Image by Mike Shaver via Flickr CC2.0
The dinosaurs were on their way out before the asteroid hit, researchers say. It seems the big lizards’ numbers were gradually declining for at least 40 million years before the final extinction event. This decrease in dinosaur population likely favoured the rise of mammals, which began flourishing in ecological niches previously occupied by dinosaurs. Using statistical analysis, researchers created a model that revealed the extinction rates for different groups of dinosaurs began surpassing speciation rates around 24 million years before the impact. When the different groups of dinosaurs are considered separately, extinction rates begin exceeding speciation rates as early as 53 million years before impact.
Authors:
Manabu Sakamoto, Michael J. Benton, and Chris Vendittia
Corresponding authors:
Manabu Sakamoto and Chris Vendittia
Original paper published on April 18, 2016 in Proceedings of the National Academy of Sciences of the United States of America.
