Paleontologists say they’ve identified a new species of marine reptile in the ophthalmosaurid genus Platypterygius that lived approximately 125 million years ago.
A pair of Platypterigius sp. Image credit: Dmitry Bogdanov / CC BY 3.0.
Ophthalmosauridae are a family of ichthyosaurs that lived during the Jurassic and Cretaceous periods.
These ichthyosaurs appeared worldwide during the Early Bajocian, around 170 million years ago, subsequent to the disappearance of most other ichthyosaur lineages after the end of the Toarcian, 174 million years ago.
Two ophthalmosaurida lineages are known; one includes two genera: Aegirosaurus and Ophthalmosaurus, and the other includes three genera: Brachypterygius, Caypullisaurus and Platypterygius.
The newly-identified species, Platypterygius elsuntuoso, belongs to the latter genus.
This marine reptile swam in the Early Barremian seas, approximately 125 million years ago.
“The morphology of the new specimen concurs with the diagnostic features of Platypterygius, supporting its inclusion in this genus,” said lead author Dr. María Páramo-Fonseca and her colleagues from the Universidad Nacional de Colombia and the Museo Geológico Nacional José Royo y Gómez.
“The differences noted between the specimen and all other Platypterygius species, support the erection of a new species, Platypterygius elsuntuoso.”
Platypterygius elsuntuoso, holotype. Scale bars – 10 cm. Image credit: Páramo-Fonseca et al., doi: 10.15446/esrj.v28n2.112332.
The fossilized remains of a juvenile or subadult Platypterygius elsuntuoso were collected in 1999 by researchers from the Fundación Colombiana de Geobiología.
The specimen consists of an almost complete skull, some axial elements including the atlasaxis and a few cervical vertebrae, the left coracoid, and a few phalanges.
“The specimen was found in a concretion in La Cabrera hill, northwest of Villa de Leiva (Boyacá, Colombia) where the Arcillolitas abigarradas Member of the Paja Formation outcrops,” the paleontologists said.
“Its exact geographic provenance is unknown, so it was not possible to determine its precise stratigraphic position.”
“However, numerous ammonoid specimens were extracted from the same concretion and some of them have been preliminarily identified as Acanthoptychoceras.”
The researchers conducted the morphological comparisons of Platypterygius elsuntuoso with the Cretaceous and Late Jurassic ophthalmosaurid ichthyosaurs.
They also revised the genus Platypterygius based on published descriptions and direct observations on the Colombian material.
“We concluded that Platypterygius is a genus distinguished by a characteristic forelimb structure and a particular combination of skull features,” they said.
“We emended its diagnosis and recognized as valid the Barremian to lower Cenomanian species: Platypterygius platydactylus, Platypterygius americanus, Platypterygius australis, Platypterygius hercynicus, Platypterygius sachicarum, Platypterygius birjukovi and the new species Platypterygius elsuntuoso.”
“Thus, Platypterygius was a cosmopolitan genus that diversified as it conquered the waters of the Early to early Late Cretaceous oceans and seas.”
The discovery of Platypterygius elsuntuoso is reported in a paper in the Earth Sciences Research Journal.
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María E. Páramo-Fonseca et al. 2024. A new species of Platypterygius (Ophthalmosauridae) from the lower Barremian of Colombia and assessment of the species composition of the genus. Earth Sci. Res. J 28 (2): 103-126; doi: 10.15446/esrj.v28n2.112332
