Scientists have always thought that archosauromorpha, an animal group that includes crocodiles, birds and dinosaurs, reproduced only by laying eggs. But now, paleontologists have uncovered a 250-million-year-old fossil of a strange long-necked marine reptile with an embryo inside, demonstrating live birth in archosauromorphs for the first time and forcing a rethink of reproductive evolution.
Researchers at the University of Bristol and the Hefei University of Technology in China actually discovered the embryonic specimen a few years ago. Sitting inside the belly of a marine dinosaur-relative called Dinocephalosaurus that thrived in the South China sea during the Middle Triassic period, the team suspected at first that it might have been the creature's last meal.
Further examination led to the conclusion that it is in fact an embryo. It rests inside the rib cage of the fossilized mother and faces forward, whereas eaten animals will typically face backward after the predator swallows them head-first to help them down the hatch. Another helpful tidbit of evidence backing up the team's theory was the fact that the swallowed reptile is the same species as the mother.
(Score: 2) by butthurt on Saturday February 18 2017, @12:01AM
journal link (full text was available to this non-subscriber):
http://www.nature.com/articles/ncomms14445 [nature.com]