FIRST GIANT PTEROSAUR FROM THE LATE CRETACEOUS OF SOUTH AMERICA

AGNOLIN, F. L.; NOVAS, F. E.; KUNDRAT, M.; EZCURRA, M. D.; ISASI, M. P.; AHLBERG, P. E.

San Juan

Congreso; IV Congreso Latinoamericano de Paleontologia de Verterbados; 2011

Universidad Nacional de San Juan

South America has yielded abundant and diverse pterosaur remains from Early and early Late Cretaceous ages from Brazil and Argentina (Codorniú and Gasparini, 2007). In contrast, the Late Cretaceous bone record of South American pterosaurs is still scarce and restricted to a handful of fragmentary specimens. We present here a partial dentary symphysis belonging to a large-sized azhdarchid pteranodontoid collected from levels of the Maastrichtian Allen Formation, from a fossil site located 90 km SE from General Roca, Río Negro Province, Argentina. Other fossils collected from the same horizon and locality include indeterminate fishes (isolated vertebrae, scales), fragmentary turtle shells, and plesiosaur remains. The preserved length of the dentary is 264 mm. It is elongated, transversely compressed, and toothless. Its external surface is longitudinally striated and highly vascularized by numerous small pits. The internal microstructure is composed of cancellous bone, as typically occurs in pterosaurs. As in most pterosaurs the bone cortex is very thin, being approximately 0.3 to 1.0 cm in thickness. A curious character is conformed by the high number (6 or more) of large slit-like lateral neurovascular foramina along the symphysis, and by a deeply concave median groove at the bottom of the dentary symphysis. The dentary is referred as to the Azhdarchidae (Nessov, 1984), a group of pterosaurs particularly abundant and diverse worldwide during latest Cretaceous times (Company et al., 1999; Butler et al., 2009). This clade comprises several species of long?necked pterosaurs ranging from 2.5 to 12 meters in wing span, thus including the largest known flying vertebrates, such as the gigantic Quetzalcoatlus and Hatzegopteryx (Kellner and Langston, 1996; Buffetaut et al., 2002). The specimen here reported represents the first unambiguous evidence of a South American azhdarchid pterosaur, and represents the largest known pterosaurian recorded on this continent.