Mysterious ichthyosaur cemetery could also be breeding floor

About 230 million years ago, large dolphin-like reptiles known as ichthyosaurs congregated in safe waters to breed — just like many modern-day whales.

That’s the conclusion researchers reached after studying the mysterious ichthyosaur burial site at Berlin Ichthyosaur State Park in Nevada.The park has the richest collection of fossils in the world show nylonone of the biggest Ichthyosaur have found (Serial Number: 8/19/02).

“Here’s what we’re seeing in modern marine vertebrates – gray whales make [the] Randall Irmis, a paleontologist at the Utah National Museum of State History in Salt Lake City, said “travel to Baja California every year” to breed.concealed warm water supply whale safety (Serial Number: 1/19/80).

this New discoveryDescribed on December 19 current biology, suggesting that this behavior “goes back at least 230 million years,” Irmis said. “It really connects the past to the present in a big way.”

Erin Maxwell, a paleontologist at the State Museum of Natural History in Stuttgart, Germany, said the idea of ​​ichthyosaur birthplaces had been suggested before and was even widely known, often incorporated into artist’s depictions of the creatures. Not involved in new research. But, she said, this study “is the first to support these speculations with data.”

Nevada’s treasure trove of ichthyosaur fossils has been a mystery to paleontologists for decades. One curiosity is that many of the ichthyosaur fossils are gathered in what is now the park, but about 230 million years ago this was part of a tropical ocean.Another oddity is that the site seems to be almost entirely occupied by giant 14-meter-long adults S. popularization. Then there are the tantalizing questions that lead to death.

Scientists have previously suggested that the reptiles, which may have been about the length of a school bus when they grew up, clustered together before somehow killing them off en masse for unknown reasons.

There are several specimen bags or quarries scattered throughout the park. All told, Irmis and colleagues found at least 112 individual ichthyosaurs in these quarries, including one where park officials half-encased previously found bones in rock for public viewing.

That snapshot of death meant scientists could examine how the fossils were arranged relative to each other, perhaps gaining insight into the reptile’s behavior, said Neil Kelly, a paleontologist at Vanderbilt University in Nashville.

Kelley, Irmis and colleagues used digital cameras and laser scanners to collect bone bed measurements from hundreds of semi-buried reptiles and combined the data into a 3-D model of the site. The team also studied the size and shape of bones across the park, including some that are now in museum collections. The researchers analyzed the chemical composition of the surrounding rocks and pored over old photographs and field records.

These fragments of evidence help researchers begin to understand what they’re looking at—and potentially solve at least one long-standing mystery: what brings these creatures together.

Although almost all parks show nylon The scientists found that while the skeletons were of fully grown adults, the site did have some very small ichthyosaur remains.Using micro-computed tomography, a 3D imaging technique that uses X-rays to see inside fossils, researchers have found that some of the tiny bones are those of embryos and newborns show nylon.

This discovery led the team to conclude that the site was a birthplace. This, the researchers say, could explain why so many of the same creatures pop up in the same place with newborns.

The site also appears to be show nylon for a long time. The researchers found that not all quarries date back to roughly the same time, with different quarries separated by at least hundreds of thousands of years.

As for what killed the reptiles, “we don’t know,” Irmis said.

Hypotheses for mass die-off events include harmful algal blooms or massive volcanic activity. But new petrochemical data ruled out a culprit for these events.

Some animals from each quarry may still die en masse. Bringing these creatures together in one place to breed could make the reptiles vulnerable to sudden catastrophic events that bury them in sediment, such as undersea landslides.

But the discovery of the fossils could also represent “just normal mortality over time,” Irmis said, given how the creatures seemed to come to the site time and time again.