ELAPIDAE, Boie, 1827

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 : 435-436

ELAPIDAE indet.

MATERIAL EXAMINED. — 3 precaudal vertebrae ( BSPG 1997 XIII 643-645).

LOCALITY. — Griesbeckerzell 1a.

DESCRIPTION

Precaudal vertebrae ( Fig. 13 )

In lateral view, the neural spine is very low, although the distal tip is not preserved in all specimens. In one specimen ( BSPG 1997 XIII 643), the base of the neural spine indicates that the cranial and caudal margins were not inclined. The interzygapophyseal ridges are well developed and the epizygapophyseal ridges are generally missing. Lateral foramina are situated in shallow depressions. The diapophysis is larger than the anteriorly situated parapophysis (both structures are strongly damaged in the largest specimen). The parapophyseal process is very short. The straight subcentral ridges are distinct and extend as far as the postero-ventral tip of the lateral wall of neural arch. The hypapophysis is straight ; the tip is not preserved, but was directed postero-ventrally.

In dorsal view, the largest vertebrae are relatively short and wide.The prezygapophyseal articular facets are broadly oval to subtriangular; the only preserved fragmentary prezygapophyseal process is short and reaches approximately ⅓ to ½ of the prezygapophyseal facet length. The zygosphene possesses a wide median and two distinct lateral lobes. A median notch occurs in the zygosphenal lip in two of the specimens (BSPG 1997 XIII 644, 645).

In ventral view, the anterior base of the hypapophysis is triangularly widened. The triangular ventral surface of the anterior keel is rounded. In middle trunk vertebrae the narrow part of the hypapophysis begins at about ⅓ of the centrum length. Subcotylar tubercles are absent. Subcentral ridges are prominent, relatively sharp, and more prominently expressed in posterior precaudal vertebrae. Subcentral grooves are indistinct in anterior trunk vertebrae, and thus the centrum is triangular in shape and flat. On the other hand, the subcentral grooves are distinct and relatively deep in posterior precaudal vertebrae. The fragmentary postzygapophyseal articular facets are irregular and somewhat enlarged laterally.

In cranial view, the neural arch is moderately vaulted and the neural canal is rounded with wide lateral sinuses. The paracotylar foramina are large and situated in wide bowl-like depression on either side of the rounded cotyle. The ventral base of the cotylar rim is flat.

In caudal view, the neural arch is moderately vaulted; the ventral portion of the lateral walls of neural arch is clearly bent medially. The condyle is rounded. Measurements of the best preserved vertebra are as follows: cl = 5.12 mm; naw = 3.56 mm; cl/naw = 1.44.

DISCUSSION

The trunk vertebrae show the typical features of elapid snakes: 1) low neural spine (although usually not preserved); 2) presence of a short hypapophysis; and 3) weakly developed or absent epizygapophyseal spines. The largest vertebra (BSPG 1997 XIII 643) has a slightly enlarged vertebral centrum, contrary to that of Naja romani (Hoffstetter, 1939) , which is almost identical to that seen in the morphotype Elapidae B from the French early Middle Miocene of Vieux-Collonges ( Ivanov 2000). It appears that the Griesbeckerzell vertebra belongs to the genus Naja Laurenti, 1768 based mainly on the larger dimensions and low cl/naw in comparison to Micrurus (precise measurements were impossible due to poor preservation). Furthermore, this vertebra may be related to certain extant Asiatic members of the genus Naja as suggested by Ivanov (2000).It is possible that the two smaller vertebrae belong to the genus Micrurus .

Figures

FIG. 13.— Elapidae indet.from the Middle Miocene (MN 6, base) of Griesbeckerzell 1a; trunk vertebra (BSPG 1997 XIII 643) in lateral (l), dorsal (d), ventral (v), and caudal (ca) views. Abbreviations: scg, subcentral groove; other abbreviations: see Figure 4.