The strange lives of polar dinosaurs

On a balmy Sunday morning in early March, I'm on a beach in southern Australia looking for ice—or at least traces of it. It's summer in the Southern Hemisphere, and most of the beachgoers sloshing through the rising tide or walking their dogs are wearing T-shirts and shorts. Tom Rich, a paleontologist at Museum Victoria in Melbourne, leads the way along the low, tawny cliffs that crowd the shoreline. Rich is 66, with a stubbly silver beard, sparse gray hair and slanting eyebrows that give his face a sad, world-weary look. He was raised in Southern California and Texas but has spent his professional life in Australia. During more than three decades down under, he's picked up Aussie citizenship and plenty of the country's colorful lingo, but his accent remains stubbornly American. "I sound like I just got off the plane," he says. This part of the coast, known as Flat Rocks, is near the resort town of Inverloch, about a two-hour drive southeast of Melbourne through farms and woodland parched by more than a decade of drought. Rich stops next to a pile of rubble at the base of a cliff. "That's it," he says. Partly buried by flakes of battleship-gray rock is a telling geological formation. Tongues of dark tan sediment droop into the lighter-colored layer below. The formation is called a "cryoturbation" and was caused when once-frozen clay sank into an underlying layer of sand during a thaw long ago. Snow and ice are rare in this part of Australia today.

But evidence from Flat Rocks and other nearby sites confirms that a little over 100 million years ago, "it was bloody cold around here," as Rich puts it. Though about a third of Australia now lies within the tropics, back then the continent sat about 2,000 miles south of its current position, snuggled against Antarctica. Southeastern Australia probably had a climate similar to that of Chicago, if not Fairbanks. All the more surprising, then, that dinosaurs thrived here at that time.