Turtles, known for their distinctive armored shells and adaptations to both terrestrial and aquatic habitats, have long puzzled scientists regarding their evolutionary origins. Despite being among the longest-living animals, their unusual anatomy has made it difficult to determine their exact place on the reptilian family tree.

For decades, many paleontologists have pointed to Eunotosaurus africanus, a reptile from about 260 million years ago characterized by broad ribs that may have been precursors to a turtle’s shell, as the likely common ancestor of modern turtles. However, genetic analyses have provided contrasting evidence, indicating that turtles might be more closely related to archosaurs—a group that includes crocodiles, birds, dinosaurs, and pterosaurs—rather than to Eunotosaurus.

In a recent study published in the journal Current Biology, Xavier A. Jenkins of the American Museum of Natural History and his colleagues present new findings that aim to reconcile these differing viewpoints. The researchers argue that turtles are indeed part of the archosauromorph lineage, rather than descending directly from Eunotosaurus. Their conclusion is supported by both anatomical data and genetic evidence, providing a more comprehensive understanding of turtle evolution.

The timing of turtles’ emergence is also notable. They evolved shortly after the Permian-Triassic extinction event, approximately 252 million years ago, which was the most severe mass extinction in Earth’s history. This period saw reptiles diversifying rapidly across the supercontinent Pangea, leading to a proliferation of new forms. Within roughly 40 million years following this extinction, turtles underwent significant evolutionary transformations that established many of the characteristics seen today.

These findings contribute to resolving a long-standing debate about turtle origins by integrating fossil morphology with molecular data. According to Jenkins, understanding the placement of turtles among archosauromorphs aligns with the broader patterns of reptile diversification after the Permian-Triassic extinction and highlights how rapidly key adaptations, such as the development of the shell, could arise in evolutionary terms.

While some aspects of turtle ancestry continue to be explored, this study marks a significant step toward clarifying their evolutionary history and relationships to other reptiles.