WASHINGTON (Reuters) – When paleontologist Thomas Mörs examined a microscope while examining tiny 40 million-year-old fossils discovered on Seymour Island, near the tip of the Antarctic Peninsula, he was quite surprised – the hip bones and skull of a frog.
Paleontologists working on the site of the island of Seymour, in Antarctica, where fossils of an Eocene frog were discovered, are seen in this photo released on April 24, 2020 in Stockholm, Sweden. Jonas Hagstrom / Swedish Museum of Natural History / Disclosure via REUTERS
The small amphibian of the Eocene era was a helmeted frog – about 4 cm long – closely related to five species of helmeted frogs still native to Chile. These frogs are named for the shape of their heads.
“It was a totally unexpected discovery under the microscope. I found the hip bone for the first time and realized directly that I found an Antarctic frog – the first. It is the first Antarctic amphibian for more than 200 million years. So exciting, ”said Mörs, a scientist at the Swedish Museum of Natural History and lead author of research published this week in Scientific Reports.
The discovery illustrates how Antarctica, six million years before it became the desolate land of ice and snow so familiar today, housed forests, rivers and lakes teeming with life.
"It tells us that entire ecosystems can be destroyed by global climate change and that it can go quickly," said Mörs.
The climate of Antarctica at the time resembled the modern Valdivian rainforest in Chile, very humid with temperatures during the hottest months, averaging 14 degrees Celsius.
The southernmost continent on Earth boasted an abundance of plant and animal life before it became a frozen wasteland, with numerous dinosaurs previously identified along with flora, including conifers, ferns and flowering plants.
By the time the frog jumped and dined with insects, layers of ice were already forming in the highlands of the interior of Antarctica.
"Given that there is geological evidence of some glaciation 40 million years ago, it is interesting that the climate was still suitable for vertebrates that live on land in cold blood," said Mörs.
Until now, the known prehistoric amphibians of Antarctica were members of extinct lineages. The newly identified frog has many living relatives. South American helmeted frogs are part of a group called Australobatrachia, or "southern frogs", which also have members who live in Australia and New Guinea.
Frogs first appeared during the Triassic period some 250 million years ago, before dinosaurs.
"Frogs were known from all continents except Antarctica," added Mörs. "And now we know that they lived in the seven, before one of them froze."
Reporting by Will Dunham; Editing by Sandra Maler
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