Saull accumulated at 15 Aldersgate Street a large geological collection, together with some antiquities, mostly from London. It was described by
John Timbs in 1855: and
Richard Owen, Mantell borrowed the fossil from Saull and did more work developing it from its matrix, publishing detailed results to correct Owen's 1842
Report. Owen later wrote that the
Dinosauria were largely based in their characters on this one specimen, now NHMUK PV OR 37685 (previously BMNH 37685) in the
Natural History Museum. [...] a private collection, which the proprietor liberally allows to be inspected on Thursdays, from 11 A.M. The Antiquities, principally excavated in the metropolis, consist of early British vases, Roman lamps and urns, amphora, and dishes, tiles, bricks, and pavements, and fragments of Samian ware; also, a few Egyptian antiquities: and a cabinet of Greek, Roman, and early British coins. The Geological Department contains the collection of the late Mr. Sowerby, with additions by Mr. Saull, F.G.S.; together exceeding 20,000 specimens, arranged according to the probable order of the earth's structure. Every article bears a descriptive label: and the localisation of the antiquities, some of which were dug up almost on the spot, renders these relics so many medals of our metropolitan civilisation. Saull began to swap fossils with
Gideon Mantell, a fellow collector, in 1830. In 1831 he purchased the geological collection of
James Sowerby, previously on display in
Lambeth; in 1833 he made it known that the weekly viewing time for his collection was open to working people, and in 1835 he rebuilt his museum. This specimen originated in the
Isle of Wight, and is now in the
Natural History Museum; the significance of the fused
vertebrae with it came to Owen after his 1841
BAAS talk in
Plymouth. It was a key step in postulating the
Dinosauria. In fact Owen reviewed numerous specimens in 1842, of which those held by
George Bax Holmes and Saull were the prominent examples in private hands; the sacrum has been called a "major factor" in erecting
Dinosauria, and has been regarded as the first true dinosaur specimen. ==Activist==