Another potential solution to the mystery of mammalian extinctions has been proposed – they may have been caused by perturbations in the Earth’s orbit and axial tilt. The theory is that these changes of position relative to the sun would have caused climatic changes that would have thrown previously stable habitats into fiercely competitive environments. I’m no scientist, but I’m always a bit leery of single-cause explanations for events of this magnitude, and so I am encouraged to see the researcher in question describe this as “a crucial missing piece in the puzzle”.