The historical taxonomy of the small theropod dinosaurs from the Wealden Group (Lower Cretaceous) of England is confused and complex. Of the twelve species names, several are synonymous and the remainder are mostly nomina dubia. Among the latter are the probable bird Wyleyia valdensis, the probable oviraptorosaur Thecocoelurus daviesi and the enigmatic forms Ornithodesmus cluniculus and Calamosaurus foxii. It has traditionally been thought that Calamospondylus oweni, the first British small theropod (or supposed theropod), was renamed and redescribed as Poekilopleuron pusillus, a taxon later given its own genus, Aristosuchus. Fox's correspondence with Owen, and discrepancies in the descriptions of these specimens, show that C. oweni and A. pusillus were based on different specimens. A. pusillus is based on a sacrum and partial pubes from a compsognathid coelurosaur. The whereabouts of the type specimen for C. oweni is presently unknown.
Naish, D. (2002). The historical taxonomy of the Lower Cretaceous theropods (Dinosauria) Calamospondylus and Aristosuchus from the Isle of Wight. Proceedings of the Geologists’ Association, 113(2), 153–163. https://doi.org/10.1016/S0016-7878(02)80017-7