Thursday, July 12, 2012

[Paleontology • 2010] Archaeoistiodactylus linglongtaensis • A new pterosaur (Pterosauria) from Middle Jurassic Tiaojishan Formation of western Liaoning, China

A new pterosaur Archaeoistiodactylus linglongtaensis gen. et sp. nov. is erected based on an incomplete skeleton with a partial skull and lower jaw. The new taxon is characterized by circular tooth sockets of anterior mandibular teeth,the anterior teeth of the upper jaw bearing posteriorly directed crowns,a relatively short metacarpus,and wing phalanges 2 and 3 and the tibia subequal in length. It possesses some plesiomorphic characters such as short metacarpals and circular tooth sockets. The pointed jaw tip present in the new taxon indicates that the expanded jaw tips of later istiodactylids are a derived character state,and the new taxon represents the first istiodactylus-like pterosaur found from the pre-Late Jurassic deposits,which provides a key role in our understanding the origin and evolution of the known istiodactylid pterosaurs. Archaeoistiodactylus is regarded as the ancestor form of the known istiodactylid pterosaur.

Key Words: Archaeoistiodactylus, Pterosauria, Middle Jurassic, Tiaojishan Formation, western Liaoning 

Archaeoistiodactylus linglongtaensis (Lu and Fucha 2010) was originally described as a Middle Jurassic ancestor of Istiodactylus. This specimen has not been tested due to its poor preservation, but the available data suggests a sister relationship with Austriadactylus cristatus (above) based on available evidence. The actual ancestors of Istiodactylus were found in Late Jurassic and Early Cretaceous sediments. The shape of the pelvis, sternal complex, metacarpus prepubis and various other sizes and proportions puts Archaeoistiodactylus near this clade.

Martill and Etches (2012) suggest that the holotype specimen might actually be a poorly preserved specimen of Darwinopterus.

LÜ Junchang & FUCHA Xiaohui. 2010. A new pterosaur (Pterosauria) from Middle Jurassic Tiaojishan Formation of western Liaoning, China. Global Geology (English Edition), 13(3/4)∶ 113-118.

David M. Martill and Steve Etches. 2012. A new monofenestratan pterosaur from the Kimmeridge Clay Formation (Upper Jurassic, Kimmeridgian) of Dorset, England. Acta Palaeontologica Polonica in press. DOI:10.4202/app.2011.0071.