Tertiary Mammal Evolution in the Context of Changing Climates, Vegetation, and Tectonic Events
Annual Review of Ecology and Systematics
1993
Journal Article
24
467-500
0066-4162
evolutionary trends mammalian adaptations tertiary communities tertiary biogeography tertiary botany great american interchange north-atlantic late miocene fort-ternan southern asia eocene fossil diversity faunas paleoecology Tapir Bibliography
Evolutionary trends among mammals over die past 66 Myr have been profoundly influenced by changing climates, in turn the result of tectonic events. The global tropical forest type of ecosystem of the early Tertiary was disrupted by Late Eocene climatic changes, with the extinction of most archaic mammalian lineages and the appearance of most modem families. Later Tertiary trends reflect increasing aridity, with the appearance of open-habitat mammals such as grazing ungulates, although true grasslands probably did not appear until die Late Miocene in the New World and the Pliocene in the Old World. Patterns of mammalian diversity track paleotemperature curves for the northern latitudes, with maxima in the early Middle Eocene and early Middle Miocene. Major dispersals occurred at times of sea level lows, resulting in loss of endemism in originally isolated continents such as South America and Africa, and changes in faunal composition across Holarctica. Dispersal in conjunction with climatic changes accounted for major extinction events in the Late Eocene to Early Oligocene, at the end of the Miocene, and in the mid Pliocene. Outstanding problems include the origin and dispersal routes of many extant orders that appeared at the start of the Eocene and the apparent asymmetry of many dispersal events. Finally, although many higher latitude paleoenvironments resembled present day equatorial ones, such as Early Eocene tropical forests and Late Miocene savannas, the mammalian paleocommunities were not precise analogs of present day communities in similiar Recent habitats.