A new genus and species of mosasaurid being named Sarabosaurus dahli has been discovered by a team of paleontologists from the United States, the Netherlands and France.
Life reconstruction of the mosasaur Plioplatecarpus, a distant relative of Sarabosaurus dahli. Image credit: Sci.News / Dmitry Bogdanov.
Mosasaurs were a group of large predatory marine reptiles that inhabited all of the world’s oceans during the Late Cretaceous epoch, between 90 and 66 million years ago.
These creatures went extinct during the end-Cretaceous extinction event which killed non-avian dinosaurs and 75% of life on the planet.
Although their relationship to other reptiles is not completely certain, mosasaurs appear to be closely related to a group known as monitor lizards.
The largest known mosasaur is Tylosaurus (Hainosaurus) bernardi, which could reach 17 m (56 feet) in length.
The newly-identified species, Sarabosaurus dahli, was much smaller — approximately 3 m (10 feet) long.
The marine reptile lived during the Early Turonian age of the Cretaceous period, about 93.7 million years ago.
“Sarabosaurus dahli is the oldest mosasaurid taxon known from the Western Interior Seaway,” said Utrecht University paleontologist Michael Polcyn and colleagues.
Schematic reconstruction of the skull of Sarabosaurus dahli showing preserved elements in (A) lateral, (B) dorsal, and (C) ventral views. Scale bar – 10 cm. Image credit: Polcyn et al., doi: 10.1016/j.cretres.2023.105621.
The fossil material of Sarabosaurus dahli was found in February 2012 in the Tropic Shale in Glen Canyon National Recreation Area, Utah, the United States.
The holotype specimen preserves significant portions of the skull and postcranial skeleton.
According to the team, Sarabosaurus dahli possessed a unique circulatory pattern in the basicranium (inferior region of the skull), uniting this species with the mosasaur subfamily Plioplatecarpinae.
“Our phylogenetic analysis recovers Sarabosaurus dahli as the sister taxon to Yaguarasaurus and all other later diverging plioplatecarpines, with Russellosaurus and Tethysaurus as successive sister species,” the authors said.
“Tylosaurine mosasaurids retain the primitive condition of the basisphenoid vascularization pattern and implies a tylosaurine-plioplatecarpine divergence in the Late Cenomanian or earliest Turonian.”
The discovery is reported in a paper in the journal Cretaceous Research.
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Michael J. Polcyn et al. A new lower Turonian mosasaurid from the Western Interior Seaway and the antiquity of the unique basicranial circulation pattern in Plioplatecarpinae. Cretaceous Research, published online June 14, 2023; doi: 10.1016/j.cretres.2023.105621
