Skulls and Brains of Early Mammalian Ancestors – #365papers – 2017 – 102

#365papers for April 12, 2017

Araujo, Fernandez, Polcyn, Frobisch, and Martins, 2017, Aspects of gorgonopsian paleobiology and evolution: insights from the basicranium, occiput, osseous labyrinth, vasculature, and neuroanatomy: PeerJ 5:e3119; DOI:10.7717/peerj.3119

What’s it about?

Gorgonopsians were land-dwelling vertebrates that existed early on along the lineage that eventually gave rise to mammals and to us. They did not yet possess classically mammalian features, in particular the structure of the middle ear, but they did share in common with us a skull shape called synapsidy. This feature distinguishes all mammals and their ancestors from other ‘reptiles’ like dinosaurs, lizards, snakes, and turtles, as well as birds.

The authors of this paper used Propagation Phase Contrast Synchrotron Radiation-based micro-Computed Tomography (a technique a little like a CAT-scan or an MRI) to examine two fossil gorgonopsian skulls. With this method, they were able to essentially take apart the bones of the skull and study their relationships. They were also able to look at the shape of the brain itself, as well as determining where the major blood vessels went and examine the structure of the inner ear.

Why does it matter?

The details of how the little bones at the base of the skull (the basicranium) fit together tells us a lot about the evolutionary history of vertebrates. Those bones are shared with our earliest vertebrate ancestors (fish) and exist in all vertebrates. With this study, the authors can better understand what makes synapsids unique among vertebrates and what makes gorgonopsians unique among synapsids.

Why did I read this?

Gorgonopsians are cool, cool animals. They are also an important group that I cover in my vertebrate paleontology course, so this paper is a great reference.

Head of the gorgonopsian Saurotonus. Credit: CC 3.0 By-SA

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