comment on this calibration


 node name
Pseudoscorpiones     Look for this name in NCBI   Wikipedia   Animal Diversity Web
  recommended citations
Wolfe et al. 2016
  node minimum age
98.17 Ma
This fossil is sourced from amber mines in the Hukawng Valley of Kachin State, northern Myanmar (formerly Burma). The depositional age of Burmese amber was estimated from U-Pb dating of zircons from the volcaniclastic matrix surrounding the amber (Shi et al.,2012). Shi et al. (2012) argue the amber is not older than its associated sediments, as burial and preservation would have to be rapid for survival of organic material, so the amber was probably formed at, but not earlier than the U-Pb date: at 98.79 Ma±0.62 Myr. Therefore, a minimum age for any fossil from Burmese amber deposits is 98.17 Ma.
  node maximum age
514 Ma
A soft maximum constraint comes from the oldest chelicerate W. barbarahardyae from the Emu Bay Shale on Kangaroo Island, SouthAustralia, which has been correlated based on trilobite biostratigraphy to the upper part of the P. janeae Zone in mainland South Australia (Jell in Bengtson et al., 1990; Fig. 2 in Jago et al., 2012). As this is equivalent to the Canglangpuan Stage in South China and the late Botoman inSiberia (Gehling et al., 2011, Fig. 9), the Emu Bay Shale can be dated to Cambrian Series 2, Stage 4, providing a maximum age of ~514 Ma.
 primary fossil used to date this node 
Protofeaella peetersae, Henderickx and Boone, 2016
Location relative to the calibrated node: Crown

[show fossil details]
     Locality: Hukawng Valley
     Geological age: Cretaceous, Mesozoic

More information in Fossilworks   PaleoBioDB

  phylogenetic justification
Although P. peetersae has not been included in a formal phylogenetic analysis, it was assigned to the extant family Feaellidae by Henderickx and Boone (2016:8), based on its narrow cephalothorax, granulated abdomen,and presence of small pedipalps with narrow coxa and small hands. Whilst these features are certainly found in both P. peetersae and feaellids, other features, such as slender pedipalp fingers, and the overall shape of the cephalic shield are more like those of pseudogarypids (Harvey, 1992). Both the feaellid and pseudogarypids belong to the superfamily Feaelloidea (sensu Harvey, 1992), and thus it is still likely P. peetersae belongs within the pseudoscorpion crown group.
  phylogenetic reference(s)
Henderickx, H., Boone, M., 2016. The basal pseudoscorpion family Feaellidae Ellingsen, 1906 walks the Earth for 98.000.000 years: a new fossil genus has been found in Cretaceous Burmese amber (Pseudoscorpiones: Feaellidae). Entomo-Info 27, 1–12.
Harvey, M.S., 1992. The phylogeny and classification of the Pseudoscorpionida (Chelicerata: Arachnida). Invertebr. Taxon. 6, 1373–1435.
 tree image (click image for full size) 
tree image
Figure 4 from Wolfe et al. (2016).