Silesaurus is a genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of dinosauriform

Dinosauriformes

Dinosauriformes is a clade of archosaurian reptiles that include the dinosaurs and their most immediate relatives. All dinosauriformes are distinguished by several features, such as shortened forelimbs, and an at least partially perforated acetabulum, the hole in the hip socket traditionally used...

 from the Late Triassic

Late Triassic

The Late Triassic is in the geologic timescale the third and final of three epochs of the Triassic period. The corresponding series is known as the Upper Triassic. In the past it was sometimes called the Keuper, after a German lithostratigraphic group that has a roughly corresponding age...

, approximately 230 million years ago in the Carnian

Carnian

The Carnian is the lowermost stage of the Upper Triassic series . It lasted from about 228.7 till 216.5 million years ago . The Carnian is preceded by the Ladinian and is followed by the Norian...

 faunal stage

Faunal stage

In chronostratigraphy, a stage is a succession of rock strata laid down in a single age on the geologic timescale, which usually represents millions of years of deposition. A given stage of rock and the corresponding age of time will by convention have the same name, and the same boundaries.Rock...

 of what is now Poland

Poland

Poland , officially the Republic of Poland , is a country in Central Europe bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...

.

Fossilized remains of Silesaurus have been found in the Keuper Claystone in Krasiejów

Krasiejów

Krasiejów is a village in the administrative district of Gmina Ozimek, within Opole County, Opole Voivodeship, in south-western Poland...

 near Opole

Opole

Opole is a city in southern Poland on the Oder River . It has a population of 125,992 and is the capital of the Upper Silesia, Opole Voivodeship and, also the seat of Opole County...

, Silesia

Silesia

Silesia is a historical region of Central Europe located mostly in Poland, with smaller parts also in the Czech Republic, and Germany.Silesia is rich in mineral and natural resources, and includes several important industrial areas. Silesia's largest city and historical capital is Wrocław...

, Poland, which is also the origin of its name. The type species

Type species

In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the 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 a 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

Most scientists think that Silesaurus was not a dinosaur, but rather a dinosauriform. Dinosaurian features lacking in Silesaurus include an enlarged deltopectoral crest (a muscle attachment on the humerus), and epipophysis (enlarged tendon attachment above the postzygapophysis) on the cervical vertebrae

Cervical vertebrae

In vertebrates, cervical vertebrae are those vertebrae immediately inferior to the skull.Thoracic vertebrae in all mammalian species are defined as those vertebrae that also carry a pair of ribs, and lie caudal to the cervical vertebrae. Further caudally follow the lumbar vertebrae, which also...

.

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 ornithischia

Ornithischia

Ornithischia or Predentata is an extinct order of beaked, herbivorous dinosaurs. The name ornithischia is derived from the Greek ornitheos meaning 'of a bird' and ischion meaning 'hip joint'...

n dinosaurs. Other scientists propose a basal link between the prosauropods and ornithischians.

Systematic position after Nesbitt

Sterling Nesbitt

Sterling Nesbitt , is an American paleontologist.-Biography:Sterling Nesbitt received his B.A. in integrative biology with a minor in geology from University of California Berkeley in 2004. He received his Ph.D from Columbia University in 2009, completing the majority of his research at the...

 (2011):
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External links

• Silesaurus at Thescelosaurus!, under Silesaurs