Bones of ancient reptiles can tell about the dangerous past of the Earth

(ORDO NEWS) — The teeth, fingers and auditory ossicles of an extinct, oddly shaped reptile could reveal a lot about the resilience of life on Earth , according to a new study.

In fact, paleontologists from Yale University, Sam Houston State University and the University of the Witwatersrand say the 250-million-year-old reptile known as Palacrodon fills an important gap in our understanding of reptile evolution.

It is also a signal that reptiles, plants and ecosystems may have fared better or recovered faster than previously thought after the mass extinction wiped out most plant and animal species on the planet.

“We now know that Palacrodon descends from one of the last offshoots of the reptilian tree of life prior to the evolution of modern reptiles,” said Kelsey Jenkins, a doctoral student at Yale’s School of Earth and Planetary Sciences in the Department of Arts and Sciences and first author of the study published in the Journal of Anatomy.

“We also know that Palacrodon lived after the most devastating mass extinction in Earth’s history.”

This was the Permian-Triassic extinction event that occurred 252 million years ago. Known as the “Great Dying”, it wiped out 70% of terrestrial species and 95% of marine species.

Although a large number of reptile species eventually recovered from this extinction, the details of how this happened are murky.

Researchers have spent decades trying to fill in gaps in our understanding of the key adaptations that allowed reptiles to thrive after the Permian-Triassic extinction, and what those adaptations might reveal about the ecosystems they lived in.

Palacrodon could help answer some of those questions, Jenkins says. But first, she and her colleagues needed to get a better look at the little reptile.

Until recently, all that was known about Palacrodon came from studies of skull fragments from fossils found in South Africa and Arizona. However, the information obtained from these fossils was so limited that Palacrodon was excluded from most scientific analyzes of reptile evolution.

For the new study, Jenkins and her colleagues, including co-author Bhart-Anjan S. Bhullar, assistant professor of earth and planetary science at Yale University and assistant curator of the Yale Peabody Museum of Natural History , applied a new analytical approach to the study of Palacrodon.

Specifically, they used computed tomography (CT) and microscopy to analyze the most complete specimen of Palacrodon, a fossil from Antarctica. Bhullar’s laboratory at Yale University is especially noted for the innovative use of computed tomography and microscopy to create 3D images of fossils.

Using the technology for this study, the researchers were able to obtain the characteristics of the reptile’s teeth, as well as other physical features. It turned out that Palacrodon’s teeth are best suited for grinding plant material and that the reptile is likely capable of climbing or clinging to vegetation from time to time.

“Palacrodon’s unusual teeth and some other features of its anatomy indicate that it was likely a herbivore or interacted with plant life in some way,” Jenkins said.

“This signals an early recovery of plants and, more broadly, a recovery of ecosystems after this mass extinction.”

Jenkins said the study points to the need for further study of fossils from the period just after the Permo-Triassic extinction event.

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