COLUBRIDAE, Oppel, 1811

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 : 362

COLUBRIDAE gen. et sp. indet.

( Fig. 11 )

MATERIAL. — MWQ, early Miocene, Burdigalian, Orleanian, MN 4: 1/2001 Turtle Joint: One trunk vertebra (Pal. 1484).

DESCRIPTION

Trunk vertebra

This vertebra is strongly damaged. In lateral view, the cranial margin of the neural spine is inclined anteriorly, and the caudal margin was probably inclined posteriorly. The neural spine was 1.5 times longer than high. The zygosphenal facets are widely oval in outline. In dorsal view, the prezygapophyseal articular facets are oval with the long axis directed anterolaterally. In ventral view, the subrectangular postzygapophyseal articular facets are slightly laterally elongated. In cranial view, the neural arch is vaulted. The neural canal is rounded with markedly developed lateral sinuses. The zygosphenal roof is moderately arched dorsally. Small paracotylar foramina occur on both sides of the rounded cotyle.

REMARKS

This fragmentary vertebra represents the largest colubrid specimen reported from MWQ. The vaulted neural arch, the high neural spine, the presence of parapophyseal processes (broken-off at the base) as well as paracotylar foramina on either side of the cotyle undoubtedly indicate assignment to Colubridae . However, we cannot observe the ventral part of the vertebra to check the presence/absence of a haemal keel or hypapophysis. The vertebra lacks the strong elongation and cylindrical shape of the neural arch frequently occurring in European “natricines”. Therefore, we conclude that the vertebra most probably belonged to a large-sized “ Colubrinae ”.

Figures

FIG. 11. — Colubridae gen. et sp. indet. from the early Miocene (MN 4) of MWQ. Trunk vertebra Pal. 1484 (1/2001 Turtle Joint) in right lateral (A), dorsal (B) and cranial (C) views. Abbreviations: ct, cotyle; d, diapophysis; lf, lateral foramen; na, neural arch; nc, neural canal; ns, neural spine; pctf, paracotylar foramen; prf, prezygapophyseal articular facet; zy, zygosphene. Scale bar: 2 mm.