Dec 24, 2022 I Paul Seaburn

Giant Ichthyosaur Graveyard in Nevada Was Actually a Baby Ichthyosaur Nursery

Among those who believe that the Loch Ness monster is a last survivor of a dinosaur species, the one they most often suggest is the long-necked plesiosaur – which was a saltwater creature that would have preferred the Atlantic Ocean to the loch. Yes, there have been fossils found recently in the Sahara of a smaller river-dwelling plesiosaur, but that is a long way – both physically and biologically – from Loch Ness and its monster. A dinosaur which actually lived in Scotland is the ichthyosaur – in 2015, fossils of a Dearcmhara shawcrossi – a 14-foot-long dolphin-like member of the ichthyosaur family – were found on the Isle of Skye in northwest Scotland. This medium-sized ichthyosaur roamed the seas 170 million years ago in the Jurassic Period and no one is suggesting they roam anywhere near Skye, Loch Ness or any other loch today. However, that doesn’t mean no one is studying them. Another place ichthyosaur fossils have been found is in the U.S state of Nevada, where paleontologists have long been baffled by why so many of them have been found it what eventually came to be know as the Ichthyosaur Graveyard. A new analysis of other fossils in the area has solved the mystery, and as a result, the spot may need a new nickname.

Ichthyosaur

“It’s a really fascinating site, and it’s exciting to see new research being focused on this important ichthyosaur graveyard.”

University of Manchester paleontologist Dean Lomax, who was not involved in the new study published recently in the journal Current Biology, tells Smithsonian Magazine why he’s excited about the new research in Nevada’s Berlin-Ichthyosaur State Park – so named because it surrounds one of the world’s largest caches of ichthyosaur fossils and the ghost town of Berlin. In 1896, Berlin was a gold mining boom town in Nevada’s south central Nye County, which also includes part of Death Valley National Park. Ichthyosaur fossils of the species Shonisaurus popularis were first discovered there in 1928. Subsequent excavations in what is now called the Luning Formation uncovered the remains of about 40 ichthyosaurs, including one of the largest in the world. These very large ichthyosaurs lived and died in the late Carnian age of the late Triassic period, about 237–227 million years ago. Paleontologists know why they lived here – central Nevada was covered with a warm ocean in the Triassic period. Eventually, water levels dropped and they were trapped in the shallow waters in what is now central Nevada.

Or were they?

One particular section of Berlin-Ichthyosaur State Park is known as “quarry 2.” It has the most fossils of the humpback whale-sized ichthyosaurs. As such, the fossils there have been well studied and almost all of them appear to be adults. That helped support the unproven assumption that they were trapped in the shallow waters and this “quarry 2” became an ichthyosaur graveyard … perhaps even a designated place where the ichthyosaurs came to die. However, there was no proof. That forced paleontologists to go back to old reports on digs. According to Erin Maxwell, a paleontologist at the State Museum of Natural History in Stuttgart, Germany, who was not involved in the new study, it is in one of those from 1980 that they found a clue.

“Embryonic material was mentioned from the locality in a 1980 monograph but wasn’t figured, and no details were provided in the publication.”

That was enough of a hint to inspire Smithsonian National Museum of Natural History paleontologist Nicholas Pyenson and his colleagues to go back to quarry 2 and the area around it and take a closer look. They used new technology - laser scanning, photogrammetry and computer vision workflows – in order to get a broader analysis of what was going on there in the Triassic Age than can be obtained by studying fossils in a museum. They were expecting to find something like toxic algae blooms which could have grown in the shallow waters and killed the dinosaurs – something observed in a similar dinosaur graveyard in Chile’s Atacama Desert.

What they found instead will change the history of Berlin-Ichthyosaur State Park.

“We found a dominance of adult-sized Shonisaurus and then a smaller bump of embryonic to neonatal specimens.”

Ichthyosaur fossil

Pyenson and his team were not surprised to find the adult ichthyosaur fossils – that is what the park is known for. They were surprised to find fossils of ichthyosaur embryos and newborn Shonisaurus. However, they were shocked at what they didn’t find -- intermediate-sized juveniles or subadult ichthyosaur fossils. If this were a place where adults came to die, there would be only adults. If it were a place where a disaster trapped and killed them, it would have fossils of all ages. This site had adults with embryos and newborns. That led to only one conclusion:

“Combined with geological evidence, our data suggest that dense aggregations of Shonisaurus inhabited this moderately deep, low-diversity, tropical marine environment for millennia during the latest Carnian Stage of the Late Triassic Period (237–227 Ma). Thus, philopatric grouping behavior in marine tetrapods, potentially linked to reproductive activity, has an antiquity of at least 230 million years.”

This was not a place where ichthyosaurs came to die … it was a place where ichthyosaurs came to give birth – a dinosaur nursery, and one that appears to have been used for that purpose for a long time.

“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. That means this type of behavior we observe today in whales has been around for more than 200 million years.”

According to Pyenson, these ichthyosaurs exhibited the same behavior as modern blue and humpback whales which migrate across oceans to breed and give birth in warm shallow waters where predators are scarce. That is why so many whale nurseries are found along southern coastlines and the same females show up there annually. Study coauthor Randy Irmis, chief curator and curator of paleontology at the Natural History Museum of Utah in Salt Lake City, says this is a truly revolutionary find, since ichthyosaurs have no modern relatives so paleontologists had no idea they congregated in nurseries … especially one in Nevada. Now they know – the ichthyosaurs were returning to the place of their birth to begin the cycle again. Why they died there is still a mystery … but at least they left some replacements.

Paul Seaburn

Paul Seaburn is the editor at Mysterious Universe and its most prolific writer. He’s written for TV shows such as "The Tonight Show", "Politically Incorrect" and an award-winning children’s program. He's been published in “The New York Times" and "Huffington Post” and has co-authored numerous collections of trivia, puzzles and humor. His “What in the World!” podcast is a fun look at the latest weird and paranormal news, strange sports stories and odd trivia. Paul likes to add a bit of humor to each MU post he crafts. After all, the mysterious doesn't always have to be serious.

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