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Discovery of Oldest Primate Skeleton Reveals They Lived in Trees

The discovery of 62-million-year-old primate bones in New Mexico has provided fresh evidence about how these earliest primates lived. According to the study’s lead author, Professor Stephen Chester, Torrejonia wilsoni “undoubtedly lived in trees.” The partial skeleton containing over 20 bones overturned previous theories that plesiadapiforms, an extinct group of primates, were better suited to life on the ground. The findings were published in May 2017 in Royal Society Open Science.

Based on earlier discoveries of cranial and dental fossils, paleontologists had theorized that these small primates searched the ground for insects. With this latest find, “we now have anatomical evidence from the shoulder, elbow, hip, knee, and ankle joints that allows us to assess where these animals lived in a way that was impossible when we only had their teeth and jaws,” said Chester, a professor at Brooklyn College and The Graduate School, CUNY. This skeleton indicates that plesiadapiforms were more likely to climb trees and hang onto branches. The findings link this primate, which is thought to be transitional between other types of mammals and today’s primates, to other early primate skeletons that have been identified as tree dwellers.

Skeleton composite of Torrejonia wilsoni
Skeleton composite of Torrejonia wilsoni: most elements of the composite skeleton are in ventral view, but some elements are oriented differently to better illustrate articular surfaces. Descriptions and orientations of skeletal elements organized from left to right and then from top to bottom: (a) cranial fragment of R frontal in dorsal, left lateral, right lateral views; cranial fragment of parietals in dorsal, ventral views; (b) R maxilla M1–M3 in occlusal view; L maxilla P4, M2-M3 in occlusal view; R dentary p2–m2 in buccal, lingual, occlusal views; (c) R distal humerus in ventral, dorsal, distal views; R distal radial epiphysis in distal view; R proximal radius in proximal, ventral, lateral, dorsal, medial views; R proximal ulna in ventral, lateral, dorsal, medial views; (d) R scapula fragment in ventral, lateral, dorsal views; L proximal humerus in proximal, ventral, lateral, dorsal, medial views; (e) R partial astragalus in dorsal, lateral, plantar, medial, proximal, distal views; R calcaneus in dorsal, lateral, plantar, medial, proximal, distal views; R cuboid in dorsal, lateral, plantar, medial, proximal, distal views; (f) R partial innominate in ventral, lateral, dorsal, medial views; concretion with proximal femora and L tibia with L proximal femur in ventral view, R proximal femur in ventral view; R tibia in ventral, lateral, dorsal, medial, distal views; L distal femur in ventral, lateral, dorsal, medial, distal views. Scale bars – 1 cm.
Image credit: Chester et al, doi: 10.1098/rsos.170329.

Beyond SUM

Explore This Work
Oldest skeleton of a plesiadapiform provides additional evidence for an exclusively arboreal radiation of stem primates in the Palaeocene
Royal Society Open Science, 2017

Work By
Stephen Chester (Professor, Anthropology and Archaeology) | Profile 1 | Profile 2

Colleges & Schools
Brooklyn College
The Graduate Center

Bonus Content
Earth’s Earliest Primates Lived in Treetops, Paleontologists Say (Sci-News.com)

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