Researchers discovered the first fossil of the amphibious ichthyosaur was discovered in China.
The discovery links the dolphin-like creature to its terrestrial ancestors, and fills a gap in the fossil record, the University of California, Davis reported.
The revealing fossil is believed to be a missing stage in the evolution of ichthyosaurs, a transition that occurred about 250 million years ago. Until this discovery there were no fossils that showed the transition from land to sea.
"But now we have this fossil showing the transition," said lead author Ryosuke Motani, a professor in the UC Davis Department of Earth and Planetary Sciences. "There's nothing that prevents it from coming onto land."
The groundbreaking fossil is 1.5 feet long and believed to be from the Triassic period. The ancient creature had unusually large flippers that most likely allowed it to move across the land like a seal; it also had flexible wrists, which are essential for moving across the ground. Most ichthyosaurs have long, beak-like snouts, but this new fossils was found to have a nose as short as other land animals. The amphibious ichthyosaur also had thicker bones, which would have allowed it to swim through rough coastal waters as opposed to calmer deep seas.
The creature live four million years after the worse mass extinction ever seen on Earth; the finding could have implications for how the world recovered after such a major catastrophe.
"This was analogous to what might happen if the world gets warmer and warmer," Motani said. "How long did it take before the globe was good enough for predators like this to reappear? In that world, many things became extinct, but it started something new. These reptiles came out during this recovery."
The findings were published Nov. 5 in the journal Nature.
