Vertebral pneumatic structures in the Early Cretaceous sauropod dinosaur Pilmatueia faundezi from northwestern Patagonia, Argentina

One of the diagnostic characters of dicraeosaurid sauropods is a reduction of pneumatization of dorsal and caudal vertebrae relative to their Flagellicaudata sister taxon, Diplodocidae. Here, we analyse pneumatic structures in the dicraeosaurid sauropod Pilmatueia faundezi, compare them to those of diplodocoids and report the first record of camerate chambers in a dicraeosaurid. The pneumatic structures are in a posterior cervical centrum (MLL-Pv-002) and consist of lateral pneumatic fossae on the centrum that communicate internally with large camerae. By contrast, Pilmatueia's dorsal and caudal vertebrae (MLL-Pv-005-016) lack pneumatic fossae on the centra, which is consistent with the previously reported reduced pneumaticity in dicraeosaurids. Nevertheless, the base of the neural arch and possibly the base of the bifid neural spines of a posterior dorsal vertebra (MLL-Pv-005) show pneumatic internal chambers. The pneumatic features of the Pilmatueia cervical centrum and dorsal neural arch we describe indicate that the degree of pneumatization is variable within dicraeosaurids.Fil: Windholz, Guillermo Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación en Paleobiología y Geología; Argentina. Provincia del Neuquén. Municipalidad de Plaza Huincul. Museo "Carmen Funes"; ArgentinaFil: Coria, Rodolfo Anibal. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación en Paleobiología y Geología; Argentina. Provincia del Neuquén. Municipalidad de Plaza Huincul. Museo "Carmen Funes"; ArgentinaFil: Zurriaguz, Virginia Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación en Paleobiología y Geología; Argentina. Universidad Nacional de Río Negro. Sede Alto Valle; Argentin

A reevaluation of the hyoid bones of protoceratops andrewsi granger and gregory, 1923 (ornithischia: Ceratopsia) and a review of hyoid elements in ornithischian dinosaurs

We present a reinterpretation of the bones previously identified as ossified hyoid elements in the Asian Late Cretaceous ceratopsian dinosaur Protoceratops andrewsi Granger and Gregory, 1923. Comparisons with other ceratopsian skeletons indicate that the tetraradiate bone tentatively regarded as a first ceratobranchial is actually an incomplete middle cervical rib, and the larger, flattened elements identified as second ceratobranchials are partial sternal plates. As in nearly all other ornithischian dinosaurs for which this area of the skeleton is known, the ossified hyoid apparatus of P. andrewsi probably consisted of a pair of rod-like first ceratobranchials; two additional, splint-like or sheet-like bones that are most frequently interpreted as ceratohyals may also have been present