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Pancrustacea Look for this name in NCBI Wikipedia Animal Diversity Web
Wolfe et al. 2016
node minimum age |
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 |
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.
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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.
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.
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