Chinese fossil reveals internal organs of prehistoric marine reptile

Researchers said the fossil of the Triassic Period creature Austronaga minuta was unearthed in China's Yunnan Province. (New Scientist pic)BEIJING: Scientists have discovered a fossil in China of a long-necked marine reptile from 245 million years ago that is so well preserved that it reveals the animal's stomach, liver and intestines, providing an unparalleled look at reptilian internal anatomy before the age of dinosaurs.Researchers said the fossil of the Triassic Period creature Austronaga minuta was unearthed in Yunnan Province in southern China in a region that has yielded many nicely preserved fossils dating to a time of tremendous evolutionary innovation in the aftermath of Earth's worst mass extinction of species.The fossil shows that this Austronaga individual was around 60 cm long, with a relatively small head and a narrow snout filled with fang-like teeth ideal for snaring slippery fish, a long neck and torso, and an even longer tail, with large front flippers and small hind flippers.The animal, descended from land reptiles, appears to have been an agile swimmer, mainly using its tail for propulsion, its front flippers for steering and its long neck to catch fish.Austronaga was closely related to a reptile lineage called archosaurs that includes crocodiles, dinosaurs, the flying reptiles called pterosaurs and birds.Very few animals related to this lineage evolved a marine lifestyle — Austronaga displayed the highest degree of aquatic adaptation of any of them — though there were many other kinds of marine reptiles.Most of its skeleton was preserved with the bones in the position they would have been in life.However, what makes this fossil particularly revelatory is the preservation of internal organs, a rarity, showing the complete gastrointestinal system."To our knowledge, this represents the oldest well-preserved digestive tract of any reptile," said paleontologist Stephan Spiekman of the State Museum of Natural History Stuttgart and the University of Hohenheim in Germany, one of the authors of the study published in the journal Science Advances.The fossil showed that Austronaga had a sac-like stomach with a single chamber, unlike the double chambers present in birds, crocodiles and certain dinosaurs.That means Austronaga had a simpler arrangement, with one compartment for digestion."It tells us that the double-chambered stomach likely did not …