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NEW YORK — Scientists have uncovered new clues a few curious fossil web site in Nevada, a graveyard for dozens of large marine reptiles. As an alternative of the positioning of an enormous die-off as suspected, it might need been an historic maternity ward the place the creatures got here to offer delivery.
The positioning is known for its fossils from large ichthyosaurs — reptiles that dominated the traditional seas and will develop as much as the scale of a college bus. The creatures — the title means fish lizard — have been underwater predators with massive paddle-shaped flippers and lengthy jaws stuffed with tooth.
Because the ichthyosaur bones in Nevada have 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 examine revealed Monday within the journal Present Biology.
“A number of traces of proof all sort of level in the direction of one argument right here: That this was a spot the place large ichthyosaurs got here to offer delivery,” mentioned co-author Nicholas Pyenson, curator of fossil marine mammals on the Smithsonian Nationwide Museum of Pure Historical past.
As soon as 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, mentioned lead writer Randy Irmis, a paleontologist on the College of Utah.
To get a greater take a look at the large skeletons, which boast vertebrae the scale of dinner plates and bones from their flippers as thick as boulders, researchers used 3D scanning to create a detailed digital mannequin, Irmis mentioned.
They recognized fossils from a minimum of 37 ichthyosaurs scattered across the space, courting again about 230 million years. The bones have been preserved in several rock layers, suggesting the creatures might have died lots of of 1000’s of years aside slightly than abruptly, Pyenson mentioned.
A serious break got here when the researchers noticed some tiny bones among the many huge grownup fossils, and realized they belonged to embryos and newborns, Pyenson mentioned. The researchers concluded that the creatures traveled to the positioning in teams for cover as they gave delivery, like right this moment’s marine giants. The fossils are believed to be from the moms and offspring that died there through the years.
“Discovering a spot to offer delivery separated from a spot the place you would possibly feed is admittedly widespread within the trendy world — amongst whales, amongst sharks,” Pyenson mentioned.
Different clues helped rule out some earlier explanations.
Testing the chemical compounds within the grime didn’t flip up any indicators of volcanic eruptions or big shifts to the native setting. And the geology confirmed that the reptiles have been preserved on the ocean flooring fairly removed from the shore — which means they most likely did not die in a mass beaching occasion, Irmis mentioned.
The brand new examine gives a believable clarification for a web site that’s baffled paleontologists for many years, mentioned Dean Lomax, an ichthyosaur specialist at England’s College of Manchester who was not concerned with the analysis.
The case might not be totally closed but however the examine “actually helps to unlock somewhat bit extra about this fascinating web site,” Lomax mentioned.
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The Related Press Well being and Science Division receives assist from the Howard Hughes Medical Institute’s Science and Academic Media Group. The AP is solely liable for all content material.
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