Alien rocks killed the dinosaurs

Over the course of history on our planet, an uncountable multitude of events have occured to shape the diversity of life we see today. Some will forever remain shrouded in mystery, never leaving a trace. Others, however, have left undeniable evidence of their passing. The most dramatic of these events are mass extinctions. While we may not always know what caused these unimaginable die-offs, their occurence is clearly enscribed on the fossil record. Sometimes, however, we can piece together what happened with some clever science. That's just what four Berkley scientists did in the 1980's to answer one of the most pressing questions in paleontology: what killed the dinosaurs? By analyzing the rocks found at the "boundary layer" between the Cretaceous and Tertiary periods, they discovered high levels of iridium, a platinum metal that has been depleted in the Earth's crust. They hypothesized that this iridium had an extraterrestril origin, and that an asteroid impact of massive proportion was responsible for the C/T mass extinction. This theory was further supported by the Chicxulub Crater 10 years later by Hildebrand et al.

• Original Paper
• Chicxulub Crater 

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