|It is known that modern birds evolved from dinosaurs, but a new study published in the journal Science shows that the key to this transformation was, for one particular group of giant lizards called theropods, to continually get smaller and smaller over a 50-million-year time span.|
Researchers present a detailed family tree of these dinosaurs and their bird descendants which maps out this transformation.
|They showed that the branch of theropod dinosaurs which gave rise to modern birds were the only dinosaurs that kept getting smaller. These bird ancestors also evolved new adaptations four times faster than other dinosaurs.|
"Birds evolved through a unique phase of sustained miniaturisation in dinosaurs," says lead author Associate Professor Michael Lee, from the University of Adelaide's School of Earth and Environmental Sciences and the South Australian Museum."
|"Being smaller and lighter in the land of giants, with rapidly evolving anatomical adaptations, provided these bird ancestors with new ecological opportunities, such as the ability to climb trees, glide and fly.|
|Ultimately, this evolutionary flexibility helped birds survive the deadly meteorite impact which killed off all their dinosaurian cousins."|
The study examined over 1500 anatomical traits of dinosaurs to reconstruct their family tree. The researchers used sophisticated mathematical modelling to trace evolving adaptions and changing body size over time and across dinosaur branches.