Nasutoceratops — Wikipédia

Nasutoceratops titusi

Nasutoceratops is a kind of dinosaurs from the ceratopsidae family, which lived in the upper Cretaceous during the Upper Campanian, there are approximately 76.9 and 75.5 And (millions of years), on what was then the continent of Laramidia. Discovered in 2006 in Utah, in the western United States, the only known species, Nasutoceratops titusi , was described in 2013 by Scott D. Sampson (d) and his team ^{[ first ]} .

Silhouette of Nasutoceratops With the bones found in white.

Skull diagram Nasutoceratops .

The holotype skull measures approximately 1.50 meters long. The length of his body was estimated by G. S. Paul in 2016 at 4.50 meters and its weight at 1.50 tonnes ^{[ 2 ]} .

Nasutoceratops has several unique derivative traits or autapomorphies. The part of the muzzle around the nostril is strongly developed, representing about three -quarters of the length of the skull in front of the orbits. The back of each nasal bone is dug by a large internal cavity. The contact surface between the maxilla and the Praemaxilla is exceptionally large. The maxilla also has a large internal flange in contact with Praemaxilla via two horizontal facets. The horns of the eyebrows at their base are pointed out and outside, then bend inwards and finally twist up.

Nasutoceratops also shows a unique combination of lines which in themselves are not unique. The nose horn is low and narrow, with an elongated base. Squamosal has a high crest on its upper surface, ranging from the direction of the orbit of the eye to the edge of the squamosal. The skull steering wheel is more or less circular, its widest point being at the middle of the middle. The osteoderms on the edge in the collar, the epiparitals and the episquamosals, do not have the shape of points, but have the shape of simple low croissants. The side of the steering wheel at the rear is not pole, but has an epipaietal on the midline.

The muzzle of Nasutoceratops was short and high; Its nasal bones have internal cavities that the authors consider as pneumatic excavations, invading the bone of the nasal cavity. This should be noted because the pneumatic nostrils are unknown in any other ceratopsidé, which proves that this characteristic represents a unique derivative trait of this kind. Nasutoceratops had up to 29 teeth in the maxilla, each occupied by several stacked teeth. The skull roof between the orbits is vaulted and much higher than the muzzle. Paleontologist David Hone compared the arrangement of a horizontally curved horizontal projection with that of modern cattle. The horns cover about 40% of the total length of the skull, reaching almost the level of the end of the muzzle, and with a bone nucleus length up to 457 millimeters are the longest known to all the centrosaurine, in absolute and relative terms .

The epijugal tube (cheek horn) has a length of 85 millimeters, also the largest known among the centrosaurine. The cranial collar is moderately long and pierced on both sides of a large parietal fenestre in the shape of a kidney. In addition to the median epipaietal, there are seven epiparitals on each side and about four to five episquamosals. To anterior limbs, the Cubitus is exceptionally robust with an important olecranian process. Among the three patches with fingerprints of skin found near the left shoulder, one shows a motif of large hexagonal scales from eight to eleven thousand wide surrounded by smaller triangular scales.

Nasutoceratops Is known according to the UMNH VP 16800 Holotype, an almost partially associated skull, a coronoid process, a synced vertebra, three partial anterior dorsal vertebrae, a scapular belt, a associated left footprint, parts of the right right footprint , as well as part of the right imprint. Two specimens were referenced: UMNH VP 19466, a disadvantaged adult skull made up of a premaxillary, a maxilla and a nasal incomplete, and UMNH VP 19469, a squamosal isolated from a subadadult. The holotype was discovered and collected in 2006 during the Kaiparowits Basin project, launched by the University of Utah in 2000. It was found in the sandstone of the Center Centrale of the Higher Training of Kaiparowits In the national monument Grand Staircase-Escalante, in sediments dates from the Tardif Campanian stadium in Cretaceous, about 75 million years ago.

He was appointed and described for the first time in a thesis of his discoverer Eric Karl Lund in 2010 under the name of Nasutuceratops titusi , remaining first invalid Name of dissertation . Scott D. Sampson  (d) , Eric Karl Lund, Mark A. Loewen, Andrew A. Farke and Katherine E. Clayton validly named it in 2013, modifying the generic name in Nasutoceratops . The typical species is Nasutoceratops titusi . The generic name comes from nail in Latin which means “big nose”, and ceratops , “Faced with horns” in Greek. The specific name Honore Alan L. Titus for the recovery of fossils Nasutoceratops you gsenm.

The discovery and description of Nasutoceratops is a solid argument in favor of the hypothesis of provincialism among ceratopsians. So, Nasutoceratops seemed to appreciate a tropical and marshy environment ^{[ 3 ]} .

The original classification of Nasutoceratops assigns him to the subfamily of the Centrosaurinae. Phylogenetic analysis, carried out by Sampson and his colleagues in 2013, also reveals that Nasutoceratops Place in a brother group with the genre Avaceratops ^{[ first ]} .

According to the 2013 study, the existence of Nasutoceratops strengthens the hypothesis of a fauna separation between northern and southern Laramidia. The genres of the clade housing Nasutoceratops differ from the North Centrosaurinae by the presence of long front horns and a short nasal horn, combined with development converging, as in chasmosaurinae, of low epiparital bones ^{[ first ]} .

In 2016, this clade was appointed and classified as the Nasutoceratopsini tribe by Mr. J. Ryan and his colleagues ^{[ 4 ]} .
It contains, besides Nasutoceratops , the Holotype ANSP 15800 of the genre Avaceratops ), the specimen Mor 692 (previously considered as an adult of Avaceratops ), a specimen CMN 8804 of the formation of Oldman not yet named and another ceratopsian discovered in Malta in Montana.

The cladogram from this study is reproduced below ^{[ 4 ]} :

The only known specimen of Nasutoceratops was recovered in the formation of Kaiparowits, in southern Utah. The radiometric dating at the Argon-Argon indicates that the formation of Kaiparowits was deposited between 76.1 and 74.0 million years, during the Campanian floor of the upper Cretaceous. In the Upper Cretaceous, the formation of Kaiparowits was located near the western shore of the western interior maritime route, a large inner sea which divided North America into two continental masses: Laramidia to the west and Appalachia at the ‘East. The plateau where dinosaurs lived was an old flood plain dominated by large canals and abundant swamps of peat bogs of wetlands, ponds and lakes, and was bordered by highlands. The climate was wet and damp and housed a wide range of organisms. This training contains one of the best and most continuous recordings of the terrestrial life of the Cretaceous higher than the world.

Nasutoceratops shared his paleoenvironnement with theropods such as dromaeosaridae. There is also the troodontida Talos Sampsoni , ornithomidés like Ornithomos quick , tyrannosaurs like Teratophoneus , armored ankylosauridae, duck beakeds Parasaurolophus cyrtocristatus And Gryposaurus monumentensis , Utahceratops gettyi , Kosmoceratops richardsoni et l’oviraptorosaurien Hagryphus giganteus . The paleofauna present in the formation of Kaiparowits includes chondrichtyens (sharks and rays), frogs, salamanders, turtles, lizards and crocodilians. Various primitive mammals were present, including multi -feaked, marsupials and insectivores.

Taxonomic references [ modifier | Modifier and code ]

Annexes [ modifier | Modifier and code ]

Related articles [ modifier | Modifier and code ]

external links [ modifier | Modifier and code ]

‘ New dinosaur from the lost continent of Laramidia discovered, the nasutoceratops holder », Huffington Post , July 17, 2013 ( read online )

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