What was once thought to be marine reptile death bed could be an ancient maternity ward: Study
On Monday, in a study published in the journal, ‘Current Biology’ researchers offer a new theory which is linked to the reproductive behaviour shared by several marine mammals today.
What was once thought to be a final resting place for dozens of giant marine reptiles, ichthyosaurs, which dominated the seas millions of years ago, could instead be an ancient maternity ward, a place where the prehistoric marine reptiles once gave birth. The fossils found in the United States’ of Nevada’s Humboldt-Toiyabe National Forest have puzzled scientists for a long time which led to several hypotheses over the years.
On Monday, in a study published in the journal, ‘Current Biology’ researchers offer a new theory which is linked to the reproductive behaviour shared by several marine mammals today. The scientific name for prehistoric reptiles is Shonisaurus popularis which means lizard fish and could grow at least 50 feet long.
“We present evidence that these ichthyosaurs died here in large numbers because they were migrating to this area to give birth for many generations across hundreds of thousands of years,” said the co-author of the study and curator at the Smithsonian National Museum of Natural History, Nicholas Pyenson, in a press release.
The fossils were excavated in the 1950s and found at least 37 of the ancient creatures had died at the same location over 200 million years ago. For this study, the massive skeletons were 3D scanned to create a detailed digital model, said the lead author Randy Irmis, chief curator and curator of palaeontology at the Natural History Museum of Utah.
Subsequently, they found that the bones were preserved in different rock layers suggesting that the creatures could have died hundreds of thousands of years apart rather than all at once, said Pyenson. He added that the discovery of some tiny bones among the massive adult fossils was the breakthrough in the study, as the researchers realised they belonged to embryos and newborns.
“There are other examples of ichthyosaur embryos and newborns, but this is the first time we have strong evidence for reproductive grouping behaviour,” said Irmis, in an emailed statement to CNN. This behaviour is also linked to present-day whales who typically migrate across the ocean, where there are fewer predators, to breed and give birth. It is also noted that many species gather year after year along the same coastline.
Researchers believe that the fossils are from the mothers and offspring that died there over the years, while other clues also helped rule out previous theories of a mass stranding event or ichthyosaurs being poisoned by the toxins from an algae bloom.
“We know this is something many large marine vertebrates exhibit in the present, so it makes sense that similar behaviour occurred in the past. But we really didn’t know how far back, especially with extinct animal groups like ichthyosaurs, that have no close living relatives,” said Irmis to CNN.
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