The Cenozoic Era The Modern World Emerges Climate and Life 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 Methane Degassing Event

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 Next Lecture The Pleistocene Epoch The Ice Age QUIZ on Chapter 16 p. 465-485 and MNaG-Q