Subscribe to download
Homotherium (Scimitar-toothed cat)

Homotherium is an extinct genus of machairodontine scimitar-toothed cat that inhabited North America, South America, Eurasia, and Africa during the Pliocene and Pleistocene epochs from around 4 million to 12,000 years ago. In comparison to Smilodon, the canines of Homotherium were shorter, and it was probably adapted to running down rather than ambushing prey.

Eurasia

The first fossils of this genus were described in 1846 by Richard Owen as the species Machairodus latidens. The name Homotherium (Greek: ὁμός (Hom, 'same') and θηρίον (therion, 'beast')) was proposed by Emilio Fabrini (1890), without further explanation, for a new subgenus of Machairodus, whose main distinguishing feature was the presence of a large diastema between the two inferior premolars. He further described two species in this new subgenus: Machairodus (Megantereon) crenatidens and Machairodus (Megantereon) nestianus. In 1918, the species Homotherium moravicum was described by Woldřich. In 1936, Teilhard de Chardin described the new species Homotherium ultimus based on fossils from the middle Pleistocene-aged site at Zhoukoudian. In 1972, a species Homotherium davitašvlii was described based on fragmentary material found at Kvabebi in Georgia. Further material from Odessa was tentatively assigned to this species in 2004. In 1986, the species Homotherium darvasicum was described based on material from Kuruksay, Turkey. In 1989, another species Homotherium tielhardipiveteaui was named based on fossils from Tajikistan. In 1996, Homotherium hengduanshanense was described based on fossils from the Hengduan Mountains.

There is currently only one recognised species Homotherium in Eurasia during the Late Pliocene-Pleistocene, Homotherium latidens; other species, including H. nestianus, H. sainzelli, H. crenatidens, H. nihowanensis, and H. ultimum, were proposed mainly on size differences, and do not appear to be distinct.

Africa

In 1972 a species Homotherium problematicum (originally Megantereon problematicus) was named based on fragmentary material from Africa. A second African species discovered in Ethiopia, Homotherium hadarensis, was described in 1988. In 1990, Alan Turner challenged the validity of these two species, and later authors typically refrained from referring the African fossils to any specific species. Although in 2015, further material from Dikika was tentatively referred to H. hadarensis.

A third species, Homotherium africanum (originally Machairodus africanus), has also been included.

Americas

In 1905, Merriam described a new species Machaerodus ischyrus. Subsequently, in 1918, Merriam reassigned it to a new genus Ischyrosmilus along with the new species Ischyrosmilus idahoensis. The genus Dinobastis was originally named by Cope in 1893, with the type species Dinobastis serus. In 1965, the species Ischyrosmilus johnstoni was described. In the same paper, it was noted that a comparative study of both Ischyrosmilus and Homotherium might conclude them as synonyms.
In 1966, Churcher named Dinobastis a junior synonym of Homotherium, and recombined D. serus as Homotherium serum. In 1970, a new species Ischyrosmilus crusafonti was described from the early Pleistocene of Nebraska. In 1988, after some debate, the genus Ischyrosmilus was declared a junior synonym of Homotherium and all four species were reassigned to that genus as H. ischyrus, H. idahoensis, and H. johnstoni. The same paper also proposed keeping Dinobastis serus separate from Homotherium. Up to five species have been recognised from North America: H. idahoensis, H. crusafonti, H. ischyrus, H. johnstoni, and H. serum, while other authors suggest that there are only two species, with older Blancan specimens are assigned to the species H. ischyrus, while the younger ones are assigned to the species H. serum.

In 2005, a new species Homotherium venezuelensis was described based on fossils from the Pleistocene of Venezuela. In 2022, it was proposed that Homotherium venezuelensis be reassigned to the genus Xenosmilus.