Plesiadapis tricuspidens


TAXONOMY:

MORPHOLOGY:
Plesiadapis tricuspidens had a diastema between the incisors and the cheek teeth in the upper and lower jaws (Fleagle, 1988). The dental formula of this species was 2:0:3:3 on the upper jaw and 1:0:2:3 on the lower jaw (Conroy, 1990). This species had procumbent incisors (Fleagle, 1988). The incisors were rodent-like in form (Conroy, 1990). The upper incisors of this species were arranged longitudinally rather than transversely as found in extant primates (Martin, 1990). The upper incisors had three pointed cusps towards the front, middle, and side, the anterocone, the mediocone, and the laterocone, and there was a cusp in the back called the posterocone (Conroy, 1990). Plesiadapis tricuspidens lacked lower canines (Conroy, 1990). This species has a long snout and a large premaxillary bone (Fleagle, 1988). This species had a tympanic bone which was fused to the auditory bulla and formed a bony tube (Szalay, 1975; cited in Fleagle, 1988). This species had a cranial capacity of about 18 cc and an encephalization quotient of 0.62 (Conroy, 1990). This species was found to have an overall robustness of the skeleton, with short robust limbs, laterally compressed claws, and a long, bushy tail (Fleagle, 1988). This species had an average body mass of around 2.1 kilograms (Fleagle, 1990).

RANGE:
Plesiadapis tricuspidens was found on the continent of Europe, and occurred during the early Eocene (Fleagle, 1988).

ECOLOGY:
Plesiadapis tricuspidens had teeth that were adapted for the consumption of plants (a folivore) (Conroy, 1990).

LOCOMOTION:
Based upon the postcranial skeleton this species was most likely an arboreal quadruped (Fleagle, 1988).

REFERENCES:
Conroy, G.C. 1990. Primate Evolution. W.W. Norton and Co.: New York.

Fleagle, J.G. 1988. Primate Adaptation and Evolution. Academic Press: New York.

Martin, R.D. 1990. Primate Origins and Evolution: A Phylogenetic Reconstruction. Princeton University Press: Princeton, New Jersey.

Szalay, F.S. 1975. Phylogeny of Primate Higher Taxa: The Basicranial Evidence. In Phylogeny of the Primates: A Multidisciplinary Approach. Eds. W.P. Luckett and F.S. Szalay. Plenum Press: New York.

Last updated: November 20, 2002

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