comment on this calibration


 node name
Jacanidae     Look for this name in NCBI   Wikipedia   Animal Diversity Web
  recommended citations Smith, 2015
  node minimum age
30 Ma
Jacanidae fossils are known from quarries M and E (see Rasmussen et al., 1987) of the Jebel Qatrani Formation in Egypt, which span the period between ~33-30 Ma. That age estimate has been established using biostratigraphic, radiometric, and magnetostratigraphic correlations (Seiffert, 2006 and references therein). Although remains of the jacanid Nupharanassa tolutaria are definitely older than Nupharanassa bulotorum, that taxon has not been included in a phylogenetic analysis and therefore, a more conservative date of 30.0 Ma is suggested to calibrate the split between Jacanidae and other Scolopaci until the affinities of Nupharanassa tolutaria are better established.
  node maximum age
0 Ma
none specified.
 primary fossil used to date this node 
DPC 3848
Nupharanassa bulotorum , Rasmussen et al. 1987
Location relative to the calibrated node: Stem

[show fossil details]
     Locality: Qattara Depression
     Stratum: Jebel Qatrani Formation
     Geological age: Rupelian, Oligoene, Paleogene, Cenozoic

  phylogenetic justification
The results of a combined phylogenetic analysis place Nupharanassa bulotorum as the sister taxon to the extant species Hydrophasianus chirurgus (Smith, 2011a, figure 8.4). Although material referred to three Oligocene species of Jacanidae (including Nupharanassa bulotorum) consists entirely of distal tarsometatarsi, fossil jacanid species are characterized by the “huge distal foramen, broad tendinal groove, and flattened shaft unique to this family” (Rasmussen et al., 1987:7). The relatively enlarged distal vascular foramen was optimized as an apomorphy of Jacanidae and the possession of a broad anterior groove that extends proximally form the distal vascular foramen is optimized as an apomorphy of Jacanidae, Glareolidae, and Scolopacidae among charadriiforms sampled by Smith (2011a).
  phylogenetic reference(s)
Smith, N. A. 2011a. Systematics and evolution of extinct and extant Pan-Alcidae (Aves, Charadriiformes): combined phylogenetic analyses, divergence estimation, and paleoclimatic interactions. PhD Dissertation. The University of Texas at Austin. 748pp
Rasmussen, D.T., Olson, S.L., and Simons, E.L. 1987. Fossil birds from the Oligocene Jebel Qatrani Formation, Fayum Province, Egypt. Smithsonian Contributions to Paleobiology, 62: 1-20.
 tree image (click image for full size) 
tree image
Figure 1 from Smith (2015).