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Stylatractus universus Hays, 1970

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Stylatractus universus
Skeleton consists of 1 cortical and 2 medullary shells, medullary shells spherical cortical shell prolate. Innermost shell thin-walled pores circular with hexagonal borders. Second shell thin-walled pores regular to irregular in size and shape. Cortical shell wall very thick. Pores circular to oval, 11-14 across equatorial diameter, surface varying from smooth to rough. Medullary shells connected to cortical shell by numerous stout radial beams, two lying along the major axis project through cortical shell as stout polar spines; other beams radiate out in all directions from bases attached to inner medullary shell. Some beams penetrate through cortical shell and form short primary spines. Shell bears two large nearly equal polar spines as long to half as long as major axis of cortical shell.
Diameter of innermost shell 15-20, of 2nd shell 40-50, of cortical shell (minor axis) 106-115, (major axis) 109-123, length of spines 40-120.
Stylatratus universus was wide-spread in its occurrence when it lived, having been found in equatorial Pacific and Indian Ocean sediments, Antarctic Ocean sediments in all sectors and the North Pacific. It apparently disappeared from all these areas about 400,000 years B.P. It is morphologically uniform throughout its geographic range. The only exception to this uniformity is the slightly more robust Antarctic forms, but even these individuals do not have significantly different dimensions.
Hays 1970
Stylatractus universus
Remarks: The younger form of this species has stouter polar spines and thicker cortical shell. The older form is very similar to Amphistylus angelinus (Campbell and Clark), but differs in having a more prolate cortical shell.
Abundance: Few.
Range: Upper Miocene to lower Pleistocene.

Chen 1975











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