radiolaria - rads_cat - Artocapsa livermorensis

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Artocapsa livermorensis

Citation: Artocapsa livermorensis Campbell & Clark 1944

Type specimens: pl.8, figs.10, 19, 21, 27

Type age (chronostrat): Late Cretaceous, Mesozoic.

Type repository: University of California, Museum of Paleontology, Berkeley, Holotype: Slide No.. 34523, 34526, 34533.

Shell small, generally spindle-shaped, smooth and with 5 joints; apical horn very short, like a little stub, but conical, rarely rudimentary and sometimes acentric; shell as a whole biconical (35°-50° in upper section, 10° in longer portion, finally 45°-100° in short inverted conical terminal part); cephalis, thorax, and abdomen (forming first 3 joints) and postabdomen (ultimate 2-3 joints) regularly increasing in length and diameter according to positions in linear series from apical to apertural ends, except cephalis is relatively longer than other joints; lateral shell contour unmodified by more than minor modifications at strictures which are small transverse indentations marked by thin bands, otherwise contour regular, apertural end mostly simply conical with rounded sides, but may be hollow-conical, and always with either a short conical tooth or a longer spinelike rod; wall uniformly thin; surface smooth; pores largest on ultimate joint, often crossing strictures, very well separated In clear shell substance, double-contoured, shallow, rather strictly circular, although a few are squarish, and about 40 in number on ultimate joint where they are in 3 crude transverse rows, and in perhaps 5-6 rows in longer cephalis.

Length, total, 140µm; diameter, maximum (at level of ultimate stricture), 40µm, of pores, 8.8µm.

Distinguishing features: Artocapsa livermorensis n. sp., lacks pyramidal terminal spine of A. fusiformis (Haeckel, 1887), has only 5 joints, and is much smaller. It suggests, in outline, Stichocapsa biacuminata Rüst (1885, pl. 16, fig. 15).

References:

Campbell, A. S. & Clark, B. L. (1944b). Radiolaria from Upper Cretaceous of middle California. Geological Society of America, Special Papers. 57: 1-61. gs

CATALOG OF ORIGINAL DESCRIPTIONS: Artocapsa livermorensis Campbell & Clark 1944

Artocapsa livermorensis

References:

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