The Echinoid Directory

Family Eothuriidae MacBride & Spencer, 1938, p. 95

[=Order Megalopoda MacBride & Spencer, 1938, p. 95; = Superorder Megapodacea Durham, 1966, p. 377]


 Stem group echinoids with:

  • test composed of ambulacral and interambulacral plates; plating thin and strongly imbricate throughout
  • ambulacral zones biserial; pores large, composed of a circular rim enclosing 8-12 small perforations
  • internal groove houses the radial water vessel but reportedly does not roof over it (possibly an artefact)
  • interambulacra composed of an semi-regular array of subpolygonal plates, up to 10 abreast
  • no tubercles on interambulacral plates
  • lantern broad; teeth wide and composed of a V-shaped arrangement of elements.
Upper Ordovician (Ashgill), Scotland.

MacBride & Spencer (1938) originally described this taxon as a holothurian. However, other than its rather peculiar and unique ambulacral pore structure, it conforms well in morphology to other Upper Ordovician echinoids.

MacBride, E. W. & Spencer, W. K. 1938. Two new Echinoidea, Aulechinus and Ectinechinus, and an adult plated holothurian, Eothuria, from the Upper Ordovician of Girvan, Scotland. Transactions of the Royal Society, London B229, 91-136, pls 10-17.