Researchers discover first live birth evidence in pre-dinosaur reptile

Paleontologists unearth an unexpected baby bump

Its fossil was one of many astonishingly well-preserved specimens from new "Luoping biota" locations in south-western China.

The new fossil is an unusual, long-necked animal called Dinocephalosaurus, an archosauromorph that flourished in shallow seas of South China in the Middle Triassic.

Dinocephalosaurus had a long neck and sharp teeth. "It looks superficially like the legendary Nessie".

While the embryo inside the fossil was small - around half a metre (1.6 feet) in size - it showed the tell-tale signs of being a Dinocephalosaurus, including elongated ribs and a long neck. Furthermore, the somewhat curved position was typical for am embryo. Second, the embryo's neck was pointing forward.

The young Dinocephalosaurus was facing forward in the abdominal cavity, allowing scientists to dismiss the possibility it was prey as it would have been swallowed head first. There were no known fossils like this (marine vertebrates of this age) from Australia.

Egg-laying animals typically deposit eggs holding embryos that are much less developed than the one found inside the mother Dinocephalosaurus, the research team noted. "The ancestors of Dinocephalosaurus lived on land - live birth was likely an adaptation that helped it reinvade the marine environment".

Today's birds and crocodiles along with extinct dinosaurs also make up the archosaur group.

"Our discovery pushes back evidence of reproductive biology in the clade by roughly 50 million years", write the researchers, "and shows that there is no fundamental reason that archosauromorphs could not achieve live birth".

Further, Liu said that researchers have not found any elements of a calcified eggshell around the embryo's skeleton, which proves the animal gave birth instead of laying eggs.

Lead author Professor Jun Liu from Hefei University of Technology China, said the researchers were "excited" when they first saw this embryonic specimen. "It obtains the best solution possible based on the current situation".

The discovery of this pregnant dino-relative has implications for our understanding of how the ancestors of crocodiles, such as Dinocephalosaurus, determined the sex of their offspring.

The gender of a crocodile's offspring is influenced by environmental factors. All those creatures are known to give birth that way.

Scientists who discovered the 245-million-year-old creature with its young curled inside its belly initially did not want to jump into conclusion since the smaller animal inside the ribcage could have been the larger creature's last meal.

"Reptilian eggs can not be incubated underwater; amniote embryos in shelled eggs must exchange respiratory gases with the environment across the eggshell, and this exchange is much slower in water than in air", researchers wrote in their study, which was published in Nature Communications on February 14.

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