comment on this calibration

Acrochordus javanicus

 node name
Acrochordus javanicus     Look for this name in NCBI   Wikipedia   Animal Diversity Web
  recommended citations Head et al. 2016
  node minimum age
18.05 Ma
The minimum age is based on dating of locality Y846 from the Kamlial Formation of the Siwalik Group on the Potwar Plateau of Pakistan, which is the oldest record of Acrochordus dehmi (Head, 2002, 2005).
  node maximum age
23.08 Ma
The maximum age follows Head et al. (2007) based on the first occurrence of the genus from the Aquitanian Kharinadi Formation, Gujarat, India.
 primary fossil used to date this node 
H-GSP 41555
Acrochordus dehmi, Hoffstetter, 1964
Location relative to the calibrated node: Stem

[show fossil details]
     Locality: Locality Y846
     Stratum: Kamlial Formation
     Geological age: Miocene, Neogene, Cenozoic

More information in Fossilworks   PaleoBioDB

  phylogenetic justification
Acrochordus dehmi is hypothesized to be the sister taxon to A. javanicus to the exclusion of A. arafurae or A. granulatus on the basis of parazygosphenal foramina located just ventrolaterally to the base of the zygosphene on the anterolateral surface of the neural arch (Head, 2005; Sanders et al., 2010). Acrochordus dehmi is placed within the genus Acrochordus on the basis of ventrally elongate and pendant synapophyses, hemispherical, vertically oriented and blade-like prezygapophyseal accessory processes, and multiple paracotylar foramina (Hoffstetter, 1964; Head, 2005).
  phylogenetic reference(s)
Sanders, W. J., Gheerbrant, E., Harris, J. M., Saegusa, H. & Delmer, C. (2010) Proboscidea. In: Cenozoic Mammals of Africa, (Werdelin, L. & Sanders, W. J., eds.). pp. 161-251. University of California Press, Berkeley.
Hoffstetter, R. 1964. Les serpents du Néogène du Pakistan (couches des Siwaliks). Bulletin de la Société Géologique de France, Série 7, 6:467-474.
Head, J.J. 2005. Snakes of the Siwalik Group (Miocene of Pakistan): systematics and relationship to environmental change. Palaeontologia Electronica, 8(1):16A.
 tree image (click image for full size) 
tree image