comment on this calibration


 node name
Glires     Look for this name in NCBI   Wikipedia   Animal Diversity Web
  recommended citations Benton et al. 2015
  node minimum age
56 Ma
The Wanghudun Formation, Qianshan Basin, China is of debated age. First, it was interpreted as belonging to the Paleocene Shanghuan Asian Land Mammal Age (Dashzeveg and Russell, 1988; Li and Ting, 1993). However, Missiaen (2011) suggests that the Wanghudun Formation may be closer to the Nongshanian ALMA. We use this younger estimate for age of the Wanghudun Formation for two reasons: it is the more current interpretation, and it is younger, and so more conservative. The marine correlate of the Nongshanian ALMA is the Thanetian, with a minimum bound of 56 Ma ± 0.0 Myr = 56 Ma (Gradstein et al., 2012).
  node maximum age
164.6 Ma
The soft maximum date is based on the divergence of Eutheria from other mammals in the late Jurassic, represented by Juramaia (Luo et al., 2011). This taxon is represented in the Daxigou site of the Tiaojishan Formation, Liaoning Province, Northeastern China, and has been constrained by radiometric dates to derive from deposits of just over 160 Ma in age (Luo et al., 2011). The equivalent marine stage is the Oxfordian (Gradstein et al., 2012), with a lower boundary of 163.5 Ma ± 1.1 Myr, and thus 164.6 Ma is a soft maximum.
 primary fossil used to date this node 
IVPP V4377
Mimotona lii, Dashzeveg and Russell 1988
Location relative to the calibrated node: Crown

[show fossil details]
     Locality: Anhui
     Stratum: Wanghudun Formation
     Geological age: Paleocene, Paleogene, Cenozoic

More information in Fossilworks   PaleoBioDB

  phylogenetic justification
Meng et al. (2003) placed Mimotona, and the coeval Heomys, on the stems leading to Lagomorpha and Rodentia, respectively. Using a combined morphology-DNA dataset, and noting the impact of DNA data on fossil taxa even when they are sampled for living species alone, Asher et al. (2005) also placed these taxa within Glires, but placed Heomys along with other eurymylids on the stem to Lagomorpha. Either way, these fossils provide a minimum date for the radiation of Glires.
  phylogenetic reference(s)
Meng, J., Hu, Y.M., and Li, C.K. 2003. The osteology of Rhombomylus (Mammalia, Glires): Implications for phylogeny and evolution of Glires. Bulletin of The American Museum of Natural History, 275:1-247.
 tree image (click image for full size) 
tree image
Figure 11 from Benton et al. (2014)