Alectrosaurus
| Alectrosaurus Temporal range: Late Cretaceous, ~ | |
|---|---|
| Skeletal reconstruction of the holotype | |
| Scientific classification | |
| Domain: | Eukaryota | 
| Kingdom: | Animalia | 
| Phylum: | Chordata | 
| Clade: | Dinosauria | 
| Clade: | Saurischia | 
| Clade: | Theropoda | 
| Superfamily: | †Tyrannosauroidea | 
| Clade: | †Pantyrannosauria | 
| Genus: | †Alectrosaurus Gilmore, 1933 | 
| Type species | |
| †Alectrosaurus olseni Gilmore, 1933 | |
| Synonyms | |
| 
 | |
Alectrosaurus (/əˌlɛktroʊˈsɔːrəs/; meaning "alone lizard") is a genus of tyrannosauroid theropod dinosaur 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, bipedal carnivore, 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.