An extinct, 250 million-year-old marine reptile that was lined in bony armor and swam within the shallow waters of what’s now south China might rewrite the household tree of armored marine reptiles and trace at why they first emerged, a brand new research reveals.
The newfound species, named Prosaurosphargis yingzishanensis, was recognized from a partial skeleton first found in 2019 at Yingzishan quarry in China’s Hubei Province. P. yingzishanensis belongs to the household Saurosphargidae, a gaggle of armored marine reptiles with broadened dorsal ribs that made them seem rather more stocky than different marine reptiles. (Sauorsphargidae is a mix of the Greek phrases for lizard, “sauros,” and leatherback turtle, “sphargis.”)
Researchers described P. yingzishanensis in a research revealed Aug. 8 within the journal Evolutionary Biology.
P. yingzishanensis doubtless grew to round 5 ft (1.5 meters) lengthy and was lined in osteoderms — bony scales and plates discovered in lots of residing reptiles, armored dinosaurs and a few mouse tails. It was doubtless “one of many greater marine reptiles” residing in its ecosystem on the time, research lead writer Andrzej Wolniewicz, a paleobiologist at Hefei College of Know-how in China and the Polish Academy of Sciences, instructed Stay Science in an electronic mail.
Till now, the oldest saurosphargids dated again to round 245 million years in the past in the course of the mid-Triassic interval. Scientists do not know whether or not P. yingzishanensis was a direct ancestor to those later saurosphargids or a separate lineage, Wolniewicz mentioned. However the total physique plan of the newly described species strongly hints that all the group might have been beforehand misclassified, he added.
Saurosphargids have lengthy been thought of a sister household of the sauropterygians, a extra various group of extinct marine reptiles together with armored turtle-like creatures referred to as placodonts and long-necked predators reminiscent of plesiosaurs.
However the researchers famous a lot of similarities between P. yingzishanensis and a few of the plesiosaur-like sauropterygians, which suggests the 2 teams could also be extra intently associated than beforehand thought, Wolniewicz mentioned. In consequence, the research authors have proposed that the saurosphargids needs to be reclassified as a sub-group of sauropterygians.
The researchers additionally consider that sauropterygians and different teams of marine reptiles, reminiscent of ichthyosauromorphs, which embrace ichthyosaurs and thalattosaurs, could also be extra intently associated to the clade Archelosauria — a gaggle that features residing and extinct turtles and archosaurs, which embrace crocodilians and birds — than beforehand thought.
The big variety of physique armor throughout all these teams, excluding birds, additionally means that their bony plating was key to residing in shallow water habitats, Wolniewicz mentioned. In addition to offering safety from predators, this heavy plating might have enabled marine reptiles to beat points with buoyancy by weighing them down and forage across the seafloor, the place a majority of prey can be discovered, he added.
The researchers hope the area the place the P. yingzishanensis fossil was found will reveal extra historic species that would bridge the hole between the traditional reptile teams and fill in additional lacking items of their evolutionary historical past.