SERPENTES, Linnaeus, 1758

Albino, Adriana María, 2000, New record of snakes from the Cretaceous of Patagonia (Argentina), Geodiversitas 22 (2), pp. 247-253 : 250-251

Order SERPENTES incertae sedis ( Fig. 3 )

MATERIAL EXAMINED. — MPEF-PV 642, trunk vertebra.

REMARKS

It is a small, narrow, rather depressed and elongated vertebra. It has no marked median notch in the posterior border of the neural arch. This is a plesiomorphic state in snakes. The roof of the neural arch is depressed in posterior view. The neural spine is long, inclined and posteriorly thick. The zygapophysial plane is located at a high level and the prezygapophysial facets are clearly slanting like in primitive snakes. There is not a true prezygapophysial process (plesiomorphic state), although there is an expansion under the prezygapophysial articular facets and the vertebra is wider at that level. The postzygapophyses are at a higher level than the prezygapophyses. The thin zygosphene is narrower than the cotyle, it is elevated at a medium level and its roof is not notched. The neural canal is large. The subcentral ridges of the vertebral centrum are not well defined and anteriorly the centrum is not significantly widened. There is not a marked haemal keel. The cotyle is large, wider than high and there are no paracotylar foramina. The subcentral and lateral foramina are present. The combination of characters in the fossil has not been found in any known snake, however, it is not conven-

D

ient to designate a new taxon because at the moment there is a unique preserved vertebra.

Figures

FIG. 3. — MPEF-PV 642, Serpentes incertae sedis, trunk vertebra. A, anterior view; B, posterior view; C, lateral view; D, dorsal view; E, ventral view. Scale bar: 3 mm.