Nimravides is a genus of extinct saber-toothed cats that was endemic in North America during the Late Miocene, from 11 to 6.5 Ma.^[1] Despite its scientific name, Nimravides does not belong to the Nimravidae, but is a true cat belonging to the family Felidae.^[2]

The genus Nimravides was originally described by Kitt in 1958 for the species "Pseudaelurus" thinobates.^[3] In 1969, Dalquest described the species Pseudaelurus hibbardi.^[4] The species Machaerodus catocopis was described by Cope in 1887, based on a partial mandible from the Loup Fork Beds.^[5] The species Pseudaelurus thinobates and Pseudaelurus pedionomus were both described by James Reid MacDonald in 1948.^[6][7]

In 1975, Martin and Schultz reassigned Machairodus catacopsis to Nimravides and suggested that N. thinobates was a junior synonym of the former species.^[8] The species N. galiani was first described in 1981 based on fragmentary material from the Love Bone Beds in Florida. The same paper also described additional fossils of N. thinobates compared to the holotype of N. catacopsis, and concluded that N. catacopsis was best considered a nomen vanum and the material assigned to it should be considered N. thinobates.^[9]

"Pseudaelurus" pedionomus was reassigned to Nimravides in 1990 by Beaumont.^[10] In 2003, Tom Rothwell reassigned Pseudaelurus hibbardi to Nimravides.^[11] And in 2010 it was suggested that N. hibbardi was a junior synonym of Adelphailurus kansensis.^[12] In 2013, Mauricio Anton et al. suggested that N. catacopsis should be re-reassigned back to Machairodus.^[13] But this was refuted in 2022 by Jiangzuo et al. and also assigned M. lahayishupup to N. catocopis, considering it as a local subspecies due to its dental difference being a intraspecific variation based on the large sample.^[1]

Nimravides catocopis, the largest and latest species, was quite large, measuring 100 cm (1.0 m) at the shoulder and was similar in size to a large tiger. It was also possessed of long, powerful legs and a long back.^[14] Based on mandibular and dental sizes, this species was slightly larger than M. aphantistus on average. Hh2 populations of N. catocopis grew rather large, with two large femurs, presumably males, reaching lengths similar to the American lion.^[1] The supposed subspecies N. catocopis lahayishupup was also quite large; fossil humerus bones measuring 18 in (46 cm)attributed to the species suggest that this cat was far larger than a modern lion, which has a 13 in (33 cm) humerus. It is estimated to have weighed between 241 and 348 kg, with a mean weight of 277 kg; one particularly large specimen was estimated to weigh 410 kg.^[15]

N. catocopis lahayishupup (Previously considered M. lahayishpup) may have preferred prey that typically weigh 413-1,386.3 kg with the maximum prey size being 1.6 tonnes, although it may not have been a large prey specialist.^[16]

N. catocopis lahayishupup is found is Hemphillian rocks from Chalk Hills Formation, Rattlesnake Formation, McKay Formation, and Ogallala Formation.^[17] Within those formations, it coexisted with other Miocene animals such as Teleoceras fossiger, Indarctos oregonensis, and Hemiauchenia vera. It would've would have most likely preyed on the large animals that it lived alongside, which included rhinoceroses, and Hemiauchenia.^[18][19]

Due to the differences in cranial and forelimb morphology, Amphimachairodus didn’t have a competitive edge over Nimravides, implying that neither newcomer or endemic species were superior to one another in hunting adaptations.^[1]