A revision of the pterodactyloid pterosaur Herbstosaurus pigmaeus Casamiquela, 1975 from the Late Jurassic of Argentina.

Abstract

Herbstosaurus pigmaeus Casamiquela, 1975 is a Late Jurassic pterosaur from northwestern Patagonia. It is based on the natural moulds and a few bony patches of the sacrum, prepubis, ilium, and both femora of a small-sized specimen. The phylogenetic relationships of this species have been a matter of debate, having been originally interpreted as a theropod dinosaur and subsequently as a pterosaur, either as an indeterminate pterodactyloid or a probable dsungaripteroid. However, a detailed and updated reassessment of its anatomy was still lacking. Here, we redescribe and compare the holotype and only known specimen of Herbstosaurus pigmaeus. We agree with previous authors in that the specimen is diagnostic to the species level and provide an emended diagnosis, including two autapomorphies. Quantitative phylogenetic analyses consistently find Herbstosaurus pigmaeus as deeply nested within the Pterodactyloidea and as a member of the Dsungaripteroidea. The dsungaripteroid affinities of Herbstosaurus pigmaeus are weak, based solely on femoral character-states, but is the most parsimonious hypothesis with the evidence at hand. The recognition of Herbstosaurus pigmaeus as a deeply nested pterodactyloid expands the taxonomic diversity of the pterosaur record of southwestern Gondwana during the Late Jurassic.