Bear - Evolutionary History

Evolutionary History

The family Ursidae is one of nine families in the suborder Caniformia, or "doglike" carnivores, within the order Carnivora. Bears' closest living relatives are the pinnipeds, canids and musteloids.

The following synapomorphic (derived) traits set bears apart from related families:

  • presence of an alisphenoid canal
  • paroccipital processes that are large and not fused to the auditory bullae
  • auditory bullae are not enlarged
  • lacrimal bone is vestigial
  • cheek teeth are bunodont and hence indicative of a broad, hypocarnivorous (non-strictly meat-eating) diet (although hypercarnivorous (strictly meat-eating) taxa are known from the fossil record)
  • carnassials are flattened

Additionally, members of this family possess posteriorly oriented M2 postprotocrista molars, elongated m2 molars, and a reduction of the premolars.

Modern bears comprise eight species in three subfamilies: Ailuropodinae (monotypic with the giant panda), Tremarctinae (monotypic with the Spectacled Bear), and Ursinae (containing six species divided into one to three genera, depending upon authority).

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