Some years ago, radar imaging revealed a massive impact crater along the northern shore of the Yucatan Peninsula. This impact, known as the Chixilub Impact Event dated to around 65 million years ago, corresponding to the end of the Mesozoic era--the extinction of the Dinosaurs. Now, an even larger crater has been found under a mile of snow and ice in the Antarctic. And this crater is dated to a far larger extinction event at the P-T boundary about 250 million years ago which nearly wiped out every living thing on the planet and may have caused the breakup of a supercontinent containing what is today Australia and Antarctica.