Sunday, December 3, 2017

[Paleontology • 2017] Argentinadraco barrealensis • A New Azhdarchoid Pterosaur (Pterosauria, Pterodactyloidea) with An Unusual Lower Jaw from the Portezuelo Formation (Upper Cretaceous), Neuquén Group, Patagonia, Argentina


 Argentinadraco barrealensis
Kellner & Calvo, 2017


ABSTRACT

A new azhdarchoid pterosaur from the Upper Cretaceous of Patagonia is described. The material consists of an incomplete edentulous lower jaw that was collected from the upper portion of the Portezuelo Formation (Turonian-Early Coniacian) at the Futalognko site, northwest of Neuquén city, Argentina. The overall morphology of Argentinadraco barrealensis gen. et sp. nov. indicates that it belongs to the Azhdarchoidea and probable represents an azhdarchid species. The occlusal surface of the anterior portion is laterally compressed and shows blunt lateral margins with a medial sulcus that are followed by two well-developed mandibular ridges, which in turn are bordered laterally by a sulcus. The posterior end of the symphysis is deeper than in any other azhdarchoid. This unique construction of the lower jaw suggests the existence of an elaborate interlocking mechanism with the upper jaw. Furthermore, although speculative, it is advocated here that Argentinadraco barrealensis might have used the lower jaw to obtain its prey by cutting or ploughing through unconsolidated sediment in shallow waters, a feeding behavior not previously proposed for pterosaurs.

Key words: Pterosauria; Pterodactyloidea; Argentinadraco; Patagonia; feeding behavior; Cretaceous


SYSTEMATIC PALEONTOLOGY
Pterosauria Kaup, 1834
Pterodactyloidea Plieninger, 1901

Azhdarchoidea Nessov, 1984
?Azhdarchidae Nessov, 1984

Argentinadraco gen. nov.
Type species: Argentinadraco barrealensis gen. et sp. nov.

Etymology: From Argentina, the country where the specimen was found and draco, from the Latin meaning dragon.

Figure 2. Argentinadraco barrealensis n. gen, n. sp., lower jaw (MUCPv-1137).
 (a) right lateral view; (b) dorsal (occlusal) view. Abbreviations: dep, depression; dcr, dentary crest; manr, mandibular ramus; mat, matrix; rid, ridge; sul, sulcus; sym.ve, ventral segment of the symphysis; l, left; r, right. Scale bar equals 50 mm.

Argentinadraco barrealensis gen. et sp. nov.

Holotype: An almost complete lower jaw housed at Centro Paleontológico Lago Barreales (CePaLB), of the Universidad del Comahue (MUCPv-1137; Figs. 2, 3).

Etymology: After Lake Barreales, where the specimen was found.

Horizon, age and locality: Portezuelo Formation, Neuquén Subgroup, Neuquén Group, Late Cretaceous, Turonian-Coniacian (Leanza and Hugo 2001). The material comes from the Futalognko site, northern coast of the Lake Barreales, Neuquén Province, Patagonia, Argentina (Fig. 1).

Diagnosis: Argentinadraco barrealensis is an azhdarchoid that presents the following autapomorphies: mandibular symphysis with marked concave ventral margin (lateral view); presence of two well-developed mandibular ridges on the dorsal surface of the posterior end of the mandibular symphysis; and a lateral sulcus on each side of the ridges. It can further be distinguished from all other azhdarchoids by possessing a small dentary sagittal crest.



Alexander W. A. Kellner and Jorge O. Calvo. 2017. New Azhdarchoid Pterosaur (Pterosauria, Pterodactyloidea) with An Unusual Lower Jaw from the Portezuelo Formation (Upper Cretaceous), Neuquén Group, Patagonia, Argentina. Anais da Academia Brasileira de Ciências. DOI: 10.1590/0001-3765201720170478

Argentinodraco barrealensis, a New pterosaur from Argentina. It lived at Proyecto Dino, Neuquén with Futalognkosaurus, Megaraptor,Unenlagia.

  


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