Frog Fossils in Antarctica Offer Evidence of Warmer Past

Reconstruction of Eocene helmeted frog on the Antarctic Peninsula. (Arttwork by Pollyanna von Knorring, Swedish Museum of Natural History. Photo by Simon Pierre Barrette and José Grau de Puerto Montt, Wikimedia Commons [CC BY-SA 3.0], and Mats Wedin, Swedish Museum of Natural History.

(CN) — Frog fossils found for the first time in Antarctica provide evidence of a warm and temperate climate in the Antarctic Peninsula and the existence of freshwater habitats which supported the earliest known modern amphibians 40 million years ago, a study in Scientific Reports revealed Thursday.

The discovery of 40 million-year-old fossilized hip and skull bones from the helmeted frog family is the first evidence of cold-blooded amphibians or reptiles from families still in existence to be found on Antarctica.

“The Seymour Island frog reported herein is the first vertebrate indicative of freshwater habitats on the Eocene Antarctic Peninsula, following invertebrate and plant evidence,” the study reports.

With the new discovery, frogs — which have the wideset distribution of amphibians — have now been found on all seven continents. And researchers are now hypothesizing “Antarctica may have acted as a center of diversification” for the helmeted frog species, remains of which have also been found in Australia.

“So far, Antarctica has been considered as a dispersal route, but not as a probable place of origin. The new fossil finds support the hypothesis that Antarctica may have acted as a center of diversification for [helmeted frogs],” according to the study.

Researchers believe the fossils are evidence the climate of the Antarctic Peninsula during the late middle Eocene geological period prior to its separation from the southern supercontinent Gondwana may have been comparable to the humid and temperate climate in the forests of South America today, where all five living species of the helmeted frog are exclusively found.

The frogs today inhabit lowland areas of Chile east of the Andes Mountains near lakes, ponds and streams.

The previous oldest helmeted frog fossils were found in Argentina, according to the study.

The finding suggests South American forests may be the modern equivalent of the Antarctic climate just prior to glacier formation on the continent.

The fossil frog remains were found on Seymour Island during summer expeditions between 2011 and 2013.

Researchers say the discovery is an ancient example of how climate change impacts where different species can survive, similar to how humans have adapted more recently to climate change.

“The fossil finds of a frog and marsupial from Seymour Island, and their fossil and recent distributions, represent outstanding examples of the role of global climate change on shifting biogeographic ranges,” the study found.

“Despite global cooling and the disappearance of the habitats of these groups over large areas from Antarctica to Patagonia, they maintained their relictual [population] occurrence in the Nothofagus forests of the central Chilean Andes,” according to the study.

The report was published by Thomas Moers of the department of paleobiology at the Swedish Museum of Natural History. In an email, Moers said the discovery of helmeted frog fossils is evidence of the dramatic impact climate change can have on species’ survival.

“It tells us that whole ecosystems can be wiped out by global climate change, and that it might go fast,” Moers said.

“Even in dramatic climate change, some (few!) species can survive if there are relict areas available,” he added.

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