An artist’s conception of tadpole and adult Notobatrachus degiustoi in a Mid-Jurassic pond in Patagonia.Credit...Gabriel Lío
The New York Times Trilobite column has a story about what may be the largest tadpole species ever discovered. Notobatrachus, an ancient relative of modern frogs, lived around 161 million years ago in present-day Santa Cruz Province, Argentina. In 2020, a team of paleontologists from Argentina and China uncovered hundreds of adult fossils of Notobatrachus, each about the size of a bullfrog. Among these, they found a well-preserved 6-inch tadpole fossil, complete with a bony vertebral column that helped confirm it as a juvenile Notobatrachus. For full details, refer to the study published in the journal Nature.
The most notable feature of the find, however, was the tadpole’s gill system, which it used to filter food particles out of the water, as is the case with modern tadpoles. “We now know that this filter feeding system was present since the beginning of the group,” Dr. Chuliver said, adding that the gill system is still found in over 6,000 species of tadpole frogs today.
The gap between the first known frogs in the Triassic Period and the previous oldest-known tadpoles in the Cretaceous Period led some researchers to wonder whether the ancestors of frogs had a metamorphosis at all, Dr. Chuliver said. Some researchers pointed to the old lineage of living frog species, such as the cliff chirping frogs of Texas, whose life cycle skips the tadpole stage entirely.
