[1][5] Riley and Stutchbury did not mean to assign these species to Saint-Hilaire's genus of teleosaurids; they simply did not know the name had been used.

Only in 1840 do Riley and Stutchbury fully describe their two species of Palaeosaurus, each based on a single sharp tooth from the Late Triassic Period.

American paleontologist Edward Drinker Cope named a third species, Palaeosaurus fraserianus, in 1878, for an isolated tooth found in Triassic rocks in Pennsylvania.

In 1964, Owen's mis-classified specimens caused American Edwin Harris Colbert to classify prosauropods into two groups – Palaeosauria, which included Palaeosaurus and Teratosaurus, thought to be carnivorous because of the chimaeric nature of Palaeosaurus; and Plateosauria, which included Thecodontosaurus and Plateosaurus, which had been described with the correct skulls, and therefore were correctly described as a herbivorous group.

In 2007, Peter Galton, reviewing the archosaurian fossils of the 1834 Bristol finds, reaffirmed the identification of the two teeth and humeri of Palaeosaurus platyodon (Rileya) as belonging to a phytosaur, and regarded P. cylindrodon (Palaeosauriscus) as an indeterminate archosaur.

He agreed with Benton that Rileya is dubious, but suggested that Palaeosauriscus may be valid, based on its now-destroyed tooth with a "subcircular cross-section and fine, obliquely inclined denticles".

[2] In 1932, Von Huene assigned new material to Palaeosaurus; numerous prosauropod bones found in Germany.

In 1973, Peter Galton, a British paleontologist, moved the species into its own genus, creating the new combination Efraasia diagnosticus.