Proa

Norman, David B., 2015, On the history, osteology, and systematic position of the Wealden (Hastings group) dinosaur Hypselospinus fittoni (Iguanodontia: Styracosterna), Zoological Journal of the Linnean Society 173 (1), pp. 92-189 : 154

PROA VALDEARINNOENSIS MCDONALD, ESPÍLEZ, MAMPEL, KIRKLAND & ALCALÁ, 2012 B

Proa comprises cranial and postcranial remains of several individuals of a medium-sized ornithopod (5– 6 m long) collected from the Escucha Formation (lower Albian) of Teruel, Spain. This taxon is only known from a preliminary description of some of the principal cranial bones, the pelvis, and femur ( McDonald et al., 2012b).

Teeth and jaws

The maxillary crowns are morphologically similar to those of Hy. fittoni in that they are typically lozengeshaped with a distally offset, high primary ridge flanked by a variable number of strand-like accessory ridges ( McDonald et al., 2012b: fig. 7). The dentary crowns are broader and more shield-shaped but appear to lack the shoulder-like coronal margin seen in the crowns of Hy. fittoni , and have a rather more symmetrical (almost triangular) profile in lingual aspect. The primary ridge is distally offset and the secondary ridge (mesially positioned) is described as being of equal prominence, and faint multiple accessory ridges are also present. One functional tooth and one replacement crown is present in each alveolus. The dentary is well preserved and has a prominent, perpendicular coronoid process that has an expanded apex. The dentary ramus is arched along its length and is comparatively stout; its external surface of its distal end is modified to form a horizontal ridge and adjacent channel to accommodate the lateral arm of the large predentary bone. The alveolar recess is marked by replacement grooves for the teeth that do not form parallel grooves, but are shaped to accommodate the expanded crowns. The posterior alveoli extend posteriorly as far as the posteri- or margin of the base of the coronoid process.

Appendicular skeleton

The ilium has a prominent, thick preacetabular process that is twisted axially, terminating in a horizontally orientated flange. The dorsal margin of the ilium is convex and posterodorsal to the ischiadic peduncle there is a prominent bulbous facet. The dorsal edge of the postacetabular process is elongate and curves smoothly ventrally, with no obvious abrupt break in slope; the ventral edge of this process was not described. In the structure of the preacetabular process, the dorsal margin of the iliac blade, and the bulbous facet, this ilium is distinct from that of Hy. fittoni . The pubic peduncle appears to show a well-developed supra-acetabular crest that does not form a lip along the dorsal margin of the acetabulum. The pubis has a notably elongate prepubic process, which forms a parallel-sided, comparatively narrow plate that is not expanded toward its distal end; this morphology is unlike that seen in Hy. fittoni . The femur, although somewhat crushed and distorted, appears to have a straight shaft, and does not seem to display the angularity of the shaft seen in Hy. fittoni . The femoral head is globular and offset medially, but it is unclear whether the posterior side of the head was notched; the anterior trochanter appears to be robust and similar in form to that of Hy. fittoni , and the fourth trochanter is large and of the crested form. The extensor intercondylar groove is completely enclosed by expansion of the adjacent condyles, and unlike the morphology seen in Hy. fittoni .