An international team of researchers led by researchers from Instituto Superior Técnico have demonstrated that the brain of gorgonopsians, a subgroup of mammals, was similar to reptiles. “If we do not understand what happened with mammalian ancestors, it is impossible to understand how we, humans, have reached this point”, says Ricardo Araújo, the first author of the new study published in PeerJ.
This conclusion was reached using synchrotron radiation X-ray microtomography at the European Synchrotron Radiation Facility, in Grenoble. This technology allows to understand anatomical details that had never been studied, such as arteries and veins. The x-ray beam obtained from the synchotron is one hundred billion times brighter than a hospital X-ray source, “allowing us to observe fossils in a more detailed way”, explains Rui Martins, the other Portuguese researcher who leads the project.
The team of researchers demonstrated that although the gorgonopsians and mammals were very much alike, in evolutionary terms their brain was similar to reptiles. The study shows that the neocortex was not yet developed on gorgonopsians, but on the other hand brain regions responsible for basic functions (e.g. cerebellum) were preponderant.
Although their brain was similar to reptiles, the skull had a completely different organisation. The methodology revealed that modifications occurred in the skull bones during the evolutionary transition up to the gorgonopsians.
The “gorgonopsians” lived in the Permian period, more than 250 million years ago, and belonged to a different group of reptiles. They lived millions of years before the dinosaurs and were extinguished during the Permian-Triassic transition.
The researchers Vincent Fernandez, Michael Polcyn and Jörg Fröbish are also involved in this study.