The first record of viperid snakes (Reptilia, Serpentes) from the Balearic Islands (Spain): fossils from the Neogene, with description of a new species from the Pliocene.

Two viperid snakes, Vipera natiensis sp. n. (belonging to the Vipera aspis group) and Vipera sp., have been found in the Pliocene of Minorca. On the other hand, an indeterminate viperid extends back the fossil record of the family in the Balearic Islands, to the Middle Miocene. These fossils represent the first report of viperids from the Balearic Islands. Vertebra of Vipera natiensis sp. n. are characterised by a concave anterior border of zygosphene, dorsoventrally flattened, short (as wide as long) and blunt prezygapophyseal processes. Centrum convex in transverse section, subcentral margins poorly marked and presence of two well defined subcotylar tubercles. Hypapophysis located posteriorly on the centrum and not prolonged anteriorly, or only slightly prolonged as a keel. The dorsal border of the neural spine is slightly thickened; the posterior border of the neural spine is markedly inclined posteriorly; as a result, the spine forms a posterior point, which is more or less developed, depending on the position of the vertebra along the vertebral column. The presence of Viperidae in the Neogene of the Balearic Islands involves the existence of a terrestrial connection between this archipelago and the continent during the Early Miocene and/or Middle Miocene and perhaps the presence of a later connection during the Late Miocene.