Gilmoreosaurus, Brett-Surmann, 1979

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 : 161-162

GILMOREOSAURUS MONGOLIENSIS ( GILMORE, 1933) – (PRIETO- MÁRQUEZ & NORELL, 2010)

Gilmoreosaurus comprises the partial remains of four individuals of a hadrosauromorph collected from the Iren Dabasu Formation, Erenhot, China: Turonian−Coniacian ( Sues & Averianov, 2009). However, it should (again) be noted that estimates of the age of these beds have ranged from Albian to Maastrichtian ( Prieto-Márquez, 2011a).

Teeth and jaws

The maxillary crowns are narrower than the dentary crowns, but have a more prominent median primary ridge. The dentary crowns have a single median (or submedian) lower primary ridge. Neither dentary nor maxillary crowns appear to have accessory ridges. The marginal denticles are also ledge-like and bear mammillae [these were also reported to be present in Protohadros , Lophorhothon , and some lambeosaurines ( Prieto-Márquez & Norell, 2010: 18)]. The dentary ramus is imperfectly known, but differs very little from that described in Bactrosaurus , its sympatric contemporary. This dental morphology is distinct from that seen in Hy. fittoni .

Axial skeleton

The axial skeleton is very similar to that described in Bactrosaurus , and displays no distinct characters of significance.

Appendicular skeleton

The pectoral girdle and forelimb are very similar in morphology to those described above for Bactrosaurus . The ilium differs in the more posterior positioning of the transverse expansion of the dorsal iliac blade when compared to that of Bactrosaurus , and in the development of a bar-like postacetabular process. The pubis has a prepubic process that is less expanded proximally, the distal expansion is less extreme, and the process overall appears to be longer than that seen in Bactrosaurus . The remaining elements of the pelvis and hindlimb seem indistinguishable in these two taxa; however, the unguals of the pes are notable narrower and taper to a bluntly truncated tip, rather than been broad and rounded as in the case of those described for Bactrosaurus (cf. Prieto-Márquez & Norell, 2010: fig. 18 and Godefroit et al., 1998: pl. 14).

SHUANGMIAOSAURUS GILMOREI YOU, JI, LI & LI, 2003 A

This taxon is represented by a few cranial elements collected from the Sunjiawan Formation (‘middle’ Cretaceous), Beipiao, Liaoning, China. The specimens, a maxilla plus articulated lacrimal and an edentulous dentary, were not associated and show evidence of post-mortem distortion, which may have contributed to the way in which its anatomy has been described and interpreted. In systematic analyses You et al. (2003a) placed this taxon as the sister taxon to the Hadrosauridae (= Euhadrosauria sensu Weishampel et al., 1993; Norman, 2014) and McDonald (2012b) placed it at just one further step removed.

Teeth and jaws

Only maxillary crowns are known and exhibit a lanceolate shape, have a single median primary ridge and no accessory ridges, and the mesial and distal margins of the crowns bear denticles. The dentary is very elongate and slightly arched along its length; it also appears to have had a relatively short diastema. The medial surface of the dentary ramus shows a deep and elongate alveolar trough that is backed by sets of alveolar grooves that appear to show the outlines of replacement crowns, rather than forming consistent parallel troughs (this is a nonhadrosauromorph characteristic). The alveolar trough extends back toward the posterior margin of the base of the coronoid process. The coronoid process is elongate but appears to form an obtuse angle to the long axis of the dentary ramus. The extent of post-mortem distortion in this specimen (which is clearly evident in the maxilla that is described) makes it difficult to discern genuine and unique anatomy from structures that may simply reflect postburial distortion.

Axial and appendicular skeletons

Unknown.