Fossil Dental Exams Reveal How Tusks First Evolved and Why They Are Unique Only to Mammals
Published:01 Nov.2021    Source:Harvard University, Department of Organismic and Evolutionary Biology

In a new paper published October 27 in the Proceedings of the Royal Society B researchers trace the first tusks back to ancient mammal relatives that lived before the dinosaurs and shed light on the evolution of mammalian tusks by first defining what makes a tusk a tusk. Tusks are this very famous anatomy, but until I started working on this study, I never really thought about how tusks are restricted to mammals, said lead author Megan Whitney, postdoctoral fellow in the Department of Organismic and Evolutionary Biology, Harvard University.

 
‘We were able to show that the first tusks belonged to animals that came before modern mammals, called dicynodonts,’ said Kenneth Angielczyk, co-author and curator at Chicago’s Field Museum. ‘They’re very weird animals.’Dicynodonts, though not mammals, are distant relatives and are more closely related to mammals than dinosaurs and other reptiles. Dicynodonts lived between 270-201 million years ago and included a diverse range of animals from tiny rat-like dicynodonts to huge elephant-sized dicynodonts. They are known for having a very peculiar arrangement of teeth. A defining feature of these animals, first discovered 176 years ago, is the protruding tusks in their upper jaws. Most had two upper tusks that came down from the canine position, but they rarely had additional teeth. Instead, dicynodonts had a beak at the front of their mouths that was made of keratin and resembled a turtles beak.