Washington, July 24 : A new study has suggested that though dinosaurs may have been the largest land animals of the Cretaceous period, but they were probably conspicuously absent from the 'terrestrial revolution' of that time, in which the number of land species rose rapidly.
According to a report in New Scientist, Graeme Lloyd at the University of Bristol, UK, carried out the study, along with his team.
They studied all of the existing dinosaur taxonomic literature to produce a 'supertree' of dinosaur species.
The new supertree, which includes 440 of the 600 known dinosaur species, shows that the dinosaurs evolved rapidly during their first 50 million years.
By the Middle to Late Jurassic, a period famous for its giant dinosaurs including Diplodocus and Allosaurus, dinosaur evolution had slowed to a crawl.
It remained at that low level throughout the following Cretaceous period, a time of plenty in Earth's terrestrial history in which flowering plants, lizards, snakes, birds and mammals all became much more numerous.
Dinosaurs apparently did not take advantage of the abundant food supply that emerged during the Cretaceous Terrestrial Revolution.
"Our supertree allows us to look for unusual patterns across the whole of dinosaurs for the first time," said Lloyd. "It is the most comprehensive picture ever produced of how dinosaurs evolved," he added.