Serpentes Linnaeus, 1766

Conrad, J. L., 2008, Phylogeny And Systematics Of Squamata (Reptilia) Based On Morphology, Bulletin of the American Museum of Natural History 2008 (310), pp. 1-182 : 107

Serpentes Linnaeus, 1766

(figs. 54C, 55C, 56B)

DEFINITION: Typhlops lineolatus ater , Anomalepis mexicanus , Vipera aspis , Python molurus , and all descendants of their last common ancestor.

DIAGNOSIS: This clade is diagnosed by 16(1) nonsutural contacts between the premaxilla and maxilla, 29(1) weakly inclined anterior margin of the maxillary nasal process, 31(0) paleochoanate condition, 61(3) subolfactory processes of the frontal contact the parasphenoid, 65(0) frontal fails to contact the maxilla, 91(1) absence of a postfrontal, 135(1) absence of a processus ascendens tecti synotici, 150(2) elongate, posterolaterally directed, spheno-occipital tubercles, 167(1) absence of a mandibular symphysis, 180(0) dentary extends posteriorly no further than the coronoid process, 181(0) Meckel’s canal open, 184(2) absence of a posterodorsal coronoid process on the dentary, 187(2) dentary primarily supported by the surangular, 190(1) posterior terminus of the splenial at or anterior to the coronoid apex, 191(2) presence of an intramandibular joint in which the angular receives the splenial, 194(1) anterior end of coronoid abutting the dentary (rather than overlapping it), 210(0) retroarticular process without torsion, 214(2) ‘‘modified pleurodont’’ dental attachment (sensu Zaher and Rieppel, 1999a), and 235(2) presence of zygosphenes which face ventrolaterally (fig. 44B).

COMMENTS: The definition of Serpentes as a node containing extant snakes here is in keeping with those of previous such definitions and applications of the group name ( Rage, 1984; Estes et al., 1988; Lee, 1997, 1998, 2000, 2001; Lee and Caldwell, 2000; Caldwell, 1999a; Apestiguía and Zaher, 2006). Under this definition, Ophidia might be invoked as a stem-based name to include taxa that would be identified as snakes, but which fall outside of the crown group (e.g., Najash rionegrina ; Apestiguía and Zaher, 2006).