comment on this calibration


 node name
Pantherophis+Pituophis     Look for this name in NCBI   Wikipedia   Animal Diversity Web
  recommended citations Head et al. 2016
  node minimum age
11.93 Ma
USNM 125457 was encased in a local ash deposit that is geochemically matched with the Ibex Hollow Tuff, radiometrically dated to 11.93 Ma (Tucker et al., 2014).
  node maximum age
None specified
 primary fossil used to date this node 
USNM 125457
Pantherophis, NO REFERENCE
Location relative to the calibrated node: Crown

[show fossil details]
     Locality: Ibex Hollow Tuff
     Geological age: Miocene, Neogene, Cenozoic

  phylogenetic justification
Assignment to Pantherophis is based on a premaxilla with thin, dorsomedially angled maxillary processes, a blunt, rounded anterior margin, and laterally expanded ascending processes forming a keyhole shape in anterior view.
  phylogenetic reference(s)
Head, J.J., K. Mahlow, and J. Müller. 2016. Fossil calibration dates for molecular phylogenetic analysis of snakes 2: Caenophidia, Colubroidea, Elapoidea, Colubridae. Palaeontologia Electronica, 19.2.2FC
[View electronic resource]
 tree image (click image for full size) 
tree image
Figure 1 from Head et al. (2016).