En el reciente simposio "Sauropod dinosaurs: new insights into their biology, ecology, and evolution" que ha tenido lugar en el XVI Annual Meeting de la European Association of Vertebrate Paleontologists (EAVP) se presentó nueva información sobre los saurópodos del yacimiento de Gnatalie en una comunicación titulada "Diplodocines of the Gnatalie Quarry, a new bone-bed accumulation from Southern Utah (Morrison Fm., USA)". Esta pequeña presentación se ha centrado en el importante registro de saurópodos diplodócidos hallado en el yacimiento de Gnatalie, que es parte de los trabajos paleontológicos del Natural History Museum of Los Angeles County desde el año de 2007, y cuenta con la participación del Grupo de Biología Evolutiva de la UNED desde su descubrimiento.
El resumen es el siguiente:
A new Morrison bone-bed (Brushy Basin Member) from San Juan County yields abundant remains of sauropods as well as more fragmentary fossils of theropods, ornithopods, and thyreophorans. The ‘Gnatalie quarry’ (locality LACM 7683; Natural History Museum of Los Angeles County) contains the remains of at least two sauropod clades: Diplodocinae and Macronaria. Previous works have suggested for the presence of two diplodocine taxa. This fossil-site has produced several partially complete diplodocine individuals in articulation or in association, and many isolated sauropod bones. Five diplodocine sets that might correspond to three or four individuals are described and briefly discussed herein. The performed phylogenetic analyses place all these sets within the clade Barosaurus+Diplodocus, sharing the presence of a double posterior centroparapophyseal lamina on posterior dorsal vertebrae, straight ventral surface with projected chevrons facets in mid-caudal vertebrae, or high twisted humeral shaft (>40º). The presence of pneumatic foramina until the 16th caudal vertebra (and perhaps beyond), deep ventral hollow in anterior- and middle-caudal vertebrae, or hook-like ambiens process, all support the inclusion of these specimens within Diplodocus. The recovered phylogenetic hypothesis and the detailed comparative analyses support a close relationship of the Gnatalie diplodocines with Diplodocus hallorum. However, the most complete specimen presents an exclusive combination of characters, with some possible reversals to the plesiomorphic condition in Galeamopus+derived diplodocines. For the moment, the Gnatalie assemblage appears to comprise only one diplodocine form, corresponding to the most southwestern occurrence of Diplodocus in the Morrison Formation, west to the paleo-Lake T’oo’dichi’.
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