Micrurus cf. gallicus Rage & Holman, 1984

Ivanov, Martin & Böhme, Madelaine, 2011, Snakes from Griesbeckerzell (Langhian, Early Badenian), North Alpine Foreland Basin (Germany), with comments on the evolution of snake faunas in Central Europe during the Miocene Climatic Optimum, Geodiversitas 33 (3), pp. 411-449 : 433-434

Micrurus cf. gallicus Rage & Holman, 1984

MATERIAL EXAMINED. — 1 precaudal vertebra ( BSPG 1997 XIII 642).

LOCALITY. — Griesbeckerzell 1a.

DESCRIPTION

Precaudal vertebra ( Fig. 12 )

In lateral view, the vertebra is elongated. The neural spine is low; the cranial margin was most probably vertical or inclined caudally.The interzygapophyseal ridges are moderately well developed. The lateral foramina are small and not situated in depressions.The subcentral ridges are blunt but well developed, and extend from the heavily damaged synapophyses to the proximal margin of the condyle; they are slightly bent in dorsal direction.The distal tip of the straight and probably short hypapophysis is broken off.

In dorsal view, the zygosphenal lip shows a wide median and two distinct lateral lobes. The prezygapophyses are broken off. Epizygapophyseal spines are missing.

In ventral view, the hypapophysis extends cranially as far as the smooth cotylar rim. Blunt subcentral ridges are separated from the hypapophysis by wide and shallow subcentral grooves. The subcentral foramina are extremely small and barely visible at the base of the hypapophysis. The postzygapophyseal articular facets are subrectangular.

In cranial view, the neural arch is moderately and regularly vaulted; the neural canal (filled with firm sediment) displays wide lateral sinuses. The zygosphenal lip is almost straight, it is wide in comparison to the rounded cotyle.

In caudal view, the postzygapophyseal articular facets are horizontal and the zygantral area (also filled with firm sediment) is relatively wide. The condyle is rounded.Measurements of the vertebra are as follows: cl = 4.55 mm; naw = 3.02 mm; cl/naw = 1.51.

DISCUSSION

The vertebra represents an adult individual with a neural canal that is characterized by a large diameter in comparison with the cotyle. Relatively small dimensions of the vertebra, together with an elongated vertebral centrum, short hypapophysis directed more posteriorly than ventrally, low neural (l) ns (d) (v) spine, and small cotyle and condyle are typical for the genus Micrurus . The vertebra does not differ from that of Micrurus gallicus reported originally from the French late Middle Miocene locality La Grive M ( Rage & Holman 1984). However, the material does not allow for a safe species identification.

Figures

FIG. 12. — Micrurus cf. gallicus from the Middle Miocene (MN 6, base) of Griesbeckerzell 1a; trunk vertebra (BSPG 1997 XIII 642), in lateral (l), dorsal (d), ventral (v), and caudal (ca) views. Abbreviations: see Figures 4 & 6.