Patriofelis

Patriofelis ("father of cats") is an extinct genus of carnivorous placental mammals from the extinct subfamily Oxyaeninae within the extinct family Oxyaenidae, which lived from the early to middle Eocene, during the Bridgerian stage of NALMA. The first remains were discovered in 1869 by geologist Ferdinand Vandeveer Hayden, and the genus was named the following year by Joseph Leidy. Over the next few decades, additional specimens would be named from the same locality (or similar ones), many assigned to genera of their own or to separate species within Patriofelis. Now, only two are recognised: Patriofelis ulta, the type species, from the lower Bridger Formation and the Huerfano Formation of Colorado, and P. ferox, from the lower Bridger and lower Washakie Formations of Wyoming and Colorado, and the Clarno Formations at the John Day Fossil Beds National Monument, Oregon.

Patriofelis is the largest oxyaenid to preserve postcranial fossils (fossils which come from behind the skull). P. ulta, the smaller species, has been estimated at around , while the larger P. ferox has been estimated at . Patriofelis had a skull around the same size as of that of a lion, though shorter and broader in a way often likened to otters. A semi-aquatic lifestyle has been suggested for Patriofelis, though there are aspects of its anatomy which make this very unlikely. Its backbone was stiffened by bony structures which projected from its vertebrae, inhibiting the usual mammalian swimming method, in which the spine undulates up and down. Originally it was suggested to be a turtle specialist, though its teeth were not adapted for crushing, but rather for slicing. While some older sources reported that Patriofelis had limited arm flexibility, recent studies have shown that its forearms were capable of a great degree of pronation and supination. Though there are various hypotheses for how Patriofelis lived, the most likely is that it was a terrestrial ambush predator which hunted by grappling its prey.