comment on this calibration

Hemichordata

 node name
Hemichordata     Look for this name in NCBI   Wikipedia   Animal Diversity Web
 
  recommended citations
http://palaeo-electronica.org/content/fc-1 Benton et al. 2015
 
  node minimum age
504.5 Ma
Rhabdotubus johanssoni was recovered from shales within the Eccaparadoxides pinus Zone (=Ptychagnostus praecurrens Zone) (Bengtson and Urbanek, 1986) which occurs within Cambrian Series 3, Age 5 (i.e. pre-Drumian) of GTS2012 (Peng et al., 2012).
 
  node maximum age
636.1 Ma
A soft maximum constraint is based on 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 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 out 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 
 
SMNH Cn 67217
Rhabdotubus johanssoni , Bengtson and Urbanek, 1986
Location relative to the calibrated node: Crown

[show fossil details]
     Locality: Narke(n), Sweden
     Stratum: Eccaparadoxides pinus Zone
     Geological age: Cambrian, Paleozoic
     [View locality in Paleobiology Database]


More information in Fossilworks   PaleoBioDB
 
 

 
  phylogenetic justification
Rhabdotubus johanssoni exhibits clear evidence of cortical banding which demonstrates membership of total group, if not crown-Pterobranchia and, therefore, membership of crown-Hemichordata.
 
  phylogenetic reference(s)
Bengtson, S., and Urbanek, A. 1986. Rhabdotubus, a Middle Cambrian rhabdopleurid hemichordate. Lethaia, 19:293-308.
 
 tree image (click image for full size) 
tree image
Figure 2 from Benton et al. (2014)
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