A Late Triassic pterosaur from the Northern Calcareous Alps (Tyrol, Austria)

Abstract Disarticulated skeletal remains of an eudimorphodontid pterosaur from the Late Triassic of the Karwendel Mountains in Tyrol, Austria, are described and figured. It is the second record of Triassic pterosaurs from the Northern Calcareous Alps, after previous discoveries in the Southern Calcareous Alps of northern Italy. The fossil material — isolated jaws, bones and fragmentary skeletal parts of one individual — was collected from the Norian Seefeld Beds (also called ‘Bitumenmergel’ or ‘Seefelder Fischschiefer’) near Seefeld in Tyrol. The fossiliferous formation of largely bituminous and calcareous layers originated on top of an extended marine carbonate platform, an equivalent to the nearly contemporaneous limestones and dolomites in the Southern Calcareous Alps, as exposed in Lombardy and Friuli in Italy, that has produced pterosaur fossils since 1973. Based on the biostratigraphic significance of conodont index fossils, the Seefeld Beds can be dated as Late Norian, most likely Sevatian. Sufficiently well-preserved skeletal elements include a jugal, isolated teeth, both mandibular rami with a dentition of uni-, tri- and pentacuspid teeth, cervical, dorsal and caudal vertebrae, ribs, sternum, scapulocoracoids, humerus, first wing phalanx, pelvis and tibia/fibula. There are morphological characters that support a subadult stage of the individual with an estimated wing span of 70–80 cm. The dentition is comparable to Eudimorphodon ranzii Zambelli from the Norian Calcare di Zorzino of Cene near Bergamo, northern Italy. However, some skeletal proportions and osteological features are distinctive from this taxon, as well as from a second species, Eudimorphodon rosenfeldi Dalla Vecchia from the Norian Dolomia di Forni of Friuli, northern Italy. The meaning of these differences in the Seefeld specimen, in particular the relatively long tibia and short wing phalanx 1, is discussed. The caudal zygapophyses and haemal arches are not elongated into the rod-like bony extensions significant for other known rhamphorhynchoid pterosaurs. It appears, however, that all speciments of Eudimorphodon lack elongated caudal zygapophyses. This might be evaluated as a primitive trait for these basal pterosaurs. The typical dentition permits the assignment of the Seefeld pterosaur to the genus Eudimorphodon. The fragmentary state of the skeleton and somewhat different skeletal proportions allow the author only to refer the specimen to Eudimorphodon cf. ranzii Zambelli 1973.