By P.J. Currie, W. Langston, D.H. Tanke
Within the first monographic remedy of a horned (ceratopsid) dinosaur in virtually a century, this enormous quantity offers one of many closest appears to be like on the anatomy, relationships, progress and edition, habit, ecology and different organic features of a unmarried dinosaur species. The examine, which was once carried out over twenty years, was once attainable due to the discovery of a densely packed bone mattress close to Grande Prairie, Alberta. The locality has produced plentiful continues to be of a brand new species of horned dinosaur (ceratopsian), and elements of at the least 27 person animals have been recovered. This new species of Pachyrhinosaurus is heavily relating to Pachyrhinosaurus canadensis, that is identified from more youthful rocks close to Drumheller and Lethbridge in southern Alberta, yet is a smaller animal with many modifications within the decorative spikes and bumps at the cranium. The adults of either species have sizeable bosses of bone within the positions the place different horned dinosaurs (like Centrosaurus and Triceratops) have horns. although, juveniles of the hot species resemble juveniles of Centrosaurus in having horns instead of bosses. cranium anatomy undergoes awesome alterations in the course of development and the horns over the nostril and eyes of the Pachyrhinosaurus juveniles remodel into bosses; spikes and horns advance at the most sensible of and in the back of the frill that extends again over the neck. No reason has been made up our minds for the obvious catastrophic dying of the herd of Pachyrhinosaurus from the Grande Prairie sector, however it has been urged that such herds can have been migratory animals. as well as the most descriptive paper, the quantity contains info at the distribution of bones in the bone mattress itself, and a state of the art electronic remedy of CT-scan information of the fossils to bare the anatomy of the animal's mind.
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Extra info for A New Horned Dinosaur From an Upper Cretaceous Bone Bed in Alberta
In well-developed examples, the rostra I comb comprises two or three massive anteriorly directed hook-like projections that are arranged in tandem on the narial bridge. Such projections do not occur in any other ceratopsian, including P. canadensis, where the anterior edge of the nasal is smoothly rounded (Figs. 9A, 9C). The lowest two projections arise from the premaxillae; the third, uppermost projection is formed by the blunt thickened ends of the nasal bones, which clasp the dorsal processes of the fused premaxillae between them.
Canadensis clearly within the Centrosaurinae (Langston 1967). On the medial side of the premaxilla is a single modest transverse shelf of bone. This shelf, which is in contact with and is anchored to the anteriorly directed processes of the maxilla, is homologous with a pair of shelves (one anteroventral to the other) that occur in all other centrosaurines (Sampson 1995). There are substantial differences in the direction and inclination of the premaxillary-rostral margin, which can be straighter and less complicated in some examples than in others.
There is some indication that the suture may be partially closed sometimes. However, because the prefrontals and frontals do not take part in the formation of the boss in P. lakustai, the structure is referred to as the nasal boss (as opposed to a A New Horned Dinosaur From an Upper Cretaceous Bone Bed in Alberta • 27 nasofrontal boss) in this paper. Langston (1975) inferred the possible presence of frontal or prefrontal involvement in the boss of P. canadensis by the presence of a low, sagittal ridge at the back of the boss.
A New Horned Dinosaur From an Upper Cretaceous Bone Bed in Alberta by P.J. Currie, W. Langston, D.H. Tanke