Chamaeleonidae

Villa, Andrea & Delfino, Massimo, 2019, A comparative atlas of the skull osteology of European lizards (Reptilia: Squamata), Zoological Journal of the Linnean Society 187 (3), pp. 828-928 : 853

Chamaeleonidae ( Fig. 14C–E )

Prefrontals of Chamaeleo chamaeleon have a subrectangular orbitonasal flange, with a moderately shallow ventral concavity ( Fig. 14C ). They are anteroposteriorly elongated in dorsal view ( Fig. 14E ), with an anterior end that is strongly narrower than the posterior one. The anterodorsal process is long and thick, and contacts the anterior dorsal process of the maxilla, forming the dorsal margin of the external nares. A subtriangular or subrectangular orbitonasal flange projection is present on the ventromedial corner of the flange ( Fig. 14C ): it is longer than the moderately small posteroventral process and does not display projections by its tip. Another (lateral) process develops form the anterior margin, just ventrally to the posterior end of the anterodorsal process ( Fig. 15 ). This lateral process is short and moderately large in lateral view, and contacts the facial process of the maxilla. The lateral process marks the lateral margin of the large lacrimal foramen, whose medial margin is composed of a wide notch on the lateral margin of the orbitonasal flange. The dorsal process is laminar, posteriorly rounded and mediolaterally expanded ( Fig. 14D, E ). Its posterior end contacts the postorbital with a slightly interdigitated suture. A series of tubercles with an irregular dorsal margin (but rather rounded) runs along the dorsolateral margin of the bone (i.e. on the anterodorsal process and on the dorsal process; Fig. 14D, E ), forming a continuous ridge that starts on the anterior dorsal process of the maxilla and ends posteriorly on the squamosal (passing also through the postorbital). The dorsal surface of the bone has an ornamentation made of small tubercles ( Fig. 14E ).

Figures

Figure 14. Prefrontals – A–B, Laudakia stellio (HUJ.OST-Z-5), right prefrontal in dorsal (A) and dorsolateral (B) views. C, Chamaeleo chamaeleon (MNHN 2002–24), right prefrontal in posterior view. D–E, Chamaeleo chamaeleon (NHMW 611), left prefrontal in dorsal (D) and medial (E) views. F–H, Lacerta bilineata (MDHC 381), left prefrontal in dorsal (F), lateral (G) and posterior (H) views. I–K, Ophisops elegans (MDHC 281), right prefrontal in dorsal (I), posterior (J) and lateral (K) views. L–N, Ti. lepidus (MDHC 216), left prefrontal in dorsal (L), posterior (M) and lateral (N) views. O–Q, Ab. kitaibelii (MDHC 239), right prefrontal in dorsal (O), posterior (P) and lateral (Q) views. R–T, Tr. aurata (MDHC 280), left prefrontal in dorsal (R), posterior (S) and lateral (T) views. U–W, Anguis gr. An. fragilis (MDHC 102), left prefrontal in dorsal (U), posterior (V) and lateral (W) views. X–Z, Pseudopus apodus (MDHC 214), left prefrontal in dorsal (X), posterior (Y) and lateral (Z) views. Abbreviations: adp, anterodorsal process; dp, dorsal process; n, notch of the lacrimal foramen; ofp, orbitonasal flange projection; onf, orbitonasal flange; pc, palpebral crest; pj, projection; pvp, posteroventral process; t, tubercle. Scale bars = 1 mm.

Figure 15. Articulated skull of Chamaeleo chamaeleon (NHMW 721) in lateral view, showing the lateral process of the prefrontal (lp) and the lacrimal foramen (lf). Scale bar = 1 mm.