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 fromnorthwestern 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 beenoriginally interpreted as a theropod dinosaur and subsequently as a pterosaur, eitheras an indeterminate pterodactyloid or a probable dsungaripteroid. However, a detailedand updated reassessment of its anatomy was still lacking. Here, we redescribe andcompare the holotype and only known specimen of Herbstosaurus pigmaeus. We agreewith previous authors in that the specimen is diagnostic to the species level and providean emended diagnosis, including two autapomorphies. Quantitative phylogeneticanalyses consistently find Herbstosaurus pigmaeus as deeply nested within thePterodactyloidea and as a member of the Dsungaripteroidea. The dsungaripteroidaffinities of Herbstosaurus pigmaeus are weak, based solely on femoral character-states,but is the most parsimonious hypothesis with the evidence at hand. The recognitionof Herbstosaurus pigmaeus as a deeply nested pterodactyloid expands the taxonomicdiversity of the pterosaur record of southwestern Gondwana during the Late Jurassic.