Newly-Discovered Fossils Reveal How Ancient Dogs Differed From Today's Faithful Compan
These canines are believed to have roamed the San Diego area up to 28 million years ago.

By Adele Ankers
Updated: 3 May 2022 

Palaeontologists have unearthed the fossilized skeletal remains of a long-extinct dog species, providing new information about the evolution of the mammal.

The San Diego Union-Tribute reports that the rare fossil ended up at the San Diego Natural History Museum after being spotted protruding out of an excavated chunk of rock during a construction project in the southern region of San Diego in 2019. Palaeontologists at the museum later picked up their tools and brushes to uncover the fossil embedded within.

Image credit: William Stout.

Once the paleo team brought the fossilized cheekbones and teeth to the surface, they were able to identify the canine. They discovered that the fossil belonged to a group of animals called Archeocyons, aka "ancient dog," that would have roamed the area we now know as San Diego between 24 million and 28 million years ago during the late Oligocene epoch.

"It's like you've found a tree branch, but you need more branches to figure out what kind of tree it is," said curatorial assistant Amanda Linn, who is said to have spent nearly 120 hours chipping away at the rock to unearth the ancient dog fossil. "As soon as you uncover the bones, they start to disintegrate... I used a lot of patience, and a lot of glue."

Linn said the "picture got clearer" every time they uncovered a new bone, and fortunately for science, they uncovered a lot of bones in the process. The fossil was very much intact, with the skull, teeth, spine, legs, ankles, and toes all emerging from the rock to give the team a better view and fresh insight into how ancient dogs differed from today's faithful companions.

Post-doctoral researcher Ashley Poust, who worked on the project alongside Linn and the museum's curator of palaeontology Tom Deméré, said the Archeocyon was comparable in size to that of today's gray fox. To further support that, Poust highlighted a foxlike creature in William Stout's mural (pictured above) for its resemblance to the ancient dog species.

It's also understood that the Archeocyon "walked on its toes" and had "nonretractable claws," which could have been used to climb up trees where it's possible they may have taken up residence. They are also said to have had long legs to be able to chase their prey across long distances, paired with a strong, muscular tail that they likely used for balance.

More details about the species will no doubt come to light following further examination of the fossilized remains. "Nothing makes a curator happier than having visiting researchers to the collection," Deméré said, extending an invite to his academic peers. "A nearly complete skeleton like this can answer all sorts of questions, depending on who's interested."