 The mastodon tusks were later determined to be 22,000 years old.In addition several archaeological sites on the Delmarva peninsula with suggestive (but not definitive) dating between 16,000 and 18,000 years have been discovered by Darrin Lowery of the University of Delaware.These factors led Stanford and Bradley to reiterate in 2014 their academic advocacy of pre-Clovis peoples in North America and their possible link to paleolithic Europeans.