A new study has revealed that the giant carnivorous dinosaurs gradually shrank over 50 million years to evolve into agile flying birds.
The discovery was made by the scientists from the University of Southampton.
The scientists derived the conclusion after studying a map of family tree of dinosaurs and their bird descendants.
Study co-author Darren Naish, a Vertebrate Palaeontologist in University of Southampton, said, “These bird ancestors also evolved new adaptations like wings, feathers, wishbones and four times faster than other dinosaurs.”
While studying the family tree, the researchers also showed that the branch of theropod dinosaurs, leading to the evolution of modern birds, was the only animal that kept getting inevitably smaller.
Lead author Michael Lee says, “Birds evolved through a unique phase of sustained miniaturisation in dinosaurs.”
Michael Lee is Associate Professor in School of Earth and Environmental Sciences and the South Australian Museum at the University of Adelaide.
“Being smaller and lighter in the land of giants, with rapidly evolving anatomical adaptations, provided these bird ancestors with new ecological opportunities like the ability to fly, glide and even climb trees,” Lee said while adding , “Finally, this evolutionary flexibility supported birds to survive in the deadly meteorite event that had tremendous impact on the dinosaurian extinction.”
For the study, the researchers reconstructed a family tree of dinosaurs. For this, they examined over 1,500 anatomical traits of the animal. They took help of sophisticated mathematical modelling to keep track of evolving adaption and the changing size of the body over the time and across dinosaur branches.
“The birds out-shrank from their dinosaurian ancestors, out-evolved and survived where their larger, less evolvable relatives could not,” said Lee.
The study researchers concluded that the branch of dinosaurs that led to evolution of birds was more evolutionary innovative than any other family of dinosaurs.
This evolutionary line was continued being experimented with different and often drastically smaller body sizes. But other dinosaur groups failed to reciprocate and ended up getting locked into narrow ecological niches. And this finally led to their extinction.
The study was published in the journal Science.