Scientists have uncovered new clues a couple of curious fossil website in Nevada, a graveyard for dozens of big marine reptiles.

Instead of the positioning of an enormous die-off as suspected, it might need been an historical maternity ward the place the creatures got here to provide delivery.

The website is legendary for its fossils from big ichthyosaurs — reptiles that dominated the traditional seas and will develop as much as the dimensions of a bus. The creatures — the identify means fish lizard — had been underwater predators with massive paddle-shaped flippers and lengthy jaws stuffed with enamel.

Since the ichthyosaur bones in Nevada had been excavated within the Nineteen Fifties, many paleontologists have investigated how all these creatures might have died collectively. Now, researchers have proposed a special concept in a research printed on Monday within the journal Current Biology.

“Several lines of evidence all kind of point towards one argument here: That this was a place where giant ichthyosaurs came to give birth,” stated co-author Nicholas Pyenson, curator of fossil marine mammals on the Smithsonian National Museum of Natural History.

Once a tropical sea, the positioning — a part of Nevada’s Berlin-Ichthyosaur State Park — now sits in a dry, dusty panorama close to an deserted mining city, stated lead writer Randy Irmis, a paleontologist on the University of Utah.

To get a greater take a look at the large skeletons, which boast vertebrae the dimensions of dinner plates and bones from their flippers as thick as boulders, researchers used 3D scanning to create an in depth digital mannequin, Mr Irmis stated.

They recognized fossils from a minimum of 37 ichthyosaurs scattered across the space, relationship again about 230 million years. The bones had been preserved in several rock layers, suggesting the creatures might have died lots of of 1000’s of years aside reasonably than abruptly, Pyenson stated.

A significant break got here when the researchers noticed some tiny bones among the many huge grownup fossils, and realised they belonged to embryos and newborns, Pyenson stated.

The researchers concluded that the creatures travelled to the positioning in teams for defense as they gave delivery, like immediately’s marine giants. The fossils are believed to be from the moms and offspring that died there through the years.

“Finding a place to give birth separated from a place where you might feed is really common in the modern world — among whales, among sharks,” Mr Pyenson stated.

Other clues helped rule out some earlier explanations.

Testing the chemical compounds within the filth didn’t flip up any indicators of volcanic eruptions or big shifts to the native atmosphere. And the geology confirmed that the reptiles had been preserved on the ocean ground removed from the shore — which means they in all probability didn’t die in a mass beaching occasion, Mr Irmis stated.

The new research presents a believable clarification for a website that has baffled paleontologists for many years, stated Dean Lomax, an ichthyosaur specialist on the University of Manchester who was not concerned with the analysis.

The case will not be totally closed but however the research “really helps to unlock a little bit more about this fascinating site”, Mr Lomax stated.