comment on this calibration


 node name
Polyneoptera     Look for this name in NCBI   Wikipedia   Animal Diversity Web
  recommended citations
Wolfe et al. 2016
  node minimum age
319.9 Ma
The insect beds where this species was located are near Xiaheyan Village in the Qilianshan Mountains, Zhongwei County, Ningxia Huizu Autonomous Region, northwest China (Zhang et al., 2013). The insect fossil deposits are within the uppermost unit of the upper Tupo Formation (synonyms Hongtuwa or Zhongwei Formation). The presence of the ammonoids Reticuloceras reticulatum, Gastrioceras listeri and Gastrioceras montgomeryense and conodonts Declingnathodus noduliferous and Neognathodus symmetricus indicate a Namurian B/Cage (Xie et al., 2004; Yang, 1987; Yang et al., 1988; Zhang et al., 2013).The (late) Namurian-(early) Westphalian boundary is defined by the earliest occurrence of the goniatite G. subcrenatum (Waters and Davies, 2006), but lacks a precise isotopic date. Pointon et al. (2012) estimated an age of c. 319.9Ma for the base of the Westphalian (top of the Namurian, only slightly younger than the Marsdenian) based on Milankovitch cycles of sedimentation, giving a minimum age for Xiaheyan fossils.
  node maximum age
411 Ma
A soft maximum age is estimated from R. praecursor, the oldest hexapod, from the Early Devonian (Pragian) Rhynie Chert of Aberdeenshire, Scotland. Spore assemblages of the Windyfield and stratigraphically underlying Rhynie Chert are dated to the early but not earliest Pragian to early (earliest?) Emsian (polygonalis-emsiensis Spore Assemblage Biozone) (Parry et al., 2011). Radiometric dating of the underlying Milton of Noth Andesite at ca. 411 Ma (Parry et al., 2011, 2013) has been subject to a dispute over its temporal relationship to hot spring activity associated with the cherts (Mark et al., 2011, 2013) and predates the biostratigraphic dating of the Rhynie Chert relative to the global dating of the base of the Pragian Stage. Therefore, a soft maximum constraint may be defined at 411 Ma for the Rhynie Chert.
 primary fossil used to date this node 
GMCB 04GNX1001-1
Qilianiblatta namurensis, Zhang et al. 2013.
Location relative to the calibrated node: Crown

[show fossil details]
     Locality: Xiaheyan Village
     Stratum: Tupo Formation
     Geological age: Carboniferous, Paleozoic

More information in Fossilworks   PaleoBioDB

  phylogenetic justification
Q. namurensis has not been included in formal phylogenetic analysis, but the fossil exhibits some apomorphic characters uniting it with crown group Blattodea, specifically presence of a deeply concave CuP in the forewing (Prokop et al., 2014). Additional data from forewings of the CNU specimen shows the RA with branches translocated to RP, as in cockroaches, suggesting this species could be stem Blattodea (Guo et al., 2013). However, there has not been a cladistic analysis of wing venation characters for both fossil and extant Blattodea and/or Dictyoptera, thus we agree with the more conservative view (Kjer et al., 2015; Legendre et al., 2015; Prokop et al., 2014) that roachoids likely represent a diverse and speciose fauna on the stem group of Dictyoptera. Nonetheless, placement of Q. namurensis on the stem lineage of Dictyoptera identifies it as a member of crown Polyneoptera.
  phylogenetic reference(s)
Prokop, J., Krzeminski, W., Krzeminska, E., Hörnschemeyer, T., Ilger, J.-M., Brauckmann, C., Grandcolas, P., Nel, A., 2014. Late Palaeozoic Paoliida is the sister group of Dictyoptera (Insecta: Neoptera). J. Syst. Palaeontol. 12, 601–622.
Guo, Y., Béthoux, O., Gu, J., Ren, D., 2013. Wing venation homologies in Pennsylvanian “cockroachoids” (Insecta) clarified thanks to a remarkable specimen from the Pennsylvanian of Ningxia (China). J. Syst. Palaeontol. 11, 41–46.
 tree image (click image for full size) 
tree image
Figure 21 from Wolfe et al. (2016).