The discovery of a new fossil in Southern California has offered researchers a more complete look at an ancient dog species. Found by paleontologists at the San Diego Natural History Museum, the skeleton is believed to belong to a group of early canids called Archeocyons. Researchers estimate the fossil’s age at around 24 million to 28 million years old.
Archeocyons, a name that means “ancient dog,” is still a big mystery to scientists. Although there’s proof they once existed, there are still many questions that have yet to be answered. We don’t know much about their body structure, diets, hunting habits, and relation to other dog-like species.
A nearly complete fossil like this one can help fill these gaps in our knowledge.
The San Diego Natural History Museum received this specimen back in 2019, when the museum’s paleo monitor noticed bones sticking out of some excavated rock at a major construction site. (A California law requires paleontologists to supervise big construction projects to spot and protect any fossils.) But they weren’t able to dig into the rock until December 2021 due to the pandemic.
Once they got the go-ahead, curatorial assistant Amanda Linn’s duty was to unearth the skeleton. But it wasn’t easy. Linn spent close to 120 hours over three months trying to reveal the fossil.
“As soon as you uncover the bones, they start to disintegrate,” Linn told the San Diego Union-Tribune. “I used a lot of patience, and a lot of glue.”
It took some work to figure out what they were looking at. The bones were jumbled and very fragile; it wasn’t until Linn uncovered the cheekbone and omnivorous teeth that the researchers understood this was a doggy ancestor.
“It’s like you’ve found a tree branch, but you need more branches to figure out what kind of tree it is,” explained Linn. “Every time I uncovered a new bone, the picture got clearer. I’d say, ‘Oh look, here’s where this part matches up with this bone, here’s where the spine extends to the legs, here’s where the rest of the ribs are.’”
The Archeocyon skeleton isn’t a hundred percent complete — a portion of its long tail is missing. But that hasn’t dampened the importance of this find. It has already offered insight into what Archeocyons might have looked like.
According to the museum’s post-doctoral researcher, Ashley Poust, the length of the skeleton’s ankle bones implies it was a long-distance runner. Its feet also appear suited to climbing nimbly into trees. Unlike a large wolf or domestic dog, Archeocyons were about the size of a grey fox and had long legs, a small head, and a strong tail used for balance.
It’s not uncommon to find Archeocyon fossils in the Pacific Northwest, but Southern California rarely sees such finds. Over the years, glaciers and shifting tectonic plates have destroyed or hidden many fossils from that time period. It was really fortunate for researchers to discover a mostly intact skeleton like this in such a rare location.
As of now, the fossil is still embedded in the rock. Museum curator of paleontology Tom Deméré halted any further work, concerned about the potential damage it could cause to the skull. He’s hoping a carnivore researcher can stop by to study the specimen before they continue uncovering it.
“Nothing makes a curator happier than having visiting researchers to the collection,” Deméré said. “Hopefully, someone comes along. A nearly complete skeleton like this can answer all sorts of questions, depending on who’s interested.”
