From the week of September 7, 2007. The source of the K-T asteroid.
The paper is in Nature, so it won't be generally available on the Web.
It is a terrific paper. Assuming the orbital mechanics and computer
programs are done properly, the authors identify the KT asteroid as
most likely a member of a family of asteroids formed in the Jurassic
as a result of a major collision in the asteroid belt, that were then
spread out into the inner Solar System over the next 100 million
years. The crater Tycho on the Moon may have been formed by another
member. As Claeys and Tagle mention in a commentary (also in Nature),
it is spine-chilling to think that the dinosaurs were doomed before
most of them had even evolved! There will be discussion and LOTS of
empty speculation, but unless the foundations of this paper are flawed
seriously, it will become a classic. Instructors in History of Life
courses should make sure they understand the outline of the story:
it's accessible to and should be fascinating for undergraduates.
http://news.nationalgeographic.com/news/2007/09/070905-asteroid-crash.html
National Geographic News
http://www.terradaily.com/reports/Large_Asteroid_Breakup_Likely_Source_Of_Mass_Extinction_Impact_65_Million_Years_Ago_999.html
Terra Daily site
http://news.bbc.co.uk/2/hi/science/nature/6980468.stm
BBC News
http://www.sciencenews.org/articles/20070908/fob3.asp
Article by Ron Cowen (no relation) in Science News
http://www.swri.org/press/2007/asteroid.htm
Useful images
Hope this helps.
Cheers
Richard