The Echinoid Directory

Family Phymosomatidae Pomel, 1883, p. 90

[=Cyphosominae Lambert, 1897, p. 498; includes Trochalosomina Lambert, 1897, p. 515. ]


Phymosomatoida with:

  • apical disc relatively large; monocyclic with plates only loosly associated with the corona and usually missing. Periproct large with angular edges such that periproctal plates partially tesselated into disc;
  • ambulacral plating polygeminate, with phymosomatid-style compounding; second lowest element in each compound plate the largest, extending from adradial to perradial suture, and bearing the primary tubercle; lowermost and uppermost elements smaller but also extending the full ambulacral width; other elements demiplates;
  • primary tubercles imperforate and usually distinctly crenulate; those of ambulacral and interambulacral zones similar in size.
Upper Jurassic - Eocene, Europe, North America, Middle East, North Africa.
Type Phymosoma
Classification and/or Status Acroechinoidea, Calycina, Phymosomatoida
Closely resembling Emiratiidae in apical disc morphology, but with imperforate tubercles, and phymosomatid-style plate compounding. Members of an unnamed clade have imperforate tubercles that are non-crenulate, and diadematid rather than phymosomatid plate compounding. Possibly paraphyletic by exclusion of Glyptocidaris.

Lambert, J. 1897.  Note sur quelques Echinides Eocenes de l\'Aude (I. Endocycles). Bulletin de la Societe geologique du France, serie 3 25: 483-517.

Pomel, A. 1883. Classification méthodique et Genera des Échinides vivante et fossiles. Thèses présentées a la Faculté des Sciences de Paris pour obtenir le Grade de Docteur ès Sciences Naturelles 503, Aldolphe Jourdan, Alger, 131 pp.