comment on this calibration


 node name
Neornithes     Look for this name in NCBI   Wikipedia   Animal Diversity Web
  recommended citations Benton et al. 2015
  node minimum age
66 Ma
Lithostratigraphic unit K3 of Vega Island, Antarctica, dated as mid- to late Maastrichtian, ~68–66 Ma (Clarke et al., 2005). This quoted age range is based on biostratigraphic and field evidence for age (Pirrie et al., 1997), and a radiometric date of 71.0 Ma from an underlying rock unit.
  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 
MLP 93-I-3-1
Vegavis iaai, Clarke et al., 2005
Location relative to the calibrated node: Crown

[show fossil details]
     Locality: Vega Island, Antarctica
     Stratum: Sandwich Bluff Member of the Lopez de Bertodano Fo
     Geological age: Modern, Holocene, Quaternary, Cenozoic

More information in Fossilworks   PaleoBioDB

  phylogenetic justification
Vegavis iaai is identified as a galloanserine, a neognath, and a neornithine on the basis of phylogenetic analysis (Clarke et al., 2005). It shows twenty synapomorphies that place it successively within Ornithurae (e.g., at least ten sacral vertebrae, domed humeral head, patellar groove present), Neornithes (e.g., at least 15 sacral vertebrae, anteriorly deflected humeral deltopectoral crest), Neognathae, Anseriformes (diminutive pectineal process on pelvis, hypotarsus with well developed cristae and sulci), and Anatoidea (e.g., lack of sternal pneumatic foramen, apneumatic coracoid).
  phylogenetic reference(s)
Clarke, J.A., Tambussi, C.P., Noriega, J.I., Erickson, G.M., and Ketcham, R.A. 2005. Definitive fossil evidence for the extant avian radiation in the Cretaceous. Nature, 433:305–308.
 tree image (click image for full size) 
tree image
Figure 10 from Benton et al. (2015).