Dire Wolves

The remains of thousands of these extinct Pleistocene carnivores have been recovered from the La Brea Tar Pits in Los Angeles.

A new study of dire wolves' genetics has startled paleontologists found that these animals were not wolves at all, but the last of the canid lineage that evolved in North America.

Ever since they were described in the 1850s, dire wolves captured the human imagination. Their remains are found pretty much throughout much of the Americas, from Idaho to Bolivia. Dire wolf's tar-preserved remains reveal imposing hunters up to six feet long, with skull adaptations to take down enormous, struggling megafauna.

Skeletal resemblances between dire wolves and today's smaller grey wolves suggested a closer kinship. Paleontologists long assumed that dire wolves made themselves at home in North America before grey wolves followed them across the Bering Land Bridge from Eurasia. Now some well-preserved DNA may fundamentally change that story.

Researchers hoped to pinpoint dire wolves were related to other wolves. The dire wolves were possibly a specialized lineage or subspecies of a grey wolf but the new evidence suggests otherwise. Preliminarily genetic analysis indicated that other dire and grey wolves were not close relatives.

By sequencing five genomes from dire wolf fossils between 50,000 and 13,000 years old, the scientists found that the animals belonged to a much older lineage of dogs. Dire wolves, the data suggests, had evolved in the Americas, and had no kinship with the grey wolves in Eurasia; the last time dire wolves and grey wolves shared a common ancestor was about 5.7 million years ago.

The strong resemblance between the two, the researchers say, is a case of convergent evolution. This occurs when different species develop similar adaptations or even appearances thanks to a similar way to life. Sometimes such convergence is only rough, such as both birds and bats evolving wings despite their different anatomy. In the case of dire and grey wolves, a dedication to chasing large herbivores resulted in two different canid lineages independently producing similar wolflike forms.

These results totally shake up the idea that dire wolves were just bigger cousins of grey wolves. In fact, the similarity between the two has led grey wolves to be taken as proxies for dire wolf biology and behavior, from pack dynamics to the sound of the animal’s howls.

The dire wolf’s new identity means that many previous assumptions including what it looked like in life inquire reinvestigation. The study in ancient of ancient DNA and proteins from fossils and bones is rapidly rewriting the Ice Age and more recent history of North America’s mammals.

These findings may mean dire wolves need a new genius name to indicate that they are not actually part of the grey wolf’s genius, Canis. The name Aenocyon, meaning “terrible wolf,” was a name coined a century ago. But the researchers do not expect their findings to completely overturn tradition, and Aenocyon dirus would likely still be called the dire wolf. They would join the club of things like maned wolves is called wolves which are called wolves but are not really.

These predators had become specialized in hunting camels, horses, bison, and other herbivores in North America for millions of years. As those prey sources disappeared so did the dire wolves. In contrast to grey wolves, which are a model of adaptation dire wolves appear to be much less flexible to deal with changing environments and prey.

Nor did dire wolves leave a genetic legacy beyond their ancient bones’ decaying DNA. Canids such as coyotes and wolves can mate and produce hybrids, but dire wolves apparently did not do so with any other canid species that remain alive today.

Excerpted from Scientific American Magazine.

April 20212. Pages 10 to 13.