| 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.