comment on this calibration


 node name
Altocrustacea     Look for this name in NCBI   Wikipedia   Animal Diversity Web
  recommended citations
Wolfe et al. 2016a
  node minimum age
514 Ma
Y. dianensis 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 ist he proposed third stage of the Cambrian System for the International Geologic Timescale (Peng et al., 2012a). Thus, a minimum constraint can be established on the age of the top of the Nangaoan, which has been dated to 514 Ma (Peng et al., 2012a; Peng and Babcock, 2008).
  node maximum age
636.1 Ma
A soft maximum constraint is based on that used by Benton et al.(2015), the maximum age interpretation of the Lantian Biota (Yuan et al., 2011). This, together with the Doushantuo Biota (Yuan et al.,2002), provides a series of Konservat-Lagerstätten preserving the biota in Orsten- and Burgess Shale-like modes of fossilization. None of these Lagerstätten, least of all the Lantian, preserves anything that could possibly be interpreted as even a total group eumetazoan and on this basis we define our soft maximum constraint at 635.5 Ma ±0.6 Myr (Condon et al., 2005) and, thus, 636.1 Ma.
 primary fossil used to date this node 
YKLP 10840
Yicaris dianensis, Zhang et al. 2007
Location relative to the calibrated node: Crown

[show fossil details]
     Locality: Yongshan, Yunnan Province
     Stratum: Yu’anshan Formation
     Geological age: Cambrian, Paleozoic

  phylogenetic justification
Several phylogenetic analyses of morphology (Edgecombe, 2010; Legg et al., 2013; Wolfe and Hegna, 2014) and morphology plus molecules (Oakley et al., 2013) place Y. dianensis within the crown group of Pancrustacea. Key characters include the presence of epipodites on thethoracic limbs; paddle-shaped mandibular and maxillary exopods;and the protopodite of post-mandibular limbs elongated as soft, setiferous endites. Any position supported within the crown group of Pancrustacea is within crown Euarthropoda.
  phylogenetic reference(s)
Edgecombe, G.D. 2010. Palaeomorphology: fossils and the inference of cladistic relationships. Acta Zool. 91, 72–80.
Legg, D.A., Sutton, M.D., Edgecombe, G.D. 2013. Arthropod fossil data increase congruence of morphological and molecular phylogenies. Nature Communications 4, 2485.
Wolfe, J.M., and Hegna, T.A. 2014. Testing the phylogenetic position of Cambrian pancrustacean larval fossils by coding ontogenetic stages. Cladistics 30, 366–390.
Oakley, T.H.,Wolfe, J.M., Lindgren, A.R., and Zaharoff, A.K. 2013. Phylotranscriptomics to bring the understudied into the Fold: Monophyletic Ostracoda, fossil placement, and Pancrustacean phylogeny. Mol. Biol. Evol. 30, 215–233.
 tree image (click image for full size) 
tree image
Figure 1 from Wolfe et al. (2016).