In the Early Cretaceous period, just over 100 million years ago, Australia lay alongside Antarctica, which straddled the South Pole as it does today. Australia's southeastern corner, now the state of Victoria, lay well inside the Antarctic Circle. At that time, the region hosted an assemblage of animals and plants that lived under climate conditions having no modern analogue. The average temperature appears to have ranged from frigid to low temperate. Through the long winter, the sun did not shine for weeks or months at a time.
Many dinosaur lineages survived in this strange environment after they had died out in other places. At least one member of the group evolved an adaptation to the cold and to the dark that is interesting both in itself and for what it tells of the passing of a biological epoch. If global cooling indeed killed the dinosaurs, as many paleontologists have suggested, then Australia's species were the ones most likely to have survived the longest. Did their adaptations to an already marginal climate help them survive a sharp cooling trend, one that caught species living on other continents unprepared?