page_title: Plesiadapis
section_title: Anatomy and remains
hierarchical_section_title: Plesiadapis / Anatomy and remains
caption_attribution_description: English: Plesiadapis
context_page_description: Plesiadapis is one of the oldest known primate-like mammal genera which existed about 55–58 million years ago in North America and Europe. Plesiadapis means "near-Adapis", which is a reference to the adapiform primate of the Eocene period, Adapis. Plesiadapis tricuspidens, the type specimen, is named after the three cusps present on its upper incisors.
context_section_description: Nearly all of what is known about the anatomy of plesiadapiforms comes from fragmentary jaws and teeth, so most definitions of plesiadapiform genera and species are based on dentition. Plesiadapis' dentition shows a functional shift toward grinding and crushing in the cheek teeth as an adaptation towards increasing omnivority and herbivority. The dental formula for Plesiadapis is  
  The skull of Plesiadapis is relatively broad and flat, with a long snout with rodent-like jaws and teeth and long, gnawing incisors separated by a gap from its molars. Orbits are still directed to the side, unlike the forward-facing eyeballs of modern primates that enable three-dimensional vision. Although its braincase was small by today's standards, it was larger in proportion to the rest of the animal's overall body mass than in the contemporary hoofed mammals, for instance. Plesiadapis had mobile limbs that terminated in strongly curved claws, and it sported a long bushy tail which is beautifully preserved in the Menat skeletons. The way of life of Plesiadapis has been much debated in the past. Climbing habits could be expected in a relative of the primates, but tree-dwelling animals are rarely found in such high numbers. Based on this and other evidence, some paleontologists have concluded that these animals were mainly living on the ground, like today's marmots and ground squirrels. However, more recent investigations have confirmed that the skeleton of Plesiadapis is that of an adept climber, which can be best compared to tree squirrels or to tree-dwelling marsupials such as possums. The short, robust limbs, the long, laterally compressed claws, and the long, bushy tail indicate that it was an arboreal quadruped. Remains found showed that it had a body mass of around 2.1 kilograms (4.6 lb).
caption: Restoration
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