Corythosaurus
Summary 3
Corythosaurus /ˌkɒrɪθoʊˈsɔːrəs/ is a genus of hadrosaurid "duck-billed" dinosaur from the Upper Cretaceous Period, about 77–75.7 million years ago. It lived in what is now North America. Its name means "helmet lizard", derived from Greek κόρυς. It was named and described in 1914 by Barnum Brown. Corythosaurus is now thought to be a lambeosaurine, related to Nipponosaurus, Velafrons, Hypacrosaurus, and Olorotitan. Corythosaurus has an estimated length of 9 metres (30 ft), and has a skull, including the crest, that is 70.8 centimetres (27.9 in) tall.
Corythosaurus is known from many complete specimens, including the nearly complete holotype found by Brown in 1911. The holotype skeleton is only missing the last section of the tail, and part of the forelimbs, but was preserved with impressions of polygonal scales. Corythosaurus is known from many skulls with tall crests. The crests resemble the crests of the cassowary and a Corinthian helmet. The most likely function of the crest is thought to be vocalization. As in a trombone, sound waves would travel through many chambers in the crest, and then get amplified when Corythosaurus exhaled. A Corythosaurus specimen has been preserved with its last meal in its chest cavity. Inside the cavity were remains of conifer needles, seeds, twigs, and fruits: Corythosaurus probably fed on all of these.
The two species of Corythosaurus are both present in slightly different levels of the Dinosaur Park Formation. Both still co-existed with theropods and other ornithischians, like Daspletosaurus, Brachylophosaurus, Parasaurolophus, Scolosaurus, and Chasmosaurus.
enson et al. (2012) estimated that Corythosaurus has an average length of 9 metres (30 ft).[1] Richard Swann Lull's earlier length estimate, published in 1942, found a slightly longer total length of 9.4 m (31 ft), a size similar to Lambeosaurus lambei, another Canadian lambeosaurine.[2] In 1962, Edwin H. Colbert used models of specific dinosaurs, including Corythosaurus, to estimate their weight. The Corythosaurus model used, was modelled by Vincent Fusco after a mounted skeleton, and supervised by Barnum Brown. After testing, it was concluded that the average weight of Corythosaurus was 3.82 tonnes (3.76 long tons; 4.21 short tons).[3] More recent size estimates of Corythosaurus, published in 2001, find the genus to be among the largest hadrosaurids, only smaller than Shantungosaurus and Parasaurolophus. The total length of Corythosaurus specimen AMNH 5240 was found to be 8.1 m (27 ft), with a weight of 3.0785 tonnes (3.0299 long tons; 3.3935 short tons).[4]
Proportionally, the skull is much shorter and smaller than that of Edmontosaurus (formerly Trachodon), Kritosaurus, or Saurolophus, but when including its crest, its superficial area is almost as large.[5]
A set of characters were indicated by Barnum Brown in 1914 to distinguish Corythosaurus from all other hadrosaurids from Alberta: a comparatively short skull with a high helmet-like crest formed by the nasals, prefrontals and frontals; the nasals not being separated in front by the premaxillaries; a narrow beak, with an expansion in front of an elongated naris; and a small narial opening.[13]
In 1916, Brown expanded the character set to include more features; in the revised version: a comparatively short skull with a high helmet-like crest formed by nasals, prefrontals and frontals; the nasals not being separated in front by premaxillaries; a narrow beak, expanded section in front of the elongated nares; a small narial opening; a vertebral formula of 15 cervicals, 19 dorsals, 8 sacrals, and 61+ caudals; possession of dorsal spines of a medium height; high anterior caudal spines; long chevrons; long scapulae, possessing a blade of medium width; a radius considerably longer than humerus; comparatively short metacarpals; an anteriorly decurved ilium; a long ischium with a foot-like terminal expansion; a pubis with an anterior blade that is short and broadly expanded at end; a femur that is longer than the tibia; the phalanges of pes are short; that the integument over the sides and tail composed of polygonal tuberculate scales without pattern but graded in size in different parts of the body; and a belly with longitudinal rows of large conical limpet-like scales separated by uniformly large polygonal tubercles.[14] Again, the presumed traits of the snout are incorrect because Brown confused the praemaxillae with the nasal bones and the nasal bones with the frontals. Most of the postcranial traits are today known to be shared with other lambeosaurines.
Fontes e Créditos
- (c) Etemenanki3, alguns direitos reservados (CC BY-SA), http://commons.wikimedia.org/wiki/File:Corythosaurus_skull_Royal_Tyrrell.jpg
- (c) calgaryzoo, todos os direitos reservados
- Adaptado por calgaryzoo de uma obra de (c) Wikipedia, alguns direitos reservados (CC BY-SA), https://en.wikipedia.org/wiki/Corythosaurus
