The
first fossil of a frog found in Antarctica gives new insight into the continent’s
ancient climate.

Paleontologists
uncovered fragments of the frog’s hip bone and skull in 40-million-year-old
sediment collected from Seymour Island, near the tip of the Antarctic
Peninsula.

Scientists
have previously found evidence of giant amphibians that walked Antarctica during the
Triassic Period, over 200 million years ago, but no traces on the continent of
amphibians like those around today (SN: 3/23/15). The shape of the newly
discovered bones indicates that this frog belonged to the family of Calyptocephalellidae,
or helmeted frogs, found today in South America.

The
fossilized frog’s modern relatives live exclusively in the warm, humid central
Chilean Andes. This suggests that similar climate conditions existed on Antarctica
around 40 million years ago, researchers report April 23 in Scientific
Reports

illustration of ancient Antarctica
A new frog fossil suggests that millions of years ago, at least part of Antarctica (shown in this illustration) looked a lot like the Chilean Andes.Pollyanna von Knorring/Swedish Museum of Natural History, Simon Pierre Barrette, José Grau de Puerto Montt, Mats Wedin/Swedish Museum of Natural History, Wikimedia Commons (CC BY-SA 3.0)
illustration of ancient Antarctica
A new frog fossil suggests that millions of years ago, at least part of Antarctica (shown in this illustration) looked a lot like the Chilean Andes.Pollyanna von Knorring/Swedish Museum of Natural History, Simon Pierre Barrette, José Grau de Puerto Montt, Mats Wedin/Swedish Museum of Natural History, Wikimedia Commons (CC BY-SA 3.0)

That offers a clue about how fast Antarctica switched from balmy to bitter cold (SN: 4/1/20). Antarctica quickly froze over after splitting from Australia and South America, which were once all part of the supercontinent Gondwana (SN: 10/10/19). But some geologic evidence suggests that ice sheets began forming on Antarctica before it fully separated from the other southern continents about 34 million years ago.

“The question is now, how cold was it, and what was living on the continent when these ice sheets started to form?” says study coauthor Thomas Mörs, a paleontologist at the Swedish Museum of Natural History in Stockholm. “This frog is one more indication that in [that] time, at least around the Peninsula, it was still a suitable habitat for cold-blooded animals like reptiles and amphibians.”