All the dinosaurs are referred to by the names given to them by the mainstream scientific community (despite the island being completely isolated from that community)... including the ones that haven't yet been discovered and named at the time the books are set in.
Not the only terms either; words such as "taxi" and "helium" didn't exist yet either.
The Dinotopians are probably using whatever words the specific species of animals are using for themselves, so we could probably consider this a Translation Convention.
The fact that the Latin translation of Tyrannosaurus rex is a minor plot point in The World Beneath rules out Translation Convention. Denison also expresses fear of them — in 1862, four decades before the species was named.
Dinotopians use leathers, skins, furs, and otheranimal products were seen in use by the Dinotopians. In Journey to Chandara it's explained when Arthur Dennison is given a new journal bound in the skin of an Intellectual Animal "whose dying wish was to donate his body to science".