Prosaurolophus
Prosaurolophus maximus at the Royal Tyrrell Museum
- Prosaurolophus maximus
- Prosaurolophus blackfeetensis
Prosaurolophus ( " before Saurolophus ", compared to the later living dinosaur with a similar head crest ) was a genus of dinosaur bird Beck from the group of Hadrosauridae. The genus currently contains two valid species, of which fossils have been found of at least 25 individuals in North America. The fossils date from the Middle to the Upper Campanian ( Upper Cretaceous ). The skeletons were in the Dinosaur Park Formation in Alberta, Canada, and about the same old Two Medicine Formation in Montana, USA, have been found.
- 6.1 Literature
Features
Prosaurolophus corresponded in his anatomy typical Hadrosauriern. He reached a body length of eight to nine meters and had a very large head, which was at a 8.5 -meter copy 0.9 meters long. As with most Hadrosauriern the front portion of the head was flattened and widened like a beak, which he was able to bite off leaves from the trees of North American forests. In the oral cavity, he had thousands of small teeth, by which the plant material was crushed before Abschlucken.
As a striking feature Prosaurolophus had on his forehead before the eyes of a comparatively small and triangular -shaped end comb, which was formed by the nasal bones and the sides formed by their concave shape wells. The forelimbs were formed as compared to other Hadrosauriern relatively short.
The two species P. maximus and P. blackfeetensis differed mainly in the proportions of the skull and the size of the frontal ridge. P. blackfeetensis had a narrower and longer face also migrated in this type of the front ridge during the growth to the rear in the direction of the eyes.
Sites and history
Fossils of Prosaurolophus are known from North America of two sites, the Dinosaur Park Formation. Than the top layer of the Judith River Group in Alberta, Canada, and about the same old Two Medicine Formation in Montana, USA From the type species P. maximus fossil skeletal remains of at least 25 individuals and seven complete skulls are known to be present during P. blackfeetensis a partially complete skeleton with skull and several individual bones. Both Fund areas are characterized by a variety of skeletal remains.
The earliest fossils of the type species P. maximus were described in 1916 by the American paleontologist Barnum Brown of the American Museum of Natural History. He discovered in 1915 a skull near the Red Deer River near the town of Ville Steve in Alberta, Canada ( Dinosaur Park Formation), which is today as AMNH 5836 in the American Museum of Natural History. He described the genus in 1916 as Prosaurolophus and took it with respect to the 1912 also described by him Saurolophus This had as a striking new style brow ridge, which, however, was designed to be longer and larger. 1924 William Parks described a nearly complete skeleton with skull. To this day, are known from Canada and the formation in Montana fossils of about 25 individuals, partly in the form of almost complete skeletons and skulls.
1992 described the paleontologist Jack Horner of the Museum of the Rockies with P. blackfeetensis a second type on the basis of a skeleton that was in the Two Medicine Formation, more precisely in Glacier County discovered. The material was stored together with the remains of three or four other copies as MOR 454 at the Museum of the Rockies. The fossils were found together, so it is assumed that they have lived together and collected during a drought near a water source.
System
Lophorhothon
Prosaurolophus
Edmontosaurus
Brachylophosaurus
" Kritosaurus " australis
Naashoibitosaurus
Saurolophus
Prosaurolophus got its name in reference to the hadrosaur Saurolophus, who had a similarly configured comb, in the belief that it could be located the same to an ancestor (previous Saurolophus ). In what is in fact a closer relationship between the two genera is unclear; by some authors, it is believed, others arrange both types at various stages of the system.
According to the current idea Prosaurolophus is placed in the Hadrosaurinae and thus into the close relationship of the genera Brachylophosaurus, Edmontosaurus, Maiasaura and Gryposaurus. The members of this group are characterized by the lack of a full brow ridge, which is available at Saurolophus.
Within the genus two valid species are described, nouns dubia are not available. The type species P. maxima was described in 1916 first described by Barnum Brown of the Two Medicines formation. 1992 described the paleontologist Jack Horner of the Museum of the Rockies with P. blackfeetensis a second type, which differed from P. maximus mainly by the proportions of the skull and the size of the frontal ridge.
Paleoecology
The Dinosaur Park Formation, was found in the Prosaurolophus maximus, is considered previously flat landscape with rivers and floodplains that became more swampy by the transgression of the Western Interior Seaway to the west. The climate was warmer than present-day Alberta, without frost, but also moist with dry periods. The vegetation consisted mainly of coniferous plants with an understory of ferns, tree ferns and seed plants. Within this well-studied fossil deposit remains could be found by Prosaurolophus only in the top layer, which was more influenced by the sea than the lower layers. Within this layer, whose age has been dated to 76-74 million years it represents the most common hadrosaur dar. addition Prosaurolophus were also many other skeletons of dinosaurs have been found, including the Ceratopsidae Centrosaurus, Styracosaurus and Chasmosaurus, of belonging to the tyrannosaurids Gorgosaurus, the Ankylosauria Edmontonia and Euoplocephalus and with Gryposaurus, Corythosaurus, Lambeosaurus Parasaurolophus and a number of other hadrosaur.
The time is approximately equal to an arranged Two Medicine Formation, was discovered in the blackfeetensis P., is especially known for the fossils of dinosaur nests, eggs and young animals of the hadrosaur Maiasaura and Hypacrosaurus stebingeri and the troodontids Troodon. In addition, skeletal remains of tyrannosaurids Daspletosaurus, the Caenagnathiden Chirostenotes, the Dromaeosauriden Bambiraptor and Saurornitholestes, the ankylosauruses Edmontonia and Euoplocephalus, the Hypsilophodontiden Orodromeus and the Ceratopsiden Achelousaurus, Brachyceratops, Einiosaurus and Styracosaurus ovatus were. The site was further away from the Western Interior Seaway, she was also higher and was drier than the Dinosaur Park Formation.
Paleobiology
Nutrition
Prosaurolophus, like all hadrosaur, a large herbivore, who was by his beak like extended and complex skull in a position similar to crushing plant parts by moving the chewing. Its teeth were continuously replaced, and were in dental packets of several hundred teeth in the jaw, of which only a fraction is used simultaneously. The plant material was demolished with its beak wide of plants from the ground to about four meters high and remained through cheek -like formations in the mouth. Like other hadrosaurs this species probably moved away quadrupedally ( quadruped ) and bipedal ( biped ).
Social behavior
The fact that the fossils were found in bone camps me several skeletons is deduced that these animals at least partly lived in groups. About the cranial skeleton, there are other assumptions for the social behavior: The bony brow comb could have had a function as a visual means of communication, also the existence of bag-shaped and membranous diverticula will be accepted at the nasal cavity, which could have served the communication and acoustically addition to the visual function. Additionally, it had several potential methods for display in a social setting.