In the study, David Grossnickle, now a doctoral student at the University of Chicago and P. David Polly, a professor in the Department of Geological Sciences in the College of Arts and Sciences, present evidence that mammal varieties declined during the great angiosperm radiation of the mid-Cretaceous, a time when a great diversity of flowering plants appears in the fossil record.
Grossnickle said that at the middle of the Cretaceous, a time when the early angiosperms are radiating, we find a surprising decrease in the diversity of mammals.
He said that it's not until the end of the Cretaceous, close to the time of the extinction of the dinosaurs, that we actually see a rebound in mammalian diversity and the first appearance of purely herbivorous mammals.
Previous literature suggested the spread of angiosperms, along with the evolution of pollinating insects, may have spurred an increase in the diversity of mammals. The idea made sense: The radiation would likely have resulted in more food sources from seeds, fruits, leaves and insects.
Grossnickle and Polly found, however, that while the number of mammal species may have increased, their variety decreased. Most of the mammals that survived were small, insect-eating animals.
The study has been published in the journal Proceedings of the Royal Society B.
--ANI (Posted on 03-10-2013)