WednesdayOctober 27, 2010

(The Phanerozoic Eon)

The Launch PadWednesday, 10/27/10

The beginning of the Cambrian period marks an important event

in animal evolution, the appearance of organisms with

__________________.A. wingsB. cells

C. shells and other hard partsD. vertebrae

E. none of the above

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The Phanerozoic EonThe Phanerozoic Eon

encompasses 542 million years, and is still the current

Eon. The Phanerozoic Eon is

divided into the Paleozoic, Mesozoic, and Cenozoic Eras.

The Phanerozoic Eon The Paleozoic

Era

The Paleozoic Era was

dominated by continental collisions as

Pangaea began to assemble.

The Phanerozoic Eon The Paleozoic

Era At this time

the Caledonian, Appalachian,

and Ural Mountains

were formed.

The Phanerozoic Eon The Paleozoic Era

The early Paleozoic Era consisted of the Cambrian and Ordovician

Periods.This was known as

the “Age of Invertebrate

s.”

The Phanerozoic Eon The Paleozoic Era

The middle Paleozoic Era consisted of the Silurian and

Devonian Periods.This was known as the “Age of

Fishes.”

The Phanerozoic Eon The Paleozoic Era

The later Paleozoic Era consisted of the Carboniferous

Mississippian, Carboniferous Pennsylvanian, and Permian

Periods.This was known as the “Age of

Amphibians.”

The Paleozoic Era: Life ExplodesThe Paleozoic Era marks the first

appearance of life-forms with hard parts such as shells.

Life in the early Paleozoic was restricted to the seas and

consisted of several invertebrate groups including:

This development resulted in abundant Paleozoic fossils.

TrilobitesCephalopods

SpongesCorals

Paleozoic Marine Invertebrates

Figure 12.26

The Paleozoic Era: Life ExplodesDuring the Paleozoic, organisms diversified

dramatically.Insects and plants moved

onto land.Lobe-finned fishes adapted to

land and became the first amphibians.

Large tropical swamps in the Pennsylvanian period

became the major coal deposits of today.

Figure 12.28

Figure 12.27

Pennsylvanian-Age Coal Swamp

Figure 12.29

The Paleozoic Era: Life ExplodesA mass extinction at the close of the

Paleozoic Era destroyed 70% of

all vertebrate species on land and 90% of all

marine organisms.

Figure 12.A (left)

Figure 12.A (right)

The Phanerozoic Eon The Mesozoic Era

Early in the Mesozoic Era, much of the land was above sea level.

By the middle Mesozoic, seas invaded western North America.

Pangaea began to break apart and the westward-moving North American plate began to override the Pacific plate.

This resulted in crustal deformation along the entire western margin of North America.

The Sierra Nevada and Rocky Mountains were formed at this time.

The Phanerozoic Eon The Mesozoic Era

The Mesozoic Era was known as the “Age of Reptiles.”

The early Mesozoic Era consisted of the Triassic Period.

The Mesozoic Era: Age of the ReptilesThe Mesozoic, literally the era of middle life, is often called the “Age

of Reptiles.”By the way, dinosaurs were not lizards!

Formation of the Pangaea

supercontinent

Figure 12.19 D

The Mesozoic Era: Age of the ReptilesOrganisms that survived the extinction at the

end of the Paleozoic began to diversify.

The Mesozoic Era: Age of the ReptilesGymnosperms (cycads, conifers, and ginkgoes) became the dominant trees of the Mesozoic.

The Mesozoic Era: Age of the ReptilesReptiles became the dominant land animals.

Mesozoic Era: Age of the ReptilesThe first reptiles were small, but evolved

rapidly, particularly the dinosaurs.

Diversity of reptiles included:The Mesozoic Era: Age of the Reptiles

large herbivorous dinosaurs such as Apatosaurus

large carnivorous dinosaurs such as Allosaurus

Pterosaurs or flying reptiles

and Archaeopteryx, the predecessor of modern birds

Archaeopteryx fossilArchaeopteryx

fossil

Ichthyosaur Fossil

Figure 12.C-B

The Phanerozoic Eon The Mesozoic Era

The Mesozoic Era was known as the “Age of Reptiles.”

The middle Mesozoic Era consisted of the Jurassic Period.

The Phanerozoic Eon The Mesozoic Era

The Mesozoic Era was known as the “Age of Reptiles.”

The late Mesozoic Era consisted of the Cretaceous Period.

A few types survived, including the turtles, snakes,

and lizards

The Mesozoic Era: Age of the Reptiles

At the close of the Mesozoic Era, many reptile

groups became extinct.

The Phanerozoic Eon The Cenozoic Era

Much of North America was above sea level throughout the Cenozoic Era.

Eastern and Western margins of the continent experienced markedly contrasting events.

Atlantic and Gulf coastal regions, removed from active plate boundaries, were tectonically stable.

In the West, the Laramide orogeny (Rocky Mountains) was ending, the Basin and Range Province was forming, and

volcanic activity was extensive.

The Phanerozoic Eon The Cenozoic Era

In the Cenozoic, mammals replaced the reptiles as the dominant vertebrate life-forms on land.

Two groups of mammals evolved, the marsupials and the placentals.

One tendency was for some mammal groups to become very large.

Late Pleistocene extinctions eliminated these larger animals.

Figure 12.35marsupial

placental

The Phanerozoic Eon The Cenozoic Era

The Cenozoic could also be called the “Age of Flowering Plants.”

Flowering plants (angiosperms) strongly influenced the evolution of both birds and

herbivorous mammals throughout the Cenozoic.

Figure 12.34A