Tuesday, May 06, 2014 – A new study suggests that the shrinking of dinosaurs as they evolved may have helped the group that became birds to continue exploiting new ecological niches; even today. The study ‘weighed’ hundreds of dinosaurs by estimating their body mass based on the thickness of their leg bones.

‘Dinosaurs aren’t extinct; there are about 10,000 species alive today in the form of birds. We wanted to understand the evolutionary links between this exceptional living group, and their Mesozoic relatives, including well-known extinct species like T. rex, Triceratops, and Stegosaurus,’ said Dr Roger Benson of Oxford University’s Department of Earth Sciences, who led the study. ‘We found exceptional body mass variation in the dinosaur line leading to birds, especially in the feathered dinosaurs called maniraptorans. These include Jurassic Park’s Velociraptor, birds, and a huge range of other forms, weighing anything from 15 grams to 3 tonnes, and eating meat, plants, and more omnivorous diets.’

The study is titled “Rates of Dinosaur Body Mass Evolution Indicate 170 Million Years of Sustained Ecological Innovation on the Avian Stem Lineage“.

Shrinking May Have Aided Evolvability in Dinosaurs and Birds

Credit: Roger Benson