The Echinoid Directory

Polytaxicidaris Kier, 1958, p. 10

Diagnostic Features
  • Test moderately large; probably depressed in profile.
  • Only disarticulated plates of the apical disc preserved; genital plates large, with 6-8 gonopores arranged as an arc on each plate.
  • Ambulacra narrow, biserial throughout; strongly imbricate adorally. Pore-pairs adradial, the two pores slightly elongate. Well developed flange extends adradially beneath interambulacral plates. Tubercle present perradially on most plates.
  • Interambulacra with up to 6 columns of approximately hexagonal plates, imbricating strongly adapically. Each with a large central primary tubercle that is perforate and non-crenulate; boss surrounded by a well marked areole, and around edges of plates there are secondary tubercles and granules.
  • Adapical interambulacral plates lacking primary tubercles.
  • Primary spines moderately long and slender, without cortex or ornament. Approximately half test diameter in length.
  • Lantern large; teeth grooved and serrated at tip.
Lower Carboniferous, USA.
Name gender feminine
Polytaxicidaris dyeri Kier, 1958, p. 11, by original designation.
Species Included
  • P. dyeri Kier, 1958; Osagean, Indiana, USA.
  • P. lirata Kier, 1965; Chester, Oklahoma, USA.
Classification and/or Status

Stem group Echinoidea; Archaeocidaridae.

Possibly paraphyletic by exclusion of Archaeocidaris.


Similar to Archaeocidaris in most features but having more than four columns of interambulacral plates in each zone. Isolated plates of Archaeocidaris and Polytaxicidaris are indistinguishable. Deneechinus has more columns of interambulacral plates (8-12) in each zone, the interambulacral plates are smaller and more strongly imbricate, and the primary tubercles less prominent on the plates.

Kier, P. M. 1958. New American Paleozoic echinoids. Smithsonian Miscellaneous Collections 135(9), 26 pp. 8 pls.

Kier, P. M. 1965. Evolutionary trends in Paleozoic echinoids. Journal of Paleontology 39, 436-465, pls 55-60.