Saurischia
The basal lizards Beck dinosaur Eoraptor
- Worldwide
The lizards Beck dinosaurs ( Saurischia ) in addition to the bird Beck dinosaurs ( Ornithischia ) one of the two lines of development of the Dinosaurs ( Dinosauria ).
This classification of dinosaur was a large step towards a better understanding of the relationships of dinosaurs and succeeded in 1887. Until then, quite a few well-preserved skeletons were described, Harry Govier Seeley struck by King's College London, that they are in reference to the different structure of their pelvic bone could be divided two groups. Seeley described it as Saurischia (lizard dinosaur Beck ) and Ornithischia ( bird Beck dinosaurs). Today, they are defined as all dinosaurs that are more related to Allosaurus than with Stegosaurus.
Features
In the lizards the dinosaurs pelvic pelvic bones are arranged approximately as with other reptiles. Of large blade-shaped upper bones, ilium ( ilium ), is connected through a series of strong ribs with the spine; its lower edge forms the upper part of the hip joint socket ( acetabulum ). Under the ilium is the pubic bone ( pubis ), a large bone, pointing down and slightly forward. Behind it is the ischium ( ischium ), which faces backwards. All three bones are involved in the formation of the acetabulum, a deep, round hole in the side of the pool is at the dinosaurs. In addition, they share about a dozen more derived features, including a special form of external nasal openings, the extension of the posterior cervical vertebrae, an enlarged fifth finger, and the construction of the vertebrae and the extremities.
System
The Saurischier be divided into the ever advancing on two legs ( bipedal ), mostly carnivorous theropods and the four-legged, herbivorous Sauropodomorpha which produced the largest land animals that ever inhabited the earth. Among the theropods include most of the " feathered dinosaur " as well as the birds.
The following cladogram makes the family relationships of the main groups of the Saurischia clear:
Theropods
Prosauropoda
Sauropoda
Basal Saurischia without assignment to a higher clade are:
- Eoraptor
- Guaibasaurus
- Saturnalia
- Alwalkeria
- Chindesaurus