Modiomorphoida, Newell, 1969

Kiel, Steffen, Campbell, Kathleen A. & Gaillard, Christian, 2010, New and little known mollusks from ancient chemosynthetic environments, Zootaxa 2390 (1), pp. 26-48 : 37

Order Modiomorphoida

Remarks: This order was introduced by N.D. Newell (in Moore and Teichert 1969, p. 393) for a “heterogeneous, poorly understood assemblage” of extinct Paleozoic marine bivalves. Subsequent suggestions on constituting taxa, systematics, and nomenclature were recently summarized by Griffin and Pastorino (2006). The essence is that the modiomorphoids are now a heterogeneous, poorly understood assemblage of extinct Paleozoic to Neogene marine bivalves. They are characterized by a modiolin shape; a small and deep anterior adductor scar, often supported by a so-called myophoric buttress; differentiated subumbonal cardinals and long laterals, teeth may also be reduced; and the shell microstructures are nacreous and homogenous. Suggested systematic affinities include the Anomalodesmata, Carditioidea, Modiolopsidoidea, Mytiloida, and Palaeoheterodonta ( Kelly et al. 2000; Griffin and Pastorino 2006). Kelly et al. (2000) placed Caspiconcha – the genus concerned here – in the family Modiomorphidae , subfamily Myoconchinae .