The first edition of the trilobite Treatise was published as one part, 560 pages long, in 1959. It covered approximately 1200 genera. Some 5000 genera are now known, representing a 430% increase over a fifty year period. An international team of over twenty specialists has been brought together to share the immense task of preparing diagnoses and assembling essential data on these. Within National Museum Wales, two groups are being examined — the Paradoxidoidea from the Cambrian, which includes the well-known Paradoxides davidis from St Davids, and the Proetoidea, which range in age from the Ordovician to the Permian, and include the last-known trilobites.
The quantity of material is such that the original one volume will be superseded by (probably) four volumes; the first was published in 1997, and the second is expected within the next two years. The end of the project is some years off yet.