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. 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 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.

Systematic position after Ezcurra (2006):