comment on this calibration


 node name
Pantopoda     Look for this name in NCBI   Wikipedia   Animal Diversity Web
  recommended citations
Wolfe et al. 2016
  node minimum age
429.8 Ma
This fossil is preserved as a carbonate concretion from the volcaniclastic Herefordshire Lagerstätte of Herefordshire, England, at the Sheinwoodian-Homerian stage boundary, within the Early Silurian Wenlock Series (Siveter, 2008). As the Homerian begins at 430.5 Ma ± 0.7 Myr, a minimum age constraint for the Herefordshire can thus be placed at 429.8 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 
OUM C.29571
Haliestes dasos, Siveter et al., 2004
Location relative to the calibrated node: Crown

[show fossil details]
     Locality: Herefordshire Lagerstätte
     Geological age: Silurian, Paleozoic

More information in Fossilworks   PaleoBioDB

  phylogenetic justification
Arango and Wheeler (2007) resolved H. dasos as sister to part of Ammotheidae (nested within clade of Ammotheidae, Callipallenidae, Nymphonidae, Pallenopsidae, Phoxichilidiidae, Rhynchothoracidae), i.e. as crown-group Pantopoda. H. dasos was classified separately from extant pycnogonids (Pantopoda) as an Order Nectopantopoda by Bamber (2007), although without explicit phylogenetic justification. It should be noted that H. dasos was included in the phylogenetic analysis of Legg et al. (2013), and resolved as sister-taxon to Palaeopantopus,which in turn resolved as sister-taxon to extant pycnogonids, however, just three extant exemplars were included in this study and as this was not extensive enough to determine the exact position of these fossil taxa with respect to crown-group exemplars, we continue to follow Arango and Wheeler (2007) in their placement.
  phylogenetic reference(s)
Arango, C.P., Wheeler, W.C., 2007. Phylogeny of the sea spiders (Arthropoda, Pycnogonida) based on direct optimization of six loci and morphology. Cladistics 23, 255–293.
 tree image (click image for full size) 
tree image
Figure 3 from Wolfe et al. (2016).