Spectacular fossil preserves internal organs of ancient marine reptile
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- Austronaga minuta — a 60-cm-long-necked marine predator from 245 million years ago — is the oldest reptile ever found with an intact digestive system, discovered in Yunnan province, China in 2023.
- The fossil preserves almost the entire skeleton along with the stomach, liver, intestines, blood vessels, and even the scales of a partially digested fish meal.
- Austronaga belongs to archosaurs — the group including dinosaurs, birds, and crocodiles — dating to the Triassic Period when dinosaurs first evolved, but is not itself a dinosaur.
- The fossil reveals that the basic plan of the reptilian digestive tract has changed little in 245 million years, with its straight, simple intestines mirroring those of most modern predatory fish-eating reptiles.
- Stephan Spiekman of the Natural History Museum Stuttgart described the animal as a good, agile swimmer that used its tail for propulsion, long front flippers for steering, and long neck to catch fish.
- Unlike a 380-million-year-old armoured fish fossil — described by John Long of Flinders University in 2022 as having the oldest known organs of any vertebrate — Austronaga's internal organs are only preserved in two dimensions.
Why it matters: Paleontologists gain a rare window into early archosaur anatomy that constrains how much digestive innovation has occurred across 245 million years of reptile evolution. The specimen also visually captures a predator's last meal, turning a single fossil into direct evidence of Triassic food-web behavior — not just skeletal morphology.
