Scientists have discovered the oldest fossil of a giant tadpole that roamed 160 meters ago.
A new fossil discovered in Argentina surpasses the previous paleontological record by about 20 million years.
Embedded in the sandstone slab are parts of the tadpole’s skull and spine, along with impressions of its eyes and nerves.
“This is not only the oldest known tadpole, but also the most exquisitely preserved,” said study author Mariana Sulliver, a biologist at Maimonides University in Buenos Aires.
Researchers know that frogs were around 217 million years ago. But how and when they become tadpoles is unclear.
This new discovery adds some clarity to that timeline. At about 6in (16cm) long, the tadpole is a younger version of the extinct giant frog.
“This helps shorten the time frame for a frog to become a frog,” said paleontologist Ben Klickman of the Smithsonian’s National Museum of Natural History, who was not involved in the research.
The results were published Wednesday in the journal Nature.
The fossil is very similar to present-day tadpoles – even containing remains of the gill scaffolding system that modern-day tadpoles use to extract food particles from water.
That means amphibians’ survival strategy has been tried and true for millions of years, helping them outlast many mass extinctions, Klickman said.
