Wolves from the past: living with sabertooths
If I could travel back in time to the late Pleistocene of Rancho la Brea in California, I would sure try to set the controls of my time machine so as to coincide with one of the rare entrapment episodes, when the trashing of one large bison or horse trapped in the sticky asphalt attracted dozens of large, hungry predators. It has been calculated that one such episode every ten years would be enough to account for the thousands upon thousands of fossils accumulated at the site, so for most of the time life around the tarpits would be business as usual, and our trip around the area would be just like any safari in today’s African reserves -meaning that the big carnivores would be rather difficult to come across! We would probably drive for hours and see impressive herds of mammoths, horses and bison, but we would just wonder, where the carnivores are?
But if our arrival coincided with an entrapment episode, there is one carnivore we would be more likely to see than any other: the dire wolf, Canis dirus. Known from the bones of more than 1600 individuals from the site, this was obviously one of the dominant predators in the area, and it would stand its ground to such impressive competitors as the sabertooth cat Smilodon fatalis or the even larger American lion, Panthera atrox.
What did Canis dirus look like? Reading the paleontological literature I came across texts describing it as a “hyena-like wolf”, with short legs and a massive head with a powerful crushing dentition. However, a visual inspection of dire wolf fossils showed them to be perfectly wolf-like to me. In order to get a clearer idea of how the animal would look in life, I made a careful drawing of the skeleton using as main reference the descriptions, photographs and measurements made by American paleontologist John Merriam, together with my own photos of dire wolf fossils from different sites.
The result: a skeleton that showed only slight differences from that of a modern gray wolf, which can be summarized as follows: the dire wolf was on average a little larger, with a slightly larger head and feet that were a bit shorter. Those differences were clearly evident when you compared the measurements, but they were so slight that the overall visual impression when looking at the skeleton was overwhelmingly wolf-like.
Then I proceeded to add soft tissue from the inside out, starting with the deep muscles -those whose attachments leave clearest impressions on the bone- and then adding more superficial layers.
To reconstruct the animal’s fur, I used as reference the coat of its closest living relatives, that is, wild extant members of the genus Canis. In these animals, from jackals to coyotes to gray wolves, fur color patterns are variable but can be described as variations on a theme, and a very stable one, so the phylogenetic affinities of Canis dirus leave us little room for invention in terms of its coat colour.
So I think that in our time travel we would come across packs of very wolf-like animals, strong and resourceful canids that were able to thrive in an environment packed with the most dangerous competitors. Their extinction, like that of their fearsome felid enemies, is a fascinating, standing mystery.
All art published in our book “Dogs: their fossil relatives and evolutionary history”, by Xiaoming Wang, Richard Tedford and Mauricio Anton, Columbia University Press, New York 2008.