‘Sea monster’ fossils offer signs of ichthyosaur migration 230 million years ago - The Washington Post

The bones recovered astatine the Nevada tract travel from the elephantine ichthyosaur Shonisaurus, which resembled an enormous, out-of-shape dolphin. Shonisaurus glided barge-like thousands of miles done an water known arsenic Panthalassa, the past mentation of today’s Pacific, to breed and present their offspring, according to a caller survey successful Current Biology.

The uncovering offers a uncommon model into the behaviors of prehistoric animals, thing that is not ever captured by idiosyncratic fossils. It raises the anticipation that further clues embedded successful sediment and ungraded whitethorn connection a deeper knowing of marine reptiles that inhabited the satellite agelong earlier humans.

The earliest known evidence of migration dates backmost much than 300 cardinal years to past Bandringa sharks with agelong spoon bill-shaped snouts and prehistoric fish with armored plates. Today billions of animals migrate, including taxon arsenic divers arsenic hummingbirds and humpback whales, monarch butterflies and bluish wildebeests.

Clues from akin fossils recovered successful different regions suggest that Shonisaurus migrated to cardinal Nevada from parts of modern-day California, Alaska and New Mexico.

If so, that behavior could nexus the prehistoric Shonisaurus, the largest carnal to question the oceans successful the Triassic period, with modern giants — the bluish whales observed contiguous with their calves successful the Gulf of California. Whales thin to migrate to warmer waters to springiness birth, past to cooler waters that are affluent successful nutrients.

“One has to wonderment if the aforesaid ecological rules are astatine play adjacent though determination are implicit 200 cardinal years betwixt [whales and Shonisauruses],” said Nicholas D. Pyenson, 1 of the caller paper’s authors who works successful the section of paleobiology astatine the National Museum of Natural History.

Not each experts successful the tract judge Pyenson and his colleagues person solved the enigma surrounding the large abundance of Shonisaurus bones astatine the tract and the implicit lack of immoderate different ichthyosaurs.

“This survey is astir apt not the last word, but it’s a bully measurement forward,” cautioned Martin Sander, a prof of paleontology astatine the University of Bonn successful Germany and probe subordinate astatine the Natural History Museum of Los Angeles County.

Sander, who was not progressive successful the study, added “I’m not wholly convinced. It’s a bully thought but it’s awfully hard to prove.”

The skeletons astatine Berlin-Ichthyosaur State Park successful West Union Canyon amusement that the Shonisaurus grew up to 50 feet, 5 times the magnitude of a modern dolphin, and weighed astir 22 tons, the equivalent of 3 ample elephants. Their offspring were lone a fewer feet long.

Charles L. Camp, a University of California astatine Berkeley paleontologist, was archetypal to excavate the alternating layers of limestone and mudstone astatine the tract successful the 1950s. He immediately wondered what mightiness relationship for the ample clump of Shonisaurus skeletons.

“He thought it mightiness beryllium a wide stranding,” similar those involving whales, said Neil P. Kelley, different of the paper’s authors and an adjunct prof successful Vanderbilt University’s section of world and biology sciences.

But the fossil grounds disproves that hypothesis, showing that the skeletons had settled underwater acold from shore.

The effort to explicate wherefore Shonisaurus bones person truthful acold been the lone ichthyosaur fossils discovered astatine the Nevada tract became a feat of technological detective work. Researchers combined 3D scanning and geochemistry with much accepted tools specified arsenic depository collections, tract notes, photographs and archival materials.

They came to presumption migration arsenic the astir apt script aft eliminating different possibilities. Testing the sediment revealed an lack of the mercury levels that would person signaled volcanic activity, which is believed to person caused the largest wide extinction 252 cardinal years ago.

Researchers were besides capable to destruct the anticipation that a deadly algal bloom poisoned the marine reptiles.

In the end, lone the migration script appeared to marque sense.

“Shonisaurus decidedly occurs astatine different locations truthful the genus had a wide geographic range, and it is precise tenable that these ample individuals traveled agelong distances, arsenic astir ample marine vertebrates bash today,” Kelley said. “It should beryllium imaginable to stitchery further information successful the aboriginal which could trial the hypotheses we contiguous successful the paper, including migration.”

At slightest 2 different mysteries stay surrounding the past marine reptiles called ichthyosaurs.

Sander astatine the University of Bonn said ichthyosaurs, similar oversea turtles, were primitively onshore animals of immoderate kind, “but they look successful the fossil grounds arsenic afloat blown unfastened water animals. We don’t person the close rocks to amusement however the ichthyosaurs went to the sea.”

Also, portion Shonisaurus went extinct astir 200 cardinal years agone astatine the extremity of the Triassic, “smaller ichthyosaurs survived into the Jurassic and beyond with the full radical going extinct astir 88 cardinal years agone successful the Cretaceous,” Kelley said. Why the tiny ichthyosaurs survived and the giants didn’t is not clear.

Pyenson cannot assistance but deliberation that the eventual destiny of Shonisaurus carries a acquisition for modern-day bluish whales, and different cetaceans, galore of which are present classified arsenic endangered.

“We should privation a world,” helium said, “with these ample water giants successful it.”