Saurosuchus
Skeletal reconstruction of Saurosuchus galilei
Argentina ( Ischigualasto Formation )
- Saurosuchus galilei
Saurosuchus ( " lizard crocodile "; sauros = " lizard, lizard"; suchus = " crocodile " ) is an extinct genus of archosaurs from the relatives of crocodiles. Traditionally it is attributed to the Rauisuchia, although many researchers believe this group is currently invalid ( as paraphyletic ). This carnivore was significantly larger than its close relative with a length of 7 m, only the less well known Fasolasuchus could have been larger.
Saurosuchus lived during the Upper Triassic in what is now Argentina and is known by several partial skeletons from the Ischigualasto Formation, a major fossil site. The holotype specimen consists of a complete, but deformed skull, vertebrae, osteoderms, and a part of the basin. From other skeletons the hind legs, the tail, the neck and the shoulder blade are well known. Some teeth and skull fragments from the Chinle Formation in Arizona have also been attributed Saurosuchus; later studies showed, however, that these bones do not belong to Saurosuchus, but to another related species. Saurosuchus in 1959 described by Osvaldo Reig first time scientifically. The only way is Saurosuchus Galilean.
Description
Saurosuchus is one of the largest Rauisuchia. Since a complete skeleton is not known, its size is estimated at about 6 to 9 m. As related genera ran Saurosuchus quadruped ( four legged ). He had a deep skull, which is narrow in the area of the skull broad and the eyes. The teeth are large, recurved and serrated. The skull roof and the upper jaw showing depressions, a feature that is not found in other Rauisuchiern. The frontals ( Fronatle ), located at the top of the skull are magnified and into thick ridges above the eyes. The cervical vertebrae are shortened and robust, and formed a strong neck. On the back skin were bone plates (so-called osteoderms ), which were arranged in two rows on each side of the body. The individual osteoderms were sheet- shaped and close to one another.
System
Saurosuchus was probably closely related to the genera Batrachotomus and Prestosuchus. The systematic position of these three genera is disputed. For example, take Stephen Brusatte and colleagues ( 2010) Saurosuchus, Batrachotomus and Prestosuchus together as Prestosuchidae. These form the sister taxon of Rauisuchidae that summarize among other Rauisuchus and Postosuchus. Both groups belong to the Rauisuchia.
Nesbitt (2011), however, holds the Rauisuchia and Prestosuchidae for paraphyletic: Do not include according to him all the descendants of their common ancestor. He comes to the conclusion that Saurosuchus, Batrachotomus and Prestosuchus independently split off from the main line of development, which leads to the crocodiles. He writes these genera to the Loricata, a group to which the crocodiles and some other original, crocodile -like representatives are counted. The following cladogram shows the classification of Rauisuchia by Nesbitt (2011) is:
Poposauroidea
Prestosuchus
Saurosuchus
Batrachotomus
Fasolasuchus
Rauisuchidae
Paleoecology
The fossils date from around 230 million years old layers of the Ischigualasto Formation in Argentina. He probably was one of the top predators in its habitat. Other carnivores of the Ischigualasto Formation include the smaller Venaticosuchus, a Ornithosuchidae that Chiniquodontidae (a group of therapsids ), as well as some of the earliest dinosaurs, such as the 1 m long Eoraptor and the larger, about 3 m long with a Herrerasaurus. Typical herbivores in this ecosystem were Hyperodapedon, a Rhynchosauria; some Aetosauria; Ischigualastia, a Dicynodontia from the Kannemeyeridae; some Traversodontidae as Exaeretodon, a group of Therapsida, and herbivore dinosaurs like Pisanosaurus.