Yesterday we looked at three bears, Ursus, Arctodus (Fig. 1) and Ailuropoda (the polar bear, the short-faced bear and the panda bear). They do not form a single bear clade in the large reptile tree (LRT, 1299 taxa), but each is more closely related to small weasels and grew to bear-size by convergence.
Arctodus is most closely related to today’s wolverine (Gulo gulo, Figs. 1, 2) among tested taxa, and the similarities are immediately apparent. Have they ever been tested together before? Let me know if this is so.
Arctodus simus (Leidy 1854; Cope 1874; up to 3 to 3.7m tall) is the extinct short-faced bear, one of the largest terrestrial mammalian carnivores of all time. Long limbs made it a fast predator. Being related to the wolverine made it short-tempered and dangerous.
Gulo gulo (Linneaus 1758; up to 110 cm in length) is the extant wolverine, a ferocious predator resembling a small bear. Note the tail length is midway between the long tail of weasels and the short tail of birds.
The skulls of Gulo and Arctodus
(Figs. 4, 5) despite their size differences, are quite similar. Both display sexual dimorphism.
sheds light on phylogenetic interrelationships.
Cope ED 1879. The cave bear of California. American Naturalist 13:791.
Leidy 1854. Remarks on Sus americanus or Harlanus americanus, and on other extinct mammals. Proceedings of the Academy of Natural Sciences of Philadelphia 7:90.
Linnaeus C 1758. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata.