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.
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.”