He contributed geological memoirs to the "Transactions" of the Geological Society, the "Annals of Philosophy", and the "Philosophical Magazine". In 1821, in collaboration with Henry De la Beche he distinguished himself by describing, from fragmentary remains, the saurian Plesiosaurus in a paper for the Geological that also contained an important description and analysis of all that had been learned to that point about the anatomy of ichthyosaurs including the fact that there had been at least three different species. His predictions about the plesiosaur were proved correct by the discovery of a nearly complete skeleton by Mary Anning in 1823, which Conybeare described to the Geological Society in 1824. Among his most important memoirs is that on the south-western coal district of England, written in conjunction with Dr Buckland, and published in 1824.