ELEPHANT: MAMMOTH ; MASTODON; etc.
The Carnivora begin in the Eocene with gen eralized carnivorous types as Creodonta (q.v.) that are easily confounded with the early ungu lates; in fact. the Creodonta is considered to be the ancestral group of both the Ungulata and the Carnivora and possibly also of the Ganodonta (primitive edentates) and the Podeutia. Eight families of creodonts are recognized. mostly from the Eocene of Europe and the United States. The more important genera are Arctoeyon, Mes onyx, Patriotelis, Hyfenodon. Some creodonts found in the Santa Cruz formation (Lower Ter tiary) of Patagonia present interesting marsu pial features. The true carnivores have larger, more deeply convoluted brains and strong sec torial teeth, with an accentuation of all other carnivore characteristics. The dogs, hears, weasels. civet eats, hyenas. cats, all have an cestral lines extending more or less into the early Tertiary, and some instructive phyiogenetic series have been demonstrated. The marine carnivores (Pinnipedia ) possibly had their ancestor in the Eocene creodont Patriofelis.
The shrews and moles of Eocene time present less marked differences from their modern de scendants than do any other types of mammals.
Almost nothing is known of the ancestry of the bats. Among the Rodentia, the characteristic feature in the dentition. namely the chisel-shaped incisor teeth growing from persistent pulps. is seen in fossils from the early Eocene. Such forms are Esthonyx and Tillotherium of North American deposits. The hares, rabbits, rats, mice, squirrels• and beavers appeared in the Miocene.
Primates are represented in the Eocene and Miocene beds of North America and Europe by fossil skeletons which combine the characters of the lemurs and apes. and which may be con sidered as ancestral apes. These are Anapto morphus, Adapis, and Megaladapis. The true ape. appeared in the Aliddle _Miocene of Europe and enjoyed a rapid evolution, for many genera have been found in the Miocene and Pliocene de posits there. They are all closely allied to the modern genera of Europe, Africa, and Asia. Fossil traces of man are very rare.