Restoration of the Early Triassic mammal-like reptile Thrinaxodon emerging from its Antarctic den. Credit: copyright, Jude Swales.
Posted on 06/07/2008 7:53:24 PM PDT by NormsRevenge
Cat-sized reptiles once roamed what is now the icebox of Antarctica, snuggling up in burrows and peeping above ground to snag plant roots and insects.
The evidence for this scenario comes from preserved burrow casts discovered in the Transantarctic Mountains, which extend 3,000 miles (4,800 km) across the polar continent and contain layers of rock dating back 400 million years.
"We've got good evidence that these burrows were made by land-dwelling animals rather than crayfish," said lead researcher Christian Sidor, a vertebrate paleontologist at the University of Washington and curator at UW's Burke Museum of Natural History and Culture.
Ancient digging
About 245 million years ago, floodwaters likely overflowed river banks in parts of Antarctica, sending water and sand across the landscape and into various animal homes, such as burrows. No animal bones or remains were found inside the burrows, suggesting the burrow dweller must have escaped the deluge, according to study researcher Molly Miller of Vanderbilt University.
When the waters receded, the sand inside of these burrows hardened into casts. The largest burrow cast, measuring 14 inches (35 cm) long, 6 inches (16 cm) wide and 3 inches (9 cm) deep, was buried in rock layers of the Wahl Glacier dating back to about 245 million years ago during the Early Triassic period.
"The burrow is an inclined hole and at the end of the burrow the animal would scrape out a larger area and that's where it would huddle down," said Miller, a geologist.
Nine smaller burrow casts previously were discovered in the Allen Hills region in southern Victoria Land and date to the early Middle Triassic. The newly discovered casts predate fossils of tetrapods in the area, pushing back the date for such four-legged vertebrates (animals with backbones) living in Victoria Land by at least 15 million years, Sidor said.
"This would be the earliest record of any kind of tetrapod in that part of Antarctica," Miller told LiveScience.
Burrow dwellers
None of the burrows contained animal remains. However, the burrows' sizes and shapes, along with associated scratch marks, are nearly identical to tetrapod burrows found in South Africa also dating to the Triassic.
One of these South African burrows contained a complete skeleton of an extinct mammal-like reptile called Thrinaxodon liorhinus. The larger burrow from the Wahl Glacier was likely crafted by the same type of animal, Sidor said.
The term "mammal-like reptile" is actually a little misleading. The animals belonging to this group do have a mixture of mammalian and reptilian characteristics, Sidor said, but the group is actually more closely related to mammals than to reptiles. And today's mammals are the living descendants of mammal-like reptiles, he said.
"Thrinaxodon is a distant relative of mammals," Sidor said. "It lived in the Early Triassic whereas the first mammals are Late Triassic/Early Jurassic in age. Thrinaxodon is not related to any specific type of mammals but to mammals in general."
Based on comparisons with other South African burrows, the researchers speculate the smaller burrows in Victoria Land housed mole-sized reptiles called Procolophonids.
"We have documented that tetrapods were burrowing, making dens in Antarctica, back in the Triassic," Sidor said. "There are lots of good reasons for burrowing at high latitudes, not the least of which is protection from the elements."
Different Antarctica
At the time the ancient animals presumably were excavating their subterranean homes, Antarctica would have been ice-free, with a cool temperate climate, Miller said. And Antarctica and southern Africa could have shared residents, since during the Triassic, the two regions were connected as part of the supercontinent Pangea.
The Permian-Triassic extinction had just occurred, and so very few tetrapods existed at the time, with just seven tetrapod genera identified in Antarctica.
Today, no land-based animals live in Antarctica, where temperatures stay below freezing and the earth is covered in ice. (Penguins and seals of Antarctica are dependent on the sea.)
The research, supported by funding from the National Science Foundation, is detailed in the June issue of the Journal of Vertebrate Paleontology.
Restoration of the Early Triassic mammal-like reptile Thrinaxodon emerging from its Antarctic den. Credit: copyright, Jude Swales.
NOT!
Where's this guys scales?
They found some holes, and the only logical conclusion is that they must have been made by this thing.
Wow, I’m sure we could sell these on Rodeo Drive, they’d have to be defanged and declawed but the exoticness, oy veh.
There’s little doubt that there was abundant life on Antarctica in the past.
It wasn’t at the South Pole for most of the time.
There is no reason to doubt that there are huge oil and gas reserves there....
...Unless you think the world is 6,000 years old. The conversation pretty much ends at that point.
In his bathroom. Some things never change...
Don't tell my wife though, she has a kind of fetish for ferrets.
Luckily I put my foot down after her pet RATS died. Yup, she loves rats to.
GEE, I bet the world would be much better off without RATS.
They found burrows in South Africa. One of them contained a skeleton.
From this, we can gather that the burrows in Antarctica were dug by cat-sized mammal-like reptiles which huddled together, lived 400 million years ago, enjoyed watching sunsets, blinked an average of 7 times a minute, dreamed in color and chewed their food slowly.
How do we know all this? I told you -- we found a burrow in South Africa. It contained a skeleton. THAT'S why we know so much about life in Antarctica!!
They burrowed from South Africa to Antarctica. “I knew I should have made a left turn at Albuquerque.â€
So global warming was good then but bad now?
The ecosystem CANNOT SURVIVE without the genetic information of EACH and EVERY species. If the Stinking Hairless Jumping Rat of South Azania is allowed to go extinct, we will never find a cure for cancer, all crops will die, and the oceans will flood Coney Island.
What if you think petroleum has nothing to do with dead animals?
We could call them Merrets, ya.
Antarcdic Meerrets, yes Ma’dam, from the Triassic.
Loverly creatures, easily house broken, although we recommend one of our Eco-borro-habitat tm. for their
natural comfort.
I believe it’s quite taken with you too.
See! It likes you.
Jerome bring the lady a bandage, and another glass of Champagne.
Why not? There weren't too many Cajuns around back then, so the mudbugs would've had a chance to get reeeeeal big!
Ah! But coal does have a biological origin!
And three are vast deposits down there, too.
It depends. If you think it just seeps up from the earth's core, then you're a lunatic. If you think it is derived primarily from organic matter like dead plankton, plant material, and fish poop that sinks to the ocean floor and is eventually buried, I'd say you're correct.
Nobody is arguing that oil comes from dead dinosaurs or other reptiles.
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