Ceratosauria

Skelettrekostruktion of Aucasaurus

  • Worldwide

The Ceratosauria are a form- rich group of basal (original ) theropod dinosaurs. She was spread throughout the world and existed from the Jurassic to the Cretaceous. Representatives of this group were small to large, mostly bipedal carnivores current, which exhibited some complex skull head ornaments like horns. The Ceratosauria includes besides a number of basal genera the Abelisauroidea with a, which in turn comprise Noasauridae and Abelisauridae.

The group was not recognized until the late 1980s as a separate line of development of theropods and their fossil record is still very patchy. That may partly be because they occurred appears to be mainly in the southern hemisphere ( Gondwana ) from where the fossil record is generally still very patchy. However, in the southern hemisphere, they were a very important group and there have apparently the ecological niches of both the large and the small carnivorous dinosaurs filled. Thus, the smallest known Cerato dinosaurs, Ligabueino heard from the Lower Cretaceous of Argentina, with an assumed height of 60-70 centimeters of the smallest prey dinosaurs, while Carnotaurus and Aucasaurus from the Upper Cretaceous of Argentina with 8-9 meters in length were probably the largest carnivores of their ecosystems.

Originally Coelophysoidea were classified within the Ceratosauria. Today, these groups are usually considered paraphyletic, the Coelophysoidea are therefore classified outside the Ceratosauria.

  • 2.1 Research history and the term Neoceratosauria
  • 2.2 Outer systematics
  • 2.3 Internal systematics

Features

Ceratosauria were small to large theropods, some forms reached a length of ten meters.

Trunk and limb skeletal

They had 17 ( Elaphrosaurus ) to 22 ( Carnotaurus ) Präsacralwirbel ( vertebrae before the sacrum), ten cervical vertebrae, which formed an S-shaped neck. The exact number of caudal vertebrae is not exactly known for Ceratosaurus 50 specified. Your vertebral anatomy was more like the Tetanurae than the Coelophysoidea. The bones of the hind legs of the Ceratosauria are hollow and thin-walled. They were characterized by greatly shortened arms that were so reduced in some forms, such as Carnotaurus, they probably hardly had a function.

The skulls were large, built high, the snout short and broad. The cranial window often reached twice the size of the eye sockets. In addition, numerous special adaptations to the skulls in different groups are conspicuous, such as the horn on the nose with Ceratosaurus and horns on the frontal bones of Carnotaurus, Majungasaurus and other Abelisauriden. The maxilla is short and, built high with the exception of the Noasauridae. The front legs have grown together with each other and with the parietal bones.

System

Research history and the term Neoceratosauria

The group Ceratosauria was first erected in 1884 by Othniel Charles Marsh, and initially contained only the Ornithomimidae and Ceratosauridae. The Ceratosauridae Marsh put on earlier in the same year - the beginning of a redundant group, which contained Ceratosaurus as the sole representative. In the following period the name Ceratosauria found little use, and it was a dispute about which species should be classified within this group. It was not until the late 20th century, the name was established: To use Rowe and Gauthier (1990 ) the name Ceratosauria to summarize ( Dilophosaurus, Coelophysis and Megapnosaurus ) and the genus Ceratosaurus family Coelophysidae. Later, the close relationship of Ceratosaurus with the Abelisauridae became obvious why Novas (1992 ) aufstellte a new group within the Ceratosauria that Neoceratosauria: This should Ceratosaurus, Noasaurus and Abelisauridae summarize, excluding Coelophysidae. Since then, the group of basal theropod Ceratosauria were considered, which should Coelophysidae (or something more comprehensive Coelophysoidea ) on the one hand, and the later appearing in the fossil record Neoceratosauria on the other side include. Today, most researchers consider the grouping Neoceratosauria Coelophysoidea as paraphyletic: So the Coelophysoidea have already split off earlier and independently of the Neoceratosauria from the main line of development of the theropods. The Coelophysoidea are therefore classified outside the Ceratosauria, where the name Neoceratosauria is often understood as a synonym of the name Ceratosauria.

The following cladogram shows the original, now rejected by most researchers define the Ceratosauria with the subgroups Coelophysoidea and Neoceratosauria:

Coelophysoidea

Neoceratosauria

Tetanurae

Outer systematics

The Ceratosauria were split fairly early on the main development branch of the theropods. They are the sister group of the Tetanurae, which belong to most other theropods, including birds. Together, the Ceratosauria and Tetanurae form the taxon Neotheropoda. Another group of basal theropods, the Coelophysoidea, form the sister group of the Neotheropoda.

Coelophysoidea

Ceratosauria

Tetanurae

Inside systematics

Within the Ceratosauria there are in addition to the basal, especially Jurassic forms the Abelisauroidea that were widespread in the Cretaceous on the southern continents. They include all theropods more closely related sastrei with Carnotaurus Ceratosaurus than with nasicornis. The Abelisauroidea be divided into Noasauridae and Abelisauridae. The latter are defined as Abelisaurus comahuensis and Carnotaurus sastrei whose youngest common ancestor and all its descendants. The Noasauridae were initially created just for Noasaurus leali. Today you some other genera are attributed.

Pliensbachian Maastrichtian Mya (unit) Archosaur Ornithodira Nasal bone Digital Object Identifier Paul Sereno
173489
de