? Benthopectinidae Verrill, 1894 Fig. 6A–B, F

? Benthopectinidae Verrill, 1894: 217 .

Material

Seventeen marginal ossicles; the inferomarginal figured (Fig. 6A) is MHI 2183/7; the other inferomarginal and oral ossicle illustrated here are MHI 2183/8 and 9. All are from the Maantang Formation (Carnian, Upper Triassic; sample C30) at Jiancougou, Sechuan Province, China.

Description

The inferomarginal and oral ossicles are strongly reminiscent in shape and external sculpture of those of benthopectinids; compare Fig. 6A–B with benthopectinid marginals (Fig. 6C–E), and the oral (Fig. 6F) with those of benthopectinids (Fig. 6G–I).

The inferomarginals share a number of similarities to those of benthopectinids (Fig. 6A–E), notably the coarse, longitudinally arranged rows of rugosities, the presence of a large spine (or pedicellaria) base close to the abactinal margin of the plate, and the marked asymmetry of the distal inferomarginals, in which the distal height is less than the proximal one. The oral ossicles (Fig. 6F) are remarkably similar to those of benthopectinids in the evenly convex actinal margin, the distally angled apophyse and the shape of the adambulacral articulation (Fig. 6G–I). However, the material available to date is too limited, and in the absence of ambulacrals and adambulacrals, this referral is very tentative.