An international scientific team investigated a rich fossil bed in Nevada's Humboldt-Toiyabe National Forest's famed Berlin-Ichthyosaur State Park, where several 50-foot-long ichthyosaurs (Shonisaurus popularis) lay petrified in stone.
The work gave a convincing explanation as to how at least 37 of these aquatic reptiles came to meet their ends in the same place - a conundrum that has puzzled paleontologists for more than half a century.
The study provides evidence that these ichthyosaurs perished in significant numbers at the site because they had been traveling to this place for hundreds of thousands of years to give birth.
Fossil CSI
JEAN-FRANCOIS MONIER/AFP via Getty Images
The results, published today in the journal Current Biology, look at a rich fossil bed in Nevada's Humboldt-Toiyabe National Forest's famed Berlin-Ichthyosaur State Park (BISP), where several 50-foot-long ichthyosaurs (Shonisaurus popularis) are petrified in stone, as per ScienceDaily.
Led by Neil Kelley, Vanderbilt University scientist and former Smithsonian's National Museum of Natural History Peter Buck postdoctoral fellow, and co-authored by the museum's curator of fossil marine mammals Nicholas Pyenson, 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.
Some paleontologists have speculated that BISP's ichthyosaurs - predators resembling oversized chunky dolphins that have been designated as Nevada's state fossil - died in a mass stranding event similar to those that occasionally afflict modern whales, or that the creatures were poisoned by toxins from a nearby harmful algal bloom.
The difficulty is that these hypotheses lack strong lines of scientific evidence to back them up.
To solve this prehistoric mystery, the team used newly developed paleontological techniques such as 3D scanning and geochemistry, as well as conventional paleontological perseverance, sifting 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 that scientists at research institutions can study them more closely, the main attraction for visitors to the Nevada State Park-run BISP is a barn-like building that houses Quarry 2, an array of ichthyosaurs that have been left embedded in the rock for the public to see and appreciate. Quarry 2 features incomplete skeletons from an estimated seven individual ichthyosaurs that all appear to have perished around the same period.
Kelley, Pyenson, and the research team worked with Jon Blundell, a member of the Smithsonian Digitization Program Office's 3D Program team, and Holly Little, a long-time collaborator with Pyenson and the 3D Program team who is now the informatics manager at the museum's Department of Paleobiology.
While Pyenson and Kelley used traditional paleontological techniques to physically measure bones and study the site, Little and Blundell used digital cameras and a spherical laser scanner to take hundreds of photographs and millions of point measurements, which were then stitched together using specialized software to create a 3D model of the fossil bed.
The ages of the numerous fossil beds of BISP were separated by at least hundreds of thousands of years, if not millions of years, according to further analysis of the various strata in which the various clusters of ichthyosaur bones were discovered.
With these discoveries in mind, Kelley said the next step in this line of research is to look into other ichthyosaur and Shonisaurus sites in North America to start recreating their prehistoric world.
This may involve looking for additional breeding sites or areas with a greater variety of other species that could have been productive feeding grounds for this extinct apex predator.
During a period of the dinosaur era, ichthyosaurs-predatory marine reptiles with the ability to reach enormous sizes-ruled the seas, as per Live Science.
Ichthyosaurs held the title of maritime apex predators for a significant portion of the millions of years that dinosaurs ruled over the landmasses of Earth.
Before dinosaurs (about 230 million years ago) and ichthyosaurs (about 90 million years ago) emerged on Earth, these enormous "sea monsters" proliferated here about 250 million years ago.
Nonavian dinosaurs went extinct nearly 66 million years ago.
Ichthyosaurs evolved into a variety of body types, but their evolution can be summed up as beginning with eel-like forms and progressing to the dolphin-like appearance that is characteristic of most later ichthyosaur species.
Reptilian ichthyosaurs, which have streamlined bodies, fins, and extended heads with a pointed noses, are not closely related to fish or dolphins.
Instead, in a case of convergent evolution, different and unrelated lineages of swimmers, including ancient reptiles like the ichthyosaurs, sharks, and fish like sturgeons, came to resemble one another as a result of similar evolutionary pressures.
