Proceratosauridae

Proceratosauridae is a family or clade of tyrannosauroid theropod dinosaurs from the Middle Jurassic to the Early Cretaceous.

== Distinguishing features == Unlike the advanced tyrannosaurids but similar to primitive tyrannosauroids like Dilong, proceratosaurids were generally small (with the exception of the possible proceratosaurids Yutyrannus and Sinotyrannus) and had fairly long, three-fingered arms capable of grasping prey. In comparison to other members of Tyrannosauroidea, proceratosaurids can be distinguished by the following features according to phylogenetic analyses by Averianov et al. (2010) and Loewen et al. (2013) : A sagittal cranial crest formed by the nasals starting at the junction of the premaxilla and nasals. Extremely elongated external nares, with posterior margins posterior to the anterior margin of the antorbital fossa and maxillary fenestrae. A short ventral margin of the premaxilla. The depth of the antorbital fossa ventral to the antorbital fenestra being much greater than that of the maxilla below the antorbital fossa. A ventrally concave ischium. A convex tubercule on the anterior margin of the pubis just ventral to contact with the ilium. A short and shallow concave step on the anterior margin of the maxilla.