Sivasmilus

Sivasmilus is a fossil genus of machairodontine (saber-toothed cat) from the Early or Middle Miocene of Pakistan. It contains one species, Sivasmilus copei, which is known from a single fossil, a partial lower jawbone, that was collected from the Chinji Formation in the Lower Siwaliks. The fossil was originally described in 1915 by British paleontologist G. E. Pilgrim, who assigned it to the prehistoric feline species Sivaelurus chinjiensis. It was subsequently used as the basis of a new genus and species in 1929 by Miklós Kretzoi. Sivasmilus copei was a medium-sized, cat-like animal that weighed between 30 and 50 kilograms (66 and 110 lb) and lived in a swampy forest environment.

History and naming

The holotype and only specimen assigned to Sivasmilus, a partial left mandible labelled GSI-D 151, was collected from the Chinji type locality in the Salt Range of the Siwaliks. The similarly sized holotype of Sivaelurus chinjiensis was also found at this site, which led paleontologist Guy Ellcock Pilgrim to provisionally assign GSI-D 151 to S. chinjiensis when he described the fossil in 1915.

In 1929, American paleontologist William Diller Matthew considered the holotype of Sivaelurus to be distinctly feline, but the mandible fragment GSI-D 151 to be distinctly machaerodont (saber-toothed cat) based on features of the teeth. Hungarian paleontologist Miklós Kretzoi reached a similar conclusion that same year in a wholly separate paper and erected the new genus and species Sivasmilus copei for it; no etymology was given for either name. In his 1932 paper on Siwalik carnivorans, Pilgrim acknowledged this reassignment and agreed with its machaerodont affinities, stating that he had sought to avoid establishing an ill-defined genus when he assigned it to Sivaelurus.