An international group of scientists say that large dinosaurs shrunk to small birds to survive over a period of around 50 million years.
Researchers have drawn a comprehensive dinosaur family tree along with their bird descendants, which shows the likeliness of the transformation. Scientists say that theropod dinosaurs kept getting smaller and then evolved into modern birds.
Darren Naish, Vertebrate Paleontologist at the University of Southampton, who is also the co-author of the study, says that these theropod dinosaurs were able to evolve faster than other dinosaurs and developed features, wings and wishbones to evolve into modern birds and adapt to the changing world. Birds evolved as a result of an exceptional phase of constant miniaturization of the theropod dinosaurs.
The dinosaurs, which are estimated to have weighed around 440 pounds, or 200 kg, evolved over a period of 50 million years and shrunk to just 1.7 pounds or 0.8 kg.
"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," says Michael Lee, lead author of the study and an Associate Professor from the University of Adelaide's School of Earth and Environmental Sciences and the South Australian Museum.
The researchers observed 120 theropod dinosaurs and analyzed 1,500 anatomical traits, which involved techniques used in the process of restructuring virus evolution. The scientists examined dinosaur lineage that are believed to have evolved to birds as well as giants such as the Tyrannosaurus rex (T-Rex) and Giganotosaurus. The scientists explain that they observed the evolution rate of different theropod dinosaurs and found that the fastest-evolving are the ones, which are ancestors of birds.
The scientists also suggest that these dinosaurs demonstrated their ability to be the most adaptable and also long-term survivors, which are also found as modern birds today.
The researchers also say that the crow-sized Archaeopteryx is the most primitive known bird. Scientists say that Archaeopteryx lived around 150 million years back and was mainly found in Germany. The bird had primitive traits like teeth and a bony tail but also possessed some aspects found in the modern bird.
Over time, these birds evolved even more and developed features, wings and smaller teeth.
The recent study about the evolution of birds from dinosaurs has been published in the journal Science.