OREGON MUSEUM FOSSIL CONFIRMED AS 30-MILLION-YEAR-OLD DOG

A fossil held in an Oregon museum collection for decades has been confirmed as the most complete skeleton of a pre-Ice Age dog discovered in North America. Palaeontologists from the University of Michigan identified the remains as belonging to Mesocyon coryphaeus, a canid species that lived over 30 million years ago. The fossil was initially discovered in the late 1980s near John Day Fossil Beds National Monument on Bureau of Land Management lands. When first unearthed, researchers mistakenly believed it belonged to an early relative of sheep, camels or pigs, before later recognising it as a dog fossil. The skeleton is missing only the tail and parts of the animal's hands and feet, making it exceptionally complete.

Researchers carefully extracted the fossil and its surrounding rock in the late 1980s, wrapping it in a plaster jacket for protection. In the 1990s, scientists separated the head for display and identified it as a canid. The remainder of the skeleton was uncovered in 2012 by park palaeontologists, including Jennifer Cavin. Comparative analysis of the teeth, skull and other skeletal features confirmed the identification. The fossil possessed an osteochondroma, a hereditary bone growth on the wrist found in approximately 60 per cent of earliest dog fossils, and a baculum, or penis bone, indicating the specimen was male.

Analysis of the skeleton revealed Mesocyon coryphaeus differed substantially from modern dogs. The animal had robust, shorter and stockier bones unsuited for running, and could rotate its forearms for grappling and climbing—abilities absent in contemporary canines. Fossil evidence indicated the prehistoric dog occasionally walked heel-down rather than on its tiptoes like modern dogs. Anne Kort, lead author of the study published in the Journal of Palaeontology, noted that Mesocyon coryphaeus had previously been identified only by single skulls, making this complete skeleton a significant discovery for understanding pre-Ice Age canid evolution.