More than 100 fossil specimens at Seattle’s Burke Museum provide a fresh window into how life thrived in Antarctica about 250 million years ago, thanks to global warming.
The slabs of rock document a time in the early Triassic Era when temperatures got so warm that Earth’s tropics were a virtual “dead zone.” The flip side of that climate equation is that Antarctica, which was still connected to what’s now Africa back then, was temperate enough to support weird sorts of amphibians and other forms of life.
“Nothing lives at these high latitudes today,” said Christian Sidor, a University of Washington paleontologist who’s also the Burke Museum’s curator of vertebrate paleontology. “But in the Triassic, we have good evidence that these animals were probably not only living in these areas, but breeding there. So they were there year-round. … How did these animals live in environments that we don’t have a good analog for today?”
Sidor and his colleagues collected the specimens during a three-month expedition to the Fremouw Formation in the Transantarctic Mountains. The November-to-January trek required setting up a base camp on Shackleton Glacier, shipping in supplies months in advance, and using helicopters like Uber cars to get around the rocky terrain amid bone-chilling temperatures.
“It’s the most logistically intensive research you could ever do,” Sidor said on Wednesday during an informal news conference at the museum.
Expeditions like this don’t happen very often: There have been only three previous paleontological excavations in the Shackleton Glacier area, in 1970-71, 1977-78 and 1995-96. The 2017-2018 trek brought together about 10 researchers from UW and other institutions, and involved six weeks of field work.
The prize finds include fossil traces of salamander-like amphibians known as temnospondyls, pre-dinosaur reptiles such as Prolacerta and Procolophon, and distant mammal relatives including Lystrosaurus and Thrinaxodon.
Such species are of interest in part because they’re found in Antarctica as well as Africa, demonstrating that the two continents were once joined together in a supercontinent known as Pangaea. The fossils also help document which types of creatures survived the Permian-Triassic extinction event, known as “the Great Dying,” which some scientists have linked to a dramatic increase in volcanic greenhouse gases.
The amphibian fossils could be particularly telling. “In the past, we’ve known which families of amphibians have been there, but not which species,” Sidor said in a Burke Museum blog posting. “Because we found so many, and they’re so well-preserved, we’ll be able to tackle that question.”
One fossil clearly shows the outlines of a Procolophon skeleton, part of a rock that was cleaved in two by natural processes over millions of years. Sidor said another paleontologist on the team, Roger Smith of the Iziko South African Museum, picked up the rock at a place that previous expeditions had explored and spotted the fossil imprint on the underside. “We were the ones who were lucky enough to lift up the right rock,” Sidor said.
Other fossils document the traces of Antarctica’s Triassic environment, frozen in time: the imprint of raindrops on mud, the footprints of a not-yet-identified animal, and the scrape marks that were made by a creature as it burrowed through the soil.
Some of the specimens are on display in the Burke Museum’s “Testing, Testing 1-2-3” exhibit of scientific work in progress, but most of them will remain boxed up until they’re moved into the New Burke Museum next door. The New Burke opens to the public in the fall of 2019.
The material brought back from Antarctica should keep paleontologists busy for years to come. UW graduate student Meg Whitney, for example, is studying the structure of fossil bones and teeth at a microscopic scale to understand how Triassic creatures were affected by extreme seasonality at polar latitudes.
The recent expedition marked Whitney’s first trip to Antarctica, but the experience left an impression at least as deep as the imprint of a Triassic fossil.
“It’s unlike anything else,” Whitney told GeekWire. “It’s pretty hard to go back to commuting on a bus after commuting on a helicopter every day to work.”