absolute magnitude africa alaska alligator antarctica antelope aquitanian age armadillo australia australopithecine bear blancan burdigalian california camel cenozoic chalicothere china civet climate coati cretaceous crocodile cyprus deciduous deer dog early pleistocene elephant eurasia europe gelasian giraffe glacier gomphothere grassland great american interchange hipparion holocene horse human evolution hyrax ice sheet india international commission on stratigraphy isotope isthmus of panama japan johns hopkins university kangaroo langhian late pleistocene list of fossil sites mediterranean sea meridiungulata messinian middle pleistocene miocene monotreme neogene new zealand north america notoungulata older dryas opossum oxygen ozone layer piacenzian pig pinniped plate tectonics platypus pleistocene primate quaternary rhinoceros saber-toothed cat scorpius-centaurus association sea ice sea lion serravallian sloth south america sparassodonta stegodon stellar classification stratum supernova tethys ocean thylacine thylacoleo titanis tortonian tundra ungulate venomous snake weasel whale wikimedia commons wombat younger dryas zanclean