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Journal of Paleontology

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Cardiocystella, A New Cornute Stylophoran from the Upper Cambrian Whipple Cave Formation, Eastern Nevada, USA

¹ Department of Earth and Planetary Sciences, University of Tennessee, 1412 Circle Drive, 306 Earth and Planetary Sciences Building, Knoxville 37996-1410, <csumrall@utk.edu>;
² Department of Geological Sciences, Jackson School of Geosciences, University of Texas at Austin, 1 University Station C1100, Austin 78712-0254, <echino@mail.utexas.edu>;
³ Department of Geology, Smith College, 44 College Lane, Northampton, Massachusetts 01063, <spruss@email.smith.edu>;
⁴ Department of Geological and Earth Sciences, Stanford University, Stanford, California 94350, <sethf@stanford.edu>

The first 20% of the full text of this article appears below.

	INTRODUCTION

 
TWO NEW well-preserved cornute stylophorans from the Upper Cambrian Whipple Cave Formation represent a new genus and species assigned here to Cardiocystella prolixora. These nearly complete specimens contain morphological information not available from other cornute specimens previously collected from this formation. Both specimens are preserved with superior faces exposed. One specimen contains a nearly complete theca but a somewhat disrupted aulacophore, whereas the other theca has been partially damaged by burrows but has a nearly complete but moderately eroded aulacophore. Cardiocystella prolixora exhibits wide marginals, abundant supracentral platelets, and an aulacophore with cover plates. Supracentral platelets cover much of the interior regions of the theca, which lacks a visible zygal bar in both specimens. In holotype 1791TX13, a bulge in the superior face of the theca likely shows the zygal bar position. The wide marginals of these new specimens resemble those of a specimen previously described from a partial theca and aulacophore assigned to Archaeocothurnus species indeterminate (Sumrall et al., 1997); however, the specimens described here are heart-shaped rather than boot-shaped. The placement of this specimen in a new genus and species is based on its unique marginal shape and arrangement.

	PREVIOUS WORK

 
Echinoderm members of the Cambrian Evolutionary Fauna, such as cornute stylophorans, eocrinoids, homoiosteleans, and edrioasteroids, are major contributors to skeletal concentrations in Upper Cambrian strata of the Great Basin (Sumrall et al., 1997). However, articulated specimens are rarely found. Recent fieldwork in the Upper Cambrian Whipple Cave Formation (Fig. 1) yielded two exceptionally-preserved cornute stylophorans. These specimens are nearly complete and contain morphological information that has not been preserved in cornute specimens previously collected from the Whipple Cave Formation.

View larger version (13K):    FIGURE 1—Locality map of the Upper Cambrian Whipple Cave Formation, Sawmill Canyon, White Pine County, eastern Nevada. Specimens were . . . [Full Text of this Article]