When most people think of the Jurassic period of the Earth, they picture massive dinosaurs. What they don’t often think about is frogs, but perhaps they should.

It has long been known that various amphibians, including frogs and toads, lived during this time, and even much further back. If frogs and toads lived, it stands to reason that so did tadpoles, but up until recently, no fossils of them had been found.

This is likely due to the fact that they were relatively soft-bodied, making it rare for them to become fossils.

That has changed, however, with a fossil tadpole that was found in what is today called Patagonia and scientists have dated it back to 161 million years ago, which breaks the record for the oldest tadpole fossils (the previous record dated them back to 145 million years ago).

The lead author of the study of this fossil, Dr. Mariana Chuliver Pereyra from the La Plata National University commented on this find in a statement given to IFLScience, saying:

“The habitat wherein this tadpole lived was probably a shallow pond, which dried out periodically, since it was under variable climatic conditions. As with most extant species, not all tadpoles succeed in metamorphosing, so many of them die when the ponds dried out. Our tadpole probably died naturally, and after its death was covered by volcanic ash and silt, which is a fine grain sediment. The deposition of these fine sediments promoted an exquisite preservation of the specimen, which lasted more than 160 million years.”

They believe that this tadpole is a member of the Jurassic frog Notobatrachus degiustoi, which has long since gone extinct. It is one of the best-known amphibian species of the time.

This tadpole, and therefore the frog it would have become, was quite large at 16 centimeters (6.3 inches) in length.

Chuliver Pereyra went on to say:

“One of the most groundbreaking aspects of this finding is that it provides the first evidence for the presence of a tadpole followed by a drastic metamorphosis on the life cycle of anurans from the very beginning of the evolutionary history of the group. Moreover, we proved that the presence of a larval stage with filter-feeding habits was a key trait that was already present in the anuran life cycle more than 160 million years ago.”

This is a fascinating find that allows scientists to learn more about how these ancient animals lived, and how they evolved to what we see today.

The study was published in Nature.I, for one, am glad modern frogs are not so big.

If you thought that was interesting, you might like to read about why we should be worried about the leak in the bottom of the ocean.