Sunday, 17 June 2012

A Silesaurid Dinosauriform from the Late Triassic of Morocco.

Dinosauriforms are the group of Archosaurs including the Dinosaurs and those species more closely related to them than to the Crocodilians or Pterosaurs. Within this group the Silesaurids are the branch most closely related to to the dinosaurs. They lived in the Middle-to-Late Triassic, but probably did not survive until the end of that period.

In a paper published in the journal Acta Palaeontologica Polonica on 11 July 2011, Christian Kammerer of the Division of Paleontology and Richard Gilder Graduate School at the American Museum of Natural HistorySterling Nesbitt of the Jackson School of Geosciences at the University of Texas at Austin and Neil Shubin of the Department of Organismal Biology and Anatomy at the University of Chicago, describe a new species of Silesaurid Dinosauriform from the Late Triassic of the Argana Basin in Morocco.

The new species is named as Diodorus scytobrachion; Diodorus being both a semi-mythical king of the Berbers and a Greek Historian (Diodorus Siculus) who wrote about North Africa, scytobrachion meaning 'leathery arm' in Greek, and being the name of another  Greek scholar (Dionysius Scytobrachion) who studied North Africa. It is described from a partial dentary, three isolated teeth, two humeri, a metatarsal and a femur; not all from the same individual, but which Kammerer et al. believe all come from the same species. 

(A₁) Photograph of right dentary in lateral view. (A₂) Photograph of right dentary in medial view. (A₃) Interpretive drawing of (A₁). (A₄) Interpretive drawing of (A₂). (B) Isolated tooth. Kammerer et al. (2011).

(A₁) Photograph of right humerus in anterior view. (A₂) Photograph of right humerus in proximal view. (A₃) Photograph of right humerus in posterior view. (A₄) Photograph of right humerus in distal view. (B₁) Photograph of isolated metatarsal in anterior view. (B₂) Photograph of isolated metatarsal in distal view. Kammerer et al. (2011).

(A) Photograph of left femur in anterior view. (B) Photograph of left femur in lateral view. (C) Photograph of left femur in medial view; the image is presented as a stereopair, two versions of the same image side by side, which can, with the right equipment, be seen in 3D. (D) Photograph of left femur in Proximal view. (E) Photograph of left femur in distal view. Tags: (1) Distal
condyles of femur divided posteriorly between 1/4 and 1/3 the length of the shaft. (2) Notch ventral to the proximal head of the femur. (3) Posteromedial tuber absent on the proximal portion of the femur. (4) flat medial articular surface of the femur head in dorsal view. Kammerer et al. (2011).


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