Dolphin-Like Ichthyosaur Represents Missing Link

The first fossil of a dolphin-like ichthyosaur has been found in China, and this amphibian represents the missing link between it and its terrestrial ancestors, according to a recent study.

Ichthyosaurs are marine reptiles hailing from the Age of Dinosaurs about 250 million years ago, and until now there was no fossil evidence of their transition from land to sea.

Now, thanks to a team of researchers at the University of California (UC), Davis, this discovery is filling in a gap in the fossil record.

"We have this fossil showing the transition," lead author Ryosuke Motani, a professor in the UC Davis Department of Earth and Planetary Sciences, said in a statement. "There's nothing that prevents it from coming onto land."

Discovered in China's Anhui Province, the 248-million-year-old fossil lived during the Triassic period. It measures roughly 1.5 feet long, and unlike ichthyosaurs fully adapted to life at sea, this one had unusually large, flexible flippers that likely allowed for seal-like movement on land.

Most ichthyosaurs have long, beak-like snouts, but the amphibious fossil shows a nose as short as that of modern-day land reptiles.

The new fossil indicates that this particular ichthyosaur sported thicker bones than previously seen, likely due its transition onto land. Most marine reptiles, when they first adapted to life on legs, developed thicker bones in order to swim through rough coastal waves before entering the deep sea.

And for this team of scientists, the new dolphin-like ichthyosaur not only represents a missing link in their evolution, but also may shed light on how animals will cope with climate change. This animal managed to survive about four million years after the mass extinction event that wiped out the dinosaurs, which was supposedly linked to global warming, making scientists wonder how today's animals and plants will adapt to our warming world.

The findings were published in the journal Nature.