'Sea Monster' Ichthyosaur Fossil Shows Oldest Live Birth Discovered, Settles Land vs. Water Argument
A new discovery of an ichthyosaur fossil from the Mesozoic era shows the oldest "sea monster" babies ever uncovered, beating out the previous record by ten million years, according to a new study.
The 248 million-year-old fossil indicates to researchers that the ichthyosaur was in a difficult labor when she passed, with one embryo inside, and another in the pelvis. A third embryo found nearby suggests it was a stillborn.
The biggest discovery, however, was with the new information that the eel-like species gave birth on land, and not in water. Since ichthyosaurs evolved on land before becoming aquatic creatures, it also means that the first species to live in water were actually giving birth on land, like their ancestors.
It means "live bearing did not evolve in water as scientists thought," said Ryosuke Motani, a prehistoric marine reptile expert at the University of California, Davis. "Our assumption was wrong."
Researchers came to the conclusion after discovering that the offspring in the fossil were emerging head-first, a trait belonging to animals that give birth on land (those air-breathing creatures born in water, such as dolphins and whales, emerge tail-first to avoid suffocation).
"This land-style of giving birth is only possible if they inherited it from their land ancestors," Motani told Live Science. "They wouldn't do it if live birth evolved in water."
Ichthyosaurs were dubbed "sea monsters" because of their history as a top ocean predator during the same period that the dinosaurs ruled the land. The creature measured in as long as a bus with features including massive eyes and teeth-filled snouts.
The skeleton was discovered by researchers only after they reached their lab in China. It was originally picked up in a rock slab with a Saurichthys fish fossil, which they said is not from the same time period. It now sits at the Anhui Geological Museum in Hefei, China.
The team's detailed report was published Wednesday in the journal PLOS ONE.