SKULL OF UROPELTINAE 



125 



mnr**inni»yP>y.:F^^&mmi V ti)U, i." 'A 'l*L 



Fig. 3 The snout complex of Pseudotyphlops philippinus ( BMNH 1978. 1092). 



maxilla, a unique condition among snakes (Fig. 4). The suspension 

 of the snout complex from the braincase is more elaborate in 

 uropeltines than it is in other basal alethinophidians (Rieppel 1978). 



The parietal of uropeltines forms distinct anterolateral, i.e., 

 supraorbital processes which may or may not contact the prefrontal 

 (Fig. 3). In Cylindrophis maculatus and in Anomochilus (Cundall & 

 Rossman 1993), as well as in Melanophidium punctatum, the 

 supraorbital process of the parietal participates in the suspension of 

 the prefrontal. In other uropeltines, the contact between parietal and 

 prefrontal may be reduced or absent, due to a relatively shorter 

 supraorbital process of the parietal (this character is bilaterally 

 variable in the skull of- Platyplecturus). The optic foramen is located 

 between the frontal and parietal in Melanophidium and Platy- 

 plecturus, but within the frontal in Plecturus, Rhinophis, and 

 Uropeltis (Underwood, 1967: 64). In Pseudotyphlops (Fig. 3A) and 

 Teretrurus, the optic foramen is a slit-like opening in the posterior 

 margin of the frontal. The parietal carries a low sagittal crest in the 

 relatively large Pseudotyphlops (Fig. 5C). In the other species with 

 smaller skulls, such a sagittal crest is at best very faintly developed 

 in the posterior part of the parietal (Fig. 5A-B). In some uropeltines 

 such as Rhinophis and Uropeltis (Fig. 5B), the parietals are not 

 completely fused in their posterior part. A supratemporal is absent in 

 uropeltines, and the quadrate is suspended from the otic capsule in a 

 relatively low position. The suprastapedial process of the quadrate is 

 very elaborate in uropeltines, and as in Anomochilus (Cundall & 

 Rossman 1993), it exceeds the shaft of the quadrate in length. 



In Anomochilus, the anterior end of the edentulous palatine shows 



some elaboration into a broader structure that receives the medial 

 (palatine) process of the maxilla in a deep facet (Cundall & Rossman 

 1993, Fig. 2B). In uropeltines, the anterior process of the palatine is 

 modified to form a broad wing which establishes a broad ventral 

 overlap with the posterolateral part of the vomer, and which receives 

 the well developed medial process of the maxilla in a deeply 

 recessed lateroventrally facing facet (Fig. 2). The infraorbital nerve 

 (maxillary division of the trigeminal nerve) pierces the bottom of 

 this recessed facet to become the superior alveolar nerve. The 

 morphology of the palatine in Anomochilus is intermediate between 

 that of Cylindrophis on the one hand, and that of uropeltines on the 

 other (Cundall & Rossman 1993). Palatine teeth are absent in 

 Anomochilus and uropeltines with the exception of Melanophidium 

 wynaudense . The ectopterygoid and pterygoid are reduced in 

 uropeltines (and even more so in Anomochilus: Cundall & Rossman 

 1993), and the pterygoid is edentulous. 



The para-basisphenoid is relatively broad in uropeltines, gradually 

 becoming narrower anteriorly and tapering to a pointed tip between 

 the choanal processes of the palatines. The ventral surface of the 

 para-basisphenoid is distinctly convex in Pseudotyphlops resulting 

 in the formation of ventrolateral ridges. These are at best weakly, or 

 only very faintly, developed in other, smaller, species with a para- 

 basisphenoid that has a flat or even slightly convex ventral surface. 

 Along the lateral edge of the para-basisphenoid the ossified crista 

 trabecularis ends behind the anterior margin of the laterally descend- 

 ing flange of the parietal in most taxa except for Teretrurus and 

 Rhinophis drummondhayi, where it ends at the anterior margin of the 



