Terrestrial Vertebrates of the Cenozoic:
Mammals of the early Paleogene were considerably more primitive than their modern relatives. Tended to have:
During Eocene, establishment of the major radiations of mammals. Different continents dominated by different groups:
During Eocene and later, mammals tend to develop bigger brains, longer legs, and walk on toes.
Eocene sees first bats (flying mammals) and many marine mammal groups.
Also, major radiation of bird groups.
Major faunal turnover in late Eocene extinction: origination and diversification of many groups in North America; European fauna replaced by primarily Asian forms.
During the early part of the Oligocene: extinction of the multituberculates.
With spread of grasslands in early Neogene (or late Paleogene in South America) comes shift from browsing to grazing among some groups of ungulates; perhaps also origin of pack hunting among carnivorans. Among smaller animals, also some grassland- related diversifications:
At around 3 Ma, rise of the Isthmus of Panama allows the Great Faunal Interchange:
Also around 3 Ma, rise of continental glaciation produces tundra-adapted mammals: wooly mammoths, wooly rhinos, musk oxen, etc. Faunal communities migrate polewards during interglacials, equatorwards during advances
At beginning of Pleistocene: widespread interchange in animals across the Bering Land Bridge (some had gone on earlier). Among immigrants out of America: horses, camels. Immigrants into North America include: bison, wooly mammoths, humans.
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