Neochoristodera, Evans & Hecht, 1993

Gao, Ke-Qin & Fox, Richard C., 2005, A new choristodere (Reptilia: Diapsida) from the Lower Cretaceous of western Liaoning Province, China, and phylogenetic relationships of Monjurosuchidae, Zoological Journal of the Linnean Society 145 (3), pp. 427-444 : 439

Suborder Neochoristodera

Consisting of the traditional familial groups, Champsosauridae and Simoedosauridae ( Fig. 6 ), the taxon Neochoristodera as named by Evans & Hecht (1993) designates the same clade as the name Champsosauriformes Hay, 1929. However, the name Neochoristodera has been widely accepted, while the name Champsosauriformes has not been mentioned in the literature for more than 50 years; thus, the latter name is here treated as a nomen oblitum (a forgotten name). The suborder Neochoristodera is a robust clade that can be unambiguously diagnosed by the following synapomorphies: external nares terminal and confluent (1-2; possibly also in Cteniogenys ); dorsal flange of maxilla low and strongly inrolled (6-2); nasals elongate and fused (9-2); nasals intervene between premaxillae (10-1); orbit small and dorsally directed (11- 2); dorsal process of squamosal slender and elongate to middle level of infratemporal fenestra (13-1); supratemporal fenestra posteriorly flared and substantially larger than orbit (14-2); vomer/maxilla contact present (19-1); palatal foramen opens between pterygoid and palatine without contribution from the vomer (21-2); quadratojugal bears a cotyle meeting a rounded quadrate articulation (26-1); pterygoid process of quadrate low, slender and horizontal with a reduced pterygoid facet (27-1); nasopalatal trough present (29-1); pterygoids meeting in a long midline suture (31-1); interpterygoid vacuity small and near posterior border of suborbital fenestra (32-1); basal infolding of tooth enamel present (37-1); pterygoquadrate foramen present and enclosed between neomorph and quadrate (41-1); neurocentral sutures remain open in adult (51-1); presacral vertebral centra short and spool-like (53-1); number of ossified carpal elements seven or fewer (60-1); bone structure pachyostotic in adult (62-2); iliac blade dorsal margin essentially horizontal, blade expanded (63-1); clavicular facet on interclavicle continuous across midline in smooth curve (66-1); constriction of ilium between iliac blade and acetabulum as a well-defined neck (74-1; reversal in Ikechosaurus ).

Figures

Figure 6. Comparison of the two equally parsimonious trees (TL = 123 steps; CI = 0.85; RI = 0.87) derived from analysis of data presented in Appendices 1 and 2.