Nimravidae

The family Nimravidae was named by American paleontologist Edward Drinker Cope in 1880,^[9] with the type genus as Nimravus. The family was assigned to Fissipedia by Cope (1889); to Caniformia by Flynn and Galiano (1982); to Aeluroidea by Carroll (1988); to Feliformia by Bryant (1991); and to Carnivoramorpha, by Wesley-Hunt and Werdelin (2005).^[10]

Nimravids are placed in tribes by some authors to reflect closer relationships between genera within the family. Some nimravids evolved into large, toothed, cat-like forms with massive flattened upper canines and accompanying mandibular flanges. Some had dentition similar to felids, or modern cats, with smaller canines. Others had moderately increased canines in a more intermediate relationship between the saber-toothed cats and felids. The upper canines were not only shorter, but also more conical, than those of the true saber-toothed cats (Machairodontinae). These nimravids are referred to as "false saber-tooths". The barbourofelids were for a while no longer included in Nimravidae, following elevation to family as sister clade to the true cats (family Felidae).^[11][12] However, majority of recent studies have returned them to Nimravidae, with one study suggesting they are part of Nimravinae.^{[1][5][13][6][7]}

Not only did nimravids exhibit diverse dentition, but they also showed the same diversity in size and morphology as cats. Nimravids such as Barbourofelis morrisi, Eusmilus sicarius, and Hoplophoneus occidentalis were leopard-sized,^[14][15][16] while some, such as Albanosmilus jourdani and E. adelos, were the size jaguars to small lions.^[1][17] The largest nimravids, Quercylurus and Barbourofelis fricki, were able to reach even larger sizes, weighing 200 kg (440 lb) and 328 kg (723 lb) respectively.^[18][1] Dinaelurus had the short face, rounded skull, and smaller canines of the modern cheetah,^[1] and some such as E. bidentatus and Nanosmilus, were only the size of a small bobcat.^[19][20]

More information Tribe, Image ...

Family †Nimravidae

Tribe	Image	Genus	Species
		†Dinailurictis (Helbing, 1922)	†D. bonali
		†Dinictis (Leidy, 1854)	†D. felina
		†Eofelis (Kretzoi, 1938)	†E. edwardsii †E. giganteus
		†Saketoteron (Srivastava & Verma, 1970)	†S. tatroinse
		†Maofelis[21] (Averianov et al., 2016)	†M. cantonensis
		†Pangurban[2] (Poust et al, 2022)	†P. egiae
		†Pogonodon (Cope, 1880)	†P. davisi †P. platycopis
		†Quercylurus (Ginsburg 1979)	†Q. major
†Nimravini		†Dinaelurus (Eaton, 1922)	†D. crassus
		†Nimravus (Cope, 1879)	†N. brachyops †N. intermedius
†Hoplophoneini		†Hoplophoneus[22] (Cope, 1874)  (Subgenus: †Eusmilus[22] (Eaton, 1922))	†H. bidentatus   †H. cerebralis  †H. dakotensis †H. mentalis †H. occidentalis †H. oharrai †H. primaevus  †H. sicarius  †H. villebramarensis
		†Nanosmilus (Martin, 1992)	†N. kurteni

Close

Most nimravids had muscular, low-slung, cat-like bodies, with shorter legs and tails than are typical of cats. Unlike extant Feliformia, the nimravids 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. They are assumed to have had a cartilaginous housing of the ear mechanism.^[24] Nimravid feet were short, indicating they walked in a plantigrade or semiplantigrade posture, i.e., on the flat of the feet rather than the toes, like modern cats.^[25]

Although some nimravids physically resembled the saber-toothed cats, such as Smilodon, they were not closely related,^[26] but evolved a similar form through parallel evolution. They had synapomorphies with the barbourofelins in the cranium, mandible, dentition, and postcranium.^[27] They also had a downward-projecting flange on the front of the mandible as long as the canine teeth, a feature that also convergently evolved in the saber-toothed sparassodont Thylacosmilus. While most nimravids were thought to have been ambush predators,^{[28][29][30][31]} some such as Eusmilus adelos and Pogonodon davisi were recovered as pounce-pursuit predators.^[32] Albanosmilus whitfordi and Dinaelurus are thought to have been cursorial predators, although no post cranial remains have been found for Dinaelurus.^[33][34][1]

A 2021 study has shown that a sizeable number of species developed feline-like morphologies in addition to saber-toothed taxa.^[5]

The ancestors of nimravids and cats diverged from a common ancestor soon after the Caniformia–Feliformia split, in the middle Eocene about 50 million years ago (Ma), with a minimum constraint of 43 Ma.

Some of the first nimravids, Maofelis and Pangurban, appeared in the Middle Eocene epoch of Asia and North America respectively.^[8][35]

The global climate at this time was warm and wet, but was trending cooler and drier toward the late Eocene. The lush forests of the Eocene were transforming to scrub and open woodland. This climatic trend continued in the Oligocene, and nimravids evidently flourished in this environment. North America and Asia were connected and shared much related fauna.^[36] Their diversification and increase in body size coincided with the decline and extinction of the oxyaenids, which opened the cat-like carnivore niche.^[37] Nimravids made their appearance in Europe within MP21 following Grande Coupure.^[38]

Barbourofelines probably evolved from nimravines dispersing into Africa during the Oligocene. The presence of large hyaenodonts prevented them from reaching a large size but were able to carve a niche due to their dental morphology. Eventually, they dispersed from Africa into Eurasia and later into North America.^[1]