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The Echinoid Directory

Contributed by Andrew Smith, September 2006

Orthopsis Cotteau, 1864, p. 550

[=Arialopsis Lambert & Thiery, 1925, p. 566, type species Orthopsis similis Stolizcka, 1873; ?= Miorthopsis Pomel, 1883, p. 100, type species Orthopsis flouesti Cotteau, 1867; =Stephanopsis Lambert, 1900, p. 29 (non Cambridge 1869); = Stephomma Stechow, 1921, p. 263, type species Orthopsis similis, 1873 ]

Diagnostic Features
  • Test of modest size depressed with rounded ambitus.
  • Apical disc small and dicyclic with relatively large periproct; anterior genital plates larger than posterior genital plates.
  • Ambulacra narrow and compound in acrosaleniid style. All elements similar and reaching the perradial suture.
  • Pore-pairs uniserial adapically and adorally with no phyllode development (might be slight offset close to peristome).
  • Primary tubercle uniting two of the three plates and with granules only on third element, adapically. At ambitus the primary tubercle can overlap all three elements in a triad.
  • Interambulacral zones wide with large primary interambulacral tubercle flanked by a prominent secondary tubercle on either side and slightly higher in larger individuals. Remainder of plate covered in sparse granules.
  • Tubercles non-crenulate and perforate; areole never sunken.
  • Buccal notches present but relatively small. Lantern support of slender auricles.
  • Lantern stirodont, with keeled teeth and unfused epiphyses.
  • Spines simple and cylindrical, without cortex; pointed distally; solid.
Distribution Jurassic - Cretaceous (Maastrichtian); Europe. North Africa, Middle East, India, South America.
Name gender feminine
Type Cidarites miliaris d\'Archiac, 1837, p. 9, pl. 11, fig. 8, by original designation.
Species Included A number of species have been distinguished but all need to be carefully examined and properly diagnosed.
  • O. miliaris d'Archiac, 1837; Upper Cretaceous, Europe, North Africa
  • O. occidentalis Cragin, 1893; Albian, USA
  • O. indicus Duncan, 1887; Cenomanian-Turonian, India
  • O. rupellii Gras, 1849; Barremian, France
  • O. similis Stolizcka, 1873; Campanian-Maastricthian, India

The following taxa have been assigned to Orthopsis wrongly
Classification and/or Status Acroechinoidea, Carinacea, Orthopsidae
Remarks The original description of the lantern of Orthopsis by Checcia-Rispoli (1933) erroneously stated that the lantern was camarodont. The discovery of new material with in situ lantern elements shows that the lantern is actually stirodont, with keeled teeth and unfused epiphyses (Smith 1995).

Checchia-Rispoli, G. 1933. Illustrazione di alcuni Echinidi del Maestrichtiano della Tripolitania. raccolti da Ignazio Sanfilippo. Memorie della Societa geologica Italiana 1, 1-22, pls 1-2.

Cotteau, G. 1864, in 1861-1867. Paleontologie francaise. Terrains Cretaces Tome VII. Echinides. V. Masson, Paris. 892 pp, pls 1007-1204.

Smith, A. B. 1995. Late Cretaceous echinoids from the United Arab Emirates-Oman borders region. Bulletin of the Natural History Museum, London (Geology) 51(2) 121-240.