Extinct family of dinosaurs
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) :
Classification.
The family belongs to the tyrannosaur lineage. It was first named in 2010 by Oliver Rauhut and colleagues in their re-evaluation of the type genus, "Proceratosaurus". Their study supported the idea that "Proceratosaurus" is a coelurosaur, a tyrannosauroid, and most closely related to the Chinese tyrannosauroid "Guanlong". They defined the clade containing these two dinosaurs as all theropods closer to "Proceratosaurus" than to "Tyrannosaurus", "Allosaurus", "Compsognathus", "Coelurus", "Ornithomimus", or "Deinonychus". Later studies included the Russian "Kileskus" and the Chinese "Sinotyrannus" in the family. Recently, Proceratosauridae has been found to include "Proceratosaurus", "Guanlong", "Kileskus", "Sinotyrannus", and the genera "Stokesosaurus", "Juratyrant", and "Dilong" previously recognized as non-proceratosaurid tyrannosauroids. In their re-evaluation of "Proceratosaurus", Rauhut "et al." stated that tooth taxa from the Late Jurassic and Early Cretaceous previously assigned to the dromaeosaurid subfamily Velociraptorinae may instead be proceratosaurid in nature, due to the similarity between the teeth of the two groups and the fact that velociraptorines are otherwise unknown from the fossil record until the Late Cretaceous. This would mean that "Nuthetes" and other dubious genera are potential proceratosaurids.
Below is the cladogram by Loewen "et al." in 2013.
An analysis by Brusatte "et al." in 2016 provides both parsimony and Bayesian phylogenetic analyses, with "Yutyrannus" being placed within Proceratosauridae as a sister taxon to "Sinotyrannus" and "Juratyrant" and "Stokesosaurus" being placed as more advanced tyrannosauroids in each instance. The Bayesian analysis is shown below.