Hypselospinus, Norman, David B., 2010

Norman, David B., 2010, A taxonomy of iguanodontians (Dinosauria: Ornithopoda) from the lower Wealden Group (Cretaceous: Valanginian) of southern England, Zootaxa 2489, pp. 47-66 : 55

Hypselospinus gen. nov.

Figs 5–10

Etymology. From hypselos (Gr. = high/tall) + spina (L. = backbone). A reference to the singularly slender and elongate neural spines found on the dorsal, sacral and caudal vertebrae.

Type and only species. Hypselospinus fittoni ( Lydekker, 1889) .

Diagnosis. As for type species (below).

Figures

FIGURE 5. Hypselospinus fittoni (Lydekker, 1889) comb. nov. NHMUK R 1635, holotype ilium. A. Lateral view. B. Posterior view to show the inflected shelf, lateral ridge and brevis fossa. C. Medial view showing the form of the sacral rib scars. D. Dorsal view showing the transversely narrow dorsal margin of the ilium compared with that of B. dawsoni (Fig. 3 B). The mediodorsal edge of the ilium shows an abscess-like excavation that may be pathological in origin. Even though the dorsal margin is eroded laterally posterior to the ischial peduncle (cross-hatched area) there is little indication of a laterally everted edge. Abbreviations: acet – acetabulum; brf – brevis fossa; lr – lateral ridge that bounds the brevis fossa; nde – narrow dorsal edge to the iliac blade; path? – probable pathological structure; prp – preacetabular process; srs – sacral rib scar on medial surface of iliac blade. Broken surfaces indicated by cross-hatching.

FIGURE 6. Hypselospinus fittoni (Lydekker, 1889) comb. nov. NHMUK R 1635, additional postcranial remains recovered from the same locality and horizon as the holotype ilium (Fig. 5) at Shornden. A – C. Posterior portion of sacrum (lateral, ventral and dorsal views respectively). D, E. Anterior caudal centrum, in right lateral and anterior views respectively. F. Proximal left ischium, a water-rolled and polished fragment. The ischium is of different preservation and is very probably transported to a greater extent than the other type specimens – and in any case shows no diagnostic features beyond being the proximal fragment of an ornithopod ischium. Abbreviations: cr – caudal rib; hf – haemal arch (chevron) facet; il – base of iliac peduncle; k – keel on ventral surface of sacral centrum; nc – floor of canal for spinal cord; obt – base of obturator process; pu – base of pubic peduncle; sr – fragments of the sacral ribs. Broken surfaces indicated by cross-hatching.

FIGURE 7. Hypselospinus fittoni (Lydekker, 1889) comb. nov. NHMUK R 1148, referred specimen. The right femur, illustrated as part of the holotype of Iguanodon hollingtoniensis Lydekker, 1889. A. Anterior view. B. Anteromedial view. Abbreviations: aig – anterior intercondylar groove almost occluded by shoulders developed from the distal articular condyles; at – anterior trochanter; 4 t – fourth trochanter and associated muscles scars associated with the caudifemoral complex. Broken surfaces are indicated by cross-hatching.

FIGURE 8. Hypselospinus fittoni (Lydekker, 1889) comb. nov. Referred material. NHMUK R 811, crushed sacrum (part of the holotype of Iguanodon hollingtoniensis) in ventral (A; note remains of midline keel is preserved despite crushing) and dorsal (B) views. NHMUK R 811 b, crushed ilium (part of the holotype of I. hollingtoniensis) in lateral (C) and medial (D) views. Note the deep, narrow preacetabular process with a low curved medial ridge, the flat iliac blade with a narrow dorsal edge and that the ventral postacetabular margin is indented and curves upward away from the ischial peduncle. Abbreviations: k – keel on ventral surface of the sacrum; mr – low, curved ridge on the medial surface of the preacetabular process; nc – floor of canal for the spinal cord; nde – narrow dorsal edge to the ilium; prp – preacetabular process; sr – fragments of the sacral ribs. Broken surfaces indicated by cross-hatching.

FIGURE 9. Hypselospinus fittoni (Lydekker, 1889) comb. nov. NHMUK R 604, referred specimen. A, B. Anterior – mid dorsal vertebra in left lateral and anterior views respectively. C. Anterior caudal vertebra in left lateral view. Abbreviations: cr – caudal rib; dia – diapophysis; em – everted articular margin of the centrum; hf – haemal arch (chevron) facet; par – parapophysis; poz – postzygapophysis; prz – prezygapophysis.

FIGURE 10. Hypselospinus fittoni (Lydekker, 1889) comb. nov. Referred material. NHMUK R 1831, right dentary. A. Medial view, reproduced from Owen (1874: pl. 1, fig. 1). B. Medial view, sketch drawing taken from the original dentary (December 2009). C. The ‘ Brickenden jaw’ (NHMUK 28660). Sketch (November 2009) in medial view for comparison with NHMUK R 1831 (above). This is the right dentary of a large iguanodontian of robust build (attribution unconfirmed at present but it may prove to be attributable to B. dawsoni – Norman in preparation) collected by Col. Brickenden from a quarry near Cuckfield, Sussex. Abbreviations: am – level of alveolar margin; at – ‘ anomalous tooth’ (no longer associated with the jaw); br – extensively broken and crushed dorsal portion of the dentary ramus; ds – dentary-dentary symphysis; m – matrix infill of the Meckelian canal, the medial surface of the postdentary bones and the alveoli; mgr – Meckel’s groove; mt – matrix and tooth crown removed since the lithograph was prepared; pr – ‘ prong’ at the anterior end of the dentary ramus that locks against the lateral surface of the median ventral flap of the predentary; sh. alv – large area of the posterior alveolar shelf that has been sheared away post-mortem.