What does compelling mean in the sentence?
That would appear to be some pretty compelling evidences. Mammoth bones have also been found at some other Clovis sites.

Question

Answer

compelling 
adj
1. arousing or denoting strong interest, esp admiring interest
2. (of an argument, evidence, etc.) convincing

It means convincing evidence (a lot of evidence to support the argument for or against something).

Don’t miss out on the opportunity to learn a language from the comfort of your own home. Browse our selection of experienced language tutors and enroll in your first lesson now!