Scientists believe that the meteorite impact blamed for the extinction of most life on Earth at the time, may have actually kicked off a literal "Dark Age" that became the ultimate factor.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/drastic-climate-change-thanks-soot-meteorite-impact-may-have-wiped-out-dinosaurs
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/daily-news-analysis-delhi
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/climate-change
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/droughts
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/mammals
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/climate-impacts
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/extinct-species
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/global