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Mononykus
''Mononykus'' ( , sometimes ; meaning "one claw") was a theropod dinosaur from late Cretaceous Mongolia (Nemegt Formation, about 70 million years ago) with long, skinny legs. It moved about on two legs, was likely very nimble and could run at high speeds, something that would have been useful in the open desert plains where it lived. It had a small skull, and its teeth were small and pointed, suggesting that it ate insects and small animals, such as lizards and mammals. Its large eyes might have allowed ''Mononykus'' to hunt by night, when it was cooler and there would have been fewer predators about. ''Mononykus'' was originally named ''Mononychus'' in 1993, but later that year, it was renamed because the original name had already been used for a beetle named by Johann Schueppel, a German entomologist.
==Description==
''Mononykus'' was a small dinosaur, only long. 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'' is currently represented by a single holotype specimen, catalog number IGM N107/6. This specimen consists of a partial skeleton lacking a tail, and only small fragments of skull bones, including a complete braincase. Several other specimens were later misclassified as ''Mononykus'', including specimens with partial tails (initially misinterpreted as being very short, though later specimens showed they were long and thin) and complete skulls showing a distinct, mostly toothless form.〔Suzuki, S., Chiappe, L. M., Dyke, G.J., Watabe, M., Barsbold, R., and Tsogtbaatar, K. (2002). "A new specimen of ''Shuvuuia deserti'' Chiappe et al., 1998 from the Mongolian Late Cretaceous with a discussion of the relationships of alvarezsaurids to other theropod dinosaurs." ''Contributions in Science'', 494: 1–18.〕 However, these specimens have since been reclassified in the new genus ''Shuvuuia''.〔Chiappe, L. M., Norell, M. and Clark (1998). "The skull of a relative of the stem-group bird ''Mononykus''." ''Nature'', 392: 275–278.〕 Because of this, many reconstructions of ''Mononykus'' in art and mounted skeletons in museums are in fact based mainly on ''Shuvuuia''.
While ''Mononykus'' was formally described in the 1990s, it was reported that a specimen possibly belonging this genus had already been unearthed by the Andrews expedition decades before. The specimen had been in the American Museum of Natural History collection, labeled simply as "bird-like dinosaur". However, given the reassignment of the other specimens to related genera, and the difference in age (the AMNH specimen is from the older Djadochta Formation), it is unlikely to be ''Mononykus''.〔Mortimer, M. (2004), ("Ornithomimosauria" ), ''The Theropod Database'', accessed June 30, 2009.〕
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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