The excavations in Inner Mongolia, China, scientists have discovered a new species of dinosaur the size of a parrot with only one finger.
Scientists named the new dinosaur Linhenykus monodactylus, in honor of the nearby city of Linhe. The research work has been published in the online version of the Protocols of the National Academy of Sciences (PNAS).
The new dinosaur belongs to the family Alvarezsauroidea, suborder of carnivorous dinosaurs Theropoda. Theropods are the ancestors of modern birds and their group includes such well-known dinosaurs like Tyrannosaurus and Velociraptor.
An international team of paleontologists discovered fossil, preserved in the rocks of the Upper Cretaceous of Education Vulansuhaya, located near the border between Mongolia and China. Education was formed 84-75 million years ago and is known to a rich collection of the fossil vertebrates, including the recently discovered theropod species theropod exquisitus Linheraptora Linheraptor. Participants of the expedition in the field excavation was found not complete skeleton consisting of bones of the spine, upper limbs and pelvis fragments almost as much as the hindquarters.
Linhenykus, most likely, had a pair of long legs and massive, but the growth was not more than a parrot. New theropod distinguished by the fact that both his legs were only one large claw, which the animal could have used to dig into insect nests. This feature makes the model found the only known dinosaur with one finger and highlights a wide range of evolutionary modifications of the hand that occurred in other theropods.
Michael Pittman (Michael Pittman) of University College London, co-author of the study and a member of the expedition, discovered a new pattern observed: "Initially, flightless theropods had five fingers, but in the course of evolution, the next species have only three toes. Tyrannosaurs distinguished presence of only two fingers but odnopaly Linhenykus showed how diverse and challenging indeed been modified structure of theropod hands. "
Most of the dinosaurs theropods have three fingers on each hand, but in most species except alvarezsauroids Linhenykus two outer fingers are greatly reduced in size, and are apparently useless structures. The presence of only one finger in the species Linhenykus, which theoretically is a relatively simple kind of type alvarezsauroid, shows that these underdeveloped fingers were not present in all members of the group. The reasons for the gradual disappearance of the two outer fingers of the species Linhenykus still unclear, but perhaps it reflects the result of natural selection.
Shuaner Jonah (Jonah Choiniere), and co-author of one of the participants, who discovered a sample of the Division of Paleontology at the American Museum of Natural History, said: "The residual structures, like legs in whales and snakes, may appear and disappear seemingly randomly in the course of evolution. Dinosaurs kind Linhenykus release rudimintarnost external fingers early species alvarezsauroids and emphasize the complexity in the evolution of these underdeveloped fingers. "
Linhenykus dinosaurs lived together with the same kind of similar sized theropod dinosaurs, but the features of their skeleton may reflect differences in behavior or nutrition. Linhenykus also lived near the small mammals, lizards, dinosaurs positive tubular (ankylosaurs) and horned dinosaurs (ceratopsians).
Original: Physorg Translation: M. Potter