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The Echinoid Directory

Family Paleopneustidae A. Agassiz, 1904, p. 150

[= Palaeopneustidae Mortensen, 1950, p. 181]

Diagnosis

 Paleopneustinid spatangoids with:

  • ambulacrum III pores small and undifferentiated, associated with simple sensory tube-feet
  • paired ambulacra petaloid and flush; petals long, parallel-sided and open distally
  • Labral plate large; extending to third or fourth ambulacral plate
  • periproct large and marginal or inframarginal
  • marginal and peripetalous fascioles generally absent from adults.
Range
Eocene to Recent; widespread.
Remarks
Distinguished from Pericosmidae by the effective lack of a frontal groove and its broad, flush petals that extend most of the distance to the ambitus.