The Echinoid Directory

• Test ovate with shallow anterior sulcus; posterior face truncate. Test depressed in profile with rounded ambitus.
• Apical disc ethmophract with four gonopores; central.
• Anterior ambulacrum depressed adapically; narrow, with differentiated pore-pairs; frontal groove shallowing towards ambitus.
• Paired ambulacra relatively short; sunken and parallel-sided. Anterior pair longer than posterior pair.
• Petals with smooth perradial zone.
• Peristome D-shaped and with opening facing forward; with narrow rim. Labrum slightly projecting.
• Labral plate elongate; extending to second ambulacral plate. Episternal plates alternate rather than opposite.
• Periproct towards top of posterior truncate face.
• Subanal fasciole present; ovate.
• Dense granular bands at ends of petal but not developed into a true peripetalous fasciole.
• Aboral tubercles small and uniform; set in a fine groundmass of granules.

Upper Cretaceous (Campanian-Maastrichtian) to Palaeocene, Europe, Ukraine, Madagascar.

Diplodetus brevistella Schluter, 1900, p. 364, by original designation.

• D. brevistella Schluter, 1899;
• D. parvistella (Schluter, 1899); Maastrichtian, The Netherlands and Belgium.
• D. americanus Stephenson, 1941; Campanian-Maastrichtian of SE USA and The Netherlands.
• D. bucardium (Goldfuss, 1829); Maastrichtian, The Netherlands and Belgium.
• D. duponti (Lambert, 1911); Maastrichtian, The Netherlands, Germany.
• D. nutrix (Lambert, in Boule, 1899); Campanian-Maastrichtian, Madagascar.
• D. gauthieri Cottreau, 1908; Maastrichtian-Danian, Madagascar.
• D. coloniae (Cotteau, 1877); Palaeocene, western Europe, Ukraine.

Spatangoida, Micrasterina, Micrasteridae.

?Paraphyletic (by exclusion of Cyclasterinae)

Differs from Plesiaster only in having shorter petals. Jagt (2000) gives a detailed account of the genus in the Maastricht district.

Jagt, J.W.M. 2000. Late Cretaceous-Early Paleogene echinoderms and the K/T boundary in the southeast Netherlands and northeast Belgium. Part 4. Echinoids. Scripta Geologica 121, 181-375.

Schluter, C. 1900. Ueber einige Kreide-Echiniden. Zeitschrift der deutschen geologischen Gesellschaft, 52, 360-379, pls 15-18.

Stokes, R. B. 1979. The echinoid genus Diplodetus from the Santonian to Danian of Northern Europe. Neues Jahrbuch fur Geologie und Palaontologie Mh. 1979(10), 619-630.