The partial fossil skeleton of an ichthyosaur, giant marine reptiles that evolved from land reptiles and moved to the water, was recovered in China and may show a live birth, Ryosuke Motani from the University of California, Davis, said.
The maternal skeleton was associated with three embryos and neonates: one inside the mother, another exiting the pelvis -- with half the body still inside the mother -- and the third outside of the mother, Motani and colleagues report in the journal PLoS ONE.
The headfirst birth posture of the second embryo indicates that live births in ichthyosaurs may have taken place on land instead of in the water, the researchers said.
"The study reports the oldest vertebrate fossil to capture the 'moment' of live-birth, with a baby emerging from the pelvis of its mother," Motani said. "The 248-million-year old fossil of an ichthyosaur suggests that live-bearing evolved on land and not in the sea."