Answer:
they competed along side other loner predators and lost this also killed off cave bear and smilodon humans won cause of throwing spears
Improved: Why/How did these animals become extinct? Many hypotheses exist. The Dire Wolf skeleton is more stout than that of the Gray Wolf, suggesting an adaptation for power rather than speed. Most of its prey species were rather sedentary herbivorous animals that were not able to run very fast to escape predation. Scientists suspect that once those relatively slow-moving prey animals became extinct, the Dire Wolf may not have been able to hunt and capture swifter prey in order to survive.
Source?: http://www.sdnhm.org/exhibits/mystery/fg_direwolf.html