Chamaeleo chamaeleon (Linnaeus, 1758)

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 : 83-91

chamaeleon than with Hoplocercus spinosus , Polychrus marmoratus , or Iguana iguana .

DIAGNOSIS: This stem-based taxon diagnosed by the following unambiguous synapomorphies: 27(1) absence of midline contact of the maxillae behind the premaxillary nasal process, 90(0) absence of a postorbital tuberosity, 117(0) absence of ventromedial processes (basipterygoid buttresses) on the pterygoid, 118(2) absence of pterygoid teeth, and 189(0) a shortened splenial (see character description above).

COMMENTS: Chamaeleontiformes, as defined here, is essentially equivalent to Cha- Fig. 55. Continued.

Fig. 55.

maeleonidae as described by Frost and Etheridge (1989). Frost and Etheridge considered their Chamaeleonidae to be ‘‘equivalent to Acrodonta of Estes et al. (1988)’’ ( Frost and Etheridge, 1989: 32), but explicitly

Continued.

included the Priscagama gobiensis and Priscagaminae as incertae sedis. Estes et al. (1988) defined Acrodonta as a crown group and in both Frost and Etheridge (1989) and, in the current analysis (figs. 16A, 17A, 18A), the

Fig. 55. Continued.

Fig. 55.

Priscagama gobiensis -like taxa fall outside the radiation of acrodonts. Thus, Chamaeleontiformes is used to name the clade Frost and Etheridge (1989) recognized as Chamaeleonidae .

Isodontosaurus gracilis is a chamaeleontiform according to the current analysis. Isodontosaurus bears an unusual combination apomorphic features making it somewhat problematic for phylogenetic placement ( Gao and Norell, 2000) and also make it a reasonable intermediate between ‘‘iguanids*’’ and higher chamaeleontiforms. A more complete morphological treatment may add further evidence to support this phylogenetic hypothesis.

A recent analysis by Conrad and Norell (2007a) identifies a dichotomy between cha- Continued.

maeleontiforms and pleurodontans. In that analysis Isodontosaurus gracilis is found to be a basal iguanomorph. Further investigation may help to sort out the differences between this analysis and that one.

Although Chamaeleo chamaeleon is used in the definition of this taxon, it does not appear in the phylogenetic analysis. However, the monophyly chamaeleonids has never been questioned, and Chamaeleonidae is consistently cited as an unmistakable natural group (see the section on taxon sampling above; also see Hillenius, 1978; Moody and Rocek, 1980; Rieppel, 1981b, 1987; Estes et al., 1988; Frost and Etheridge, 1989; Macey et al., 2000).

All of the chamaeleontiforms currently included in the analysis are from Africa, Fig. 56. Continued. Fig. 56. Continued.

Fig. 56.

Asia, Australia, or Europe. The fossil priscagamids and the potential chamaeleontiform Arretosaurus ornatus (see below) are from Mongolia. Tinosaurus and Pseudotinosaurus were not included in the present analysis, but show some chamaeleontiform and/or acrodontan characteristics, including acrodont dentition with heterodonty ( Marsh, 1872; Estes, 1983; Rage, 1987; Alifanov, 1993b; Augé and Smith, 1997; Li and Xue, 2002; Auge´, 2003). The various species of Tinosaurus and Pseudotinosaurus are all poorly known; they are represented by fragmentary maxillae and dentaries that may or may not Continued.

be diagnostic at the generic or specific levels and probably do not form monophyletic groups. Even so, Tinosaurus stenodon ( Marsh, 1872) is significant in that it probably represents the only known American chamaeleontiform.