Cidaroids have a relatively conservative test morphology and their taxonomy has proved difficult. Mortensen (1903, 1928) based his taxonomy on fine details of spine and pedicellarial morphology, which unfortunately are rarely preserved in fossil taxa. His taxonomy was widely criticized for being oversplit (e.g. Clark 1909, Philip 1964) but formed the basis for the Treatise on Invertebrate Paleontology classification. Numerous fossil genera have been created since then but the only large cladistic analysis of the group to date is that of Smith & Wright (1989). Here the scheme of Kroh & Smith (2010) is followed.
Any taxonomic framework for cidaroids needs to start with the extant taxa. Many fossils are too poorly known to be classified with certainty and can only be included tentatively. The following taxonomic scheme is used here.
Order Cidaroida Claus, 1880
Crown group Cidaroida
Stem group Cidaroida
Superfamily Histocidaridea Kroh & Smith, 2011
Superfamily Cidaridea Kroh & Smith, 2011
Some of these are almost certain to prove paraphyletic (e.g. Polycidaridae). For an alternative classification of just Jurassic taxa see Vadet (1991, 2004).
Clark, H. L. 1909. The Cidaridae. Bulletin of the Museum of Comparative Zoology at Harvard College 51(7), 165-230, pls 1-11.
Kroh, A. & Smith, A. B. 2010. The phylogeny and classification of post-Palaeozoic echinoids. Journal of Systematic Palaeontology 8, 147-212.
Mortensen, T. 1928. A monograph of the Echinoidea. 1, Cidaroidea. C. A. Reitzel, Copenhagen.
- Philip, G. M. 1964. The Tertiary echinoids of South-East Australia. Proceedings of the Royal Society of Victoria 77, 433-477, pls 58-67.
- Smith, A. B. & Wright, C. W. 1989. British Cretaceous echinoids. Part 1, General introduction and Cidaroida. Monograph of the Palaeontographical Society [publication no. 578, issued as part of volume 141] p. 1-101, pls 1-32.
- Vadet, A. 1991. Revision des "Cidaris" du Lias et du Dogger Europeens. Memoires de la Societe academique du Boulonnais 10, 1-176.
- Vadet, A. 2004. Echinides fossiles du Boulonnais du Bajocien au Tithonien. Annales de la Societe d'Histoire Naturelle du Boulonnais 3 (2), 1-35.