Alectrosaurus

Alectrosaurus (; meaning "alone lizard") is a genus of tyrannosauroidtheropoddinosaur that lived in Asia during the Late Cretaceous period, about some 96 million years ago in what is now the Iren Dabasu Formation.

It was a medium-sized, moderately-built, ground-dwelling, bipedalcarnivore, estimated at 5 to 6 m (16 to 20 ft) with a body shape similar to its much larger advanced relative, Tyrannosaurus. Alectrosaurus was a very fast running tyrannosauroid as indicated by the elongated hindlimbs that likely filled the niche of a pursuit predator, a trait that seems to be lost by the advanced and robust tyrannosaurids, in adulthood.