The Strange Lives of Polar Dinosaurs

How did they endure months of perpetual cold and dark?

(Cheryl Carlin)
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Most of the dinosaur bones they find at Flat Rocks, Kool explains, come from "hypsis" (pronounced HIP-sees), short for hypsilophodonts. These small, darting plant-eaters typically stood about as tall as turkeys. Their distinctive thighbones, which sport a downward-pointing spur, are easy to recognize. But this year's dig has also turned up some rarer finds, such as a thumbnail-size tooth from an as yet unnamed meat-eating dinosaur. One rock yielded a long, black fang that looks like an obsidian toothpick and may have come from a pterosaur, a type of flying reptile. And just two months ago, Rich's colleague Anthony Martin of Emory University in Atlanta announced that patterns in a 115-million-year-old layer of mud at Flat Rocks are dinosaur tracks. The 14-inch-long, three-toed footprints came from a type of meat-eating dinosaur called a theropod. Judging from the size and spacing of the prints, it must have stood about 12 feet high, making it the largest carnivorous dinosaur known to have lived there.

Promising fossils get wrapped in toilet tissue and newspaper for protection. Back at the museum, preparators will remove the encasing rock with tools that range from tungsten carbide needles to miniature, hand-held jackhammers powered by compressed air. Even unpromising chunks of rock will be pounded down to nuggets the size of sugar cubes; the team will check the bits for mammal jaws that are so small they could fit on a postage stamp.

It was the prospect of finding ancient mammal bones—not dinosaurs—that drew Rich to Australia. He was never a dinomaniac, not even as a child. What hooked his imagination, though, were the early mammals that scurried around at the same time as the dinosaurs. One illustration in a book he read as a boy portrayed the animals as snacking triumphantly on dinosaur eggs. Rich went with the evolutionary winners and studied fossil hedgehogs for his doctorate at Columbia University.

He landed in Australia in the early 1970s with no job and no intention of looking for one. His wife, Patricia Vickers-Rich, also a paleontologist, was in the country to follow up on her PhD research on fossil birds. But while thumbing through a newspaper "to get an idea what this country was about" he saw a help wanted ad for a curator at the local museum. He got the job and works there to this day. Rich and his wife—now a professor at Monash University in Melbourne and chief collaborator on the dinosaur research—stayed here because, he says, "the country was wide open" for studying the early evolution of mammals and birds.

In 1982, Rich met some museum volunteers eager to get their hands dirty at a dinosaur dig, but he initially resisted their pleas. He knew of a site 180 miles west of Flat Rocks that he had dubbed Dinosaur Cove after finding a few unidentifiable bone fragments there years earlier. Excavating there would require tunneling into cliffs—a dangerous proposition—with no guarantee of finding anything. But in 1984 he finally gave in, and within weeks the team found several dinosaur bones and a tooth.

For ten years Rich and a mostly amateur crew blasted, bored, picked and chiseled into the steep hillside. They dug two tunnels, each more than 60 feet long, and moved more than 600 tons of rock, much of it by hand. Rich says that "you wouldn't have to work that hard in Montana," which is famous for its dinosaur deposits and where the tectonic movements that hoisted the Rockies exposed bone-harboring rock strata. In contrast, Rich calls Australia, where dinosaur sediments are mostly buried deep, a "crappy country for dinosaur fossils."

By weight, the haul from the decade-long Dinosaur Cove dig was relatively small, about 100 pounds of fossils, and only traces of the mammals Rich covets—an arm bone and a shard of tooth. But the finds supplied clues about polar dinosaurs' metabolism and their strategies for weathering the long winters. They even provided a rare glimpse of the creatures' brains. Poring over the skeletons made Rich one of the world's experts on polar dinos.

At the time dinosaurs arose, around 220 million years ago, the earth's continents were fused into a single supercontinent we now call Pangea. It began breaking up around 200 million years ago, and Australia and Antarctica, which were still stuck together, stayed near the South Pole. When the fossilized creatures Rich studies were scurrying around, about 100 million years ago, southern Australia sat close to the bottom of the planet, and was just starting to pull away from Antarctica. (Australia's current position reflects that it has been inching northward "at the rate your fingernails grow," Rich says.)

During the animals' heyday in the early Cretaceous period, the sun didn't rise in southern Australia for one and a half to four and a half months every year. At the North and South poles, the gloom lasted for six months. Plant growth in these areas would have periodically slowed or stopped, potentially creating a food crisis for any dinosaurs that lived there. In more than 20 years of digging, Rich and his colleagues have found the remains of at least 15 species. For example, the knee-high hypsi Leaellynasaura amicagraphica (named for Rich's daughter, Leaellyn) once dodged predators at what is now Dinosaur Cove. Rich's son, Tim, got his name attached to another Dinosaur Cove denizen, the six-foot-tall Timimus hermani, which probably looked and ran like an ostrich.

Dinosaurs also thrived farther south. Antarctica hasn't moved much in the past 100 million years, stalling over the South Pole. Today, well-insulated animals and stubbly plants can survive the continent's brutal cold, at least close to the coast. But fossilized leaves and other plant remains suggest that during the dinosaurs' day Antarctica had a temperate climate. Judd Case of Eastern Washington University in Cheney says that Antarctic dinosaurs from the late Cretaceous period around 70 million years ago resembled those that lived in other parts of the world some 60 million years earlier. Case says this suggests that some kinds of dinosaurs hung on in Antarctica long after they had died out elsewhere. Perhaps Antarctica was an oasis for them as flowering plants spread across the rest of the world and outcompeted the pine tree relatives that warmer-climed dinosaurs ate.


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