comment on this calibration


Lineage (NCBI): root » Eukaryota » Opisthokonta » Metazoa » Coelomata
 node name
Alethinophidia     Look for this name in NCBI   Wikipedia   Animal Diversity Web
  recommended citations Head, 2015
  node minimum age
93.9 Ma
The minimum age is based on the upper bound of the Cenomanian (Ogg et al., 2012). The only specimen of Haasiophis was recovered from the ‘Ein Yabrud quarries in the Judean hills, Israel. ‘Ein Yabrud is located in either the late Cenomanian Amminadav Formation or underlying early Cenomanian Bet Meir Formation (Chalifa and Tchernov, 1982; Chalifa, 1985; Braun and Hirsch, 1994). Fish biostratigraphy has been used to infer an early Cenomanian age for ’Ein Yabrud as part of the Bet Meir Formation (Chalifa and Tchernov, 1982), but subsequent placement of localities at the base of the Amminadav Formation (Chalifa, 1985; Braun and Hirsch, 1994) suggests a middle-late Cenomanian age, and ‘Ein Yabrud is more recently considered early-middle Cenomanian (Tchernov et al., 2000; Rieppel et al., 2003).
  node maximum age
100.5 Ma
The age range presented here reflects both the overall uncertainty of the position of ‘Ein Yabrud within the Cenomanian, and the absence of any definitive snake fossils globally prior to the earliest Late Cretaceous.
 primary fossil used to date this node 
Haasiophis terrasanctus , Tchernov et al., 2000
Location relative to the calibrated node: Stem

[show fossil details]
     Locality: 'Ein Yabrud quarries in the Judean hills,
     Stratum: Amminadav Formation or Bet Meir Formation
     Geological age: Cretaceous, Mesozoic

More information in Fossilworks   PaleoBioDB

  phylogenetic justification
Haasiophis is placed within Alethinophidia as either a stem or crown macrostomatan on the basis of numerous characters including (but not limited to): quadrate suspended from free-ending process of the supratemporal; anterior dentigerous process of palatine; “alethinophidian type” (Zaher and Rieppel, 1999) tooth attachment; and loss of premaxilla- maxillary articulation (e.g., Tchernov et al., 2000; Gauthier et al., 2012).
  phylogenetic reference(s)
Tchernov, E., Rieppel, O., Zaher, H., Polcyn, M.J., and Jacobs, L.L. 2000. A fossil snake with limbs. Science, 287:2010-2012.
Gauthier, J.A., Kearney, M., Maisano, J.A., Rieppel, O., and Behlke, A.D.B. 2012. Assembling the squamate tree of life: perspectives from the phenotype and the fossil record. Bulletin of the Peabody Museum of Natural History, 53:3-308.
 tree image (click image for full size) 
tree image
Figure 1 from Head (2015).