comment on this calibration


Lineage (NCBI): root » Eukaryota » Embryophyta » magnoliids » Canellales
 node name
Canellales     Look for this name in NCBI   Wikipedia   Animal Diversity Web
  recommended citations Massoni et al. 2015
  node minimum age
125.9 Ma
Walkeripollis gabonensis comes from the upper part of Elf-Aquitaine palynological Zone C-VII (Subzone C-VIIc) in the Cocobeach sequence (Doyle et al., 1990), near the town N’Toum in northern Gabon. The age of Zone C-VII is bracketed by late Aptian marine fossils in overlying units (Doyle et al., 1977, 1990). Doyle et al. (1977, 1982) dated Zone C-VII as early Aptian, but Doyle et al. (1990) and Doyle (1992) suggested it may be late Barremian, based on the occurrence of other taxa that appear in Zone C-VII, correlative rocks in Brazil, and better-dated Barremian rocks elsewhere, notably Afropollis and the first reticulate tricolpates (Doyle et al., 1982; Gübeli et al., 1984; Penny, 1989; Regali and Viana, 1989; Doyle, 1992). Additional evidence that favors a pre-Aptian age is the absence in Zone C-VII of two groups that appear in the overlying Zones C-VIII and C-IX and the Aptian of Egypt, namely striate tricolpates, which are not known until the Albian in Southern Laurasia but occur earlier in Northern Gondwana (Penny, 1988a; Hochuli et al., 2006; Heimhofer et al., 2007; Heimhofer and Hochuli, 2010), and the non-columellar reticulate monosulcate genus Pennipollis (“Retimonocolpitesperoreticulatus, etc.), which appears just above the base of the marine Aptian of England and has never been reported from well-dated pre-Aptian rocks (Penny, 1988b; Doyle, 1992; Hughes, 1994; Hochuli et al., 2006). We therefore believe it is safe to accept a late Barremian age for Walkeripollis gabonensis and thus propose 125.9 Ma, the upper boundary of the Barremian (126.3 ±0.4 Ma; Ogg and Hinnov, 2012), as a minimum age for this fossil.
  node maximum age
0 Ma
none specified
 primary fossil used to date this node 
UCMP Elf-Aquitaine 2
Walkeripollis gabonensis, Doyle et al., 1990
Location relative to the calibrated node: Crown

[show fossil details]
     Locality: TM.1 (N’Toum No. 1) well
     Stratum: Zone C-VII (Subzone C-VIIc) in the Cocobeach seque
     Geological age: Cretaceous, Mesozoic

  phylogenetic justification
Use of fossil pollen for calibration can be questioned because it usually lacks sufficient characters for secure phylogenetic placement, but this taxon has such a unique combination of features that it could be unambiguously placed in a large-scale phylogenetic analysis. A molecular scaffold analysis placed Walkeripollis gabonensis in a single most parsimonious position as sister to Winteraceae (Doyle and Endress, 2010), one of the two families of Canellales. Synapomorphies supporting this sister-group relationship were permanent tetrads and round aperture shape. The sculpture on the pore, forming a ring around a central thin area, also suggests a close relationship between the fossil species and Winteraceae (Doyle and Endress, 2010). However, this character was not included in the Doyle and Endress (2010) data set because it was not applicable to most taxa. The sister-group relationship between living Winteraceae and Canellaceae is very well supported in the literature (e.g., Chase et al., 1993; Zanis et al., 2002, 2003; Qiu et al., 2005, 2006; Marquínez et al., 2009). We therefore consider Walkeripollis gabonensis to provide a minimum age for crown-group Canellales (Figure 1).
  phylogenetic reference(s)
Doyle, J.A. and Endress, P.K. 2010. Integrating Early Cretaceous fossils into the phylogeny of living angiosperms: Magnoliidae and eudicots. Journal of Systematics and Evolution, 48:1–35.
 tree image (click image for full size) 
tree image
Figure 1 from Massoni et al. (2015).