­Postcranial skeletal anatomy of the holotype and referred specimens of Buitreraptor gonzalezorum Makovicky, Apesteguía and Agnolín 2005 (Theropoda, Dromaeosauridae), from the Late Cretaceous of Patagonia

Federico A Gianechini; Peter J Makovicky; Sebastián Apesteguía; Ignacio Cerda

doi:10.7287/peerj.preprints.26450v1

Postcranial skeletal anatomy of the holotype and referred specimens of Buitreraptor gonzalezorum Makovicky, Apesteguía and Agnolín 2005 (Theropoda, Dromaeosauridae), from the Late Cretaceous of Patagonia

Federico A Gianechini ¹, Peter J Makovicky², Sebastián Apesteguía³, Ignacio Cerda⁴

1 Instituto Multidisciplinario de Investigaciones Biológicas (IMIBIO-SL), CONICET-Universidad Nacional de San Luis., San Luis, Argentina

2 Field Museum of Natural History, Chicago, Illinois, United States

3 CONICET. Fundación de Historia Natural ‘Félix de Azara’, CEBBAD, Universidad Maimónides., Buenos Aires, Argentina

4 CONICET. Instituto de Investigación en Paleobiología y Geología, Universidad Nacional de Río Negro, General Roca, Río Negro, Argentina

DOI: 10.7287/peerj.preprints.26450v1

Published: 2018-01-22
Accepted: 2018-01-22

Subject Areas: Paleontology, Taxonomy, Histology
Keywords: Patagonia, Late Cretaceous, Paraves, Dromaeosauridae, Unenlagiinae, Osteology, Paleohistology, Buitreraptor gonzalezorum

Copyright: © 2018 Gianechini et al.
Licence: This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.

Cite this article: Gianechini FA, Makovicky PJ, Apesteguía S, Cerda I. 2018. Postcranial skeletal anatomy of the holotype and referred specimens of Buitreraptor gonzalezorum Makovicky, Apesteguía and Agnolín 2005 (Theropoda, Dromaeosauridae), from the Late Cretaceous of Patagonia. PeerJ Preprints 6:e26450v1 https://doi.org/10.7287/peerj.preprints.26450v1

Abstract

Here we provide a detailed description of the postcranial skeleton of the holotype and referred specimens of Buitreraptor gonzalezorum. This taxon was recovered as a unenlagiine dromaeosaurid in several recent phylogenetic studies and is the best represented Gondwanan dromaeosaurid discovered to date. It was preliminarily described in a brief article, but a detailed account of its osteology is becoming known for recent work. Hitherto, the holotype is the most complete specimen found, so its exhaustive description provides much valuable anatomical information. The holotype and referred specimens preserve the axial skeleton, pectoral and pelvic girdles, and both fore- and hindlimbs. Diagnostic postcranial characters of this taxon include: anterior cervical centra exceeding the posterior limit of neural arch; antepenultimate and penultimate cervical vertebral centra with lateroventral tubercles; pneumatic foramina only in anteriormost dorsals; medial and distal caudal centra with a complex of ridges on lateral surfaces; pneumatic furcula with two pneumatic foramina on the ventral surface; scapular blade transversely expanded at mid-length; well-projected flexor process on distal humerus; dorsal rim of the ilium laterally everted; and concave dorsal rim of the postacetabular iliac blade. A paleohistological study of limb bones shows that the holotype represents a younger ontogenetic stage than one of the referred specimens (MPCA 238), which correlates with the fusion of the last sacral vertebra to the rest of the sacrum in MPCA 238. A revised phylogenetic analysis recovered Buitreraptor as a unenlagiine dromaeosaurid, in agreement with previous works. The phylogenetic implications of the unenlagiine synapomorphies and other characters, such as the specialized pedal digit II and the distal ginglymus on metatarsal II, are discussed within the evolutionary framework of Paraves.