A new member of a group peculiar to dinosaurs, alvarezsaurids, long legs and short arms, is 63 million years older than the rest of their "relatives", as published today in the journal Science. Its discoverers claim that it is an important primitive member of the lineage that includes birds and their closest theropod relatives.
Alvarezsaurids are relatively small bipedal dinosaurs , and until the discovery of this new fossil, all known examples had lived during the late Cretaceous period. However, the new member of the family, found in the Shishugou formation, in the Chinese province of Xinjiang, and baptized as Haplocheirus sollers , belonged to the late Jurassic. Jonah Choinere and his colleagues at the University of Washington assure that it is the largest alvarezsaurus known, which implies that a miniaturization process took place behind it. His skull is light and stylized. As for its upper limbs, Haplocheirus' hands have three fingers, of which the middle one is much longer than the other two. The authors suggest that over time these three toes merged into the giant claw that characterizes the Cretaceous alvarezsaurids.
