Different members of the dicynodont family evolved tusks independently at different times, and some never evolved true tusks.
Convergent evolution is when similar features evolve independently in different species or different periods in time.
For tusks to evolve, they found that a flexible ligament attaching the tooth to the jaw was needed, as well as reduced rates of teeth replacement -- a combination of features that today is uniquely found in modern mammals."It all ladders up to giving us a better understanding of the tusks we see in mammals today," said Angielczyk, speaking of the research, which published in the journal Proceedings of the Royal Society B Biological Sciences.