comment on this calibration


 node name
Viperinae     Look for this name in NCBI   Wikipedia   Animal Diversity Web
  recommended citations Head et al. 2016
  node minimum age
20 Ma
The minimum age is for the youngest age for Neogene Mammal (MN) Biochron 2, based on the age of the St-Gérand-le-Puy complex (Szyndlar and Rage, 1999, 2001). The youngest absolute age for MN2 is poorly constrained, but a minimum age of 20.0 Ma is estimated, based on correlation of the oldest MN3 fossil localities with Geomagnetic Polarity Timescale (GMPT) chron C6n (Agustí et al., 2001). Many St-Gérand-le-Puy localities are within MN 2a (e.g., Göhlich et al. 2005). If the St-Gérand-le-Puy viperid fossils are from these localities, then the minimum age would be slightly older at the top of GMPT chron 6AAn, dated to approximately 21.8 Ma (Sen, 1997 after Agustí et al., 2001).
  node maximum age
23.8 Ma
The maximum age is for the base of MN 1, the age of the oldest viperid fossil from Weisenau, Germany (Szyndlar and Böhme, 1993; Szyndlar and Rage, 1999, 2002).
 primary fossil used to date this node 
MNHNFr SG 13733
Vipera aspis complex, NO REFERENCE
Location relative to the calibrated node: Stem

[show fossil details]
     Locality: St-Gérand-le-Puy
     Geological age: Miocene, Neogene, Cenozoic

  phylogenetic justification
Assignment to Viperidae is based on a large, elongate, straight, and posteroventrally angled hypapophyses, laterally short prezygapophyseal accessory processes, large cotyle and condyle, low and flattened posterior neural arch, and elongate, anteroventrally angled parapophyseal process (sensu Head, 2005) (Szyndlar, 1991b; Szyndlar and Rage, 1999). Assignment to Viperinae relative to Crotalinae is based on the presence of low neural spines, which is restricted the “aspis complex: of extant European viperines (e.g., Szyndlar, 1984, 1991b, Szyndlar and Rage, 1999).
  phylogenetic reference(s)
Head, J.J. 2005. Snakes of the Siwalik Group (Miocene of Pakistan): systematics and relationship to environmental change. Palaeontologia Electronica, 8(1):16A.
Szyndlar, Z. and Rage, J.-C. 1999. Oldest fossil vipers (Serpentes: Viperidae) from the Old World. Kaupia. Darmstädter Beiträge zur Naturgeschichte, 8:9-20.
Szyndlar, Z. 1991. A review of Neogene and Quaternary snakes of central and eastern Europe. Part II: Natricinae, Elapidae, Viperidae. Estudios Geologicos, 47:237-266.
 tree image (click image for full size) 
tree image
Figure 1 from Head et al. (2016).