comment on this calibration


 node name
Allotriocarida     Look for this name in NCBI   Wikipedia   Animal Diversity Web
  recommended citations
Wolfe et al. 2016a
  node minimum age
497 Ma
The Orsten fossils come from the lowest zone of the late Cambrian Alum Shale, formally called the Agnostus pisiformis Zone or Zone 1, previously corresponding to the Uppermost Zone of the Middle Cambrian (Babcock et al., 2005). The A. pisiformis Zone was recently redefined as the uppermost zone of the Guzhangian, at the upper boundary of Cambrian Series 3 (Nielsen et al., 2014). This age of the uppermost stage of the Cambrian Series 3 is 499 Ma ± 2 Myr. Thus the minimum age applied to Oligostraca is 497 Ma.
  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 
UB 644
Rehbachiella kinnekullensis, Müller, 1983
Location relative to the calibrated node: Crown

[show fossil details]
     Locality: Orsten
     Stratum: Alum Shale
     Geological age: Cambrian, Paleozoic

  phylogenetic justification
Recent phylogenetic analyses including R. kinnekullensis have strongly indicated a position on the branchiopod stem lineage (morphology: Legg et al., 2013; combined morphology and molecular: Oakley et al., 2013) or the cephalocarid stem lineage (morphology: Wolfe and Hegna, 2014). Either relationship (or a strict consensus position on the stem of Branchiopoda+Cephalocarida) would still be within the crown group of Allotriocarida.
  phylogenetic reference(s)
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 15 from Wolfe et al. (2016).