The holotype, specimen MNHN 2001-4, was discovered during the early 1870s in the phosphate-bearing beds of La Penthiève (Mammilatum Zone; lower Albian) at Louppy-le-Château in eastern France,[1] which have also produced remains of plesiosaurs, ichthyosaurs, and crocodiles.

[7] Subsequently, the Pierson collection was dispersed after the death of its owner and the holotype was long believed lost to science after World War II.

[1] The casts and the incomplete maxilla allowed for a reevaluation of Erectopus by Ronan Allain in 2005, which determined that the correct taxonomic name for the material is E. superbus, as nothing indicated that Sauvage had limited the holotype to the original teeth.

A tooth, specimen UAIC (SCM1) 615, discovered sometime between 1900 and 1913 in the Cernavodă Formation in Romania was listed as belonging to Megalosaurus (Erectopus) cf.

It is the third youngest carnosaur known from the European Lower Cretaceous, after specimen MM-2-21, the "Montmirat theropod" (Valanginian) of southern France and Neovenator salerii (Barremian) from the Isle of Wight.