and weighing . Other characteristics include fused wrist bones similar to those of birds, and a keeled breastbone. It differed from close relatives Shuvuuia and Parvicursor in several details of its skeleton, including a pubic bone that is triangular in cross section, and different proportions in the toe bones. Mononykus likely had a covering of feathers, as in the fossils of its relative Shuvuuia feather traces were discovered, proving that Alvarezsauridae were among the theropod lineages with feathery or downy integument. Paleobiology Mononykus was a member of the family Alvarezsauridae and, like its relatives, had very strange, stubby forearms with one large, approximately long claw (hence its name). The other two claws had disappeared (however, a close relative of Mononykus, Shuvuuia, had two vestigial claws, alongside one large claw). The purpose of these highly specialized arms is still a mystery, but some scientists have suggested they were used to break open termite mounds (like modern anteaters), and therefore it is possible that they fed primarily on insects. In a 2001 study conducted by Bruce Rothschild and other paleontologists, 15 foot bones referred to Mononykus were examined for signs of stress fracture, but none were found. References External links In chinese but with pictures and taxon in english Late Cretaceous dinosaurs of Asia Nemegt fauna Alvarezsaurids Fossil taxa described in 1993 Taxa named by Altangerel Perle