The Echinoid Directory

 Spatangoids with:

• episternal plates biserially offset
• labral plate longitudinally elongate; flask to wedge-shaped
• peripetalous fasciole; no other fascioles ever present
• anterior ambulacrum with suckered tube-feet aborally.

Lower Cretaceous (Albian) to Recent; worldwide.

This group was recently reviewed by Neraudeau (1994). Note, however, that in that paper the generic definitions used by Neraudeau differ from those used here .

Two extant clades can be distinguished within this family: the Palaeostomatinae, characterized by having lost the anterior pair of gonopores, and the Holanthinae, characterised by the very marked narrowing of ambulacral zones at the base of the petals, where they cross the peripetalous fasciole.

Catoproctus Lambert, 1932 was established as a 'section' of Hemiaster but is too poorly known to be meaningfully compared and its family placement is uncertain.  Nordenskjoldaster Lambert, 1910 from the Cenomanian of Antarctica is also too poorly known to place but probably belongs to this family.

Neraudeau, D. 1994. Hemiasterid echinoids (Echinodermata: Spatangoida) from the Cretaceous Tethys to the present-day Mediterranean. Palaeogeography, Palaeoclimatology, Palaeoecology 110, 319-344.