Naja cf. romani (Hoffstetter, 1939)

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 : 577-579

Naja cf. romani (Hoffstetter, 1939)

Part – Palaeonaja romani . — Rage 1984: 54.

Part – Naja cf. N. romani (Hoffstetter, 1939) . — Szyndlar & Rage 1990: 387, fig. 1.

Naja sp. 1 – Ivanov 1997a: 130-131, fig. 60. MATERIAL EXAMINED. — 2 cervical vertebrae (FSL 369104, FSL 369105), 35 trunk vertebrae (FSL 369106-FSL 369115, FSL 369116-FSL 369140).

DESCRIPTION

Cervical vertebrae ( Fig. 12 A-D)

The vertebrae have short and wide vertebral centra. In lateral view, the neural spine is lower than long, its cranial margin is almost vertical or overhangs slightly posteriorly, the caudal margin overhangs posteriorly. The interzygapophyseal ridges are prominent, the distinct lateral foramina are situated in deep depressions below the interzygapophyseal ridges. The subcentral ridges are considerably developed, extending from the synapophyses to the proximal margin of the condyle. The heavily built hypapophysis is long and directed postero-ventrally. Unfortunately, its distal tip is broken off. The para- and diapophyses are well-separated from each other, the posterolaterally directed diapophyses are approximately as large as the parapophyses. The parapophyseal processes are short, directed anteriorly rather than antero-ventrally. In dorsal view, the zygosphenal lip is concave or straight (however, it may be possible that the cranial margin of the zygosphene was most likely damaged). The damaged prezygapophyseal articular surfaces were probably suborbicular, the prezygapophyseal processes are broken off at the base. Epizygapophyseal spines are indistinct. In ventral view, subcotylar tubercles occur on the ventral margin of the cotyle. Both the subcentral ridges and wide subcentral grooves are well developed, the subcentral foramina are small. The postzygapophyseal articular surfaces are roughly rounded. In cranial view, the neural arch is vaulted and the subcircular neural canal has distinct lateral sinuses. The zygosphenal lip is slightly convex. The paracotylar foramina are situated in deep and wide depressions on both sides of the rounded cotyle.

Trunk vertebrae ( Fig. 12 E-I)

The vertebrae are characterised by the relatively short and wide centra, which is a typical feature of the large colubrids. In lateral view, the neural spine is somewhat lower than long. The cranial margin of the neural spine is almost vertical, the caudal margin overhangs posteriorly. The interzygapophyseal ridges are prominent. The lateral foramina are distinct and situated in deep wide depressions. The subcentral ridges are straight or weakly arched dorsally. Epizygapophyseal spines are under-developed. The para- and diapophyses are not distinct from each other, the parapophyses are as large as the diapophyses or somewhat larg- er. The parapophyseal processes are relatively long and directed anteriorly rather than antero-ventrally. The hypapophyses are broken off at the base. In dorsal view, the zygosphenal lip is concave to straight (in many vertebrae a mechanical damage is possible), the prezygapophyseal articular surfaces are wide and oval to suborbicular, the fragmentary prezygapophyseal processes are heavily built and relatively long. Dorsal expansion of the neural spine has not been noticed. In ventral view, the prominent subcentral ridges and the deep subcentral grooves are visible. Both structures are best developed in posterior trunk vertebrae. The subcentral foramina are small and difficult to recognise. The parapophyseal processes are obtuse. The hypapophysis is gracile, the anterior keel expands near the ventral margin of the cotyle. The subcotylar tubercles are often developed. The postzygapophyseal articular surfaces are irregularly shaped. In cranial view, the neural arch is moderately arched, the neural canal is circular with short lateral sinuses, the zygosphenal lip is straight to concave. The shallow furrows separating the parapophyseal processes from the rounded cotyle are narrowed by the subcotylar tubercles. The paracotylar foramina are situated at the inner margins of deep depressions on both sides of the cotyle. The metrical measurements are as follows (n = 11): cl: or = 6.21-8.75; naw: or = 5.09-8.25; cl/naw: or = 1.01-1.28, mean 1.13 + 0.09.

DISCUSSION

The discovered vertebrae belong to a typical representative of the family Elapidae . The vertebrae are relatively large with a low ratio cl/naw and have a flattened and wide vertebral centra. Therefore, the vertebrae are assigned to the genus Naja . Three species of large cobras have been discovered in the European Cenozoic: Naja romani (Hoffstetter, 1939) , Naja iberica Szyndlar, 1985 and “ Naja (?) depereti (Hoffstetter, 1939) ”. The last known species – Naja antiqua Rage, 1976 has been reported from the middle Miocene (MN 7) of Beni Mellal in Morocco (Rage 1976). The vertebrae of Naja cf. romani are most similar to the species N. romani and especially to the material from the Austrian locality Kohfidisch (MN 11) originally (Bachmayer & Szyndlar 1985) assigned to the extinct species Naja austriaca . The species Naja austriaca was established especially because of the

A B C D

F

G

shape of the zygosphenal lip which is concave (cervical and trunk vertebrae) to crenate with three distinct lobes (posterior trunk vertebrae). The study of some East European localities (including Gritsev, Ukraine) showed that intraspecific variability has existed within the described snakes; therefore, N. austriaca was synonymised with N. romani (Szyndlar & Zerova 1990) . The vertebrae of Naja cf. romani resemble Naja romani from Kohfidisch not only in the shape of the zygosphenal lip but also in the vertical cranial margin of the neural spine. N. cf. romani differs from the recent representatives of the Asiatic cobras – N. naja (Linnaeus, 1758) (ZZSiD 358), N. spu- tatrix (Boié, 1827) (ZZSiD 470) and N. oxiana (Eichwald, 1831) (ZZSiD 474) – in the lower neural spine and the longer prezygapophyseal processes (Szyndlar 1991a).

Figures

FIG. 12. — Naja cf. romani from the lower/middle (MN 4/5) Miocene of Vieux Collonges; A-D, cervical vertebra (FSL 369105); A, lateral view; B, dorsal view; C, ventral view; D, cranial view; E-I, trunk vertebra (FSL 369113); E, lateral view; F, dorsal view; G, ventral view; H, cranial view; I, caudal view. Scale bar: 2 mm.