin mobile belt Cordilleran mobile belt Ouachita mobile belt Appalachian mobile belt
Each was the site of mountain building in response to compressional forces convergent plate boundary formed such mountain ranges as the Appalachians
and Ouachitas
Four Mobile Belts
Paleozoic North America
• Mobile belts
At the beginning of the Paleozoic, six major continents were present Baltica - Russia west of the Ural Mountains and
the major part of northern Europe China - a complex area consisting of at least
three Paleozoic continents that were not widely separated and are here considered to include China, Indochina, and the Malay Peninsula
Gondwana - Africa, Antarctica, Australia, Florida, India, Madagascar, and parts of the Middle East and southern Europe
Six Major Paleozoic Continents
Kazakhstan - a triangular continent centered on Kazakhstan, but considered by some to be an extension of the Paleozoic Siberian continent
Laurentia - most of present North America, Greenland, northwestern Ireland, and Scotland
Siberia - Russia east of the Ural Mountains and Asia north of Kazakhstan and south Mongolia
Besides these large landmasses, geologists have also identified numerous small microcontinents and island arcs associated with various microplates
Six Major Paleozoic Continents
Major extinctions during Paleozoic
OrdovicianSilurianDevonianPermian
For the Late Cambrian Period
Paleogeography of the World
M&W, Fig. 21.1a
EARTH HISTORY PALEOZOIC LIFE
M&W, Fig. 21.1b
M&W, Fig. 21.1c
• In the earliest part of the Cambrian, a few small (several millimeters in size) shelly fossils are found, but then shortly afterwards life really “takes off” with larger animals with hard skeletons and shells.
Lapworthella, Australia.
Archaeooides, Northwest Territories, Canada.
An anabaritid, Northwest Territories, Canada.
M&W, Fig. 21.1a
EARTH HISTORY PALEOZOIC LIFE
• What advantages do SHELLS provide?
Lapworthella, Australia.
-Protection from predators
-Protection from UV light (allowing animals to move into shallower water)
-When the tide goes out, shelled organisms don’t dry out
-Shells provide structural support for larger and larger organisms to evolve
Early History—Paleozoic Era
Cambrian Period 543-490 mya
Trilobites, sponges, brachiopods live in oceans
Early History—Paleozoic Era
Cambrian Period 543-490 mya
Global warming as Rodinia breaks up
Laurentia, Kazahkstan, Siberia move toward equator
Sea level rises as ice melts
Deposition of limestone common
Early History—Paleozoic Era
Cambrian Period Ordovician Period
490-443 mya
Trilobites, corals, algae, brachiopods, molluscs, in complex reef systems
First lichens and bryophytes on land
Major extinction at end of period due to ice age
Early History—Paleozoic Era
Cambrian Period Ordovician Period
490-443 mya
Laurentia begins to collide with Europe (mountain building)
Gondwana moves over pole
Land is cold and barren, warm tropical shallow marine near equator
Ice age toward end of Ordovician
For the Late Ordovician Period
Paleogeography of the World
Early History—Paleozoic Era
Cambrian Period Ordovician Period Silurian Period 443-417 mya
Abundant life in ocean, coral reefs in shallow marine near equator
Jawless fish common Echinoderms and
molluscs flourish, trilobites begin to decline
First plants on land First terrestrial
arthropods
Early History—Paleozoic Era
Cambrian Period Ordovician Period Silurian Period 443-417 mya
Gondwana moves more across south pole
Laurentia, Siberia, Baltica move toward each other at equator
Early Silurian glaciers melt and sea level rises toward end of Silurian (greenhouse effect)
For the Middle Silurian Period
Paleogeography of the World
Early History—Paleozoic Era
Devonian Period 417-354 mya Many mountain building
events
Abundant marine life including bony fish
First sharks First ferns on land as
well as tree-like plants First tetrapods and
first terrestrial arthropods
Late Devonian extinction: 70% of invertebrate species (especially marine)
Map
Early History—Paleozoic Era
Devonian Period 417-354 mya Many mountain building
events
Two supercontinents: Gondwana and Euramerica
Both continents slowly drift north
Map Map
Early History—Paleozoic Era
Carboniferous Period 354-290 mya Missisippian (354-318
mya) Pennsylvanian (318-290
mya)
Fish expand in oceans, many molluscs, corals, few trilobites.
Forests and swamps with seed plants on land
Winged insects Early amphibians on
land.
Early History—Paleozoic Era
Carboniferous Period 354-290 mya Many episodes of
mountain building
Inland seas reduced due to beginning collision of continents to form Pangaea
Ice develops over Gondwana due to climate change
Land dries due to changes in glaciation and Pangaea
Early History—Paleozoic Era
Permian Period 290-248 mya
Life in oceans diminishes Predatory ammonites First vertebrate
herbivores on land. Reptiles common on
land Many insects on land Many gymnosperm
plants 90% of marine species
experience extinction at end of period (Pangaea, flood basalts in Siberia, impact)
Early History—Paleozoic Era
Permian Period 290-248 mya Climate becomes dryer
Pangaea assembled, with only Chinas and Kazahkstan separated
Warming climate, dry interior of continent
Pangaea!