FIRST PTEROSAUR POST-CRANIAL REMAINS FROM THE LOWER CRETACEOUS LOHAN CURA FORMATION (ALBIAN) OF PATAGONIA, ARGENTINA

BELLARDINI, FLAVIO; CODORNIÚ, LAURA

AMEGHINIANA

ASOCIACION PALEONTOLOGICA ARGENTINA

Lugar: Buenos Aires; Año: 2019 vol. 56

0002-7014

. In this contribution, we present the first pterosaur post-cranial bone from the Lohan Cura Formation (Albian) of the Cerro de los Leones locality (Picún Leufú, Neuquén Province). The bone (MCF-PVPH-881) is an incomplete left ulna, preserved in three dimensions, and composed of the proximal epiphysis and part of the diaphysis. The element shares several affinities with derived pterodactyloid pterosaurs, such as a diaphysis with a sub-oval cross-section, thin bone walls, pneumatic foramina in the dorsal surface of the proximal epiphysis and between the cotyles, and wingspan reconstruction appropriate for a medium-size specimen. An analysis of the microstructure allowed us to evaluate the ontogenetic stage of the specimen. The thin-section from the mid-shaft shows a wide and sub-circular medullary cavity, encircled by a thin cortical bone ring. In the innermost cortex, secondary lamellar bone forms a distinct and avascular endosteal layer, while the cortical layer is dominated by a well-vascularized primary bone with coarse parallel fibers, as in other pterodactyloids. The presence of an avascular endosteal lamellar layer, an unremodeled cortical layer dominated by parallel-fibered bone, and a well ossified proximal epiphysis suggests that the specimen was in an advanced juvenile or sub-adult active-growth ontogenetic stage at the time of death. Considering the limited pterosaurian fossil record of Argentina, the new pterosaur specimen not only contributes to the reconstruction of the paleoecosystem of the Lohan Cura Formation in the central Neuquén Basin, but it also improves our knowledge of the taxonomic pterosaurs diversity during the Lower Cretaceous of Patagonia.