Proverrucidae Newman

Family Proverrucidae Newman, in Newman & Hessler, 1989 Diagnosis. Shell small, squat and oval and wall made up of a fixed tergum, a fixed scutum, a carina and a rostrum. Moveable tergum and scutum forming an opercular lid. Articulation between plates simple, without interpenetrant elements. Single carinolatus and rostrolatus present on free side of shell. Included genus. Proverruca Withers, 1914. Remarks. This genus was originally assigned to the Verrucomorpha by Withers (1914, 1935), and subsequently placed in the family Proverrucidae by Newman (in Newman and Hessler, 1989), together with Eoverruca Withers, 1935. In the phylogenetic scheme of Newman (1987) and Newman & Hessler (1989) proverrucids were depicted as basal to the verrucomorphs and sharing a common ancestor with the extant Neoverruca Newman, in Newman & Hessler, 1989. Gale (2014, 2020) subsequently demonstrated that Proverruca and Eoverruca were very different and placed the latter in the verrucomorph family Eoverrucidae. Proverruca is known from a single articulated individual and several hundred isolated plates (Withers 1935). Withers’s somewhat stylised figure of the articulated specimen (Withers 1914, 1935), partly reconstructed, remained the basis of our understanding of the genus for 100 years, as well as of the family Proverrucidae (Newman, in Newman and Hessler 1989). The interpretation presented by Withers was that the wall of the capitulum was made up of a loosely articulated rostrum, fixed scutum, fixed tergum, carina, a rostrolatus and a carinolatus (Withers 1935, figs 33–36). The opercular lid is made up of a moveable scutum and a moveable tergum. Withers used surface sculpture to characterise a number of species of Proverruca, all known only from a few valves. Gale (2014) redescribed the articulated specimen of P. vinculum (see Fig. 1 here) and noted that the plate which Withers identified as a carina was in fact the rostrum. The carina was known only in the articulated specimen, and in the species P. dentifer Gale, in Gale & Sørensen, 2015 from the upper lower Campanian of Ivö Klack in southern Sweden. Gale (2014) had earlier argued that Proverruca was a derived scalpelliform of uncertain affinities which was convergent in form with the Verrucomorpha. This interpretation was accepted by Chan et al. (2021).