The story of the Cretaceous Mass Extinctions is amazing. The “Impact Hypothesis” was developed at the University of California, Berkeley, in 1980 when I was there as a graduate student (to my great fortune, even if I had nothing to do with it). It seemed a real stretch at the time, but now we know it as one of those intellectual breakthroughs which changed our perspective on the History of Life. The Wikipedia page on the Cretaceous Extinctions is very good and kept updated by experts. The Sam Noble Museum has a good executive summary of the extinctions. In 2010 an Independent Study student (Megan Innis) and I had a great time at the Cretaceous-Paleogene boundary in Alabama and Mississippi.
We will emphasize the Impact Hypothesis in this course because I think it is the one best supported by the evidence. If you like your extinctions via YouTube, watch these Discovery Science videos, part 1 and part 2. The volcanic hypothesis is still alive, although on life support. Here is a nice summary of the most recent attempts to link volcanoes to the Cretaceous extinctions. In contrast with these reasonable (more or less) disputes, there are many more exotic ideas about dinosaur extinctions specifically, some tallied here and here. Let’s not forget, though, that the basic scenario of the impact hypothesis is supported by most scientists.
Remember: Review sessions every Friday, 3:30 – 4:30 pm, in Scovel 205.
Geology in the News –
The end-Cretaceous asteroid impact may have had an even more dramatic effect on climate than we thought (and that was pretty bad). I notice here that the asteroid is now expanded from 10 to 12 km in diameter. Here’s a BBC account of the same research.
Mount Etna, Europe’s most active volcano, is slowly sliding into the sea. The fear is it could catastrophically collapse, producing massive tsunamis. (I’ve been on its slopes, by the way. Fantastic place.)
Check out this story (and book) about the illegal trade in dinosaur bones. I’m pleased to see there are serious penalties for stealing from the public — and from science itself.