Field of Science

Beautiful New Aetosaur Skull Material of Stagonolepis from Poland

This is absolutely beautiful material, which allows for a detailed description of the skull of the European genus Stagonolepis.  Sulej differentiates this material as a new taxon, S. olenkae.  This material is believed to from an equivalent of the Lehrberg beds of Germany, thus from the Middle Keuper (Carnian).  Thus it is older than material from the Southwest U. S. (Calyptosuchus wellesi) that has often been assigned to Stagonolepis on the basis on radial armor patterning. The same quarry that produced these skulls provided the holotype material of the non-dinosaurian dinosauriform Silesaurus opolensis. Be advised that the evolutionary hypothesis presented here for aetosaurs is based on hypothetical stratigraphic position (which can not be precisely determined globally) and not a phylogenetic analysis. However, although I don't agree with all of the details of this paper, the specimen is perfectly preserved and provides lots of new information, especially the skull roof and braincase shown below.

Sulej, T. 2010. The skull of an early Late Triassic aetosaur and the evolution of the stagonolepidid archosaurian reptiles. Zoological Journal of the Linnaean Society 158, 860–881.

Abstract - Disarticulated bones of several individuals recovered from the Late Triassic fluvial and lacustrine deposits at Krasiejów, Poland, are here described, allowing the restoration of the skull structure of a new aetosaurian archosaur: Stagonolepis olenkae sp. nov. The Krasiejów deposits probably correspond in age to the Lehrberg Beds (late Carnian) of Baden-Württemberg, Germany. The stratigraphical position of the new taxon combined with other available evidence is used to propose a model of aetosaurian evolution. The proposed phylogenetic position of Aetosaurus ferratus (Norian, Germany) as the basal aetosaurid is refuted and this species is instead proposed to be the most derived member of the Stagonolepis–Aetosaurus evolutionary lineage. Gradual change in several morphological characters can be observed from Stagonolepis robertsoni, through the new species from Krasiejów, to the stratigraphically youngest Aetosaurus ferratus. These changes include a decrease in the number of teeth and a decrease in the convexity of the ventral profile of the maxilla. The anterior elongation of the maxilla is associated with the expansion of the anterior tip of the maxilla towards the naris. In S. robertsoni and S. olenkae, the maxilla extends to middle of the naris, whereas in Aetosaurus, it reaches the anterior half of the naris.


  1. the figures and anatomical description are pretty good in this paper, but the rest is kind of old school

    not too bad imho

  2. You don't agree with details? Why?

  3. "evolutionary hypothesis presented here for aetosaurs is based on hypothetical stratigraphic position (which can not be precisely determined globally)"

    maybe that's why


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