comment on this calibration


 node name
Chiroptera     Look for this name in NCBI   Wikipedia   Animal Diversity Web
  recommended citations Phillips, 2015
  node minimum age
45 Ma
Tanzanycteris mannardi was recovered from the lacustrine Mahenge locality in north-central Tanzania. Zircon at the base of the Mahenge sequence (~1.2 m below the fossil) was 206Pb/238U dated by Harrison et al. (2001) to 45.83 ± 0.17 Ma. The authors also considered sedimentation rates, for which minimum estimates and error on the 206Pb/238U dates allow a minimum bound of 45.0 Ma for T. mannardi and the crown chiropteran divergence. This mid-Eocene age is also consistent with the Mahenge fossil fish fauna (e.g., Murray, 2000).
  node maximum age
58.9 Ma
Several possible crown bats with putative yangochiropteran affinities occur in Early Eocene localities (Eiting and Gunnell, 2009). Bats are remarkable among mammals in that accepted crown fossil records are closely bracketed by older stem fossils from all continents except Antarctica (Ravel et al., 2011). Although no stem bats are known from prior to the Eocene, some of these records that may be used to bracket the calibration are very close to the Thanetian-Ypresian boundary and so I use the base of the Thanetian (no older than 58.9 Ma) as a soft maximum for the age of crown Chiroptera.
 primary fossil used to date this node 
TNM MP-207
Tanzanycteris mannardi, Gunnell et al., 2003
Location relative to the calibrated node: Crown

[show fossil details]
     Locality: Mahenge
     Stratum: Mahenge sequence
     Geological age: Lutetian, Eocene, Paleogene, Cenozoic
     [View locality in Paleobiology Database]

More information in Fossilworks   PaleoBioDB

  phylogenetic justification
Gunnell et al. (2003) identified a suite of characters that place T. mannardi within Yinpterochiroptera, specifically with Rhinolophoidea. These include extremely enlarged cochlea, broadened first rib, and a dorsally flared iliac blade (this later character is also shared with some probable stem chiropterans). In my combined parsimony analysis of morphological data from Gunnell and Simmons (2005) and DNA sequences from Meredith et al. (2011), T. mannardi groups with rhinolophoids with 58% bootstrap support, while its placement within crown Chiroptera receives 83% bootstrap support. In this analysis the enlarged cochlea and broadened 1st rib are unambiguous apomorphies for Rhinolophoidea, including T. mannardi. These characters are highly conserved among bats. The enlarged cochlea is otherwise only known from one species of mormoopid (although, without the enlarged cochlea fenestra) and a similar rib morphology is known from one other genus, Nycteris.
  phylogenetic reference(s)
Gunnell, G.F., Jacobs, B.F., Herendeen, P.S., Head, J.J., Kowalski, E., Msuya, C.P., Mizambwa, F.A., Harrison, T., Habersetzer, J., and Storch, G. 2003. Oldest placental mammal from sub-saharan Africa: Eocene microbat from Tanzania - evidence for early evolution of sophisticated echolocation. Palaeontologia Electronica, 5(3):10pp, 672KB;
 tree image (click image for full size) 
tree image
Figure 4 from Phillips (2015).