Oldest Preserved Reptile Stomach Found in 240-Million-Year-Old Chinese Fossil

A remarkable fossil unearthed in China is providing unprecedented insights into the early evolution of reptiles, boasting the oldest preserved stomach, liver, and intestinal soft tissue ever found in the species. The 240-million-year-old specimen, dating back to the Early Triassic period, offers a unique window into the transition from land to sea.

The fossil, named Austronaga minuta, possesses highly specialized body features that indicate an aquatic lifestyle. This discovery challenges previous assumptions about the marine colonization of archosaurs, a group of reptiles that includes birds, dinosaurs, and crocodiles. The findings suggest this process began earlier and extended further than scientists had previously believed.

Researchers from the Chinese Academy of Sciences, leading the study published in Science Advances, described the fossil as a "unique opportunity" to understand how Triassic reptiles adapted to aquatic environments. The specimen represents the earliest known stem-archosaur to display clear aquatic specializations, providing crucial evidence for evolutionary studies.

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We report on a well-preserved Triassic reptile representing the earliest stem-archosaur to evolve unequivocal aquatic specialisations. The fossil exhibits the oldest known stomach, liver and intestinal preservations in reptiles.