Earth History
GEOL 2110
The Cenozoic Era
The Modern World Emerges
Climate and Life
Major Concepts
• Greenhouse conditions that prevailed in the Cretaceous
continued into the Early Cenozoic. But dramatic cooling
episodes began in the late Eocene. This appears to be
due to changes in ocean circulation as Pangea continued
to break apart.
• This climate change resulted in a dramatic change in the
biosphere which change from tropical jungles in the early
Cenozoic to grasslands, savanahs, and temperate forests
in the Late Cenozoic.
• After the Cretaceous extinctions of the dinosaurs,
mammals saw an explosive radiation . The change over
from jungles to grass lands also caused a change from
leaf-eating to grazing mammals with more speed.
Summary of the Cenozoic
PEOMPP
Climate Change in the Cenozoic
Degassing of Methane Hydrates in
Early Eocene
USGS map of known
and suspected
methane hydrate
deposits
Seismic profile off
North Carolina
3000 m
Methane Plumes
Degassing of Methane Hydrates in
Early Eocene
Deep-sea plume of methane escaping from the sea floor
Climate Change in the Cenozoic
The Great Eocene-Oligocene Cool Down
The Great
Eocene Oligocene
Cool Down
Separation of Australia
and SA from Antarctica
triggers Glaciation and
Major Extinction of
Warm-climate Species
Climate Change in the Cenozoic
Mid-Miocene Cool Down
Mid-Miocene Cool Down (15 Ma)
Arctic – Atlantic Connection Established
Miocene
20-15 Ma
Cool Down Continues into the Pliocene
and into Today
Climate Change in the Cenozoic
Climate Change Affects the Biosphere
Warm, lush
forests/jungles of
the Eocene give
way to ….
Temperate
grasslands and
savannas of the
Miocene
Mammalian Evolution
“In the Late Cretaceous, no mammal was larger
than a house cat. By the Eocene (40Ma) all
modern orders of mammals had evolved with
some the size of a rhinoceros or elephant”
Adaptation to the Mid-Cenozoic Climate
Longer–limbed runners
Better eye sight
Cud-eaters
Hoofs replace toes
High crowned teeth that continue to grow
The Gondwanan Continents
Natural Laboratories of Speciation
Ecological Convergence
Great American Interchange
When Migration was North to South
South Americans
Isthmus established in
Mid-Pliocene (4Ma)
North Americans
Fig. 15.51b
Next Lecture
The Pleistocene Epoch
The Ice Age
QUIZ on Chapter 16
p. 465-485
and MNaG-Q