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Craniodental morphology and diet of Leptarctus oregonensis (Mammalia, Carnivora, Mustelidae) from the Mascall Formation (Miocene) of central Oregon

  • Jonathan J. Calede (a1), Winifred A. Kehl (a2) and Edward B. Davis (a3)


The Leptarctinae are an enigmatic subfamily of mustelids present in North America and Eurasia during the Miocene (Arikareean to Hemphillian North American Land Mammal Ages). Their diet and ecology have been particularly controversial. Some workers have suggested they were similar to koalas, whereas others suggested they were crushing omnivores analogous to raccoons. Leptarctus oregonensis Stock, 1930, a poorly known leptarctine from the early Barstovian, is represented by fragmented cranial elements and isolated teeth from the Mascall Formation of Oregon, and some fairly complete but undescribed material from the Olcott Formation of western Nebraska. Herein, we describe the first well-preserved skull of L. oregonensis from the type formation. Based on this new specimen, we confirm that L. oregonensis is a distinct species from L. primus Leidy, 1856 and L. ancipidens White, 1941 that is characterized by a distinct morphology of its tympanic projections and first upper molars. We are also able to describe intraspecific variation within L. oregonensis coinciding with the geographic distribution of the specimens (Oregon and Nebraska). The most variable characters are concentrated in the morphology of the frontals and the upper fourth premolar. Additional specimens will be needed to settle the debate over sexual dimorphism in this species, but this new specimen suggests that Leptarctus oregonensis, despite being one of the smallest members of the Leptarctinae, was an animal-dominated omnivore with considerable crushing ability.


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*Current address: Department of Evolution, Ecology, and Organismal Biology, The Ohio State University at Marion, 1461 Mount Vernon Avenue, Marion, Ohio 43302-5628, USA 〈


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Antón, M., Salesa, M.J., Pastor, J.F., Sánchez, I.M., Fraile, S., and Morales, J., 2004, Implications of the mastoid anatomy of larger extant felids for the evolution and predatory behavior of sabretoothed cats (Mammalia, Carnivora, Felidae): Zoological Journal of the Linnean Society, v. 140, p. 207221.
Baskin, J.A., 1998, Mustelidae, in Janis, C.M., Scott, K.M., and Jacobs, L.L., eds., Evolution of Tertiary mammals of North America. Volume 1: Cambridge, Cambridge University Press, p. 152173.
Baskin, J.A., 2005, Carnivora from the late Miocene Love bone bed of Florida: Bulletin of the Florida Museum of Natural History, v. 45, p. 419440.
Bever, G.S., and Zakrzewski, R.J., 2009, A new species of the Miocene leptarctine Leptarctus (Carnivora: Mustelidae) from the early Hemphillian of Kansas, in Albright, L.B., III., ed., Papers on Geology, Vertebrate Paleontology, and Biostratigraphy in Honor of Michael O. Woodburne: Museum of Northern Arizona Bulletin, v. 65, p. 465481.
Bonesi, L., Chanin, P., and MacDonald, D.W., 2004, Competition between Eurasian otter Lutra lutra and American mink Mustela vison probed by niche shift: Oikos, v. 106, p. 1926.
Bowdich, T.E., 1821, An Analysis of the Natural Classifications of Mammalia for the Use of Students and Travelers: Paris, John Smith, 115 p.
Carbone, C., Mace, G.C., Roberts, S.C., and Macdonald, D.W., 1999, Energetic constraints on the diet of terrestrial carnivores: Nature, v. 402, p. 286288.
Cork, S.J., Hume, I.D., and Dawson, T.J., 1983, Digestion and metabolism of a natural foliar diet (Eucalyptus punctata) by an arboreal marsupial, the koala (Phascolarctos cineveus): Journal of Comparative Physiology B: Biochemical, Systematic, and Environmental Physiology, v. 153, p. 181190.
Cuvier, F.G., 1825, in Saint-Hilaire, E.G., and Cuvier, F.G., Histoire Naturelle des Mammifères: Paris, Muséum d’Histoire Naturelle, pt. 3, v. 5, 55 p.
Davis, D.D., 1964, The giant panda: a morphological study of evolutionary mechanisms: Fieldiana Zoology Memoirs, v. 3, p. 1339.
Desmarest, A.G., 1820, Mammalogie ou description des espèces de mammifères: Encyclopédie méthodique des mammifères: Paris, Veuve Agasse, 276 p.
Dobson, G.E., 1878, Catalogue of the Chiroptera in the collection of the British Museum: London, British Museum (Natural History), 567 p.
Downs, T., 1956, The Mascall fauna from the Miocene of Oregon: University of California Publications in Geological Sciences, v. 31, p. 199354.
Dumont, M., Wall, C.E., Botton-Divet, L., Goswami, A., Peigné, S., and Fabre, A.C., 2016, Do functional demands associated with locomotor habitat, diet, and activity pattern drive skull shape evolution in musteloid carnivorans?: Biological Journal of the Linnean Society, v. 117, p. 858878.
Endo, H., Taru, H., Yamamoto, M., Arishima, K., and Sasaki, M., 2003, Comparative morphology of the muscles of mastication in the giant panda and the Asiatic black bear: Annals of Anatomy, v. 185, p. 287292.
Figueirido, B., MacLeod, N., Krieger, J., De Renzi, M., Pérez-Claros, J. A., and Palmqvist, P., 2011, Constraints and adaptation in the evolution of carnivoran skull shape: Paleobiology, v. 37, p. 490518.
Fischer, G., 1817, Adversaria zoologica: Mémoires de la Société Impériale des Naturalistes de Moscou, v. 5, p. 357472.
Flynn, J.J., Finarelli, J.A., Zehr, S., Hsu, J., and Nedbal, M., 2005, Molecular phylogeny of the Carnivora (Mammalia): assessing the impact of increased sampling on resolving enigmatic relationships: Systematic Biology, v. 54, p. 317337.
Friscia, A.R., Van Valkenburgh, B., and Biknevicius, A.R., 2006, An ecomorphological analysis of extant small carnivorans: Journal of Zoology, v. 272, p. 82100.
Fritzell, E.K., and Haroldson, K.J., 1982, Urocyon cinereoargenteus : Mammalian species, v. 189, p. 18.
Gazin, C.L., 1936, A new mustelid carnivore from the Neogene beds of northwestern Nebraska: Journal of the Washington Academy of Sciences, v. 26, p. 199207.
Goldfuss, G.A., 1817, Lipurus cinereus, Schreber’s die Saugethiere, in Abbildungen nach der Natur, mit Beschreibungan: Fortgesetzt von A. Goldfuss.
Gompper, M.E., and Decker, D.M., 1998, Nasua nasua : Mammalian Species, v. 580, p. 19.
Goswami, A., Milne, N., and Wroe, S., 2011, Biting through constraints: cranial morphology, disparity and convergence across living and fossil carnivorous mammals: Proceedings of the Royal Society B, v. 278, p. 18311839.
Hall, E.R., 1926, The muscular anatomy of three mustelid mammals, Mephitis, Spilogale, and Martes : University of California Publications in Zoology, v. 30, p. 738.
Harrington, L.A., and Macdonald, D.W., 2008, Spatial and temporal relationships between invasive American mink and native European polecats in the southern United Kingdom: Journal of Mammalogy, v. 89, p. 9911000.
Hidaka, C., Matsumoto, M., Hiji, H., Ohsako, S., and Nishinakagawa, H., 1998, Morphology and morphometry of skulls of Raccoon Dogs, Nyctereutes procyonoides, and badgers, Meles meles : The Journal of Veterinary Medical Science, v. 60, p. 161167.
Hunter, J. P., and Jernvall, J., 1995, The hypocone as a key innovation in mammalian evolution: Proceedings of the National Academy of Sciences, v. 92, p. 1071810722.
Hwang, Y. T., and Larivière, S., 2003, Mydaus javanensis : Mammalian Species, v. 723, p. 13.
Kinlaw, A., 1995, Spilogale putorius : Mammalian Species, v. 511, p. 17.
Koler-Matznick, J., Lehr Brisbin, I. Jr., Feinstein, M., and Bulmer, S., 2003, An updated description of the New Guinea singing dog (Canis hallstromi, Troughton 1957): Journal of Zoology, London, v. 261, p. 109118.
Koler-Matznick, J., Yates, B.C., Bulmer, S., and Brisbin, I.L. Jr., 2007, The New Guinea singing dog: its status and scientific importance: Australian Mammalogy, v. 29, p. 4756.
Korth, W. W., and Baskin, J. A., 2009, A new species of Leptarctus (Carnivora, Mustelidae) from the Late Clarendonian (Late Miocene) of Kansas: Annals of Carnegie Museum, v. 78, p. 2944.
Larivière, S., and Pasitschniak-Arts, M., 1996, Vulpes vulpes : Mammalian species, v. 537, p. 111.
Lee, S., and Mill, P.J., 2004, Cranial variation in British mustelids: Journal of Morphology, v. 260, p. 5764.
Leidy, J., 1856, Notices of extinct Vertebrata discovered by Dr. F.V. Hayden, during the expedition to the Sioux country under the command of Lieut. G.K. Warren: Proceedings of the Academy of Natural Sciences of Philadelphia, v. 8, p. 311312.
Lichtenstein, H., 1830, Erläuterungen der Nachrichten des Francisco Hernandez von den Cierfüssigen Thieren Neuspaniens: Abhandlungen der Königlichen Akademie der Wissenschaften zu Berlin 1827, v. 1830, p. 89127.
Lim, J.-D., and Martin, L.D., 2000, A new primitive leptarctine (Mustelidae) from the North American Miocene: Neues Jahrbuch für Geologie und Paläontologie Monatshefte, v. 10, p. 632640.
Lim, J.-D., and Martin, L.D., 2001a, A new species of Leptarctus (Mustelidae) from the Miocene of Kansas, USA: Neues Jahrbuch für Geologie und Paläontologie Abhandlungen, v. 10, p. 633640.
Lim, J.-D., and Martin, L.D., 2001b, New evidence for plant-eating in a Miocene mustelid: Current Science, v. 81, p. 314317.
Lim, J.-D., and Martin, L.D., 2002, A new fossil mustelid from the Miocene of South Dakota, USA: Naturwissenschaften, v. 89, p. 270274.
Lim, J.-D., and Miao, D., 2000, New species of Leptarctus (Carnivora, Mustelidae) from the Miocene of Nebraska, USA: Vertebrata PalAsiatica, v. 38, p. 5257.
Lim, J.-D., Martin, L.D., and Wilson, R.W., 2001, A new species of Leptarctus (Carnivora, Mustelidae) from the late Miocene of Texas: Journal of Paleontology, v. 75, p. 10431046.
Linnaeus, C., 1758, Systema Naturae per Regna Tria Naturae: Secundum Classes, Ordines, Genera, Species, cum Characteribus, Differentiis, Synonymis, Locis, 10th ed.: Stockholm, Laurentius Salvius, 824 p.
Linnaeus, C., 1766, Systema Naturæ per Regna Tria Naturæ, Secundum Classes, Ordines, Genera, Species, cum Characteribus, Differentiis, Synonymis, Locis, Tomus I, Editio duodecima, reformata: Holmiæ, Salvius, 532 p.
Long, C.A., 1973, Taxidea taxus : Mammalian Species, v. 26, p. 14.
Lotze, J. H., and Anderson, S., 1979, Procyon lotor : Mammalian Species, v. 119, p. 18.
Maguire, K.C., 2013, Understanding the paleoecology and niche dynamics of mammals in the Mascall Fauna (Middle Miocene), Oregon [Ph.D. dissertation]: Berkeley, University of California, 128 p.
Matthew, W.D., 1924, Third contribution to the Snake Creek fauna: Bulletin of the American Museum of Natural History, v. 50, p. 59210.
McGarigal, K., 2015, Biostats: Published date: February 25, 2015.
Meers, M.B., 2002, Maximum bite force and prey size of Tyrannosaurus rex and their relationships to the inference of feeding behavior: Historical Biology, v. 16, p. 112.
Myslajek, R.W., Nowak, S., Rożen, A., and Jędrzejewska, B., 2013, Diet of the Eurasian badger (Meles meles) in the Western Carpathians and its implications for species conservation in Poland: Animal Biology, v. 63, p. 271284.
Nowak, R.M., 2005, Walker’s Carnivores of the World: Baltimore, Johns Hopkins University Press, 313 p.
Oksanen, J., Blanchet, F.G., Kindt, R., Legendre, P., Minchin, P.R., O’Hara, R.B., Simpson, G.L., Solymos, P., Stevens, M.H.H., and Wagner, H., 2015, Community ecology package: Published date: April 07, 2017.
Olsen, S.J., 1957, Leptarctines from the Florida Miocene (Carnivora, Mustelidae): American Museum Novitates, v. 1861, p. 17.
Olsen, S.J., 1958, The skull of Leptarctus ancipidens from the Florida Miocene: Florida Geological Survey, Contributions to Florida Vertebrate Paleontology, v. 2, p. 111.
Pallas, P.S., 1780, Spicilegia Zoologica, quibus novae imprimis et obcurae animalium species iconibus: Berolini, G.A. Lange, 1774–1780, Fas. , 14, p. 5.
Peigné, S., Salesa, M.J., Antóm, M., and Morales, J., 2005, Ailurid carnivoran mammal Simocyon from the late Miocene of Sapin and the systematics of the genus: Acta Palaeontologica Polonica, v. 50, p. 219238.
Perry, G.C., 1810, Arcana; or, the Museum of Natural History: London, G. Smeeton, unpaginated.
Popowics, T.E., 2003, Postcanine dental form in the Mustelidae and Viverridae (Carnivora: Mammalia): Journal of Morphology, v. 256, p. 322341.
R Development Core Team, 2015, R: A Language and Environment for Statistical Computing: Vienna, Austria, R Foundation for Statistical Computing.
Riley, M.A., 1985, An analysis of masticatory form and function in three mustelids (Martes americana, Lutra canadensis, Enhydra lutris): Journal of Mammalogy, v. 66, p. 519528.
Roberts, P.D., Somers, M.J., White, R.M., and Nel, J.A.K., 2007, Diet of the South African large-spotted genet Genetta tigrina (Carnivora, Viverridae) in a coastal dune forest: Acta Theriologica, v. 52, p. 4553.
Robles, J.M., Alba, D.M., Moyà-Solà, S., Casanovas-Vilar, I., Galindo, J., Rotgers, C., Almécija, S., and Carmona, R., 2010, New craniodental remains of Trocharion albanense Major, 1903 (Carnivora, Mustelidae), from the Vallès-Penedès Basin (Middle to Late Miocene, Barcelona, Spain): Journal of Vertebrate Paleontology, v. 30, p. 547562.
RStudio, 2015, RStudio: Integrated Development Environment for R: Boston, Massachusetts, USA.
Sato, J.J., Wolsan, M., Prevosti, F.J., D’Elía, G., Begg, C., Begg, K., Hosoda, T., Campbell, K.L., and Suzuki, H., 2012, Evolutionary and biogeographic history of weasel-like carnivorans (Musteloidea): Molecular Phylogenetics and Evolution, v. 63, p. 745757.
Schinz, H.R., 1821, Das Thierreich eingetheilt nach dem Bau der Thiere als Grundlage ihrer Naturgeschichte und der vergleichenden Anatomie von dem Herrn Ritter von Cuvier: Stuttgart, Germany, Erster Band, Saugethiere und Vogel, 894 p.
Schneider, C.A., Rasband, W.S., and Eliceiri, K.W., 2012, NIH Image to ImageJ: 25 years of image analysis: Nature Methods, v. 9, p. 671675.
Schreber, J.C.D., 1776, Die Säugthiere in Abbildungen nach der Natur, mit Beschreibungen: Erlangen, Wolfgang Walther, v. 3, 361.
Schreber, J.C.D., 1777, Die Säugthiere in Abbildungen nach der Natur, mit Beschreibungen: Erlangen, Wolfgang Walther, 1112 p.
Simpson, G.G., 1930, Tertiary land mammals of Florida: Bulletin of the American Museum of Natural History, v. 59, p. 149211.
Stock, C., 1930, Carnivora new to the Mascall Miocene fauna of eastern Oregon: Carnegie Institution of Washington Publication, v. 404, p. 4348.
Storr, G.C.C., 1780, Prodromus methodi mammalium: Tübingen, Reissian, 43 p.
Tedford, R.H., Albright, L.B. III, Barnosky, A.D., Ferrusquia-Villafranca, I., Hunt, R.M. Jr., Storer, J.E., Swisher, C.C. III, Voorhies, M.F., Webb, S.D., and Whistler, D.P., 2004, Mammalian biochronology of the Arikareean through Hemphillian interval (Late Oligocene through Early Pliocene Epochs), in Woodburne, M.O., ed., Late Cretaceous and Cenozoic Mammals of North America: Biostratigraphy and Geochronology: New York, New York, Columbia University Press, p. 169231.
Thomason, J.J., 1991, Cranial strength in relation to estimated biting forces in some mammals: Canadian Journal of Zoology, v. 69, p. 23262333.
Turton, W., 1806, A General System of Nature, Through the Three Grand Kingdoms of Animals, Vegetables, and Minerals: London, Lackington and Allen, 943 p.
Valenciano, A., Abella, J., Sanisidro, O., Hartstone-Rose, A., Álvarez-Sierra, M.A., and Morales, J., 2015, Complete description of the skull and mandible of the giant mustelid Eomellivora piveteaui Ozansoy, 1965 (Mammalia, Carnivora, Mustelidae), from Batallones (MN10), Late Miocene (Madrid, Spain): Journal of Vertebrate Paleontology, e934570.
Valenciano, A., Baskin, J.A., Abella, J., Pérez-Ramos, A., Álvarez-Sierra, M.A., Morales, J., and Hartstone-Rose, A., 2016, Megalictis, the bone-crushing giant mustelid (Carnivora, Mustelidae, Oligobuninae) from the Early Miocene of North America: PLoS ONE, v. 11, e0152430.
van Gelder, R.G., 1959, A taxonomic revision of the spotted skunks (genus Spilogale): Bulletin of the American Museum of Natural History, v. 117, p. 229392.
Van Valkenburgh, B., 1990, Skeletal and dental predictors of body mass in carnivores, in Damuth, J., and MacFadden, B.J., eds., Body Size in Mammalian Paleobiology: Estimation and Biological iImplications: Cambridge, Cambridge University Press, p. 181206.
Vizcaíno, S.F., De Iuliis, G., and Bargo, M.S., 1998, Skull shape, masticatory apparatus, and diet of Vassallia and Holmesina (Mammalia: Xenarthra: Pampatheriidae): when anatomy constrains destiny: Journal of Mammalian Evolution, v. 5, p. 291322.
Wade-Smith, J., and Verts, B.J., 1982, Mephitis mephitis : Mammalian Species, v. 173, p. 17.
Wang, X., Qiu, Z., and Opdyke, N., 2003, Litho-, bio-, and magnetostratigraphy and paleoenvironment of Tunggur Formation (Middle Miocene) in central Inner Mongolia, China: American Museum Novitates, v. 3411, p. 131.
Wang, W., Qiu., Z., and Wang, B., 2004, A new leptarctine (Carnivora: Mustelidae) from the early Miocene of the northern Tibetan Plateau: implications for the phylogeny and zoogeography of basal mustelids: Zoological Journal of the Linnean Society, v. 142, p. 405421.
White, T.E., 1941, Additions to the Miocene fauna of Florida: Proceedings of the New England Zoological Club, v. 18, p. 9198.
Wilson, G.P., Ekdale, E.G., Hoganson, J.W., Calede, J.J., and Vander Linden, A., 2016, A large carnivorous mammal from the Late Cretaceous and the North American origin of marsupials: Nature Communications, v. 7, 13734. doi: 10.1038/ncomms13734.
Wolsan, M., 1993, Phylogeny and classification of early European Mustelida (Mammalia: Carnivora): Acta Theriologica, v. 38, p. 345384.
Wroe, S., McHenry, C., and Thomason, J., 2005, Bite club: comparative bite force in big biting mamamls and the prediction of predatory behavior in fossil taxa: Proceedings of the Royal Society B, v. 272, p. 619625.
Yom-Tov, Y., Yom-Tov, S., and Baagøe, H., 2003, Increase of skull size in the red fox (Vulpes vulpes) and Eurasian badger (Meles meles) in Denmark during the twentieth century: an effect of improved diet?: Evolutionary Ecology Research, v. 5, p. 10371048.
Zhai, R.J., 1964, Leptarctus and other Carnivora form the Tung Gur Formation, Inner Mongolia: Vertebrata PalAsiatica, v. 8, p. 1830.

Craniodental morphology and diet of Leptarctus oregonensis (Mammalia, Carnivora, Mustelidae) from the Mascall Formation (Miocene) of central Oregon

  • Jonathan J. Calede (a1), Winifred A. Kehl (a2) and Edward B. Davis (a3)


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