Belongs within: Euechinoidea.
The Pedinidae are a lineage of echinoids known from the Upper Triassic to the present, where they are represented by a single surviving genus Caenopedina (Fell 1966).
Characters (Fell 1966): Test subspherical, high subconical to depressed hemispherical or rotular; rigid though fragile, plates not imbricating. Ambs and interambs not extending across peristome. Ambs composed of simple or compounded diadematoid plates. Five pairs of oral plates on peristomial membrane. Gills present; gill slits shallow, notching peristomial margin. Periproct endocyclic. Apical system dicyclic; five genital pores. Tubercles noncrenulate. Spines finely striate, more or less thorny (but not verticillate); primaries solid, secondaries hollow. Spheridia unknown in fossils (but placed near tube foot of adoral secondary element of amb plates in living genus Caenopedina, where they continue to adapical region). Pedicellariae including globiferous, ophicephalous, and tridentate types.
<==Pedinidae [Pedininae, Propedinidae]
|--Echinopedina Cotteau 1866 [=Hebertia Lambert 1910 non Michelin 1859]F66
| `--*E. gacheti [=Echinus gacheti, *Hebertia gacheti]F66
|--Leiopedina Cotteau 1866 [=Chrysomelon Laube 1868]F66
| `--*L. tallevignesi (Cotteau 1856) [=Codechinus tallevignesi, *Chrysomelon tallevignesi]F66
|--Loriolipedina Lambert 1910F66
| `--*L. alpina Lambert 1910F66
|--Phalacropedina Lambert 1900F66
| `--*P. guerangeri (Cotteau 1858) [=Hemipedina guerangeri]F66
|--Pseudorthopsis Sánchez Roig 1949F66
| `--*P. cubensis (Cotteau 1881) [=Echinopedina cubensis]F66
|--Stenechinus Arnold & Clark 1927F66
| `--*S. regularis Arnold & Clark 1927F66
|--Mesodiadema Neumayr 1889F66
| |--*M. marconissae (Desor 1858) [=Hemipedina marconissae]F66
| `--M. angeliacenseF66
|--Palaeopedina Lambert 1900F66
| |--*P. globulus [=Diadema globulus]F66
| `--P. boneiF66
|--Pseudopedina Cotteau 1858F66
| |--*P. bakeri (Wright 1854) [=Pedina bakeri]F66
| `--P. divionensisF66
|--Atlasaster Lambert 1931F66
| |--A. jeanneti Lambert 1937SG93
| `--A. termieri Lambert 1931SG93
|--Caenopedina Agassiz 1869B01 [=Coenodiadema (l. c.)F66, Coenopedina (l. c.)F66]
| |--*C. cubensis Agassiz 1869F66
| |--C. diomedeaeF66
| `--C. mirabilis (Döderlein 1885)MG-H11
|--Micropedina Cotteau 1866F66
| `--*M. olisiponensis (Forbes 1850) [=Echinus olisiponensis]F66
| |--M. o. olisiponensisF66
| `--M. o. cotteauiF66
|--Phymopedina Pomel 1883F66
| |--*P. marchamensis (Wright 1855) [=Hemipedima marchamensis]F66
| |--P. bouchardiF66
| `--P. legayiF66
|--Hemipedina Wright 1855 (see below for synonymy)F66
| |--*H. etheridgei (Wright 1854) [=Pedina etheridgei, *Leiodiadema etheridgei]F66
| |--H. hudsoni Kier 1977SG93
| |--H. incipiens Bather 1990SG93
| |--‘*Archaeodiadema’ thompsoni Gregory 1896F66
| `--H. tuberculosa Wright 1860 [=*Miopedina tuberculosa]F66
|--Diademopsis Desor 1855 [incl. Hecistocyphus Pomel 1883]F66
| |--*D. serialis (Agassiz 1840) [=Echinus serialis]F66
| |--D. bonissenti [=*Hecistocyphus bonissenti]F66
| |--D. heeriF66
| |--D. micheliniF66
| `--D. microporaF66
`--Pedina Agassiz 1838 [=Propedina Lambert & Thiéry 1925; incl. Hectopedina Thiéry 1928, Megapedina Lambert & Thiéry 1910]F66
| i. s.: P. charmassei Cotteau 1885 [=*Megapedina charmassei]F66
|--P. (Pedina)F66
| |--*P. (P.) sublaevis Agassiz 1838 [=*Propedina sublaevis]F66
| `--P. (P.) gigasF66
`--P. (Stereopedina de Loriol 1902)F66
`--P. (*S.) ameghinoi (de Loriol 1902) [=*Stereopedina ameghinoi]F66
Hemipedina Wright 1855 [=Leiodiadema Quenstedt 1873; incl. Archaeodiadema Gregory 1896, Miopedina Pomel 1883, Psilosalenia Quenstedt 1873]F66
*Type species of generic name indicated
References
[B01] Boczarowski, A. 2001. Isolated sclerites of Devonian non-pelmatozoan echinoderms. Palaeontologia Polonica 59: 1–219.
[F66] Fell, H. B. 1966. Diadematacea. In: Moore, R. C. (ed.) Treatise on Invertebrate Paleontology pt U. Echinodermata 3 vol. 1 pp. U340–U366a. The Geological Society of America, Inc., and The University of Kansas Press.
[MG-H11] McEnnulty, F. R., K. L. Gowlett-Holmes, A. Williams, F. Althaus, J. Fromont, G. C. B. Poore, T. D. O’Hara, L. Marsh, P. Kott, S. Slack-Smith, P. Alderslade & M. V. Kitahara. 2011. The deepwater megabenthic invertebrates on the western continental margin of Australia (100–1100 m depths): composition, distribution and novelty. Records of the Western Australian Museum Supplement 80: 1–191.
[SG93] Simms, M. J., A. S. Gale, P. Gilliland, E. P. F. Rose & G. D. Sevastopulo. 1993. Echinodermata. In: Benton, M. J. (ed.) The Fossil Record 2 pp. 491–528. Chapman & Hall: London.