124 



O. RIEPPEL AND H. ZAHER 



Fig. 1 The skull and mandible of Pseudotyphlops philippinus (BMNH 

 1978.1092) in left lateral view. 



GENERAL ASPECTS OF THE SKULL 



The premaxilla of uropeltines is characterized by a single premaxil- 

 lary foramen (Fig. 2). The vomerine processes of the premaxilla 

 meet the vomer in a well-defined contact. The premaxilla of 

 uropeltines shows characteristic variation within the group (Rieppel 

 1977; Cundall & Rossman 1993). The anterior margin of its trans- 

 verse process is more or less evenly rounded in Melanophidiwn, 

 which correlates with a gentle anteromedial curvature of the anterior 

 end of the maxilla (Fig. 2A). The two bones closely approach each 

 other, or barely establish contact. This genus therefore retains a 

 plesiomorphic configuration of the snout, which is also inferred to 

 be present in Platyplecturus (the specimen BMNH 1930.5.8.111 

 lacks the premaxilla, but retains the maxilla which shows an 

 anteromedially curved anterior end), and which represents a con- 

 dition similar to that seen in Anomochilus (Cundall & Rossman 

 1993). The other uropeltines have a similar premaxilla, which 

 carries an anteriorly projecting, bipartite rostrum. The straight 'trans- 

 verse' processes point posterolaterally, and meet the straight maxilla 



in a shizarthrosis (Cundall & Rossman 1993; Fig. 2B-E). These two 

 elements define the lateral margins of the strongly 'telescoped' 

 (Haas 1930), i.e., tapering and pointed snout (see also Cundall & 

 Rossman 1993, Fig. 25B). 



The maxilla of basal alethinophidians carries an anterior medial 

 process (Rieppel 1977; Scanlon & Lee 2000), which is particularly 

 well developed in uropeltines, where it participates in the formation 

 of a broadly overlapping contact between maxilla, premaxilla, and 

 vomer. In Melanophidiwn, the anterior medial process of the maxilla 

 is not engaged in any such contact, but freely underlaps the 

 septomaxilla. In Pseudotyphlops, the anterior medial process of the 

 maxilla overlaps a medially extending horizontal flange of the 

 transverse process of the premaxilla in a complex, interlocking 

 premaxillary - maxillary contact (Fig. 2B, D-E). Rhinophis and 

 Uropeltis are unique in that the anterior medial process of the 

 maxilla forms a well-defined sutural contact with an anterior lateral 

 process of the vomer in front of the opening for Jacobson's organ. 



The medial or choanal processes of the palatines of uropeltines 

 are broad, arching over the choanal tubes and projecting ventrally 

 again medial to the choanal tubes. Their ventral tips are embraced 

 anteriorly by the posterior ends of the vomers, as is also the case in 

 other basal alethinophidians (Cundall & Rossman 1993; Cundall et 

 al. 1993; Rieppel 1983; Fig. 2, 3). The parasphenoid forms a sagittal 

 interchoanal process that lies between the choanal processes of the 

 palatines, as is also the case in Anomochilus and Cylindrophis 

 (Cundall & Rossman 1993; Cundall et al. 1993). The dorsal lamina 

 of the nasal is variously developed in uropeltines, but tends to be 

 relatively broad and notched anterolaterally in species with a rounded 

 snout, but slender and tapering to a fine tip in species with a strongly 

 telescoped snout. 



The snout complex is suspended from the rest of the skull at the 

 naso-frontal joint (see Rieppel 1978. for details) and through the link 

 provided by the prefrontal (Fig. 3). The maxilla of uropeltines 

 carries a well-developed ascending process that is in a firm planar 

 (i.e., not interdigitating) contact with the prefrontal. Medial to the 

 ascending process, the superior alveolar nerve canal is open dorsally 

 in uropeltines, appearing as a groove on the dorsal surface of the 



Fig. 2 A-E The palate in uropeltine snakes. A, Melanophidiwn wynaudense (BMNH 1930.5.8.124); B, Pseudotyphlops philippinus (BMNH 1978.1092) 

 C, Rhinophis sanguineus (BMNH 1930.5.8.59); D-E, Pseudotyphlops philippinus (BMNH 1978.1092). 



