Named By: Joseph Leidy - 1854.
Classification: Chordata, Mammalia, Carnivora, Nimravidae, Nimravinae.
Species: D. felina (type), D. cyclops, D. priseus, D. sqaulidens.
Size: Around 1.1 meters long.
Known locations: North America.
Time period: Rupelian to Chattian of the Oligocene, possibly into the Aquitanian of the Miocene.
Fossil representation: Several specimens.
Dinictis looked and hunted like a
cat, yet it hunted
across North America during a much earlier period before the emergence
of true cats, hence the reason why the label of ‘false
sabre-toothed cat’ is often applied to Dinictis
as well as the other
nimravids. One key difference is the construction of the auditory
bulla in the skull, however even a living Dinictis
would still look
different to a true cat since it was almost certainly plantigrade.
This means that Dinictis walked with the foot
bones flat against the
ground whereas the later and more advanced felids (true cats) walk
on only their toes, a term called digitigrade.
Although the upper canine teeth of Dinictis were no way near as large as those of some of its relatives such as Eusmilus and Hoplophoneus, they do look to be more robust. Whereas the larger toothed nimravids had laterally compressed teeth (wide when viewed from the side but thin from the front) for slicing deep into softer fleshy areas, the upper canine teeth of Dinictis where rounder and hence thicker which meant that they were not as susceptible to breakage. This suggests that Dinictis had a greater reliance upon its teeth for physically holding onto prey while it was still struggling, while larger and more specialised forms like Eusmilus would have probably had to physically restrain their prey before attempting a bite. It is also quite possible that the shorter but stronger canines were used for delivering a puncturing bite to a hard area like the cranium to try and cause a fatal brain injury, or perhaps the back of the neck where the teeth might have been able to wedge between the cervical vertebrae to sever the spinal cord.
The body proportions of Dinictis strongly suggest that it would have been an ambush hunter that lurked within the undergrowth rather than an open ground pursuit predator. This behaviour is actually very intelligent in its simplicity since most of the herbivorous mammals of the time would have been browsers of vegetation and would have inevitably had to put themselves in danger of being attacked by ambush predators like Dinictis in order to feed.
- Taxonomic and systematic revisions to the North American Nimravidae (Mammalia, Carnivora). - PeerJ. 4: e1658. - P. Z. Barrett - 2016.