Elapidae, Boie, 1827

Ivanov, Martin, 2000, Snakes of the lower / middle Miocene transition at Vieux Collonges (Rhône, France), with comments on the colonisation of western Europe by colubroids, Geodiversitas 22 (4), pp. 559-588 : 582-583

Elapidae B

Elapidae B – Ivanov 1997a: 135-137, fig. 63.

MATERIAL EXAMINED. — 17 trunk vertebrae ( FSL 369199- FSL 369208, FSL 369209- FSL 369215).

DESCRIPTION

Trunk vertebrae ( Fig. 14 )

In lateral view, the neural spine is very low, the cranial margin of the neural spine does not overhang anteriorly, the caudal margin is vertical. The interzygapophyseal ridges are mostly welldeveloped, the small lateral foramina are not situated in depressions. The distinct subcentral ridges are clearly arched dorsally. The relatively straight and very short hypapophysis is directed caudally. Its distal tip is pointed or slightly rounded. The para- and diapophyses are wellseparated from each other and the diapophyses are about as large as the parapophyses. Viewing dorsally, the diapophyses are directed posterolaterally. The parapophyseal processes are short and directed anteriorly. The condyle is situated on a short neck. In dorsal view, the zygosphenal lip exhibits distinct lateral lobes, the wide medi- an lobe is often damaged. The damaged prezygapophyseal articular surfaces were originally most probably oval, the broken off prezygapophyseal processes were probably short. Epizygapophyseal spines are lacking. In ventral view, the hypapophysis is sharp and its anterior keel expands near the cotyle. The rounded subcentral ridges are often prominent, the subcentral grooves are wide and deep only in the cranial part of vertebrae. The small subcotylar tubercles are present. The subcentral foramina are minute. In cranial view, the neural arch is more or less vaulted with the circular neural canal and the convex zygosphenal lip. The parapophyseal processes are separated from the cotyle by relatively shallow furrows. The prominent paracotylar foramina occur within deep depressions at both sides of the cotyle which is rounded to weakly flattened dorso-ventrally. The measurements of the largest vertebrae are as follows (n = 8): cl: or = 4.35-6.71; naw: or = 2.98-4.53; cl/naw: or = 1.42-1.50, mean 1.47 + 0.03.

DISCUSSION

The vertebrae have considerably elongated vertebral centra, thus at the first sight, they may suggest representatives of the subfamily Natricinae , especially Natrix or Neonatrix , rather than elapids. However, these two genera are characterised by the markedly higher neural spine and smaller dimensions ( Neonatrix ). The vertebrae of the morphotype Elapidae B are relatively large. They are assigned to the family Elapidae on the basis of the occurrence of hypapophyses in trunk vertebrae and as well as on the basis of the low neural spine. Based on the shape of the neural spine, the vertebrae belong most probably to the genus Naja . Because of the high ratio cl/naw, it is assumed that the vertebrae probably belong to the representatives of the Asiatic rather than African cobras. The morphotype Elapidae B differs from the Elapidae A in: 1) the larger dimensions of vertebrae; 2) the higher neural spine.

Figures

FIG. 14. — Elapidae B from the lower/middle (MN 4/5) Miocene of Vieux Collonges, trunk vertebra (FSL 369214); A, lateral view; B, dorsal view; C, ventral view; D, cranial view; E, caudal view. Scale bar: 2 mm.