Analysis of giant extinct marine reptile graveyard suggests mysterious site was ancient birthing ground

Today's marine giants—such as blue and humpback whales—routinely make massive migrations across the ocean to breed and give birth in waters where predators are scarce, with many congregating year after year along the ...

Now, new research from a team of scientists—including researchers with the University of Utah (Natural History Museum of Utah and Department of Geology & Geophysics), Smithsonian Institution, Vanderbilt University, University of Nevada, Reno, University of Edinburgh, University of Texas at Austin, Vrije Universiteit Brussels, and University of Oxford—suggests that nearly 200 million years before giant whales evolved, school bus-sized marine reptiles called ichthyosaurs may have been making similar migrations to breed and give birth together in relative safety. The findings, published today in the journal Current Biology , examine a rich fossil bed in the renowned Berlin-Ichthyosaur State Park (BISP) in Nevada's Humboldt-Toiyabe National Forest, where many 50-foot-long ichthyosaurs (Shonisaurus popularis) lay petrified in stone.

Co-authored by Randall Irmis, NHMU chief curator and curator of paleontology, and associate professor, the study offers a plausible explanation as to how at least 37 of these marine reptiles came to meet their ends in the same locality—a question that has vexed paleontologists for more than half a century. "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 co-author and Smithsonian National Museum of Natural History curator Nicholas Pyenson. "That means this type of behavior we observe today in whales has been around for more than 200 million years."

Adult and young of the ichthyosaur species Shonisaurus popularis chase ammonoid prey 230 million years ago, in what is now Berlin-Ichthyosaur State Park, Nevada, U.S.A. Credit: Gabriel Ugueto Read more

3D-model image of the Shonisaurus popularis fossil bed at Quarry 2 in Berlin-Ichthyosaur State Park, Nevada. Fossilized bones have been color-coded where each color corresponds to a different skeleton. Credit: Smithsonian Institution Read more

Complete tooth and partial jaws (UMNH VP 32539) of the ichthyosaur Shonisaurus popularis from Berlin-Ichthyosaur State Park, Nevada. These new fossils demonstrate that Shonisaurus was an apex predator at the top of its ecosystem. Credit: Natural History Museum of Utah / Mark Johnston Read more

Findings published today in the journal Current Biology examine a rich fossil bed in the renowned Berlin-Ichthyosaur State Park in Nevada’s Humboldt-Toiyabe National Forest, where many 50-foot-long ichthyosaurs (Shonisaurus popularis) lay petrified in stone. The study suggests that nearly 200 million years before giant whales evolved, school bus-sized marine reptiles called ichthyosaurs may have been making migrations to breed and give birth together in relative safety. To try to solve the prehistoric mystery of how these ichthyosaurs met their end, the team combined newer paleontological techniques such as 3D scanning and geochemistry with traditional paleontological perseverance by poring over archival materials, photographs, maps, field notes and drawer after drawer of museum collections for shreds of evidence that could be reanalyzed. Although most well-studied paleontological sites excavate fossils so they can be more closely studied by scientists at research institutions, the main attraction for visitors to the Nevada State Park-run Berlin-Ichthyosaur State Park is a barn-like building that houses what researchers call Quarry 2, an array of ichthyosaurs that have been left embedded in the rock for the public to see and appreciate. Quarry 2 has partial skeletons from an estimated seven individual ichthyosaurs that all appear to have died around the same time. Credit: Neil Kelley / Vanderbilt University Read more