Comments on the cervical vertebrae of the Tapejaridae (Pterosauria, Pterodactyloidea) with description of new specimens

Abstract

The cervical series is poorly known in several pterosaur clades despite the fact that distinct morphotypes of individual elements have been recognised. Among the least known is the neck of the Tapejaridae that until recently has received little attention. In order to provide further data on the tapejarid cervical anatomy, we describe three specimens from the Romualdo Formation (Lower Cretaceous, Brazil): AMNH 22568 comprises the last five cervical elements of a large individual, AMNH 24445 and MN 4728-V, both including three meso-cervical elements of small individuals. Despite size differences, AMNH 22568 and MN 4728-V are anatomically more similar to each another, showing a pattern of high, laterally flattened (blade-like) neural spines, short centra pierced by two lateral pneumatic foramina. AMNH 24445 presents a distinct anatomy, with low (but still evident) neural spines, more elongated centra with concave ventral surface, and only one lateral pneumatic foramen. Based on comparative studies we refer AMNH 22568 and MN 4728-V to the Thalassodrominae and AMNH 24445 to the Tapejarinae, helping to differentiate the cervical elements of these clades. Thalassodrominae cervical vertebrae can be distinguished by the presence of two lateral pneumatic foramina, a broad centrum (length/width ratio lower than two), and a flat ventral surface. Tapejarinae cervical vertebrae show only one lateral pneumatic foramen, the length/width ratio higher than two, and a concave ventral surface. Thalassodromine and tapejarine cervical vertebrae differ from those of azhdarchids in the presence of lateral pneumatic foramens, developed neural spine, and length/width ratio lower than three, and by being comparatively shorter.