245-Million-Year-Old Fossil Shows Intact Organs

Scientists have unearthed a stunningly preserved fossil in China belonging to Austronaga minuta, a marine reptile from 245 million years ago. This exceptionally intact specimen from the Triassic Period reveals its stomach, liver, and intestines, providing a rare glimpse into reptilian internal anatomy prior to the era of dinosaurs.

The fossil, found in Yunnan Province, indicates the Austronaga individual was about 2 feet long, featuring a long neck, a tail, and large front flippers. Researchers noted its simple, single-chambered stomach, suggesting a digestive system more basic than that of modern birds or crocodiles, and likely evolved later in archosaur lineage.

Detailed analysis of the fossil's gastrointestinal tract showed clear remnants of fish scales, confirming its diet. The preservation of hemoglobin in the ancient liver, identified by elevated iron content, is particularly astonishing, according to paleontologists. This discovery contributes significantly to understanding the aquatic adaptations and evolutionary pathways of reptiles.

Austronaga is closely related to the archosaur group, which later gave rise to dinosaurs. Its remarkable marine adaptation highlights the diversity of life that emerged after Earth's major extinction event. The findings, published in Science Advances, offer crucial data on the development of reptilian digestive systems.