Above are drawings of Hesperocyon (left) and Sunkahetanka, two early ambush-style dogs.

Climate change impacts ecosystems and how they evolve. The same holds true for canines within those ecosystems, a new study suggests. And it all has to do with elbows.

The study, published on August 18 in Nature Communications, was a joint effort between the Universidad de Málaga in Málaga, Spain; the American Museum of Natural History in New York; and Brown University in Providence, R.I.

Researchers examined 40 million year old dog fossils discovered in North America, and, specifically, the elbow joints of such fossils. It then compared those elbow joints to those from approximately two million years ago and identified morphological differences, reported the New Historian.

Older elbows, it turns out, were made for grabbing prey; “newer” elbows were made for running.

As the earth’s climate cooled and the Rocky Mountains emerged to block more humid air from the east, arid plains appeared to replace lush forests. That’s when canines’ bodies adapted to “pursuit hunting” rather than “ambush” hunting, noted the New Historian.

The researchers concluded that climate change and its impact on vegetation and habitat structure played a critical role, not only for ecological innovation but also in altering canine evolution.

Photo courtesy of Mauricio Antón, copyright © 2015 Mauricio Antón