comment on this calibration

Cepphus carbo - other Cepphus

 node name
Cepphus carbo - other Cepphus     Look for this name in NCBI   Wikipedia   Animal Diversity Web
  recommended citations Smith, 2015
  node minimum age
6.7 Ma
The vertebrate assemblages of the San Mateo Formation were reviewed by Barnes et al. (1981), who designated the lower assemblage the San Luis Rey River Local Fauna (SLRRLF), and the upper assemblage the Lawrence Canyon Local Fauna (LCLF). Based on biostratigraphic correlation of marine vertebrates and terrestrial mammals, the age of the younger LCLF has been proposed to be latest Miocene or earliest Pliocene (~5.0 Ma), and correlative with the Late Hemphillian North American Land Mammal Age (Domning and Deméré, 1984). Pan-Alcidae fossils, including the holotype humerus of Cepphus olsoni have been recovered from the older SLRRLF. Age estimates for the SLRRLF based upon terrestrial mammal and marine bird fossils range from approximately 6.7-10.0 Ma (Late Miocene or Tortonian-Messinian equivalent; Barnes et al., 1981; Domning and Deméré, 1984). Therefore, the minimum estimated age of 6.7 Ma is suggested as a minimum age of divergence for the split between Cepphus carbo and other extant species of Cepphus.
  node maximum age
0 Ma
none specified.
 primary fossil used to date this node 
LACM 107032
Cepphus olsoni , Howard, 1982
Location relative to the calibrated node: Crown

[show fossil details]
     Locality: Maasvlakte, Fauna II
     Stratum: peat soils
     Geological age: Calabrian, Pleistocene, Quaternary, Cenozoic
     [View locality in Paleobiology Database]

  phylogenetic justification
The only phylogenetic assessment of the systematic position of Cepphus olsoni recovered it as the sister taxon of the extant species Cepphus carbo, with Cepphus grylle and Cepphus columba in unresolved positions at the base of Cepphus (combined analysis; Smith, 2011).
  phylogenetic reference(s)
Smith, N. A. 2011a. Systematics and evolution of extinct and extant Pan-Alcidae (Aves, Charadriiformes): combined phylogenetic analyses, divergence estimation, and paleoclimatic interactions. PhD Dissertation. The University of Texas at Austin. 748pp
 tree image (click image for full size) 
tree image
Figure 2 from Smith (2015).