The oldest-known specimens of frogs preserved in amber have been found in Myanmar, offering scientists a rare glimpse into the evolution of the creatures, ScienceNews is reporting.
Chinese scientists working in Myanmar found a handful of chunks – four, to be exact – of the fossilized tree sap, all containing incomplete skeletons of the tiny amphibians. The chunks also contain bits of insects – likely the unfortunate frogs’ intended last meals – and, more importantly, bits of bamboo and other tropical flora. That’s the oldest evidence that’s ever been found of frogs in a tropical environment.
The Myanmar fossils are believed to be about 99 million years old. None of them are complete, and in fact, at least one of them lacks any remaining skeletal material – indeed, it was only revealed to have a general “froggy” outline after a CT scan.
In fact, so incomplete are the fossils that scientists gave them a new genus and species rather than attempt to tie them to a known one. The researchers dubbed all four fossils Electrorana limoae. “Electrum” is Latin for “amber,” “rana” Latin for “frog,” and “limoae” likely refers to the researcher who either found them or identified them, in keeping with the scientific tradition of naming new species after either their discoverer, identifier, or someone the scientist admires.
Frogs are believed to have evolved about 200 million years ago. And but for variations in the coloring and size – ranging from smaller than your thumbnail to roughly the length of a big domestic cat – frogs have always had the same general shape. However, frogs live in just about every habitat on Earth, from scorching deserts to dense tropical rainforests to suburban back yards.
That’s why studying their habitat is infinitely more important than studying their bodies, says David Blackburn, an amphibian biologist at the Florida Museum of Natural History in Gainesville.
“The aspects that make them diverse are not their skeletons, it’s their ecologies, natural histories, reproductive modes. Things that are really hard to find in the fossil record.”
The ancient frogs’ closest living relatives, according to Gizmodo, are likely fire-bellied toads and midwife toads.
“The presence of ribs and a bones in the cartilaginous plate that supports the tongue suggests an affinity with the species alive today, such as fire-bellied toads and midwife toads.”
Prior to the Myanmar discovery, the oldest known frogs found fossilized in amber were found in the Dominican Republic, and date only to 25 million years ago.