Hiscobeccus capax
Size measurements required to calculate three-dimensional shape coordinates were collected from 37 well-preserved specimens of Hiscobeccus capax. This sample included many juvenile specimens with relatively flat shells, as well as large, more mature examples with highly globose shells indicative of the adult stage of development (Figure 1).
Landmark Data
A system of 11 anatomical landmarks present throughout the ontogeny of H. capax was used to undertake a shape analysis of the taxon. Of these landmarks, 10 corresponded to points along the length of the shell commissure, including the anterior median sulcus, with the 11th landmark demarcating the point of attachment of the shell to the seafloor, on the posterior end of the shell (Figure 2). Procrustes analysis of these landmarks provided a shape coordinate constellation for each specimen, which served as the primary data for multivariate analysis (Table 1).
1:1 Scale Articulated Models
1:1 scale plastic models of three H. capax specimens were constructed using two-piece silicone molds and a urethane casting resin. The three examples of H. capax used to prepare silicone molds were chosen based on their anterior-posterior length, and fell within the lower (10-12 mm), middle (14-16 mm), and upper (18-20 mm) bins of the sample size distribution shown in Figure 1.