Newswise - How did vicious, meat-eating dinosaurs evolve into friendly,vegetarian dinos?some of which could even fly? A new kind ofdinosaur discovered in Utah may provide some clues. As anadult, this dinosaur walked on two legs, was about 13 feetlong and around 4? feet tall. It had sharp, curved,4-inch-long claws.
The dinosaur, named Falcarius, belongs to a group ofdinosaurs known as therizinosaurs. Birds evolved fromdifferent dinosaurs, called maniraptorans?a group thatincludes the dinosaur that chased the children through thekitchen in the film "Jurassic Park."
It had leaf-shaped teeth designed for shredding plants,instead of the triangular, blade-like, serrated teeth of itsmeat-eating relatives. Its pelvis was broader, giving it alarger gut to digest plant material, which is more difficultto process than meat. Its lower legs were stubby, because itno longer needed to run after prey. Its neck was long so itcould reach for tall plants.
Museum curator Scott Sampson says, "Falcarius representsevolution caught in the act, a primitive form that sharesmuch in common with its carnivorous kin, while possessing avariety of features demonstrating that it had embarked onthe path toward more advanced plant-eating forms." Nofeathers were found with the Falcarius fossils. Feathersrarely are preserved, but Sampson says, "A number of itsclose relatives found in China had feathers [preserved byunusual lake sediments], so the presumption is this animaltoo was feathered."
Dinosaur expert James Kirkland thinks the carbonate-richsediments in which the dinosaurs were buried means the areawas near a spring. The dinosaurs would have been drawnrepeatedly to the site by the water and perhaps by plantsgrowing around the spring?and then the spring wouldoccasionally would poison the animals with toxic gas or theywould drown.
He says, "Early on, two major groups of dinosaurs shifted toplant-eating, but we have virtually no record of thosetransitions. With Falcarius, we have actual fossil evidenceof a major dietary shift?This little beast is a missing link."
Sometimes ancient history isthegreatest show on earth.
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