comment on this calibration


 node name
Macropodoidea     Look for this name in NCBI   Wikipedia   Animal Diversity Web
  recommended citations Phillips, 2015
  node minimum age
15.97 Ma
Ganguroo bilamina occurs in Faunal Zones B and C of the Riversleigh local faunas (northwestern Queensland). The older of these is Faunal Zone B, from which G. bilamina is known from sites such as Wayne's Wok (including the holotype), Camel Sputum and Mike's Menagerie. Early Miocene dates have consistently been attributed to Faunal Zone B sites by biocorrelation (Black, 1997; Travouillon et al., 2006). More recently, Black et al. (2012) indicated that U/Pb radiometric dating of speleothems now confirms this timing. However, until the new dates are published I consider the top of the Early Miocene to provide a hard minimum for Riversleigh Faunal Zone B and hence, for the crown Macropodoidea divergence.
  node maximum age
54.65 Ma
Several putative crown macropodoids occur in Late Oligocene (~25 Ma, Woodburne et al., 1993; Megirian et al., 2010) Etadunna and Riversleigh Faunal Zone A sites and as such, an older maximum bound is required for this clade. Unfortunately, the preceding hiatus in the Australasian terrestrial mammal fossil record stretches back to the earliest Eocene (54.6 ± 0.05 Ma) Tingamarra site near Murgon, Queensland (Godthelp et al., 1992). This gap provides for a very conservative maximum bound, because the Tingamarra Fauna represents an early stage in the evolution of Australian marsupials (Beck et al., 2008), well before the evolution of the highly derived kangaroos and potoroos.
 primary fossil used to date this node 
QM 19915
Ganguroo bilamina, Cooke, 1997
Location relative to the calibrated node: Crown

[show fossil details]
     Locality: Riversleigh
     Stratum: Zone B
     Geological age: Miocene, Neogene, Cenozoic

More information in Fossilworks   PaleoBioDB

  phylogenetic justification
The well-sampled, matrix-based cladistic analysis of Prideaux and Warburton (2010) provides 97% bootstrap support for grouping Ganguroo with or within Macropodidae to the exclusion of Potoroidae. Several mandibulo-dental and postcranial characters provided unambiguous synapomorphies for this relationship, including bilophodont molars and a straight acromion process on the scapula. All other cladistic analyses concur with this relationship for Ganguroo, although its precise position among basal macropodids is uncertain (see Kear and Pledge, 2007). The living macropodoid clades, Macropodidae and Potoroidae, are sister taxa in all recent molecular studies (e.g., Phillips and Pratt, 2008; Meredith et al., 2008a) and each of the morphological cladistic analyses that include G. bilamina (see above) is consistent with this relationship.
  phylogenetic reference(s)
Prideaux, G.J. and Warburton, N.M. 2010. An osteology-based appraisal of the phylogeny and evolution of kangaroos and wallabies (Macropodidae: Marsupialia). Zoological Journal of the Linnean Society, 159:954-987.
 tree image (click image for full size) 
tree image
Figure 1 from Phillips (2015).