'Road-Runner' Dinosaur Lived In The Fast Lane

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A new species of dinosaur has been described by a team of researchers from Canada, Britain and China. The new species of alvarezsaur named Xixianykus zhangi was one of the smallest known dinosaurs discovered thus far and appears to have been highly adapted for a fast running lifestyle.

http://www.sciencedaily.com/releases/2010/03/100329084854.htm

This Late Cretaceous 'road-runner' had a number of adaptations for fast, efficient locomotion. Most strikingly, the upper leg (the femur or thigh bone) is particularly short in comparison to the lower leg and the foot -- a pattern seen in many running animals today. Other features of the hind limb, pelvis and backbone would have promoted stability and reduced superfluous, energy-wasting movements as Xixianykus dashed across prehistoric landscapes.

Dr. Corwin Sullivan, a Canadian researcher and one of the authors of the study said: "The limb proportions of Xixianykus are among the most extreme ever recorded for a theropod dinosaur. This doesn't provide a basis for estimating its top speed, but it does show that Xixianykus was a highly efficient runner. Several other characteristics of the skeleton reinforce this impression."