New sauropod tracks from the Yacoraite Formation (Maastrichtian–Danian), Valle del Tonco tracksite, Salta, northwestern Argentina

• Autores: Díaz Martínez, Ignacio; de Valais, Silvina; Cónsole Gonella, Carlos Alfredo
• Año de publicación: 2017
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Ciencias Exactas y Naturales; Sauropod Trackway; Caliza Amblayo Member; Uppermost Cretaceous; South America; Ciencias Exactas y Naturales
• Institución: Universidad Nacional de Río Negro

Fil: Díaz Martínez, Ignacio. Universidad Nacional de Rio Negro. Instituto de Investigaciones en Paleobiologia y Geologia. Río Negro, Argentina.
Fil: de Valais, Silvina. Universidad Nacional de Rio Negro. Instituto de Investigaciones en Paleobiologia y Geologia. Río Negro, Argentina.
Fil: Cónsole Gonella, Carlos Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto Superior de Correlación Geológica. Grupo Vinculado al INSUGEO- Centro de Estudios Geológicos Andinos; Argentina.
Fil: Díaz Martínez, Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Buenos Aires, Argentina.
Fil: de Valais, Silvina. Consejo Nacional de Investigaciones Científicas y Técnicas. Buenos Aires, Argentina.
Purpose A relative long sauropod trackway and hundreds of varied indeterminate dinosaur tracks, many of them probably related to ornitischians, were found many years ago in the Valle del Tonco tracksite (Salta, northwestern Argentina). This sauropod trackway is now described and analyzed in an updated context.Methods Ichnological analyses were mainly conducted during fieldwork. Fossiliferous surface was mapped and digitalized in order to recognize the track shape and their distribution.Results The trackway-bearing surface belongs to an inverted section from the uppermost Cretaceous Caliza Amblayo Member, the lower unit of the Yacoraite Formation in this area. The sauropod trackway is moderate to poorly-preserved and includes twelve manus?pes imprint sets as convex hyporelief (natural casts). The heteropody is high and the PTR index indicates a medium category forthe trackway gauge. The pes tracks, longer than wide, have subtriangular posterior edge and a general rhomboidal shape, lacking a lateral notch, and the digit-claw traces are laterally located. The manus tracks are subrounded torectangular with at least two short, posteriorly oriented digit imprints.Conclusions Their main features and preservation/weathering do not allow a precise assignment to a particular ichnotaxon. Taking into account the best-preserved Campanian?Maastrichtian sauropod pes tracks, two differentgeneral shapes can be differentiated: the Campanian Humaca shape (Bolivia) and the Maastrichtian Fumanya shape (Spain). The Valle del Tonco pes prints show similarities with the Fumanya shape. The presence of two pes track shapes in this age suggests that at least two different titanosaur feet morphology were present in the uppermost Cretaceous.
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