comment on this calibration


 node name
Neoaves     Look for this name in NCBI   Wikipedia   Animal Diversity Web
  recommended citations Benton et al. 2015
  node minimum age
60.2 Ma
The Waipara Greensand is dated as Paleocene: Slack et al. (2006, supplementary information) noted that the type locality of W. manneringi contained two age-diagnostic calcareous nannofossil taxa, Chiasmolithus solitus (= bidens) and Hornibrookina teuriensis, which suggest a lower Teurian age for W. manneringi of about 60.5–61.6 mya. In a revision of the dinoflagellate zonation of the Waipara Greensand, Crouch et al. (2014) mark the last occurrence of Chiasmatolithus solitus as in Chron C26r and upper NP4. In Gradstein et al. (2012), NP4 ends at 60.2 Ma, younger than the possible age range for the lower Teurian, so this is taken as a conservative hard minimum bound for Neoaves.
  node maximum age
86.8 Ma
The soft maximum constraint is based on older bird-bearing deposits that match some at least of the facies represented in the late Maastrichtian, which are broadly from the shallow marine to coastal belt, namely the Niobrara Chalk Formation of Kansas and neighboring states, dated as Santonian (86.3–83.6 Ma ± 0.5 Myr), and so 86.8 Ma.
 primary fossil used to date this node 
CM zfa35
Location relative to the calibrated node: Crown

[show fossil details]
     Locality: Waipara River M34/f453
     Stratum: Waipara Greensand
     Geological age: Selandian, Paleocene, Paleogene, Cenozoic
     [View locality in Paleobiology Database]

  phylogenetic justification
Waimanu is unequivocally a penguin, the oldest member of Spehnisciformes, and probably the oldest unequivocal neoavian at present, based on numerous phylogenetic analyses (e.g., Slack et al., 2006; Ksepka et al., 2006, 2012). Two species were named (Slack et al., 2006), both from the middle to upper Waipara Greensand, and the first of the two is selected as calibration fossil.
  phylogenetic reference(s)
Slack, K.E., Jones, C.M., Ando, T., Harrison, G.L., Fordyce, R.E., Arnason, U., and Penny, D. 2006. Early penguin fossils, plus mitochondrial genomes, calibrate avian evolution. Molecular Biology and Evolution, 23: 1144-1155.
[View electronic resource]
Ksepka, D.T., Bertelli, S., and Giannini, N.P. 2006. The phylogeny of the living and fossil Sphenisciformes (penguins). Cladistics, 22: 412-441.
Ksepka, D.T., Fordyce, R.E., Ando, T. and Jones, C.M. 2012. New fossil penguins (Aves, sphenisciformes) from the Oligocene of New Zealand reveal the skeletal plan of stem penguins. Journal of Vertebrate Palaeontology, 32:235–254.
 tree image (click image for full size) 
tree image
Figure 9 from Benton et al. (2015).