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Scientists say the fossil of a dinosaur fingernail found in Brazil provides new support for the theory of an evolutionary link between dinosaurs and birds.

Brazilian scientists dubbed the dinosaur the Dino-bird of Peiropolis, after the city in Minas Gerais state where the fossil was found some 370 miles  northwest of Rio de Janeiro. Ismar de Souza Carvalho, who co-authored the fossil study, said on Thursday that it likely belonged to an unknown group of dinosaurs who walked the Earth some 70 million years ago.

"This finding is extremely relevant because this is a new type of Terope Maniraptoran dinosaur, connected to bigger dinosaurs but also to today's birds. The anatomic structure of this claw shows, quite possibly, the link between carnivore dinosaurs and birds that exist today."

While the link between dinosaurs and birds is fairly well established in the paleontological world, at least one expert not involved in the study expressed doubt on Friday that a claw fragment could prove the existence of a previously unknown dinosaur. "If this claw was all that was found, then it would be rather extravagant to create an elaborate theory based upon it. This claw doesn't add particularly much to our knowledge of the origins of birds, but it does show that raptor dinosaurs were present in Brazil toward the end of the age of dinosaurs," said Thomas R Holtz, Jr, a vertebrate paleontologist at the University of Maryland.

"The claw is similar in shape to that of many other raptors, such as velociraptors," Holtz added in a telephone interview with The Associated Press. "But from there we can't infer it is likely a similar dinosaur."