comment on this calibration


 node name
Microcoryphia     Look for this name in NCBI   Wikipedia   Animal Diversity Web
  recommended citations
Wolfe et al. 2016
  node minimum age
129.41 Ma
C. libanensis was discovered in Cretaceous amber, from a locality in Lebanon that was not recorded (Sturm and Poinar, 1998). We therefore use a minimum age constraint from the youngest of the several known Lebanese amber localities, which all bear the same age within the early Barremian (Maksoud et al., in press). The upper boundary of the early Barremian is proposed to be the first appearance of the ammonite Ancyloceras vandenheckii (Ogg et al., 2012a). Cyclostratigraphy dates the A. vandenheckii Zone beginning at 129.41 Ma (Ogg et al., 2012a),providing a minimum age for Jezzine Lebanese amber fossils.
  node maximum age
521 Ma
A soft maximum age is obtained from the oldest mandibulate, Y. dianensis, which was recovered from the Yu'anshan Formation at Xiaotan section, Yongshan, Yunnan Province, attributed to the Eoredlichia–Wutingaspis Biozone (Zhang et al., 2007). Chinese Cambrian stratigraphy has been revised substantially and the Eoredlichia –Wutingaspis Biozone is no longer recognized (Peng, 2003, 2009). However, Eoredlichia is known to co-occur with Hupeidiscus, which is diagnostic of the Hupeidiscus-Sinodiscus Biozone, which is formally recognized as the second biozone of the Nangaoan Stage of the Qiandongian Series of the Cambrian of China (Peng and Babcock,2008). The Nangaoan is the proposed third stage of the Cambrian System for the International Geologic Timescale (Peng et al., 2012a).Thus, a soft maximum constraint can be established on the age of the lower boundary of the Nangaoan, which has been dated to 521 Ma (Peng et al., 2012a; Peng and Babcock, 2008).
 primary fossil used to date this node 
Milki No. 194/35
Cretaceomachilis libanensis, Sturm and Poinar, 1998
Location relative to the calibrated node: Crown

[show fossil details]
     Locality: Lebanese Amber
     Geological age: Cretaceous, Mesozoic

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  phylogenetic justification
C. libanensis shares morphological characters with the extant family Meinertillidae. These include the absence of scales on the scapus, pedicellus and flagellum, and the presence of a characteristic hook near the distal end of article 2 of the male maxillary palp (Sturm and Poinar, 1998). The latter character is a synapomorphy of crown Meinertillidae (Sturm and Poinar, 1998), therefore the fossil is within crown Microcoryphia.
  phylogenetic reference(s)
Sturm, H. and Poinar, G.O. 1998. Cretaceomachilis libanensis, the Oldest Known Bristle-tail of the Family Meinertellidae (Machiloidea, Archaeognatha, Insecta) from the Lebanese Amber. Dtsch. Entomol. Z. 45, 43–48.
 tree image (click image for full size) 
tree image
Figure 17 from Wolfe et al. (2016).