The holotype and only specimen assigned to Sivasmilus, a partial left mandible labelled GSI-D 151, was collected from the Chinji locality in the Salt Range, same as the holotype specimen of Sivaelurus chinjiensis; that fact along with their similar size led paleontologist Guy Ellcock Pilgrim to provisionally assign GSI-D 151 to S. chinjiensis when he described the fossil in 1915.

[1] In 1929, paleontologist W. D. 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;[2] in that same year, Hungarian paleontologist Miklós Kretzoi reached the same conclusion in a wholly separate paper and erected the new genus and species Sivasmilus copei for it.

[3] 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.

[1][4] It was noted by several authors that the chin formed a more obtuse angle with the lower edge of the ramus than was usual in "machaerodonts" (which at the time included the nimravids and barbourofelids).

[4] The genus Sivasmilus was originally assigned to the subfamily Machairodontinae in the family Felidae,[4] though a 2021 study referred it without explanation to the Barbourofelinae.