'Before the Spitsbergen discovery, the oldest ichthyosaurs in the fossil record were from China, dated to about 248 million years ago. “The problem is, [they] already look like fish: long bodies, flippers, modified tail [with] a fin,” says Kear. “They’re living in water and they don’t come out of it.”

https://www.atlasobscura.com/articles/earliest-ichthyosaur-fossil-arctic