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Alberta, Canada Night Long and gorgeous ceratopsian Pentagon and the meaning of the dinosaur biogeography Campania period

The horned dinosaurs Pentaceratops and Kosmoceratops from the upper Campanian of Alberta and implications for dinosaur biogeography
NicholasR. Longrich
The upper Campanian of theAmerican Southwest has produced dinosaurs that are unknown from the northernGreat Plains and vice versa. This has led to the idea that North America'sCampanian dinosaur fauna was characterized by high levels of endemism anddistinct faunal provinces. Here, two horned dinosaurs known from the Southwest,Pentaceratops and Kosmoceratops, are described from southern Canada.Pentaceratops aquilonius sp. nov. is represented by two frill fragments fromthe uppermost Dinosaur Park Formation near Manyberries, southeast Alberta.Features shared with Pentaceratops include large, triangular epiparietals, anM-shaped parietal posterior bar, and an epiparietal P1 that curls up and twistslaterally. The Manyberries specimens differ from Pentaceratops sternbergii andUtahceratops gettyi in that the posterior bar is broader, emargination isweakly developed, and P1 is directed dorsally, rather than anteriorly.Phylogenetic analysis places P. aquilonius as sister to a clade comprising P.sternbergii and Utahceratops. Kosmoceratops is documented by a partial skullfrom Dinosaur Provincial Park. Previously referred to Chasmosaurus, the skull exhibitsderived features inconsistent with this referral, including a reduced septalflange, a caudally inclined narial strut, a triangular narial process, areduced frontal fontanelle, a weakly hooked rostral, and a narrow, caudallyinclined internal naris. Phylogenetic analysis recovers the animal as sister toKosmoceratops richardsoni, but differences in the shape of the naris and nasalhorn suggest that it likely represents a distinct species. The presence ofPentaceratops and Kosmoceratops in Canada argues against the idea of distinctnorthern and southern faunal provinces, but the fact that they differ fromtheir southern relatives confirms that endemism was high in the Campanian. Theability of dinosaur lineages to disperse long distances across North Americasuggests that dinosaur distribution was notconstrained by geographic barriers,climate, or flora. Instead, dinosaur endemism may result from competitiveexclusion of immigrants by established populations adapted to localenvironmental conditions.