A Probable Neoceratopsian Manus Track from the Nanushuk Formation (Albian, Northern Alaska)

We report a likely neoceratopsian manus track from an exposure of the Nanushuk Formation along the Colville River in northern Alaska. The track described here containts the impressions of five digits, arranged as an arc, which identify this specimen as a manus. Details of the impression suggest that...

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Bibliographic Details
Main Authors: Fiorillo, A. R., Decker, P. L., LePain, D. L., Wartes, M., McCarthy, P. J.
Format: Article in Journal/Newspaper
Language:Spanish
Published: Ediciones Complutense 2010
Subjects:
Online Access:https://revistas.ucm.es/index.php/JIGE/article/view/JIGE1010220165A
Description
Summary:We report a likely neoceratopsian manus track from an exposure of the Nanushuk Formation along the Colville River in northern Alaska. The track described here containts the impressions of five digits, arranged as an arc, which identify this specimen as a manus. Details of the impression suggest that it is neoceratopsian rather than ankylosaurian. The length of the chord of the arc of the track is approximately 25 cm, which is half the size of manus tracks found west of Denver, Colorado, USA attributed to the 10 m long Maastrichtian Triceratops. The Nanushuk Formation is a succession of complexly intertonguing marine and nonmarine strata interpreted as shelf, deltaic, strandplain, fluvial, and alluvial overbank deposits. Deposited in the foreland basin north f the Brooks Range, the rock unit is present throughout most of the northern foothills belt and subsurface of the central and western North Slope coastal plain. Fossil and radiometric data place outcrop within the Albian. If the identification of the track is correct, this is one of the earlies occurrences of neoceratopsians from North America. The occurrence of this track in Alaska substantiates the biogeographic model of faunal exchange between Asia and North America through a Cretaceous land bridge known as Beringia. Presentamos una probable huella de mano atribuida a neoceratopsido de un afloramiento de la Formación Nanushuk a lo largo del río Colville, en el norte de Alaska. La huella descrita contiene la impresión de cinco dígitos, dispuestos en arco, que identifican este especimen como una mano. Los detalles de la impresion sugieren que se trata de un neoceratopsido mas que de un ankilosaurio. La longitud de la cuerda del arco de la huella es aproximadamente de 25 cm, lo cual es la mitad del tamano de las huellas de mano encontradas al oeste de Denver, Colorado, EE.UU, y atribuidas a Triceratops, un taxon de unos 10 m de largo de edad Maastrichtiense. La Formacion Nanushuk es una sucesion de capas de origen marino y no marino complejamente interdigitadas e interpretadas como depósitos de plataforma, deltaicos de playas progradantes, fluviales y de overbank aluvial. Depositada en una cuenca de antepais al norte del Brooks Range, la unidad de roca esta presente a lo largo de la mayor parte de la franja septentrional de colinas, y en el subsuelo de la zona central y occidental, de la llanura costera de North Slope. Los fosiles y los datos radiometricos situan este afloramiento en el Albiense. Si la identificación de la huella es correcta, es una de las apariciones más tempranas de neoceratopsidos en Norteamaerica. La aparición de esta huella en Alaska apoya el modelo biogeográfico de intercambio faunístico entre Asia y Norteamerica a traves de un puente de tierra cretacico conocido como Beringia.