Members of an expedition from the British sloop-of-war HMS Fly supposedly collected two tibiae, a fibula and two foot claws as well as some other fragments in 1844 while erecting a beacon on the coast of Cape York, Queensland in Australia.

[2] The original block was purchased by the British Museum of Natural History in 1879, from Edward Charlesworth selling the collection of the late Samuel Long Waring, and given the inventory number BMNH 49984, but the remains were not studied until 1891.

The matrix in which the bones were preserved was tested with rocks of similar age in Cape York and Durdham Downs, the latter being beds where Thecodontosaurus remains have been found in the Bristol area of England.

As early as 1906, Friedrich von Huene had described the rock matrix as 'extremely reminiscent of the bone breccia at Durdham Downs near Bristol' and had renamed the species Thecodontosaurus macgillivrayi.

[citation needed] Remains of the jaw of a sphenodont identical to Diphydontosaurus avonis, a lizard-like reptile common to the Bristol Triassic beds have been extracted.