comment on this calibration

Archonta

 node name
Archonta     Look for this name in NCBI   Wikipedia   Animal Diversity Web
 
  recommended citations
http://palaeo-electronica.org/content/fc-1 Benton et al. 2015
 
  node minimum age
61.6 Ma
The geologically oldest members of Archonta are Paleocene plesiadapids such as Paromomys farrandi (Clemens and Wilson, 2009). The upper bound of the Torrejonian North American Land Mammal Age (NALMA) correlates to the top of the Danian, 61.6 Ma ± 0.0 Myr = 61.6 Ma (Woodburne, 2004).
 
  node maximum age
164.6 Ma
The soft maximum date is based on the divergence of Eutheria from other mammals in the late Jurassic, represented by Juramaia (Luo et al., 2011). This taxon is represented in the Daxigou site of the Tiaojishan Formation, Liaoning Province, Northeastern China, and has been constrained by radiometric dates to derive from deposits of just over 160 Ma in age (Luo et al., 2011). The equivalent marine stage is the Oxfordian (Gradstein et al., 2012), with a lower boundary of 163.5 Ma ± 1.1 Myr, and thus 164.6 Ma is a soft maximum.
 
 primary fossil used to date this node 
 
UCMP 189520
Paromomys farrandi, Block et al., 2007
Location relative to the calibrated node: Crown

[show fossil details]
     Locality: Farrand Channel
     Geological age: Paleocene, Paleogene, Cenozoic


More information in Fossilworks   PaleoBioDB
 
 

 
  phylogenetic justification
Paromomys is determined phylogenetically as a member of Paromomyidae, which is sister to Plesiadapiformes + Euprimates, and so a part of total-group Primates, nested well within Archonta (Block et al., 2007).
 
  phylogenetic reference(s)
Bloch, J.I., Silcox, M.T., Boyer, D.M., and Sargis, E.J. 2007. New Paleocene skeletons and the relationship of plesiadapiforms to crown-clade primates. Proceedings of the National Academy of Sciences, USA, 104:1159-1164.
 
 tree image (click image for full size) 
tree image
Figure 11 of Benton et al. (2014).
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