latitudes prefer lower elevations and environments that have more vegetation and moisture. Behavior All species are terrestrial. Reproduction All members are viviparous, giving birth to live young. Venom Most Vipera species have venom that contains both neurotoxic and haemotoxic components. Bites vary widely in severity. V. ammodytes is most likely the one with the most toxic venom. In a study solely involving mice, Brown (1973) shows that the LD50 is about 1.2/mg/kg through an IV, 1.5 mg/Kg when injected in the peritoneum (IP) and 2.0 mg/kg when administered subcutaneously. V. berus venom is considered to be on the lower end of the scale when it comes to toxicity, (Minton, 1974) suggests that the LD50 values for mice are about 0.55 mg/kg IV, 0.80 mg/kg IP and 6.45 mg SC. Venom yield tends to be lower in this species with Minton citing 10–18 mg per bite in specimens 48–62 cm while Brown suggest only 6 mg for the same sized specimens. However, bites from Vipera species are rarely as severe as those from larger Macrovipera or Daboia. Fossil record The oldest species of this genus is the Early Miocene Vipera antiqua from Southern Germany. The earliest known Vipera antiqua fossil has been dated to 22.5 million years ago. A very large indeterminate Vipera was found in the Early Pliocene deposits of Mallorca. This species surpassed in size all modern relatives, with a length of nearly , and was one of the biggest predators of its ecosystem. Species * Not including the nominate subspecies. T: type species References Further reading Arnold EN, Burton JA (1978). A Field Guide to the Reptiles and Amphibians of Britain and Europe. London: Collins. 272 pp. . (Genus Vipera, pp. 211, 214). Boulenger GA (1896). Catalogue of the Snakes in the British Museum (Natural History). Volume II., Containing the ... Viperidæ. London: Trustees of the British Museum (Natural History). (Taylor and Francis, printers). xiv + 727 pp. + Plates I-XXV. (Genus Vipera, pp. 471–472.) Laurenti JN (1768). Specimen medicum, exhibens synopsin reptilium emendatam cum experimentis circa venena et antidota reptilium austriacorum. Vienna: Joan. Thom. Nob. de Trattnern. 214 pp. + Plates I-V. (Genus Vipera, p. 99). (in Latin). External links Snake genera Taxa named by Josephus Nicolaus Laurenti