Ophisaurus, Daudin, 1803

Ivanov, Martin, Čerňanský, Andrej, Bonilla-Salomón, Isaac & Luján, Àngel Hernández, 2020, Early Miocene squamate assemblage from the Mokrá-Western Quarry (Czech Republic) and its palaeobiogeographical and palaeoenvironmental implications, Geodiversitas 42 (20), pp. 343-376 : 354

Ophisaurus sp.

( Fig. 6 A-E)

MATERIAL. — MWQ, early Miocene, Burdigalian, Orleanian, MN 4: 1/2001 Turtle Joint: one trunk vertebra (Pal. 1407).

DESCRIPTION

Trunk vertebra

The vertebra is robustly built. The neural spine starts to rise dorsally from the area of anterior region of the neural arch. However, the dorsal portion of the neural spine is damaged. In lateral aspect, the neural spine reaches posteriorly only to the level of the anterior end of the condyle. The oval, tunnel-like neural canal is medium-sized. Pre- and postzygapophyses are well expanded laterally,but the interzygapophyseal constriction is relatively shallow, notas deep as it is inthe Pseudopus vertebrae described above.This gives Pal.1407 a broad appearance in dorsal aspect. The prezygapophyses are dorsally inclined at an angle of around 33°.The articular surfaces are large, elliptical and oblong laterally. In anterior aspect, a pair of foramina is located ventral to the prezygapophyses, approximately at the level of the dorsal margin of the cotyle.In lateral aspect,the postzygapophyses reach posteriorly approximately to the level of the mid-region of the condyle.Both condyle and cotyle are depressed.The synapophyses are well-developed, large, and located close to the anterior edge of the neural arch pedicel. They are slightly posterolaterally oriented. The ventral region of the centrum is flat, although it has two visible edges which run from the level of the cotyle and gradually weaken posteriorly. A pair of subcentral foramina is located close to the cotyle. The subcentral ridges are concave.

REMARKS

The trunk vertebra described here can be allocated to Ophisaurus based on the following features ( Čerňanský et al. 2019): 1) the lateral margins of the centrum (subcentral ridges) are concave; and 2) the height of the neural canal is greater than the height of the cotyle.

Figures

FIG. 6. — Ophisaurus and Anguinae indet. from the early Miocene (MN 4) of MWQ. Trunk vertebra Pal. 1407 (1/2001 Turtle Joint) of Ophisaurus sp. in (A) lateral, (B) dorsal, (C) ventral, (D) anterior and (E) posterior aspects. Anguinae indet.: right coronoid Pal. 1408 (1/2001 Turtle Joint) in (F) lateral, (G) medial and (H) dorsal aspects. Osteoderms Pal. 1577-1579 (2/2003 Reptile Joint) in (I-K) external aspects. Abbreviations: alp, anterolateral process; amp, anteromedial process; cd, condyle; ct, cotyle; dp, dorsal process; mr, medial ridge; muc, muscular crest; nc, neural canal; ns, neural spine; nt, notch; os, overlap surface; pof, postzygapophyseal articular facet; pp, posterior process; prf, prezygapophyseal articular facet; rd, ridge; scs, scupltured surface; syn, synapophysis. Scale bars: 2 mm.