TNRTB Archive - Retained for reference information
Article in Science provides evidence for another rapid mass extinction event (and by implication a succeeding mass speciation event) by an extraterrestrial collision event.
Brooks B. Ellwood, et al, “Impact Ejecta Layer from the Mid-Devonian: Possible Connection to Global Mass Extinctions,” Science, 300 (2003), pp. 1734-1737.
RTB article: Faint Sun Paradox