The Echinoid Directory

Contributed by Andrew Smith, September 2006

Pygopyrina hancockensis (Whitney & Kellum 1966, p. 260)

1966 Pyrina hancockensis Whitney & Kellum, p. 260, pl. 2, figs 1-3.
1987 Globator hancockensis Whitney & Kellum; Akers & Akers, p. 72.
2009 Pygopyrina hanckockensis (Whitney & Kellum); Smith & Rader, p. 42, figs 18J-O, 21.

Diagnostic Features
  • Apical disc compact, central; genital plate 3 smallest; posterior genital plates meet behind genital plate 2; posterior ocular plates meet behind posterior genital plates.
  • Ambulacra straight, narrow; pore-pairs uniserial aborally to subambitally, becoming offset into triads towards peristome. Ambulacral plating not seen in any specimen.
  • Tuberculation of small sunken primaries plus dense granules. Tubercles on oral surface slightly larger than those of aboral surface.
  • Periproct aboral in position; tear-drop-shaped, pointed adapically and rounded adorally; longer than wide. In contact with apical disc up to ca. 10 mm test length, but separated by 2 or 3 plates by 16 mm test length. Opening bounded by about 10 interambulacral plates on each side.
  • Peristome ovate, longer than wide, a little oblique with long axis running from amb. 1 to Iamb 3. Distinctly invaginated.
Distribution Glen Rose Limestone, Lower Trinity Group, Lower Albian, Lower Cretaceous, Texas, USA.
Remarks Globator incisa Agassiz, in Desor, 1842 has the periproct more marginal and the peristome somewhat smaller. In theis species the periproct remains in contact with the apical disc in juveniles (up to ca 10 mm test length) but in larger individuals up to 2 interambulacral plates come to separate the opening from the apical disc.

Witney, M. I. & Kellum, L. B. 1966. Echinoids of the Glen Rose Limestone of Texas. Papers of the Michegan Academy of Science, Arts and Letters 51, 241-263.

Smith, A. B. & Rader, W. L. 2009. Echinoid diversity, preservation potential and sequence stratigraphical cycles in the Glen Rose Formation (early Albian, Early Cretaceous), Texas, USA. Palaeobiodiversity and Palaeoenvironments 89, 7-52.