ELAPIDAE, Boie, 1827

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 : 369

ELAPIDAE gen. et sp. indet.

( Fig. 16 )

Elapidae gen. et sp. indet. – Ivanov & Musil 2004: 230.

MATERIAL. — MWQ, early Miocene, Burdigalian, Orleanian, MN 4: 1/2001 Turtle Joint: One trunk vertebra (Pal. 1500) .

DESCRIPTION

Trunk vertebra

The only preserved vertebra is fragmentary with loss of the left prezygapophysis and the right prezygapophyseal process. In lateral view, the neural spine is broken-off close to its base, but the caudal part of the neural spine indicates that it was originally rather low. The interzygapophyseal ridges are moderately developed. The epizygapophyseal ridges are missing. The subcentral ridges are arched slightly dorsally. The hypapophysis is straight and its base rises at one quarter of the centrum length. The distal termination of the hypapophysis is absent but apparently it was short and did not reach behind the caudal margin of the condyle. In ventral view, the subcentral grooves are shallow and subcentral foramina are rather small. The postzygapophyseal articular facets are subcircular to irregularly shaped. In cranial view, the neural arch is slightly vaulted, and the neural canal is rounded with a wide diameter and short lateral sinuses. The damaged cranial margin of the zygosphenal lip was arched dorsally with raised zygosphenal facets. The paracotylar foramina occur on either side of the rounded cotyle. The small laterally directed subcotylar tubercles occur at the ventral margin of the rounded cotylar rim. The vertebral dimensions are as follows: cl = 5.40 mm; naw = 3.57 mm; cl/naw = 1.51.

REMARKS

The single preserved vertebra was assigned to the family Elapidae on the basis of the presence of a short and straight hypapophysis that begins far from the ventral margin of the cotylar rim, the absence of epizygapophyseal ridges and the likely presence of a low neural spine. The morphology of Elapidae gen. et sp. indet. is identical with that of a vertebra of Elapidae indet. reported from the late Miocene (MN 9) of Rudabánya, Hungary ( Szyndlar 2005). According toSzyndlar (2005), the only preserved Rudabánya specimen is similar to numerous small-sized elapids known from the European Miocene including Micrurus ( M. gallicus Rage & Holman, 1984 ). However, the Mokrá specimen is larger. Both the morphology and dimensions of the largest vertebra resemble those of vertebral morphotype Elapidae B reported from the French early Miocene (MN 5) Vieux-Collonges site, with the exception of the rather short condylar neck in French specimens (Ivanov 2000: fig. 14). In accordance with Ivanov (2000), on the basis of relatively high cl/naw ratio, we conclude that this middle trunk vertebra of an indeterminate Elapidae from 1/2001 Turtle Joint can be attributed to large-sized elapids of possibly Asiatic origin (perhaps Naja ).

Figures

FIG. 16. — Elapidae gen. et sp. indet. from the early Miocene (MN 4) of MWQ. Trunk vertebra Pal. 1500 (1/2001 Turtle Joint) in right lateral (A), dorsal (B), ventral (C), cranial (D) and caudal (E) views. Abbreviations:cd, condyle; ct, cotyle;hy, hypapophysis;na, neural arch; nc, neural canal; ns, neural spine; pctf, paracotylar foramen; pof, postzygapophyseal articular facet; prf, prezygapophyseal articular facet; scg, subcentral groove; scr, subcentral ridge; sctt, subcotylar tubercle; zyg, zygantrum. Scale bar: 2 mm.