True - Extinction linked to Earth's tilt and orbital variations

A new study suggests that variations in Earth's orbit and tilt may be linked to extinctions of mammal species. Examining the fossilized teeth of rodents over a 22 million year period, researchers lead by Jan van Dam of Utrecht University in the Netherlands found that the disappearance of mammal species -- which survive an average of 2.5 million years before going extinct -- cluster around specific cycles at one million and 2.4 million years. The one million year cycle corresponds to wobbles in Earth's orbit, while the 970,000-year cycle is tied to shifts of the Earth on its axis. The cycles are association with lower temperatures and changes in precipitation. In Earth Science at mongabay.com