RESEARCH ARTICLE Megalictis, the Bone-Crushing Giant Mustelid (Carnivora, Mustelidae, Oligobuninae) from the Early Miocene of North America Alberto Valenciano 1,2 , Jon A. Baskin 3 , Juan Abella 4,5 , Alejandro Pérez-Ramos 6 , M. Ángeles Álvarez-Sierra 1,2 , Jorge Morales 7 , Adam Hartstone-Rose 8,9 * 1 Departamento de Geología Sedimentaria y Cambio Medioambiental, Instituto de Geociencias (CSIC, UCM), Madrid, Spain, 2 Departamento de Paleontología UCM, Facultad de Ciencias Geológicas UCM, Madrid, Spain, 3 Department of Biological and Health Sciences, Texas A&M University-Kingsville, Kingsville, United States of America, 4 Universidad Estatal Península de Santa Elena, La Libertad, Santa Elena, Ecuador, 5 Institut Català de Paleontologia Miquel Crusafont, Universitat Autònoma de Barcelona, Edifici ICP, Campus de la UAB, Cerdanyola del Vallès, Barcelona, Spain, 6 Departamento de Ecología y Geología, Facultad de Ciencias, Universidad de Málaga, Málaga, Spain, 7 Departamento de Paleobiología. Museo Nacional de Ciencias Naturales-CSIC, Madrid, Spain, 8 Department of Cell Biology and Anatomy, University of South Carolina School of Medicine, Columbia, South Carolina, United States of America, 9 Department of Anthropology, University of South Carolina, Columbia, South Carolina, United States of America * AdamHR@sc.edu Abstract We describe cranial and mandibular remains of three undescribed individuals of the giant mustelid Megalictis ferox Matthew, 1907 from the latest Arikareean (Ar4), Early Miocene mammal fauna of Nebraska, and Wyoming (USA) housed at the American Museum of Natu- ral History (New York, USA). Our phylogenetic hypothesis indicates that Ar4 specimens assigned to M. ferox constitute a monophyletic group. We assign three additional species previously referred to Paroligobunis to Megalictis: M. simplicidens, M. frazieri, and “M.” petersoni. The node containing these four species of Megalictis and Oligobunis forms the Oligobuninae. We test the hypothesis that Oligobuninae (Megalictis and Oligobunis) is a stem mustelid taxon. Our results indicate that the Oligobuninae form the sister clade to the crown extant mustelids. Based on the cranium, M. ferox is a jaguar-size mustelid and the largest terrestrial mustelid known to have existed. This new material also sheds light on a new ecomorphological interpretation of M. ferox as a bone-crushing durophage (similar to hyenas), rather than a cat-like hypercarnivore, as had been previously described. The rela- tive large size of M. ferox, together with a stout rostrum and mandible made it one of the more powerful predators of the Early Miocene of the Great Plains of North America. Introduction Megalictis ferox Matthew, 1907 [1] is a giant mustelid of the subfamily Oligobuninae and belongs to the paraphyletic group of “paleomustelids” [2]. It lived in the Early Miocene during the late Arikareean Ar4 North American Land Mammal Age 22.7–18.5 mya [3, 4] of the central PLOS ONE | DOI:10.1371/journal.pone.0152430 April 7, 2016 1 / 26 OPEN ACCESS Citation: Valenciano A, Baskin JA, Abella J, Pérez- Ramos A, Álvarez-Sierra MÁ, Morales J, et al. (2016) Megalictis, the Bone-Crushing Giant Mustelid (Carnivora, Mustelidae, Oligobuninae) from the Early Miocene of North America. PLoS ONE 11(4): e0152430. doi:10.1371/journal.pone.0152430 Editor: Brian Lee Beatty, New York Institute of Technology College of Osteopathic Medicine, UNITED STATES Received: September 8, 2015 Accepted: March 14, 2016 Published: April 7, 2016 Copyright: © 2016 Valenciano et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: All relevant data are within the paper and its Supporting Information files. Funding: A.V. has received funding from the European Union’s Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 226506 (SYNTHESYS; SE-TAF-3637), the USC School of Medicine (Columbia, South Carolina, USA), the AMNH (Collection Study Grant Program 2014) and the International Travel Grant 2015 from the Vertebrate Paleontology department of FLMNH from UF. A.V. is researcher in formation in the CSIC