Although resembling a big cat, Hoplophoneus was actually one of the Nimravids, more popularly known as the ‘false sabre-toothed cats’. Nimravids were an early branch of the Carnivora and were actively hunting long before the emergence of the true cats of the Felidae. Although they looked very similar to true cats, there were many marked differences such as non-retractable claws, and lack of inner-ear bones.
Nimravids seem to have acquired many of the traits of the later
sabre-toothed cats like Smilodon and Machairodus, since they also have
enlarged sabre-like canine teeth in the upper jaw. Hoplophoneus also had
two flanges of bone that grew downwards from the lower jaw, just as
some of the other later true saber-toothed cats. These gave extra
support and protection to the canines because when the mouth was closed
the tips of the upper canines would not extend past the lower jaw.
skull displayed here also has another incredible feature that is quite
different in Nimravids and sets them apart from Felidae. In this amazing
skull, a very nice endocast of the brain is visible. Their brain shape
and lobes are quite different than those in modern cats, being more
elongated, yet still very well equipped for hunting.
relatively short bones that make up the legs of Hoplophoneus indicate
that it accelerated quickly to top running speed, but would would not
have been as fast as some modern cats because its legs could not cover
as much ground with each stride. For this reason Hoplophoneus is
believed to be an ambush hunter that would hide in the undergrowth or
tall grasses, exploding out and chasing down prey animals before they
had time to get away.