comment on this calibration

Whippomorpha - Ruminantia

 node name
Whippomorpha - Ruminantia     Look for this name in NCBI   Wikipedia   Animal Diversity Web
  recommended citations Benton et al. 2015
  node minimum age
52.4 Ma
The cow-pig division is dated minimally by the record of Himalayacetus from the base of the Subathu Formation in Pakistan (Bajpai and Gingerich, 1998) where it co-occurs with Nummulites atacicus whose range correlates with nannoplankton zones 11-12, providing a minimum age of 52.4 Ma (Martín-Martín et al., 2001). The availability of this marine correlation for this fossil enables us to forego use of the corresponding marine stage (Ypresian).
  node maximum age
66 Ma
The absence of any crown cetartiodactyls during the Paleocene may point to a soft maximum constraint of 66.04 Ma ± 0.4 Myr = 66 Ma
 primary fossil used to date this node 
RUSB 2003
Himalayacetus subathuensis, Bajpai, S. and Gingerich, P.D. 199
Location relative to the calibrated node: Crown

[show fossil details]
     Locality: Kuthar Nala
     Geological age: Eocene, Paleogene, Cenozoic

More information in Fossilworks   PaleoBioDB

  phylogenetic justification
Himalayacetus is known only from a partial dentary and two molars, but it was claimed that these show characterisics of Pakicetidae (Bajpaj and Gingerich, 1998), The phylogenetic placement within Cetacea is controversial, and a conservative phylogenetic analysis (O’Leary and Uhen, 1999) confirmed that Himalayacetus might be more closely related to ambulocetids than to pakicetids. Either way, Himalayacetus is a member of total-group Cetacea, and nested well within crown Whippomorpha.
  phylogenetic reference(s)
O’Leary, M.A. and Uhen, M.D. 1999. The time of origin of whales and the role of behavioral changes in the terrestrial-aquatic transition. Paleobiology, 25:534–556.
Bajpai, S. and Gingerich, P.D. 1998. A new Eocene archaeocete (Mammalia, Cetacea) from India and the time of origin of whales. Proceedings of the National Academy of Sciences, USA, 95:15464-15468.
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