A New Cynodont and the Evolutionary Path to Mammals – #365papers – 2017 – 134

#365papers for May 14, 2017

Martinelli, Eltink, Da-Rosa, and Langer, 2017, A new cynodont from the Santa Maria Formation, south Brazil, improves late Triassic probainognathian diversity: Papers in Palaeontology, 1-23

What’s it about?

This paper is a description of a new species of non-mammalian synapsid from Brazil. Non-mammalian synapsids are vertebrates that are on the lineage toward mammals (and far removed from other reptiles), but lack the specific characteristics of the ear and jaw that distinguish mammals from all other vertebrates. This particular new species is based on a left lower jaw with most of its teeth.

Why does it matter?

We like to think of mammals as ‘special.’ We are mammals, after all. But our earliest ancestors looked distinctly reptilian. Cynodonts lie somewhere along the lineage where the outward appearance of ‘mammal’ was becoming apparent (they likely had fur, for example). Cynodonts lack specific structures of the ear, jaw, and teeth that are definitive of mammals. This cynodont shows characteristics that are leaning heavily toward mammalian, and helps us understand parts of the transition from ‘reptile’ to mammal.

Why did I read this?

I work with mammals. I started my career studying mammals that while still being proper mammals, don’t quite resemble the mammals we’re familiar with today. The origins and evolution of mammals have always interested me, so I was pretty-much obligated to read this paper.