Rhabdognathus rarus Swinton, 1930

Hill, Robert V., Mccartney, Jacob A., Roberts, Eric, Bouaré, Mohamed, Sissoko, Famory & O'leary, Maureen A., 2008, Dyrosaurid (Crocodyliformes: Mesoeucrocodylia) Fossils from the Upper Cretaceous and Paleogene of Mali: Implications for Phylogeny and Survivorship across the K / T Boundary, American Museum Novitates 3631 (1), pp. 1-20 : 6-7

(5 Rhabdognathus rarus Swinton, 1930 [in part])

HOLOTYPE: MNHN TGE 4031 .

NEW REFERRED SPECIMENS: CNRST SUNY 276; 277.

LOCALITY: Mali-8; Maastrichtian phosphate conglomerate.

DIAGNOSIS: As in Jouve (2007); Rhabdognathus with extremely well-developed, sharp occipital tuberosities; deeply concave caudal margin of the parietal between occipital tuberosities, the rostral extent of which reaches or almost reaches the caudal level of the supratemporal fenestra.

DESCRIPTION: CNRST SUNY 276 and CNRST SUNY 277 exhibit a similar general morphology. Both specimens preserve the caudal region of the skull roof, including parts of the parietal, squamosal, supraoccipital, and exoccipital elements. They can be identified as dyrosaurids on the basis of closely spaced otic capsules, relatively large supratemporal fenestrae, and prominent occipital tuberosities.

In dorsal view, CNRST SUNY 277 exhibits a deeply excavated caudal border of the parietal, forming a deep, U-shaped concavity (fig. 3). The parietal forms the caudomedial border of the supratemporal fenestrae. On the right side, the parietal articulates laterally with the squamosal, which forms the caudolateral border of the supratemporal fenestra. The caudal wall of each supratemporal fenestra slopes gently rostrally, and is largely visible in dorsal view. The occipital tuberosities are well developed and prominent, and visible in dorsal view, extending beyond the caudal margin of the skull roof.

In occipital view, the space between the occipital tuberosities forms a deep, hemispherical concavity whose rostralmost extent is formed by the supraoccipital. The parietal is visible as a narrow strip in occipital view, contributing to the dorsal margin of the supraoccipital region. The right posttemporal fenestra is preserved, roofed primarily by the parietal with only a small contribution from the squamosal. The occipital tuberosities are composed entirely of the exoccipitals, which also articulate with the squamosals along an oblique suture.

The morphology of CNRST SUNY 276 compares closely with that of CNRST SUNY 277, being slightly smaller in all dimensions. The distal ends of the occipital tuberosities are broken, and their caudal extent cannot be determined. Additionally, the concavity between the occipital tuberosities is somewhat less pronounced, and the supraoccipital bears a weak median ridge.