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Dog family tree traced back two million years

Doggy tales A new cache of extremely well preserved, prehistoric canine fossils is shedding light on dog and wolf ancestors from two million years ago to today.

The fossils, described in the latest issue of the Journal of Mammalian Evolution , date to that early period and belonged to a scrappy canine carnivore known as Canis etruscus that lived near Rome, Italy.

"Canis etruscus appeared approximately two million years ago and is the oldest European species referred to in the genus Canis," says lead author Marco Cherin, adding that this species "was considerably smaller than the modern wolf."

"We can suppose that it was a social dog, as most of the living species of similar size," continues Cherin, who is a researcher at Perugia University's Department of Earth Sciences. "Hunting in packs, Canis etruscus could have preyed on small to medium-sized animals."

The prey of this carnivore, which looked like a cross between a German shepherd and a wolf, would have included animals such as ancient relatives of deer and pigs.

This apparent mother of all dogs in Europe likely gave rise to another member of the dog/wolf family tree, Canis mosbachensis, about 1 million years ago. Canis mosbachensis, in turn, is considered to be a direct ancestor of modern wolves.

Dog, wolf common ancestor

Until recently, it was thought that dogs were domesticated from the grey wolf, but a separate study earlier this month countered that popular belief.

"The common ancestor of dogs and wolves was a large, wolf-like animal that lived between 9000 and 34,000 years ago," says Robert Wayne of University of California, Los Angeles, who was co-senior author of the study.

That animal went extinct thousands of years ago and, as of now, remains unknown.

What is known about dog history is that the first canines came from North America, says Cherin. The earliest documented species was Canis lepophagus, aka the "hare-eating wolf." Like the prehistoric canine from Italy, it was relatively small and had a narrow head.

Canines spread to Asia and then to Europe. It was in Eurasia at least 780,000 years ago that a dog relative might have encountered a member of our genus.

Companion or meal?

Eudald Carbonell, a professor at the University of Rovira and Virgili, says fossils of Homo antecessor — an extinct human that looked a lot like us — were found with fossils of Canis mosbachensis in Spain.

Could this very early human have enjoyed the companionship of the dog/wolf relative, or was the latter considered to be good eats or a predator? The fossil record so far, unfortunately, does not have those answers.

Carbonell and his team did find evidence for cannibalism — for nutritional purposes — among Homo antecessor individuals, so it's likely that this early, hungry human hunted the dog and wolf relative.

As the human population continued to expand and evolve in Europe and Asia, people discovered how valuable canines could be for security, hunting, companionship and more, resulting over time in the domestication of dogs.

That moment of doggy revelation might have even happened in Italy, since recent DNA evidence suggests the first domesticated dogs were from Europe.

Marina Sotnikova of the Geological Institute of Russian Academy of Sciences says the fossils discovered in Italy are "very interesting" and "allow for a more detailed study of this group of carnivores."