Researchers have discovered the oldest known fossilized tadpole in Argentinian Patagonia, which dates back to between 168 million and 161 million years ago. The fossil comes from the extinct species Notobatrachus degiustoi and shows that modern characteristics of tadpoles, such as filter-feeding and puddle-dwelling, had already evolved in some of the earliest frogs. The tadpole was well-preserved, with some soft tissue visible, including its eyes and nerves. This finding pushes back the record for the earliest known tadpoles by an additional 30 million years.
The N. degiustoi tadpole was relatively large, measuring about 16 centimeters from snout to tail tip, compared to the smaller tadpoles found in many modern species. This adds to the uniqueness of the finding, as giant tadpoles are not common today, and those that do exist often grow into relatively small adults. The fossilized tadpole also displayed evidence of filter-feeding, similar to modern tadpoles, suggesting that this feeding strategy has been successful for a long time in the evolution of frogs. The fossil revealed a well-preserved throat skeleton, indicating that the tadpole fed by sucking and straining food particles out of the water.
Evolutionary biologist Mariana Chuliver and her colleagues identified the fossilized tadpole as the same species as the adult frogs they found in the same area, based on shared features of its vertebrae. The tadpole was in an advanced stage of development, with hind legs and forelegs already formed. The discovery of this well-preserved fossil sheds light on the early evolution of tadpoles and their feeding habits, providing valuable insight into the history of these amphibians. This finding represents a significant contribution to the understanding of the ancient origins of tadpoles and their importance in the evolution of frogs.
The N. degiustoi tadpole lived during the middle of the Jurassic Period, making it one of the oldest known tadpoles to date. Prior to this discovery, the oldest known tadpoles belonged to a frog species that lived about 130 million years ago. This fossilized tadpole is unique in its size and feeding habits, providing researchers with new information about the early evolution of frogs and their tadpoles. The preserved soft tissues and detailed features of the tadpole’s anatomy offer valuable insights into the past environment and biology of these ancient amphibians.
The researchers found the fossilized tadpole while searching for dinosaur fossils in Argentinian Patagonia, highlighting the importance of exploring diverse habitats and ecosystems for paleontological discoveries. The detailed study of this well-preserved fossil has expanded our knowledge of tadpole evolution and the adaptations that early frogs developed to survive and thrive in their environments. By studying ancient fossils like this N. degiustoi tadpole, scientists can piece together the evolutionary history of amphibians and better understand the relationships between different species and their habitats over millions of years.
