Inspired by Mrclubtail1234's 'Cenozoic-ifying the series' but not totally based off of it; given how many animals were around at the time on the continent, and given how recent the period is, there are a lot of animals to work with here, including modern non-extinct ones (there are still a couple outliers from other continents, mind). Not everything has to be some obscure extinct creature.
Just the original movie
Alces alces / Moose (left) and Rangifer tarandus / caribou (right) Camelops hesternus / American camel Glyptotherium cylindricum Hemiauchenia macrocephala Mammuthus columbi / Columbian mammoth Panthera atrox / American lion Paramylodon harlani / Harlan's ground sloth Pelecanus occidentalis / Brown pelican Urocyon cinereoargenteus / Gray fox
Including the sequels/TV series
Alligator mississippiensis / American alligator and Larus delawarensis / Ring-billed gull Antilocapra americana / Pronghorn antelope (right) and Equus scotti / Scott's horse (left) Arctodus simus / Short-faced bear Bison bison / American bison Bison priscus / Steppe bison Crocodylus acutus / American crocodile Falco sparverius / American kestrel Glyptotherium sp. and Odocoileus hemionus / Mule deer Corvus corax / common raven (Rinkus) and Haliaeetus leucocephalus / bald eagle (Sierra) Homotherium serum / Scimitar-toothed cat Mammut americanum / American mastodon Megalonyx jeffersonii / Jefferson's ground sloth Meleagris gallopavo / Wild turkey Miracinonyx trumani / American cheetah Nothrotheriops shastaensis / Shasta ground sloth Ovibos moschatus / Musk ox Platygonus compressus / Flat-headed peccary Smilodon fatalis / Saber-toothed cat Taxidea taxus / American badger Titanotylopus spatulus / Giant camel Tursiops truncatus / Bottlenose dolphin Tympanuchus cupido / Greater prairie chicken Ursus americanus / American black bear Ursus arctos horribilis / Grizzly bear
Updates in the future are inevitable.