Paleontologists in Argentina made a groundbreaking discovery while searching for dinosaur fossils in Patagonia. They unearthed the oldest tadpole ever found, belonging to the frog species Notobatrachus degiustoi, dating back around 161 million years to the middle Jurassic period. This fossil is a remarkable specimen with well-preserved soft tissues, including eyeballs, gills, and nerves, providing valuable insights into frog evolution.
The discovery of this ancient tadpole may settle a long-standing debate about when the tadpole stage of frog development evolved. Some researchers believed that the most ancient frogs did not have a tadpole stage, but this fossil evidence suggests otherwise. By matching the tadpole to its adult counterpart in the fossil record, scientists can now trace the evolution of frogs more accurately.
Tadpole fossils are rare due to the delicate nature of these juvenile swimmers, who often die in water before fossilization can occur. The preservation of this tadpole’s features, such as eyes, gills, and nerves, is a testament to the exceptional conditions in which it was found. The size of the specimen, about 6 inches long with a 3-inch tail, surprised researchers, indicating that both juvenile and adult N. degiustoi frogs were unusually large for their time.
Despite its size, the N. degiustoi tadpole closely resembles modern tadpoles, suggesting that their feeding habits and biological systems have remained relatively unchanged over millions of years. The presence of spiny projections on the gills indicates a filter-feeding system similar to that of modern tadpoles, allowing them to feed on plankton, algae, and detritus in the water.
This discovery opens up new possibilities for further research in the La Matilde Formation, where more tadpole fossils could provide additional insights into the evolution of frogs. Mariana Chuliver, the lead author of the study, hopes to secure funding for future expeditions to expand the fossil record and uncover more secrets from the Jurassic era.
Sierra Bouchér, a journalist specializing in science communication, highlights the significance of this discovery in understanding prehistoric ecosystems and the evolution of amphibians. With a master’s degree in science communication and a background in animal behavior and historical ecology, Bouchér’s expertise sheds light on the importance of preserving and studying ancient fossils like the Jurassic giant tadpole.
