A team of scientists has discovered the oldest fossil of a giant tadpole ever found in Argentina, dated to over 160 million years ago. Although frogs have a documented origin up to 217 million years ago, the exact manner and timing of their evolution from the tadpole stage remained mysterious.
This exceptional discovery exceeds the previous record by about 20 million years. Trapped in a sandstone slab, the fossil preserves parts of the tadpole’s skull, spine and detailed imprints of the tadpole’s eyes and nerve structures, as explained Mariana Chuliverbiologist at the Maimonides University of Buenos Aires and author of the study.
It is the oldest tadpole fossil we know of and one of the best preserved.
A 160-million-year-old tadpole rewrites evolutionary history
This discovery helps to better define that evolutionary phase. The fossil, about 16 cm long, represents a juvenile form of an extinct giant frog species. Ben Kligmana paleontologist at the Smithsonian National Museum of Natural History, who was not involved in the study, commented on the discovery:
This discovery narrows the time frame in which the transition from tadpole to frog occurs.
The fossil’s resemblance to modern tadpoles is striking, even including the remains of the gill system, a structure that modern amphibians use to filter food particles from the water. This indicates that their survival strategy has remained unchanged for millions of years, helping them overcome multiple extinction events.
