comment on this calibration


 node name
Hemichordata     Look for this name in NCBI   Wikipedia   Animal Diversity Web
  recommended citations 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)