what was its diet?
They were carnivores, and preyed on "yesterday's camel", the Pleistocene bison, the "dwarf" pronghorn etc.
Dire wolf
Their prey included "yesterday's camel" ("Camelops hesternus"), the Pleistocene bison ("Bison antiquus"), the "dwarf" pronghorn ("Capromeryx minor"), the western horse ("Equus occidentalis"), and the "grazing" ground sloth ("Paramylodon harlani") native to North American grasslands. The Columbian mammoth ("Mammuthus columbi") and the American mastodon ("Mammut americanum") were rare at LaBrea. The horses remained mixed feeders and the pronghorns mixed browsers, but at the Last Glacial Maximum and its associated shift in vegetation the camels and bison were forced to rely more heavily on conifers.
how long ago did the dire wolf live Approximately 125,000 – 9,500 years ago. is it extinct now? Yes.
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Dire wolf [SEP] Prey
An isotope analysis of bone collagen extracted from LaBrea specimens provides evidence that the dire wolf, "Smilodon", and the American lion ("Panthera leo atrox") competed for the same prey. Their prey included "yesterday's camel" ("Camelops hesternus"), the Pleistocene bison ("Bison antiquus"), the "dwarf" pronghorn ("Capromeryx minor"), the western horse ("Equus occidentalis"), and the "grazing" ground sloth ("Paramylodon harlani") native to North American grasslands. The Columbian mammoth ("Mammuthus columbi") and the American mastodon ("Mammut americanum") were rare at LaBrea. The horses remained mixed feeders and the pronghorns mixed browsers, but at the Last Glacial Maximum and its associated shift in vegetation the camels and bison were forced to rely more heavily on conifers.