The Echinoid Directory

Paradoxechinus Laube, 1869, p. 186

Diagnostic Features
  • Test low with rounded ambitus.
  • Apical disc large; with marked sexual dimorphism. Dicyclic, with narrow, projecting ocular plates and massive genital plates. Deeply sunken in females forming marsupium but with central knob formed by inner parts of genital plates rising above level of test so as to be clearly visible in lateral view (see Philip & Foster, 1971, pl. 125, fig. 1). Sunken zone of coronal plates with fine, dense, uniform tuberculation.
  • Ambulacra relatively wide, straight; pore-pairs uniserial; plating in triads with echinid-style plate compounding. Pore-pairs arranged uniserially throughout; no crowding adorally.
  • Single primary tubercle to each compound ambulacral plate, situated close to the zone of pore-pairs. Perradial zone with marked sculpture in the form of horizontal pits.
  • Interambulacral plates wider than tall, with a single central primary tubercle plus much smaller flanking secondary tubercles. Base of primary tubercle with radial pits and ridges connecting the primaries in a vertical series.
  • Well developed ornament of wedge-shaped sutural pits and radiating groovesand ridges from the primary tubercles.
  • Primary tubercles imperforate and weakly but distinctly crenulate.
  • Peristome smaller than apical disc in females; weakly sunken; buccal notches more or less absent.
  • Auricles of perignathic girdle meeting perradially.
  • Spines and lantern unknown.
Upper Eocene - Lower Miocene, Australia.
Name gender masculine
Paradoxechinus novus Laube, 1869, p. 188, by monotypy. Holotype Natural History Museum, Vienna 9024.
Species Included
  • P. novus Laube, 1869; Oligocene-Lower Miocene, South Australia.
  • P. granulosus Philip & Foster, 1971; Upper Oligocene, South Australia.
  • P. profundi Philip & Foster, 1971; Middle Oligocene and possibly Lower Miocene, South Australia.
  • P. stellatus Philip & Foster, 1971; Upper Eocene-earliest Oligocene, South Australia.
Classification and/or Status
Euechinoidea; Camarodonta; Temnopleuroida; Temnopleuridae

The strong sexual dimorphism distinguishes this taxon from all others except Temnechinus and Coptechinus, both of which have an almost identical apical dis morphology. Paradoxechinus is distinguished from both by the rather fine pitting that occurs across the plate as well as along sutures.

Described in detail by Philip & Foster (1971).

Laube, G. C. 1869. Sitzber. Akad. Wiss. Wien. 69 (1), 186.

Philip, G. M. 1969. The Tertiary echinoids of South-Eastern Australia IV. Camarodonta (2). Royal Society of Victoria Proceedings 82, 233-275, pls 3-16.

Philip, G. & Foster, R. J. 1971. Marsupiate Tertiary echinoids from South-eastern Australia and their zoogeographic significance. Palaeontology 14, 666-695.