Osteology of Aerosteon riocoloradensis (Sereno et al. 2008) a large megaraptoran (Dinosauria: Theropoda) from the Upper Cretaceous of Argentina

ABSTRACT

Aerosteon riocoloradensis represents one of the most complete megaraptorans yet discovered. This theropod comes from Anacleto Formation (Campanian) of Mendoza Province, Argentina. The aims of this contribution are: to present a detailed, bone by bone description of this specimen with figures of each bone; provide comparisons to other closely related theropods; revise the original assignation and diagnosis of such taxa. Three bones were re-assigned and almost all the autapomorphies of Aerosteon were modified. Features in the vertebral columns, which are shared with other megaraptorans, show that these theropods shared features with basal coelurosaurs.

Anatomical Abbreviations

ACDL: Anterior centrodiapophyseal lamina; CDF: Centrodiapophyseal fossa; CPAL: Centroparapophyseal lamina; CPRL: Centroprezygapophyseal lamina; CPRF: Centroprezygapophyseal fossa; CPR-CDF: Centroprezygapophyseal-centrodiapophyseal fossa; Hye: Hyposphene; Hym: Hypantrum; ILT: Intervertebral ligament tuberosity; IPOL: Infrapostzygapophysela lamina; IZL: Intrazygapophyseal lamina; PADL: Paradiapophyseal lamina; PAD-CDF: Paradiapophyseal-centrodiapophsyeal fossa; PCDL: Posterior centrodiapophyseal lamina; POEL: Postzygaepipophysela lamina; PODL: Postzygadiapophyseal lamina; POSF: Postspinal fossa; POCDF: Postzygapophsyeal-centrodiapophyseal fossa; Poz: Postzygapophysis; PRDL: Prezygadiapophyseal lamina; PRPAF: Prezygaparapophyseal fossa; PRPAL: Prezygaparapophyseal lamina; PRSF: Prespinal fossa; PRSL: Prespinal lamina; PRD-CDF: Prezygadiapophyseal-centrodiapophyseal fossa; PRD-PADF: Prezygadiapophyseal-paradiapophyseal fossa; PRD-PODF: Prezygadiapophyseal-postzygadiapophyseal fossa; PRCDF: Prezygapophyseal-centrodiapophyseal fossa; Prz: Prezygapophyses; SDF: Supradiapophsyeal fossa; SDL: Supradiapophyseal lamina; SPOF: Spinopostzygapophyseal fossa; SPOL: Spinopostzygapophyseal lamina; SPRF: Spinoprezygapophyseal fossa; SPRL: Spinoprezygapophyseal lamina; SR(number): Sacral rib; STP(number): Sacral transverse process

KEYWORDS:

• Theropoda
• Megaraptora
• Patagonia
• Huincul formation
• Upper Cretaceous

Highlights

• The megaraptorid Aerosteon riocoloradensis is re-described and re-interpreted.

• This revision results in new autapomorphies for Aerosteon as well as new tentative characters within Megaraptora.

ACKNOWLEGMENTS

Thanks to all the team work of the Laboratorio de Anatomía Comparada y Evolución de los Vertebrados, especially to Federico Agnolin for helpful comments on the manuscript. AHM acknowledges financial support from ANPCyT FONCYT (PICT 0920-2015) for visiting the Museo de Ciencias Naturales y Antropológicas “Juan Cornelio Moyano”. FEN, AHM and AMAR thanks to Clara abal, Guillermo Campos and Edgardo Aranguez for allowing the study of material under his care. Thanks to the Editor of Historical Biology and two rewievers (Peter Makovicky and one anonymous rewiever) for improve this manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).