Meat-eating dinosaurs were very good at finding food, thus their evolutionary success over some 165 million years. But during their time on earth, they kept losing something that might seem important: their fingers. The earliest carnivorous dinosaurs had five fingers, although only four were actually functional. Many later meat eaters had only three, and evolution left the mighty Tyrannosaurus rex with only two. Now researchers have unearthed the first known dinosaur with only one finger. The new single-digit species, named Linhenykus monodactylus and described online today in the Proceedings of the National Academy of Sciences, was found in a roughly 80 million year old rock formation in Inner Mongolia. Linhenykus, which was probably about a meter tall, belongs to a family of dinosaurs called alvarezsauroids, which some researchers once thought were early flightless birds but which are now widely recognized as true dinosaurs. The team suggests that the single, clawlike digit was an adaptation for digging, perhaps for insects such as termites.
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