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1 May 2016 Eurybelodon shoshanii, an Unusual New Shovel-Tusked Gomphothere (Mammalia, Proboscidea) from the Late Miocene of Oregon
W. David Lambert
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Unusual shovel-tusked gomphothere material from the late Clarendonian Black Butte Local Fauna (Juntura Formation, Oregon), including a lower tusk, partial upper tusk, and two mandibles including a second and a third molar, has been described and referred to Platybelodon. Platybelodon has the following diagnostic characteristics: molars strongly double-trefoiled; third molar with five lophs; lower tusks short with broad and very flat profiles lacking significant dorsoventral curvature; and lower tusks lacking obvious lamination but instead filled with small, short dentinal rods. However, the Black Butte shovel-tusked gomphothere was referred to Platybelodon despite having the following conflicting features: molars with weakly developed single trefoiling; third molar with only four lophids (the fourth little more than a talonid); broad, moderately flattened, relatively elongated lower tusk with strong dorsal curvature; and lower tusk internal structure showing lamination rather than dentinal rods. In addition, both the upper and lower tusks of the Black Butte shovel-tusker have prominently corrugated enamel cortices, a feature unknown in any other gomphothere. Thus, given the lack of a single clear-cut shared diagnostic feature and the large number of differences between these taxa, the identification of the Black Butte shovel-tusker as Platybelodon must be refuted. Refutation of the Platybelodon identification requires an alternate identification to be made for the Black Butte shovel-tusker. No other known shovel-tusker genus, including the genera Amebelodon, Serbelodon, and Torynobelodon, possesses the unusual combination of tusk and cheek tooth features observed in this animal. Accordingly, it is here referred to a new genus and species, Eurybelodon shoshanii.

© by the Society of Vertebrate Paleontology
W. David Lambert "Eurybelodon shoshanii, an Unusual New Shovel-Tusked Gomphothere (Mammalia, Proboscidea) from the Late Miocene of Oregon," Journal of Vertebrate Paleontology 36(3), (1 May 2016).
Received: 28 April 2015; Accepted: 1 September 2015; Published: 1 May 2016

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