|Notocolossus gonzalezparejasi |
Riga, Lamanna, David, Calvo & Coria, 2016
Titanosauria is an exceptionally diverse, globally-distributed clade of sauropod dinosaurs that includes the largest known land animals. Knowledge of titanosaurian pedal structure is critical to understanding the stance and locomotion of these enormous herbivores and, by extension, gigantic terrestrial vertebrates as a whole. However, completely preserved pedes are extremely rare among Titanosauria, especially as regards the truly giant members of the group. Here we describe Notocolossus gonzalezparejasi gen. et sp. nov. from the Upper Cretaceous of Mendoza Province, Argentina. With a powerfully-constructed humerus 1.76 m in length, Notocolossus is one of the largest known dinosaurs. Furthermore, the complete pes of the new taxon exhibits a strikingly compact, homogeneous metatarsus—seemingly adapted for bearing extraordinary weight—and truncated unguals, morphologies that are otherwise unknown in Sauropoda. The pes underwent a near-progressive reduction in the number of phalanges along the line to derived titanosaurs, eventually resulting in the reduced hind foot of these sauropods.
Dinosauria Owen, 1842
Saurischia Seeley, 1887
Sauropoda Marsh, 1878
Titanosauriformes Salgado, Coria, and Calvo, 1997
Somphospondyli Wilson and Sereno, 1998
Titanosauria Bonaparte and Coria, 1993
Lithostrotia Upchurch, Barrett, and Dodson, 2004
Notocolossus gonzalezparejasi gen. et sp. nov.
Etymology: From the Greek notos (southern) and the Latin colossus, in reference to the gigantic size and Gondwanan provenance of the new taxon. Species name honours Dr. Jorge González Parejas, who has collaborated and provided legal guidance on the research, protection, and preservation of dinosaur fossils from Mendoza Province for nearly two decades. In so doing, he has advised researchers on the creation of a natural park that serves to protect dinosaur footprints in Mendoza.
Holotype: UNCUYO-LD 301, an associated partial skeleton of a very large individual consisting of an anterior dorsal vertebra, an anterior caudal vertebra, the right humerus, and the proximal end of the left pubis (Figs 1b, 2a–e, 3a,c,e,g and 4a–c; Supplementary Figs S1, S3). We consider these elements to represent a single titanosaurian individual because they were found within an area of 8 m by 8 m at the same stratigraphic level and are of the appropriate size and morphology to have been derived from a single skeleton.
Type locality and horizon: Cerro Guillermo, Malargüe Department, southern-most Mendoza Province, Argentina (Fig. 1a; coordinates on file at UNCUYO-LD). The holotype and referred specimen were collected 403 m apart in the basal-most bed of the Upper Cretaceous (upper Coniacian–lower Santonian, ~86 Ma) Plottier Formation of the Neuquén Group (see Supplementary Information for details).
|Figure 1: Geographic provenance and speculative reconstruction of the gigantic titanosaurian sauropod dinosaur Notocolossus gonzalezparejasi gen. et sp. nov.|
(a) Type locality of Notocolossus (indicated by star) in southern-most Mendoza Province, Argentina. (b) Reconstructed skeleton and body silhouette in right lateral view, with preserved elements of the holotype (UNCUYO-LD 301) in light green and those of the referred specimen (UNCUYO-LD 302) in orange. Scale bar, 1 m.
(All images were hand drawn by the senior author [B.J.G.R.] and subsequently edited using Adobe Illustrator software.) DOI: 10.1038/srep19165
Bernardo J. González Riga, Matthew C. Lamanna, Leonardo D. Ortiz David, Jorge O. Calvo and Juan P. Coria. 2016. A Gigantic New Dinosaur from Argentina and the Evolution of the Sauropod Hind Foot. Scientific Reports 6, Article number: 19165. DOI: 10.1038/srep19165