The news of this discovery is a couple of years old; because of the COVID lockdown, it took them a while to identify the “ancient dog” in this fossil bed:
We’re not talking about someone’s lost elderly pet.
It’s so old a creature that I found no good feature images and went with a fox because everyone calls its fossils “fox-like.”
It’s Archaeocyon — science-speak for “ancient dog.”
This multimillion-year-old canid probably came after the days of Pangurban — the other fossil San Diego carnivore we’ve met — but there were plenty of other cat-like nimravids around, and it’s unlikely that Archaeocyon barked at any of these apex predators or chased them up trees.

“MEOW!” — Hoplophoneus. (Image: ghedoghedo via Wikimwedia, CC BY- SA 3.0)
Little Archaeocyon sounds like a total wuss, according to Dr. Wikipedia:
Archaeocyon was a comparatively small and unspecialized dog. Its dentition (teeth) suggests a slightly more hypocarnivorous (omnivorous) diet than the otherwise similar Hesperocyon. The skeleton is also generalized, lacking specializations for running and retaining a plantigrade foot posture.
But I think it was badass in at least two ways:
- Despite the nimravids and other predators, fox-like Archaeocyon is considered one of the ancestral “bone-crushing dogs.”
- It lived for millions of years upwind and next door to Hell: the ignimbrite flareup that blasted out some 500,000 cubic km of volcanic debris across western North America. (Source, with a jargon alert)
We’ll take a look at that flareup tomorrow.
Eventually, towards the end of the explosive period, Archaeocyon disappeared, as did nimravids (leaving a “cat gap” in the North American fossil record until a pseudaelurine felid prowled in across a land bridge some 16 million years ago).
But during that flareup the White River Fauna downwind thrived.
Why?
I have no idea. It’s one of the more puzzling and complex parts of the story of how cats — and dogs — evolved.
Lagniappe:
I like the cat statue.
Featured image: Image by Jevgeni Fil from Pixabay