Why did at least 37 marine reptiles the size of a school bus die at the exact same location in what is now Nevada 230 million years ago?
This question has preoccupied paleontologists for decades, and many theories have been put forward about the mysterious fossil graveyard of the megafauna known as ichthyosaurs.
One theory was that the prehistoric giants were stranded en masse by toxins from the algae. But researchers are now thinking about, among other things, about Smithsonian National Museum of Natural History to a completely different explanation, which is that the fossils are there thanks to a special habit that sea giants share with some marine mammals today.
Fetuses and children were found
The researchers used 3D scans to analyze the area and fossils at Berlin Ichthyosaurus State Park in northwest Nevada.
They also studied the chemical composition of the rocks around the fossils. There they found no indications of a sudden increase in algae growth, for example, as one theory found.
Furthermore, paleontologists note that they have mostly found fossil remains of adult ichthyosaurs—not young ones. However, they did find many bones and teeth of young ichthyosaurs. The breakthrough came when so-called micro-CT scans showed these were the bones and tiny teeth of unborn and newborn ichthyosaurs.
Come to a long way
According to the researchers, this shows that marine animals would likely travel the long way to the area to give birth to their young in a safe part of the ocean, free from predators. And present-day Nevada may have been a nursery for ancient giants for countless generations and hundreds of thousands of years.
In this way, the marine reptile’s behavior is similar to that of today’s whale species, such as blue whales and humpback whales, which routinely cross oceans to give birth in areas where predators are few.
“We now have evidence that this behavior dates back approximately 230 million years,” says first author Neil Kelly. In a press release.
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