VANCOUVER — Scientists who re-examined the fossils of mastodons that once roamed what is now the Yukon and Alaska have revised their likely cause of death, concluding global cooling probably wiped out the ancient cousin of the elephant.
Earlier estimates dated the mastodon bones at about 14,000 years old, but Grant Zazula, a paleontologist in the Yukon Paleontology Program, says the fossils are now believed to be about 75,000 years old.
Instead of dying off at the end of the ice age, as first believed, Zazula says it's more likely the mastodons migrated to the area during a warming trend and then died when they couldn't survive the cold.
He says the earlier theorized extinction date — at the end of the ice age — was suspect for experts because mastodons were adapted to warmer conditions.
Zazula says the discovery is another piece of the puzzle in the disappearance of the massive creatures, and raises more questions about the extinctions of other animals presumed to have died off at the end of the ice age.
He is the lead author of a mastodon study published this week in the scientific journal Proceedings of the National Academy of Sciences.
