Silesaurus

Taxobox
name = "Silesaurus"
fossil_range = Late Triassic

---

image_width = 250px
regnum = Animalia
phylum = Chordata
classis = Sauropsida
infraclassis = Archosauromorpha
unranked_ordo = Ornithodira
unranked_familia = Dinosauriformes
genus = "Silesaurus"
genus_authority = Dzik, 2003
subdivision_ranks = Species
subdivision ="S. opolensis" Dzik, 2003 (type) "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. 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" 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 thinks 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.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.]

Systematic position after Ezcurra (2006):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.]

Ornithodira
--Pterosauromorpha
|--"Scleromochlus"
`--Pterosauria `--Dinosauromorpha
--"Lagerpeton" `--Dinosauriformes
--"Marasuchus" `--+--"Pseudolagosuchus" `--+--"Silesaurus" `--+--"Eucoelophysis" `--Dinosauria
--Saurischia
|--Herrerasauridae
`--Eusaurischia
|--Theropoda
`--Sauropodomorpha `--Ornithischia

References

External links

* [http://www.users.qwest.net/~jstweet1/dinosauromorpha.htm "Silesaurus"] at "Thescelosaurus"!, under Silesaurs