Tadpoles and adults of the extinct frog species Notobatrachus degiustoi (illustrated) lived in temporary ponds in what is the Patagonia region of Argentina today.
Illustration by Gabriel Lío

While searching for dinosaurs in the sediment and soft ash, Palentoligist Federico Agnolín and his colleagues kept stumbling across frogs at their site at Estancia La Matilde in the Santa Cruz province of Argentina. They were finding all adult Notobatrachus degiustoi, which is an extinct species. They believed that the frogs at the time did not have a tadpole stage, but they were about to learn otherwise in a very exciting discovery!

The researchers who described the fossil in Nature today estimate it to be between 161 to 168 million years old, beating the previous record holder by around 30 million years. The find provides solid evidence frogs have had a tadpole stage for at least that long. “It’s a beautiful confirmation of what many experts had suspected,” says herpetologist Alexander Haas of the Leibniz Institute in Bonn, Germany. Reconstructing tadpole evolution based on their diversity today, Haas and others previously predicted that tadpoles would have existed this early on.

The tadpole was surprisingly similar to modern tadpoles! To read the full story, visit National Geographic here!