Northern Alabama and Mississippi might not seem like the sort of places you'd go looking for sea turtles. These places are a little far from the coast to expect a sighting of the shelled seagoers. But that only holds true for the modern reptiles, of course. Sea levels were higher around 72 million years ago, a shallow seaway splitting North America in two and coasts sitting far inland of where they are today. Sea turtles swam through these ancient waters, as underscored by a new species just named by paleontologist Drew Gentry and colleagues.

The fossil turtle, Peritresius martini, was a bit of a surprise. Paleontologists had long known of another Peritresius species - called Peritresius ornatus - but fossil shell pieces found in Alabama and Mississippi led Gentry and coauthors to propose a second, distinct species. One of the ways paleontologists can tell them apart is in the ornamentation of their shells, the previously-known species having "sculptured" shell bones while Peritresius martini does not.

Despite hailing from the heyday of Cretaceous dinosaurs, though, Peritresius martini probably wouldn't have looked like unusual to our modern eyes. It was about the size of a modern green sea turtle, and, as Gentry and colleagues conclude, and this reptile was along the evolutionary stem connected to today's hard-shelled sea turtles. Looking back, Peritresius was an early glimmer of the chelonian grace of today's hawksbills and loggerheads. 

Turtle
A restoration of Peritresius martini. Credit: Drew Gentry (CC-BY)

Name: Peritresius martini

Meaning: Peritresius is an existing genus of sea turtle, and martini honors the fossil's discoverer George Martin. 

Age: Cretaceous, about 72 million years old.

Where in the world?: Alabama and Mississippi, USA.

What sort of organism?: A sea turtle related to the origin of today's hard-shelled sea turtles.

How much of the organism’s is known?: Shell pieces from multiple individuals.

Reference:

Gentry, A., Parham, J., Ehret, D., Ebersole, J. 2018. A new species of Peritresius Leidy 1856 (Testudines: Pan-Cheloniidae) from the Late Cretaceous (Campanian) of Alabama, USA, and the occurrence of the genus within the Mississippi Embayment of North America. PLOS ONE. doi: 10.1371/journal.pone.0195651

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