Paterulidae Cooper, 1956

Holmer, Lars E. & Biernat, Gertruda, 2002, Urban and Peri-urban small and medium-size Enterprise Development for sustainable Vegetable Production and Marketing Systems, Acta Palaeontologica Polonica 47 (1), pp. 141-156 : 144

Family Paterulidae Cooper, 1956 Genus Diencobolus Holmer, Popov, Koneva, and Bassett, 2001

Type species: Diencobolus simplex Holmer, Popov, Koneva, and

Bassett, 2001; Upper Cambrian, Glyptagnostus stolidotus Biozone ;

Malyi Karatau, Kazakhstan.

Diagnosis (emended).—Shell biconvex, equivalved, elongate, oval to subcircular in outline; both valves with holoperipheral growth and excentric to submarginal umbo, lacking pseudointerareas and pedicle groove; larval and post−larval shell finely pitted with subcircular pits of varying sizes (2–4 µm); ventral valve with visceral area occupying the median part of the valve posterior to mid−length; dorsal interior commonly with low median ridge widening anteriorly and bearing small, elongate suboval anterior lateral muscle scars at the posterior end; central muscle scars large, suboval, situated in the mid−valve lateral to the median ridge.

Remarks.—As noted by Holmer et al. (2001), Diencobolus is a very enigmatic genus, only somewhat comparable with Paterula , but differs in having circular, not rhomboidal, post−larval pits and in lacking an emarginature in the posterior ventral margin.