comment on this calibration


 node name
Phalacrocoracidae     Look for this name in NCBI   Wikipedia   Animal Diversity Web
  recommended citations Smith and Ksepka, 2015
  node minimum age
0 Ma
The holotype of ?Borvocarbo stoeffelensis was recovered from the fossil Lagerstätte Enspel, near Bad Marienberg in Westerwald, Rheinland-Pfalz, Germany. The Enspel deposits correspond to the upper Oligocene Mammal Paleogene reference level 28 (Mertz et al., 2007). Laser fusion 40Ar/39Ar radiometric dating of volcanic feldspars from the lower and upper basaltic flows that bound the Enspel lacustrine deposits yielded ages of 24.56 ± 0.04 to 24.79 ± 0.05 Ma (Mertz et al., 2007).
  node maximum age
24.52 Ma
None specified.
 primary fossil used to date this node 
PW 2005/5022-LS
Borvocarbo stoeffelensis, Mayr, 2007
Location relative to the calibrated node: Stem

[show fossil details]
     Locality: Enspel, near Bad Marienberg in Westerwald, Rheinland-Pfalz
     Geological age: Oligoene, Paleogene, Cenozoic

More information in Fossilworks   PaleoBioDB

  phylogenetic justification
Mayr (2001) originally described a partial right foot, tarsometatarsus, and distal tibiotarsus to ?Oligocorax sp. This specimen was later referred to ?Borvocarbo stoeffelensis when this new taxon was erected by Mayr (2007). Although Mayr (2007, 2009b) has suggested that some of the characters supporting a ?Borvocarbo stoeffelensis + Phalacrocoracidae could represent deeper synapomorphies of Phalacrocoracoidea (Phalacrocoracidae + Anhingidae) that are later lost in anhingas, the only phylogenetic analysis that has tested the relationships of ?Borvocarbo stoeffelensis recovered it as the sister taxon to Phalacrocoracidae with fairly strong support (Smith 2010). Both morphological (Cracraft, 1985; Bourdon et al., 2005; Livezey and Zusi, 2007; Smith, 2010) and molecular (Ericson et al., 2006; Brown et al., 2008; Hackett et al., 2008) analyses have been consistent in recovering strong support for a Phalacrocoracidae + Anhingidae clade. The primary exceptions to this are the nuclear dataset based on intron 7 of the β-fibrinogen gene from Fain and Houde (2004) and the mitochondrial dataset of Kennedy et al. (2005), which both recover the aberrant grouping of Sulidae + Anhingidae, a result that may be due in part to long-branch attraction (Kennedy et al., 2005).
  phylogenetic reference(s)
Smith, N.D. 2010. Phylogenetic analysis of Pelecaniformes (Aves) based on osteological data: implications for waterbird phylogeny and fossil calibration studies. PLoS ONE, 5:e13354.
 tree image (click image for full size) 
tree image
Figure 3 from Smith and Ksepka (2015).