This would have been true, if Procheneosaurus
Matthew 1920 was not a nomen nudum. This paper, a lay article on
Canadian dinosaurs, lacks an adequate enough definition of what Procheneosaurus is, among other inadequacies. He literally only states: "(5) Procheneosaurus,
â a small kind with a little bill and short round head. A fine skeleton
is on exhibition in the American Musuem.". This appears inadequate as
any diagnosis would go, and the text should not be taken as a diagnosis just to tick off on a
taxonomic checkbox.
Also, it should be noted that the holotype of Tetragonosaurus praeceps
Parks is a ROM specimen, and not that same specimen that Matthew was
referring to in his article. A perusal of Parks' paper reveals no
reference made to Matthew's 'Procheneosaurus' or to the American Museum specimen, so Tetragonosaurus shouldn't even be considered a replacement name for Procheneosaurus.
Given this second point,
Procheneosaurus should be considered an invalid genus name, given it lacks a fixed type species (ICZN Art. 67.1).