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Silesaurus
Fossil range: Late Triassic
Silesaurus BW.jpg
Scientific classification

Kingdom:

Animalia

Phylum:

Chordata

Subdivision:

S. opolensis Dzik, 2003 (type)

Class:

Sauropsida

Infraclass:

Archosauromorpha

Genus:

Silesaurus

Silesaurus is a genus of dinosauriform from the Late Triassic, approximately 230 million years ago in the Carnian faunal stage of what is now Poland.

Fossilized remains of Silesaurus have been found in the Keuper Claystone of Opole, Silesia, Poland, which is also the origin of its name.[1] The type species, Silesaurus opolensis, was described by Jerzy Dzik in 2003. It is known from some 20 skeletons, making it one of the best-represented of the early dinosaurs and related animals.

Characteristics[]

Silesaurus opolensis.

Silesaurus measured approximately 2.3 meters long (7.5 ft), and was facultatively bipedal. It was light and built for speed.

Silesaurus was an herbivore. The teeth were small, conical, and serrated. The tip of the dentary has no teeth, and some paleontologists think that it may have been covered by a beak.

Phylogeny[]

Some scientists think that Silesaurus was not a dinosaur, but rather a dinosauriform. Mikoluszko points out dinosaur features lacking in Silesaurus, including an enlarged deltopectoral crest, and epiphyses on the cervical vertebrae.

However, Silesaurus has some dinosaurian characteristics as well:

  • a brevis shelf
  • ischium with a slender shaft
  • femur with a reducted tuberosity that borders the ligament of the femoral head
  • a prominent lesser trochanter
  • an overlap of the ascending process of the astralagus with the tibia
  • a concave proximal articular surface for the reception of the distal end of the fibula on the calcaneum

As a result, alternative theories place Silesaurus at or near the base of the ornithischian dinosaurs. Other scientists propose a basal link between the prosauropods and ornithischians.[1]

Systematic position after Ezcurra (2006):[2]

Ornithodira 
 Pterosauromorpha 

Scleromochlus



Pterosauria



 Dinosauromorpha 

Lagerpeton


 Dinosauriformes 

Marasuchus




Pseudolagosuchus




Silesaurus




Eucoelophysis


 Dinosauria 
 Saurischia 

Herrerasauridae


 Eusaurischia 

Theropoda



Sauropodomorpha





Ornithischia









References[]

  1. ^ a b Dzik, J. (2003). "A beaked herbivorous archosaur with dinosaur affinities from the early Late Triassic of Poland." Journal of Vertebrate Paleontology, 23(3): 556-574.
  2. ^ Ezcurra, M.D. (2006). "A review of the systematic position of the dinosauriform archosaur Eucoelophysis baldwini Sullivan & Lucas, 1999 from the Upper Triassic of New Mexico, USA." Geodiversitas, 28(4):649-684.


External links[]

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