<p>Scientists have found a remarkable 250 million-year-old "terrible-headed lizard" fossil in China with an embryo inside the mother, providing the first evidence for live birth in an animal group previously thought to exclusively lay eggs.<br /><br /></p>.<p>"Live birth is well known in mammals, where the mother has a placenta to nourish the developing embryo," said Professor Jonathan Aitchison from University of Queensland in Australia.<br /><br />"Live birth is also very common among lizards and snakes, where the babies sometimes 'hatch' inside their mother and emerge without a shelled egg," Aitchison said.<br /><br />Until recently it was thought the third major group of living land vertebrates, the crocodiles and birds (part of the wider group Archosauromorpha) only laid eggs.<br /><br />"Indeed, egg-laying is the primitive state, seen at the base of reptiles, and in their ancestors such as amphibians and fishes," Aitchison said.<br /><br />He said the new fossil was an unusual, long-necked marine animal called an archosauromorph that flourished in shallow seas of South China in the Middle Triassic Period.<br /><br />The creature was a fish-eater, snaking its long neck from side to side to snatch its prey.<br />Its fossil was one of many astonishingly well-preserved specimens from new "Luoping biota" locations in south-western China.<br /><br />Professor Jun Liu from Hefei University of Technology in China said the researchers were "excited" when they first saw this embryonic specimen.<br /><br />"We were not sure if the embryonic specimen was the mother's last lunch or its unborn baby. Upon further preparation and closer inspection, we discovered something unusual," said Liu.<br /><br />He said the embryo was inside the mother's rib cage, and it faced forward; swallowed animals generally face backward because the predator swallows its prey head-first to help it go down its throat.<br /><br />The small reptile inside the mother was an example of the same species, researchers found.<br />"Further evolutionary analysis revealed the first case of live birth in such a wide group containing birds, crocodilians, dinosaurs and pterosaurs among others, and pushes back evidence of reproductive biology in the group by 50 million years," Liu said.<br /><br />"Information on reproductive biology of archosauromorphs before the Jurassic Period was not available until our discovery, despite a 260 million-year history of the group," said Liu.<br /><br />Professor Chris Organ from Montana State University in US said evolutionary analysis showed that this instance of live birth was also associated with genetic sex determination.<br /><br />"Some reptiles today, such as crocodiles, determine the sex of their offspring by the temperature inside the nest," he said. The research was published in the journal Nature Communications. <br /></p>
<p>Scientists have found a remarkable 250 million-year-old "terrible-headed lizard" fossil in China with an embryo inside the mother, providing the first evidence for live birth in an animal group previously thought to exclusively lay eggs.<br /><br /></p>.<p>"Live birth is well known in mammals, where the mother has a placenta to nourish the developing embryo," said Professor Jonathan Aitchison from University of Queensland in Australia.<br /><br />"Live birth is also very common among lizards and snakes, where the babies sometimes 'hatch' inside their mother and emerge without a shelled egg," Aitchison said.<br /><br />Until recently it was thought the third major group of living land vertebrates, the crocodiles and birds (part of the wider group Archosauromorpha) only laid eggs.<br /><br />"Indeed, egg-laying is the primitive state, seen at the base of reptiles, and in their ancestors such as amphibians and fishes," Aitchison said.<br /><br />He said the new fossil was an unusual, long-necked marine animal called an archosauromorph that flourished in shallow seas of South China in the Middle Triassic Period.<br /><br />The creature was a fish-eater, snaking its long neck from side to side to snatch its prey.<br />Its fossil was one of many astonishingly well-preserved specimens from new "Luoping biota" locations in south-western China.<br /><br />Professor Jun Liu from Hefei University of Technology in China said the researchers were "excited" when they first saw this embryonic specimen.<br /><br />"We were not sure if the embryonic specimen was the mother's last lunch or its unborn baby. Upon further preparation and closer inspection, we discovered something unusual," said Liu.<br /><br />He said the embryo was inside the mother's rib cage, and it faced forward; swallowed animals generally face backward because the predator swallows its prey head-first to help it go down its throat.<br /><br />The small reptile inside the mother was an example of the same species, researchers found.<br />"Further evolutionary analysis revealed the first case of live birth in such a wide group containing birds, crocodilians, dinosaurs and pterosaurs among others, and pushes back evidence of reproductive biology in the group by 50 million years," Liu said.<br /><br />"Information on reproductive biology of archosauromorphs before the Jurassic Period was not available until our discovery, despite a 260 million-year history of the group," said Liu.<br /><br />Professor Chris Organ from Montana State University in US said evolutionary analysis showed that this instance of live birth was also associated with genetic sex determination.<br /><br />"Some reptiles today, such as crocodiles, determine the sex of their offspring by the temperature inside the nest," he said. The research was published in the journal Nature Communications. <br /></p>