Abstract

Four specimens of a new cornute-grade stylophoran Ponticulocarpus robisoni new genus and species are described from the Spence Shale of northern Utah. Ponticulocarpus has wide and thin spinal and glossal processes interpreted as a mechanism for snowshoeing in a soft substrate. The presence of a posterior bar across the inferior posterior lobe, and two small bridges connecting the left adoral to M'2 on the superior face and connecting M1 to M3 on the inferior face are unique in cornute-grade stylophorans. The posterior bar may be homologous with the posterior marginals M'5 and M6 of other cornute-grade stylophorans, and an opening of the most posterior portion of the theca may have resulted in the development of the digital and glossal processes from marginals.

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