First gnathosaurine (Pterosauria, Pterodactyloidea) from the Early Cretaceous of eastern Thailand

Abstract

Pterosaur fossils in the Mesozoic formation of Southeast Asia are very scarce. A few articles reported isolated teeth and a handful of postcranial elements in northeastern Thailand. Here we report on a pterosaur upper jaw from the Early Cretaceous at Phra Prong locality of eastern Thailand, which is considered the lateral equivalent of the Sao Khua Formation of the Khorat Group. This represents the first pterosaur cranial material in Thailand. It comprises a partial rostrum, preserving eleven tooth positions, and four associated tooth crowns. The anterior tip of the rostrum is dorsoventrally flattened and laterally expanded (spoon-shaped), indicating affinities to the Gnathosaurinae (Ctenochasmatidae). Alveoli borders are conspicuously scalloped and collar-like, and the palatal surface exhibits a pair of sinusoidal grooves. These features bear a strong resemblance to the Late Jurassic gnathosaurines Gnathosaurus subulatus, Tacuadactylus luciae, and Lusognathus almadrava. Our phylogenetic analysis indicates that the Thai pterosaur is closely related to these gnathosaurines. Still, the Thai gnathosaurine is unique in exhibiting a kite-shaped rostrum expansion and is recognized as a new taxon herein named Garudapterus buffetauti gen. et sp. nov. This new specimen provides essential information regarding pterosaurs, including updated data for a better understanding of their diversity and distribution throughout Southeast Asia.