Ice Age Coyotes Were the Size of Modern Wolves

Posted on February 27, 2012

A new fossil study has found that Ice Age coyotes (Canis latrans orcutti) were about the size of modern wolves. Researchers say coyotes today are a pint-sized version of their former selves. A modern coyote is pictured next to a Pleistocene coyote skull in the above artwork by Doyle V. Trankina.

Between 11,500 and 10,000 years ago coyotes shrunk to their present size. Researchers say the sudden shrinkage was most likely a response to dwindling food supply and changing interactions with competitors, rather than the result of a warming climate.

Study co-author Julie Meachen of the National Evolutionary Synthesis Center in Durham, North Carolina, says, "Pleistocene coyotes probably weighed between 15-25 kilograms, and overlapped in size with wolves. But today the upper limit of a coyote is only around 10-18 kilograms."

Humans may have also had a role in coyote shrinkage. Early human hunters -believed to have arrived in North America around 13,000 years ago - may have helped wiped out the bigger coyotes - or the animals coyotes depended on for food - leaving only the small to survive.

The researchers believe the most likely explanation for the downsizing of coyotes is a dwindling food supply and changing interactions with competitors. About 1000 years before the sudden shrinkage in coyotes, dozens of other species were wiped out in a wave of extinctions that killed off many large mammals in North America. Until then, coyotes lived alongside a great diversity of large prey, including horses, sloths, camels, llamas and bison.

Meachen says, "There were not only a greater diversity of prey species, but the species were also more abundant. It was a great food source."

The research paper, "Evolution in coyotes (Canis latrans) in response to the megafaunal extinctions," was published here in the Proceedings of the National Academy of Sciences.

ANIMALS
EXTINCT SPECIES