Anguidae

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 : 873

Anguidae ( Figs 27Q–T , 28O–R )

In European anguids, the pterygoid has a long, slender and pointed palatine process. Both margins of this process are straight, but the lateral one can have some irregularities. The pterygoid flange is distinctly shorter (roughly half the length of the palatine process) and very slender, with a very prominent dorsal ridge. The ventral ridge is poorly developed in Anguis gr. An. fragilis ( Fig. 27R ), but well developed in Pseudopus apodus ( Fig. 27T ). The pterygoid recess is wide, deep and U-shaped in dorsal view. The long and straight quadrate process is pointed in both dorsal and lateral views. The fossa columellae is wide and deep, whereas the basipterygoid fossa is flattened, but marked by flanges both dorsally and ventrally. The flanges are moderately developed and rounded, except for the ventral one of Pseudopus apodus [the basisphenoid process of Klembara et al. (2010)], which is longer and thumb-like ( Fig. 27S, T ). The pterygoid ridge can be low or moderately developed. Pterygoid teeth are absent in Anguis gr. An. fragilis ( Fig. 27R ), but present in Pseudopus apodus ( Fig. 27T ). The maximum length of the pterygoid of Anguis gr. An. fragilis ranges from 6 mm to 10.6 mm, whereas it varies from 13 mm to more than 20 mm in Pseudopus apodus .

ECTOPTERYGOID

The ectopterygoid ( Fig. 29 ) is a small and paired bone, the morphology of which varies greatly among different groups.

Figures

Figure 27. Pterygoids. A–B, Laudakia stellio (HUJ.OST-Z-423), right pterygoid in dorsal (A) and ventral (B) views. C–D, Al. fitzingeri (MDHC 351), left pterygoid in dorsal (C) and ventral (D) views. E–F, Ti. lepidus (MDHC 216), left pterygoid in dorsal (E) and ventral (F) views. G–H, Ab. kitaibelii (MDHC 239), left pterygoid in dorsal (G) and ventral (H) views. I–J, Chalcides chalcides (MDHC 94), left pterygoid in dorsal (I) and ventral (J) views (the tip of the pterygoid flange is broken). K–L, Chalcides ocellatus (MDHC 250), right pterygoid in dorsal (K) and ventral (L) views. M–N, Ophiomorus punctatissimus (MDHC 427), right pterygoid in dorsal (M) and ventral (N) views. O–P, Tr. aurata (MDHC 280), left pterygoid in dorsal (O) and ventral (P) views. Q–R, Anguis gr. An. fragilis (MDHC 102), right pterygoid in dorsal (Q) and ventral (R) views. S–T, Pseudopus apodus (MDHC 215), left pterygoid in dorsal (S) and ventral (T) views (the anterior end of the palatine process is broken). U–V, Laudakia stellio (HUJ.OST-Z-423), right pterygoid in lateral (U) and medial (V) views. W–X, Chamaeleo chamaeleon (NHMW 611), right pterygoid in lateral (W) and medial (X) views. Abbreviations: bf, basipterygoid fossa; bp, basisphenoid process; fc, fossa columellae; isp, insertion surface of the pterygoideus muscle; pf, pterygoid flange; pp, palatine process; pre, pterygoid recess; pri, pterygoid ridge; qp, quadrate process; rpm, ridge for the insertion of the pterigomandibular muscle; rsp, ridge for the insertion of the superficial pseudotemporal muscle; vf, ventral flange. Scale bars = 1 mm.

Figure 28. Pterygoids (continued). A–B, Al. fitzingeri (MDHC 351), left pterygoid in lateral (A) and medial (B) views. C–D, Ti. lepidus (MDHC 216), left pterygoid in lateral (C) and medial (D) views. E–F, Ab. kitaibelii (MDHC 239), left pterygoid in lateral (E) and medial (F) views. G–H, Chalcides chalcides (MDHC 94), left pterygoid in lateral (G) and medial (H) views (the tip of the pterygoid flange is broken). I–J, Chalcides ocellatus (MDHC 250), right pterygoid in lateral (I) and medial (J) views. K–L, Ophiomorus punctatissimus (MDHC 427), right pterygoid in lateral (K) and medial (L) views. M–N, Trachylepis aurata (MDHC 280), left pterygoid in lateral (M) and medial (N) views. O–P, Anguis gr. An. fragilis (MDHC 102), right pterygoid in lateral (O) and medial (P) views. Q–R, Pseudopus apodus (MDHC 215), left pterygoid in lateral (Q) and medial (R) views (the anterior end of the palatine process is broken). Abbreviations: bf, basipterygoid fossa; isp, insertion surface of the pterygoideus muscle; pri, pterygoid ridge. Scale bars = 1 mm.

Figure 29. Ectopterygoids. A–E, Laudakia stellio (MDHC 245), left ectopterygoid in anterior (A), dorsal (B), ventral (C), medial (D) and lateral (E) views. F–J, Chamaeleo chamaeleon (MNHN 2002–24), right ectopterygoid in anterior (F), dorsal (G), ventral (H), medial (I) and lateral (J) views. K–L, Ac. erythrurus (UAM.R.ACVII), right ectopterygoid in ventral (K) and dorsal (L) views. M–N, Lacerta agilis (MDHC 176), left ectopterygoid in ventral (M) and dorsal (N) views. O–P, Z. vivipara (UAM.R.Lv24), right ectopterygoid in ventral (O) and dorsal (P) views. Q–R, Ab. kitaibelii (MDHC 239), right ectopterygoid in ventral (Q) and dorsal (R) views. S–T, Chalcides ocellatus (MDHC 250), right ectopterygoid in ventral (S) and dorsal (T) views. U–V, Ophiomorus punctatissimus (MDHC 427), right ectopterygoid in ventral (U) and dorsal (V) views. W–X, Tr. aurata (MDHC 280), right ectopterygoid in ventral (W) and dorsal (X) views. Y–Z, Anguis gr.An. fragilis (MDHC 102), right ectopterygoid in ventral (Y) and dorsal (Z) views. AA–AB, Pseudopus apodus (MDHC 215), left ectopterygoid in ventral (AA) and dorsal (AB) views. Abbreviations: al, anteromedial lappet of the posteromedial process; alp, anterolateral process; asm, articulation surface with the maxilla; asp, articulation surface with the pterygoid flange; dl, dorsal lappet of the posteromedial process; plp, posterolateral process; pmp, posteromedial process; vl, ventral lappet of the posteromedial process; vp, ventral process. Scale bars = 1 mm.