Diversity of anterior structures in the Raphiophoridae compared with similar structures in the Coleoptera. (a) Reconstruction of A. virginiensis, dorsal view, after Whittington & Campbell (1967). Scale bar represents 5 mm. Note that the long genal spines are not shown completely. (b) Cranidium of A. virginiensis, right lateral view. (c) Cranidium of A. spongiosus, right lateral view. (d) Cranidium of undescribed species of Ampyx (see text), right lateral view. (e) Cranidium of Bulbaspis mirabilis, dorsal view. (f) Oryctes rhinoceros, (g) Oxysternon spiniferum and (h) Megasoma elephas, all from the Coleoptera. (b)–(e) all approximately ×3, (f) ×1, (g) ×3, (h) ×1/2.

The positively allometric relationship between spine length and cranidium width for 12 specimens of A. virginiensis. The specimens used were from a bulk collection of silicified fossils dissolved out of limestone and held in the Natural History Museum, London. Only fossils from the same deposit were used. The fitted line is from a standard least-squares linear regression, and has a slope that is greater than 1 (slope=1.20, t₁₀=2.34, p<0.05). Using a reduced major axis regression (Harvey & Pagel 1991) to take account of error in the X coordinate gives a similar result (RMA slope=1.24, 95% confidence intervals 1.041–1.430). The dashed line shows a slope of 1.