Nimravidae

The Nimravidae, sometimes known as false saber-toothed cats, are an extinct family of mammalian carnivores that was endemic to North America, Europe, and Asia. Not considered to belong to the true cats (family Felidae), the Nimravidae are generally considered closely related and classified as part of suborder Feliformia. Fossils have been dated from the Middle Eocene through the Late Miocene epochs (Bartonian through Tortonian stages, 40.4—7.2 mya), spanning about 33.2 million years.

Previously classified as a subfamily of Nimravidae, in 2004, the barbourofelids were reassigned to their own distinct family Barbourofelidae.

Morphology and evolution

Most nimravids had muscular, low-slung, cat-like bodies, with shorter legs and tails than are typical of cats. Unlike extant Feliformia, the Nimravidae had a different bone structure in the small bones of the ear. The middle ear of true cats is housed in an external structure called an auditory bulla, which is separated by a septum into two chambers. Nimravid remains show ossified bullae with no septum, or no trace at all of the entire bulla. It is assumed that they had a cartilaginous housing of the ear mechanism.