Stagonolepis robertsoni Agassiz, 1844

Nesbitt, Sterling J., 2011, The Early Evolution Of Archosaurs: Relationships And The Origin Of Major Clades, Bulletin of the American Museum of Natural History 2011 (352), pp. 1-292 : 22-23

Stagonolepis robertsoni Agassiz, 1844

( fig. 8F–G)

AGE:?Late Carnian, Late Triassic ( Lucas and Heckert, 1996).

OCCURRENCE: Lossiemouth Sandstone Formation, Scotland.

HOLOTYPE: EM 27 R, impression of a segment of a ventral osteoderm.

REFERRED MATERIAL: See Walker, 1961; MCZD 2–4, braincase.

REMARKS: First regarded as a ganoid fish, Stagonolepis is one of the better known

aetosaurs largely as the result of the work of Huxley (1877) and especially Walker (1961). Although casts produced from sandstone molds represent nearly all the specimens, Walker (1961) laboriously worked to produce a rather complete anatomy of Stagonolepis . Details of the pes and other bones are missing because of the preservation of the material. I urge future workers to score characters from the actual casts and molds of the material and not reconstructions of the material, even though it is tempting given Walker’s fine work on the Lossiemouth Sandstone archosaurs. Here, I specifically use Stagonolepis so that the observations of the braincase by Gower and Walker (2002) could be included in a broader context. Furthermore, I assume all the aetosaur material from the Lossiemouth Sandstone Formation belongs to Stagonolepis robertsoni .

KEY REFERENCES: Huxley, 1877; Walker, 1961; Gower and Walker, 2002.