A four-legged, mammal-like reptile dug a lair in the Antarctic soil between 280 and 235 million years ago
Triassic-era sediments reveal that a four-legged animal — a reptile of the type from which modern-day mammals evolved — once burrowed in Antarctic soils. The findings, reported in the June Journal of Vertebrate Paleontology, are the first to show that such a creature lived so close to the poles during that time period.
Researchers uncovered a set of burrows in the Transantarctic mountain range, which juts through the ice and cuts from north to south across the continent. The underground passages, a set of tubular shafts with a W-shaped bottom, were likely made by a mammal-like reptile, says Christian Sidor, a paleontologist at the
They also discovered another set of burrows likely made by a smaller reptile.
Earlier excavations in the Karoo Basin of South Africa had uncovered a similar underground den with fossilized remains of a cat-sized reptile “curled up like a little puppy” inside, says Molly Miller, a paleontologist at
The Antarctic burrows did not contain any fossilized remains, but researchers can infer how many legs the digging animal had based on nail scratch marks found on the side and roof of the burrows, says Gideon Groenewald, a geologist at the Peace Parks Foundation in
Ancient burrows are important because they can reveal information about animal behavior and the ancient environment that ordinary fossils can’t, Sidor says.
"Burrows represent the best possible information on the behavior of the animals and give a very good indication of the paleoenvironment in which they lived,” agrees Groenewald.
The resemblance between the Antarctic burrows, called trace fossils, and those found in the
During the Triassic period, between 280 and 235 million years ago,