Polar winters weren't as cold in the Cretaceous as they are today, but they were long and dark. That has posed a puzzle: how did small dinosaurs living in polar areas survive the lean months when little food was available? The discovery of three fossil burrows in south-eastern Australia suggests they may have dug in for the winter.rnFossils from "Dinosaur Cove" in Victoria show that small plant-eating dinosaurs called hypsilophodontids were common in the area about 110 million years ago, a time when it was within what is today's Antarctic circle. The region was forested, with temperatures 6 or 7 °C warmer than such latitudes are today. But with the sun below the horizon for weeksrnor months ot the winter, tresn vegetation would have been lacking.rnPlant-eating dinosaurs had been thought to migrate long distances since fossils from a much larger related dinosaur, Edmontosaurus, have been found from northern Alaska to Montana. But last year, Eric Snively of the University of Alberta in Edmonton, Canada, showed that the fossils were not from a single species at the same time, so if the animals were moving it was over a much smaller distance. "We don't think the evidence for migration is there," he told New Scientist. Geography would have made north-south migration difficult or impossible in Australia and New Zealand.
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