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 node name
Sirenia     Look for this name in NCBI   Wikipedia   Animal Diversity Web
  recommended citations Benton et al. 2015
  node minimum age
47.6 Ma
Sirenian remains, referrable to "halitheriine" dugonids from the Mokattam Hills in Egypt, have been interpreted as Lutetian, or middle Eocene (Domning et al., 2010; Sickenberg, 1934) with a minimum bound of 47.8 - 0.2 Ma.
  node maximum age
66 Ma
Paleogene strata have yielded abundant sirenian remains, including stem taxa, for much of the Eocene (Domning et al., 2010). Tethythere (i.e., Sirenia-Proboscidea) remains are known from the Paleocene and early Eocene (Gheerbrant, 2009), but lack crown Sirenia. Hence, we define the paleontological soft maximum constraint as the base of the Paleocene, equivalent to the base of the Danian marine stage at 66.04 Ma ± 0.4 Myr = 66 Ma.
 primary fossil used to date this node 
NHMUK 46722
Eotheroides, Palmer, 1899
Location relative to the calibrated node: Crown

[show fossil details]
     Locality: Mokattam Hills
     Geological age: Eocene, Paleogene, Cenozoic

More information in Fossilworks   PaleoBioDB

  phylogenetic justification
Eotherioides is identified by Domning et al. (2010) and Gheerbrant (2005) as more closely related to Dugong than to Trichechus, and it shows apomorphies of Dugongidae, including retention of an upper dental formula of, and the deciduous P5 is not replaced (Domning et al., 2010). It is therefore nested within crown Sirenia.
  phylogenetic reference(s)
Domning, D. P., Zalmout, I. S. & Gingerich, P. D. (2010) Sirenia. In: Cenozoic Mammals of Africa, (Werdelin, L. & Sanders, W. J., eds.). pp. 147-160. University of California Press, Berkeley.
Gheerbrant, E. 2005. Paleocene emergence of elephant relatives and the rapid radiation of African ungulates. Proceedings of the National Academy of Sciences,106: 10717-10721.
 tree image (click image for full size) 
tree image
Figure 10 from Benton et al. (2015).