The Paleozoic Era! Time for BIG changes!

Geologists divided the later strata into 3 major groups Remember this? Geologists divided the later strata into 3 major groups Modern era Ice Age Cenozoic Era Dinosaurs! Mesozoic Era We will explore the Paleozoic first… Paleozoic Era About 550 million years ago Ediacaran 4 billion years of Earth history!

Paleozoic Era The more recent layers are subdivided into “PERIODS” Permian Pennsylvanian Mississippian Devonian Silurian Ordovician Cambrian Paleozoic Era Trilobites Brachiopods, Molluscs Bi-valves, Arthropods Ediacaran

The Early Paleozoic… Many new life forms with HARD SHELLS evolve… A more diverse community is present!

A typical scene in the early Paleozoic Era. Cephalopod Trilobite Crinoid Brachiopod Coral

From earlier animals with a “hint” of a backbone… There evolved the first vertebrates! Perm Penn Miss Dev Sil Ord Cam By the early Cambrian… …the first Fish swam the seas.

Ordovician New species continue to evolve… others become extinct… Perm Penn Miss Dev Sil Ord Cam

Silurian But…big changes are occurring! New species continue to evolve… others become extinct… Perm Penn Miss Dev Sil Ord Cam But…big changes are occurring!

Starting possibly as early as the later Ordovician… …land plants had been evolving! (Probable SPORES have been found) By the middle Silurian… Perm Penn Miss Dev Sil Ord Cam Early land plants looked like this…

By the start of the Devonian… The ocean is filled with life… …but the REALLY big story is elsewhere. Near the shore, or in and along streams and coastal swamps, a major invasion is taking place…

…indicate that plant life had moved ashore! Fossil stumps… …and leaves… …indicate that plant life had moved ashore! Early Devonian landscape Z. Burian (In: Špinar & Burian, 1972);

And by the end of the Devonian… …the first real forests grew. Perm Penn Miss Dev Sil Ord Cam Archaeopteris dominates

THAT produced major changes in the landscape! Earlier vegetation lacked the root systems of present-day vegetation… …plants were apparently restricted to being near water Those plants also produced little shade or leaf litter.

The evolution of new types of trees lead to a richer environment, creating more organic material…

…and probably changed stream channel morphology, and altered erosion and deposition. Braided Streams Overwhelming amounts of eroded material

Meandering Streams

Devonian As always, new species continue to evolve, and other species become extinct… Perm Penn Miss Dev Sil Ord Cam Which sometimes seems like you’re watching the same play over and over with different actors! 

…but these more minor changes are overshadowed by MAJOR developments! The first Fish evolved near the start of the Early Paleozoic… Early Fish

Later…Armored Fish evolved! (Placoderms) Some are small… … Some reach AWESOME size!

Why would some fish evolve armor? I wish he’d be more careful!  Why would some fish evolve armor? Why would they then become extinct?

And…perhaps, near those new forests… Some fish evolve sturdy fins that may help them move through shallow water. It proves to be a successful change

This is a Fish… But what is this…?

…to animals that are at least partially terrestrial! They are part of a series of fossils that show the transition from a “water animal”: a fish… Icthyostega Acanthostega Tiktaalik Pandericthyes Eusthenopteron …to animals that are at least partially terrestrial!

The newest find: Tiktaalik!

Obvious Amphibian! Transitional Forms Note Tiktaalik! Obvious Fish!

So…during the early Paleozoic… Hard shell animals evolve… Trilobites, brachiopods, corals, cephalopods “rule the seas” FISH EVOLVE… Armored fish evolve… …and then fade away. The FIRST LAND PLANTS appear… And at the end…a branch of fish evolve sturdy limbs and become the first AMPHIBIANS.

The late Paleozoic … Amphibians had already moved ashore and taken over… …and the first forests already existed… …but before the end of the Paleozoic… new creatures evolved.

Mississippian In the oceans, new species continue to evolve… Perm Penn Dev Sil Ord Cam In the oceans, new species continue to evolve…

Pennsylvanian But the action is NOT all in the ocean anymore! Perm Miss Dev Sil Ord Cam

…by the Pennsylvanian, a vast diversity of plant life had evolved… Perm Penn Miss Dev Sil Ord Cam the land was covered by new species of plants. Some of which now towered as much as 100 feet over the land…

…this is the time that great forests covered much of Illinois! The Illinois Coal Forest: a great river delta where buried trees became coal.

It’s also the time of the Illinois State Fossil… The “Tully Monster”!

During the Later Paleozoic, amphibians evolved into reptiles… With hard-shelled eggs, Reptiles were “freed” from water…

…and reptiles evolved into many different types. Early Mammals …and reptiles evolved into many different types. This diagram shows the transitional change in the jawbones from ancient Reptiles to early Mammals. Early Reptiles

…Mammal-like Reptiles appear. Near the end of the Paleozoic, as this evolutionary sequence continued… …Mammal-like Reptiles appear. Perm Penn Miss Dev Sil Ord Cam Mammal-like Reptiles are reptiles with Mammal-like features. (Obviously! : )

They do NOT look like “typical” reptiles. They aren’t quite mammals, either… …but one group WILL be!

But before this happens… There is an enormous change: The “MOTHER of ALL EXTINCTIONS!” For the Trilobites… it’s the end! Perm Penn Miss Dev Sil Ord Cam For Brachiopods… it’s never the same!

For other groups: extinction of many species! …and for the Mammal-Like Reptiles… Perm Penn Miss Dev Sil Ord Cam …almost a total wipeout!

In the later Paleozoic… Amphibians “ruled”…for a while Insects filled the land… Great forests covered the land… the “Coal Age” in Illinois Reptiles evolved from Amphibians Mammal-like Reptiles evolved… …and then much was lost in the “Great Extinction” at the end of the Paleozoic.

On to… The MESOZOIC! (Watch out for Dinosaurs!)

Same color = same bones Ichthyostega Notice the transitional changes from Eusthenopteron to Ichthyostega Eusthenopteron

Remember: in the Early Paleozoic… …life had moved from the ocean to the land…

The first land plants had evolved… The first insects roamed the land… And the first amphibians were evolving…