A team of paleontologists has found signs of hibernation in a pig-size, ancient relative to mammals which lived 250 million years ago in what is now Antarctica. Lystrosaurus, which translates to “shovel lizard,” had short, stubby tusks that grew in layers similar to tree rings. When paleontologists analyzed cross-sections of six Lystrosaurus tusks from Antarctica with four from what is now South Africa, they observed that the tusks from the Antarctic had closely spaced, thick rings, showing a slowdown in metabolism. Such a slowdown possibly emerged from stress. The new study indicates this adaptation may have a longer history than earlier imagined.