Hyperailurictis

Restoration of Mascall assemblage fauna, with Hyperailurictis in the tree at the upper right

In 1858, the paleontologist Joseph Leidy described a new species of cat, Felis intrepidus, based on lower jaw fragments (a left ramus, described, and a right ramus, mentioned only and now lost) found somewhere in Nebraska near the Niobrara river.[1] The fragments were later determined to have come from the lower Valentine Formation, making them late Barstovian in age. Leidy reassigned the specimens to Pseudaelurus as Pseudaelurus intrepidus in a 1869 paper.[2]

In 1873, an expedition collected another lower jaw from the lower Valentine Formation, which was described by Thorpe in 1922 as the holotype of the new species Pseudaelurus marshi. He also described a paratype, a left ramus collected from part of the Ogallala Group (also of Barstovian age).[3][2]

In 1934, Chester Stock assigned five specimens to Pseudaelurus intrepidus. The specimens, which included the first cranial and upper dental material to be assigned to North American Pseudaelurus, were found at an early Barstovian locality in Nevada. One specimen, a skull, would later undergo considerable plaster restoration.[2]

In 1948, J. R. Macdonald described Pseudaelurus pedionomus based on a considerable amount of material (including a good part of the skeleton) from an early Clarendonian locality in Nebraska.[4] Shortly after, he also described Pseudaelurus thinobates, a larger species from a late Clarendonian locality in California.[5] However, David Kitt removed Pseudaelurus thinobates from the genus, placing it instead as Nimravides thinobates, during a 1958 study.[6] Subsequently, a review of the genus reassigned Pseudaelurus pedionomus to the new genus as Nimravides pedionomus.[7][2]

J. R. Macdonald described a third species, Pseudaelurus aeluroides, in 1954 based on a single lower jaw fragment. The fragment was found in the lower Snake Creek locality, and was from the early Barstovian.[8] The fragment remained the only specimen assigned to Ps. aeluroides, and an examination of illustration and measurements of the fragment in 2003 lead Tom Rothwell to suggest that it actually belonged to a juvenile Ps. marshi.[2]

In 1963, some early Clarendonian material from Colorado, mostly skeletal pieces and all from a single individual, was referred to genus Pseudaelurus, but a species determination was not made.[2]

In 1969, some material from the Hemphillian of Texas was referred to the new species Pseudaelurus hibbardi.[9] Similar in size to Nimravides pedionomus, this was referred in 2003 to Nimravides hibbardi instead.[2]

In 2001, Tom Rothwell described a skeleton from the later Hemingfordian as Pseudaelurus validus. The skeleton was originally collected in 1939 from the Nambe Member locality in New Mexico. In the same paper, he also assigned a number of specimens collected from multiple localities in Nebraska, dated to the late Hemingfordian and early Barstovian.[10][2]

A systematic review of the genus in 2003 by Tom Rothwell nominated a new species, Pseudaelurus skinneri, and recombined Lynx stouti as Pseudaelurus stouti. Pseudaelurus skinneri was described based on several jaw fragments collected from various late Hemingfordian localities in Nebraska. Lynx stouti was first described in 1972 based on some late Barstovian material, a partial skull and mandible, collected in Colorado.[11] He also referred a number of other specimens, collected from early Barstovian localities in Nebraska and New Mexico and from late Barstovian localities in New Mexico and Colorado, to Pseudalurus stouti.[2]

The genus Hyperailurictis was first described in 1929 by Ketzoi, using Pseudaelurus intrepidus as the type species, proposed to include all Pseudaelurus-grade felids from North America.[12] However, this was largely ignored by later studies until a 2010 review of the Felidae as a whole brought up the proposal again, leading to some authors, though not all, recognizing the generic split.[13]