The BBC are running an article on a paper just published in Nature regarding the role the death of the dinosaurs played in the rise of our mammalian ancestors.
By examining the family tree for mammals, scientists have created a “supertree” which shows how todays different mammals are related and when they diverged. By examining the data, they can show that mammals were diversifying long before the dinosaurs died out.
Prior to this it was thought that because the dinosaurs had effectively occupied the most beneficial environmental niches, mammals were restricted to side roles in the ecosystem. Once the dinosaurs had died out, they left a huge gap in the biosphere. Mammals were then uniquely positioned to fill the newly available “gaps”. Now it seems that this may not have been the case.
According to scientists responsible for the study, mammals evolved into different orders almost 30 million years before the space impact which ruined the dinosaurs day. Once this initial diversification had taken place, mammalian orders remained pretty static for another 40 million years, until there was another upsurge in the number of orders 55 million years ago.
The full mammal family tree is available from the BBC website here. [PDF]