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Abstract
Despite that the origin of rebbachisaurids is retrieved as Late Jurassic is not until the upper Lower Cretaceous that this group can be recognised in the fossil record. The group is geographically restricted to Gondwana and Europe, and is particularly diverse in the lower Upper Cretaceous of South America. In this subcontinent, Early Cretaceous forms are solely represented by Amazonsaurus and Zapalasaurus, being the former the putative basalmost rebbachisaurid known. Here, we provide a revised description of the sauropod from the Lohan Cura Formation (Aptian–Albian) that was previously identified as Limaysaurus sp. The new information available (mainly based on new elements) allows us to recognise a new taxon, Comahuesaurus windhauseni gen. et sp. nov. The phylogenetic analysis carried out retrieved this taxon as a relatively basal form of rebbachisaurid, well separated from Limaysaurinae. In this phylogenetic context, the new taxon revealed the presence of a reduced hyposphene–hypantrum system in rebbachisaurids more derived than Histriasaurus, which is completely lost only in Limaysaurinae. Finally, a biogeographical scenario for rebbachisaurids is analysed through the use of a Dispersal, Extinction and Cladogenesis analysis, which retrieves a South American origin for this linage, and a fast dispersion to Africa and Europe during the Hauterivian–Barremian.
Acknowledgements
The materials of Comahuesaurus windhauseni were initially collected by J.F. Bonaparte, to whom we are especially grateful. P. Mannion and an anonymous reviewer improved the manuscript with constructive comments. Travel finance to carry out this work was provided by FoncyT PICT 2006-1756 (to D. Pol); Deutsche Forschungsgemeinschaft (DFG), (Project RE 2874/1-1); Jurassic Foundation (to J.L. Carballido and D. Pol); Project 02/BTE, CGL2010-16447 (J.I. Canudo), subsidised by the Ministry of Science and Innovation of Spain, the European Regional Development Fund, the Governments of Aragon (‘Grupos Consolidados’). Comparisons with relevant material were possible thanks to the collection access provided by: P. Sereno (UC); R. Coria (MCF-PVPH); A. Kramarz (MACN); E. Ruigomez (MEF); J. Calvo and J. Porfiri (MUCPv); J. Powell (PVL); L. Giraldez (CHMO); B. González Riga (IANIGLA); I. Cerda (MCS); R. Royo Torres (MPZ, CPT, CL and CLH); O. Mateus (MIGM and ML); B. Pabst and S. Hans-Jakob (SMA); J. Nour-Eddine (CPSGM); M. Sander and N. Knötschketo (DFMMh); D. Schwarz-Wings and F. Witzmann (HMN); J. Ove R. Ebbestad (PMU); F. Torcida Fernández-Baldor (MPS-RV-II); B. Battail (MNHN); X. Xu (IVPP); G. Peng and S. Jiang (ZDM); C. Ito and M. Brett-Surman (USNM); W. F. Simpson (FMNH); M. Brett-Surman (CM); J. Canale and A. Haluza (MMCH). This paper is contribution number 122 of the DFG Research Unit 533 ‘Biology of the Sauropod Dinosaurs: The Evolution of Gigantism’.