During the age of the dinosaurs, ichthyosaurs shared the world’s seas with the other great marine reptiles, plesiosaurs and mosasaurs, long before the arrival of large sharks and whales. The first ichthyosaurs appeared in the Triassic, which began about 245 million years ago. The group reached its peak of diversity during the Jurassic, then began a decline that led to its extinction in the early stages of the Late Cretaceous, several million years before the last dinosaurs died out.
Somewhere during the Middle Jurassic, according to the fossil record, ichthyosaurs experienced a major shift, as smaller ichthyosaurs began to give way to larger, more advanced ones with bigger eyes. These larger ichthyosaurs then ruled the seas until some 95 million years ago, by which time the entire group had gone extinct. Though scientists don’t know why this transition occurred, they might have found a new clue thanks to fossils unearthed on Scotland’s Isle of Skye more than a half-century ago.
Though amateur fossil collector Brian Shawcross found an array of fossilized bones at Bearreraig Bay all the way back in 1959, and donated them to Glasgow’s Hunterian Museum in the 1990s, researchers have only now identified some of the fossils—including back, tail and fin bones—as belonging to a new species of ichthyosaur that lived some 170 million years ago. According to a team of paleontologists led by scientists from Edinburgh University, the newly identified ichthyosaur helps to fill the gap in the fossil record in the Middle Jurassic period (about 176 million to 161 million years ago).
In a study published on Monday in the Scottish Journal of Geology, the scientists describe the new species for the first time. The remains they examined were incomplete, but they believe the dolphin-like predator was about 14 feet (4.3 meters) long, making it one of the smaller, more primitive ichthyosaurs. It swam in the relatively warm, shallow waters around the Isle of Skye during the Jurassic period, and preyed on the fish and squid that made up its diet. Judging from the shape of a bone in its front flippers, which appears to be different from other known ichthyosaurs, researchers believe this species may have been an especially strong swimmer.
Though the earliest ichthyosaur fossils ever discovered were found in England, this is the first one to be unearthed in Scotland. Study co-author Stephen Brusatte, a paleontologist at the University of Edinburgh, told LiveScience that “It’s one of a select few specimens of that age in the world,” adding that “this is the first time we have something distinctly Scottish.” In addition to the new species, the researchers examining the Scottish fossils uncovered teeth they believe are from Ichthyosaurus communis, earlier found to be widespread in the limestone rocks on England’s southern coast.
The scientists have dubbed the new species of ichthyosaur Dearcmhara shawcrossi. Dearcmhara (pronounced “jark vara”) is a Scottish Gaelic word meaning “marine lizard.” By naming the creature in honor of Shawcross, the man who discovered the fossils, Brusatte and his colleagues hope to encourage more amateur fossil collectors to come forward with the potentially valuable specimens that may be hidden in their own private collections. As Brusatte told the Guardian: “What people find may be really important and it would be great if there was a way to preserve them for posterity. They are part of Scotland’s heritage.”