User blog comment:BastionMonk/Proceratosaurus and Ceratosaurus/@comment-99.230.219.68-20130822004045/@comment-1791057-20130822032154

It is. Proceratosaurus is one of the earliest taxa of the clade tyrannosauroidae, and is the ancestor to Tyrannosaurus rex. Ceratosaurus is a genus of the clade ceratosauria, which includes, along with relatives of ceratosauridae like Ceratosaurus, abelisauroids and, in turn, abelisaurids like Rugops and Carnotaurus.

Also, it is worth mentioning that InGen's reconstruction of their Ceratosaurus is archaic. The true Ceratosaurus does not resemble Proceratosaurus like the JP/// Cerato does. The nasal horn on Proceratosaurus is the origins of the nasal crest that often ran across the nasil of other early tyrannosauroidae like Dilong and Sinotyrannus. Ceratosaurs, however, has three crests that adorn it's skull. Two over the orbitals and the third (which was mistaken was a horn for the longest time), over the nasil, as you can see here: http://upload.wikimedia.org/wikipedia/commons/2/23/Ceratosaurus_nasicornis_DB.jpg That is why InGen could not have "mistaken" Ceratosaurus as Proceratosaurus. They had to have been expecting certain results, and when the results did not meet expectations, the geneticists likely went back and meddled with the DNA to produce the Ceratosaurus we see in JP///.