Oldest And Best-Preserved Frog Found Trapped In Amber For 99 Million Years

The frog is exceptionally well preserved, giving researchers a glimpse into their early evolution.

The frog is exceptionally well preserved, giving researchers a glimpse into their early evolution. Lida Xing/China University of Geosciences

Around 100 million years ago, a little juvenile frog was chasing a beetle along a branch before it took an unfortunate tumble and met a sticky end in oozing sap along with its would-be prey.   

While this might not have been the preferred outcome for the frog, for scientists it has given us an incredibly rare insight into the mid-Cretaceous. This new finding is the oldest and best-preserved example of a frog in amber ever discovered. Not only that, but it also provides the first direct evidence that ancient frogs lived in wet, tropical forests.


So well preserved is the amphibian that the researchers have even been able to formally describe it as an entirely new species, Electrorana limoae. It is joined by three other partial fossils of frogs trapped in amber, all discovered in Myanmar.

The frog might well have been chasing the beetle it was preserved with. Damir G Martin

Weirdly though, these frogs did not look like the green tree frogs you’re probably imagining right now, but rather like fire-bellied and midwife toads more commonly found in Europe. This raises questions about the early evolution of frogs.

Even though most frog species alive today live in tropical rainforests that hug the equator, there are actually few fossils of amphibians from these environments. This is thought to be down to the fact that frogs are small and their bones don’t often preserve well, meaning that the majority of the frog fossils we have come from larger, stockier species that lived in dryer, more temperate habitats.

“It's almost unheard of to get a fossil frog from this time period that is small, has preservation of small bones and is mostly three-dimensional. This is pretty special,” explains David Blackburn, who co-authored the recent paper published in Scientific Reports, in a statement. “But what's most exciting about this animal is its context.”


“These frogs were part of a tropical ecosystem that, in some ways, might not have been that different to what we find today – minus the dinosaurs.”

The four fossil frogs date to around 99 million years ago. Lida Xing/China University of Geosciences

During this period, the shorelines would have been patrolled by Spinosaurus, the floodplains dotted with Gallimimus, and bees only just beginning to evolve. Now, it's likely that the tropical rainforests would have been resonating with the trill and croak of calling frogs, not unlike some environments today.

The fossils were found in Myanmar, which is the source of some truly incredibly finds of animals trapped in amber. From entire chicks, lizards, bamboo-like plants, aquatic spiders, and even the tail of a dinosaur, the deposits provide an awesome glimpse into what the rainforests were like 100 million years ago when the dinosaurs were on top.


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