Tremarctinae
The Tremarctinae or short-faced bears is a subfamily of Ursidae that contains one living representative, the spectacled bear of South America, and several extinct species from four genera: the Florida spectacled bear, the North American short-faced bears of genera Plionarctos and Arctodus, and the South American giant short-faced bears of Arctotherium. The group is thought to have originated in eastern North America, and then invaded South America as part of the Great American Interchange.Systematics
Traditionally the phylogenetic inner relationships of tremarctines had Plionarctos and Tremarctos being basal groups with respect to a short-faced bear clade of Arctodus and Arctotherium. A study of the affinities of bears belonging to Arctotherium indicates that they were more closely related to the spectacled bear than to Arctodus, implying convergent evolution of large size in the two lineages.Taxonomy
The following taxonomy of the tremarctine bears follow by Mitchell et al. :
- Subfamily Tremarctinae
- * †Plionarctos
- ** †Plionarctos harroldorum
- ** †Plionarctos edensis
- * †Arctodus
- ** †Arctodus simus
- ** †Arctodus pristinus
- * †Arctotherium
- ** †Arctotherium angustidens
- ** †Arctotherium vetustum
- ** †Arctotherium wingei
- ** †Arctotherium bonariense
- ** †Arctotherium tarijense
- * Tremarctos
- ** †Tremarctos floridanus
- ** Tremarctos ornatus – spectacled bear
