Wednesday 26 December 2018

Smok sp.: A large predatory Rauisuchian Archosaur from the Late Triassic of Poland.

During the Late Triassic two groups of Archosaurs produced large-bodied predatory forms in terrestrial environments, the Theropod Dinosaurs, and the Rauisuchians, the sister group to the Crocodylomorphs, a  group which produced some members which showed remarkable convergence with the larger Theropods. One such animal was Smok wawelski, known from the bones of at least three individuals found at Marciszów near Zawiercie in southern Poland.

In a paper published in the journal Acta Palaeontologica Polonica on 29 November 2018, Grzegorz Niedźwiedzki of the Subdepartment of Evolution and Development at Uppsala University and Ewa Budziszewska-Karwowska of the Museum of Earth Sciences at the University of Silesia, describe new material ascribed to the genus Smok from the Late Triassic Woźniki Limestone of western Zawiercie in Silesia, southern Poland.

The new material comprises two isolated teeth, a dorsal vertebra, a fragment of a humerus, a fragment of a femur, a fragment of an ischium shaft, and part of a pubic boot. This material is clearly assignable to the genus Smok, and appears to come either from a single animal or animals of very similar size (unfortunately the material was not found in situ, but rather on a spoil pile from excavations during the construction of a municipal waste site, so it is unclear how closely associated the fragments were originally). However, the vertebra differed from that of Smok wawelski in several important details, leading Niedźwiedzki and Budziszewska-Karwowska to refrain from assigning it to the species, and since there is not sufficient material to establish is the specimens represent a new species, or whether the differences to the vertebra are merely variations found in members of the same species, it is assigned only to genus level.

Comparison and details of articular surface of the mid-dorsal vertebrae (in posterior view) of the predatory Archosaurs from Late Triassic of Poland. (A) Smok sp., from Marciszów near Zawiercie. (B) Smok wawelski, from the Lipie Śląskie clay-pit at Lisowice. Scale bars are 10 mm. Niedźwiedzki & Budziszewska-Karwowska (2018). 

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