Appalachiosaurus (/ˌæpəˌleɪtʃioʊˈsɔːrəs/ AP-ə-LAY-chee-oh-SOR-əs; "Appalachian lizard") is a genus of tyrannosaurian theropod dinosaur from the Late Cretaceous period of what is now eastern North America.

It was a basal member of the Eutyrannosauria clade meaning it was rather close in relation to the true tyrannosaurids such as Tyrannosaurus.

Only a juvenile skeleton has been found, representing an animal approximately 6.5 metres (21 ft) long and weighing 623 kilograms (1,373 lb), which indicates an adult would have been significantly larger.

[1] Fossil material assigned to Appalachiosaurus is also known from the Donoho Creek and Tar Heel-Coachman formations of North and South Carolina in 2007.

The first was performed before the animal had even been named and found Appalachiosaurus to be a member of the Albertosaurinae subfamily of Tyrannosauridae, which only includes Albertosaurus and Gorgosaurus.

[8] The original description also included a cladistic analysis, finding A. montgomeriensis to be a basal tyrannosauroid outside of Tyrannosauridae.

Below is a cladogram published in 2013 by Loewen et al..[9] Dilong paradoxus Eotyrannus lengi Bagaraatan ostromi Raptorex kriegsteini Dryptosaurus aquilunguis Alectrosaurus olseni Xiongguanlong baimoensis Appalachiosaurus montgomeriensis Alioramus altai Alioramus remotus Tyrannosauridae Two vertebrae of the tail were found to be fused together, which is possibly a result of new bone growth following some sort of minor or traumatic injury.