Fossil shows ancient sea monster delivered live babies

Dinocephalosaurus gave birth to live babies, a newly found fossil suggests. Picture: Dinghua Yang/Hefei University of Technology/PA Wire
Have your say

A fossil from a reptile that lived 250 million years ago has revealed the first evidence of live birth in animals previously thought to lay eggs.

The remarkable fossil of a Dinocephalosaurus, discovered in a field in China, shows an embryo inside the ribcage of the mother.

Dinocephalosaurus was a long-necked fish-eating ­archosauromorph that flourished in the shallow seas of South China in the Middle Triassic period.

In research published in Nature Communications, experts found the embryo, a small reptile of the same species, facing forwards inside the mother.

Swallowed animals generally face backwards because the predator ingests its prey head-first to help it go down its throat.

Professor Jun Liu, from Hefei University of Technology in China, said: “We were so excited when we first saw this embryonic specimen several years ago but we were not sure if the embryonic specimen is the last lunch of the mother or its unborn baby.

“Upon further preparation and closer inspection, we realised that something unusual has been discovered.


“Information on reproductive biology of archosauromorphs before the Jurassic period was not available until our discovery, despite a history of 260 million years.”

Live birth is well known in mammals and is common among lizards and snakes, where the babies sometimes “hatch” inside their mother and emerge without a shelled egg.

Until this discovery, the third major group of living land  vertebrates – the crocodiles and birds, part of the  wider group Archosauromorpha – was thought to only lay eggs.

Egg laying is the primitive state, seen at the base of  reptiles, and in their ancestors such as amphibians and fish.




“This new specimen from China rewrites our understanding of the evolution of reproductive systems.”

An international team of scientists carried out the research on the fossil.


Professor Mike Benton,  from the School of Earth  Sciences at the University of Bristol, said: “The analysis of the evolutionary position of the new specimens shows there is no fundamental ­reason why archosauromorphs could not have evolved live birth.”