comment on this calibration

Tetraodon - Takifugu

 node name
Tetraodon - Takifugu     Look for this name in NCBI   Wikipedia   Animal Diversity Web
  recommended citations Benton et al. 2015
  node minimum age
32.02 Ma
The age of the Psekhsky Horizon is constrained by foram, nannoplankton, and dinocyst biostratigraphy (Leonov et al., 1998; Benton and Donoghue, 2006; Benton et al., 2009). The top of this horizon coincides with the first appearance of Sphenolithus predistentus and the base of Paleogene Nannoplankton Zone NP23. The base of NP23 is dated as approximately 32.02 Ma (Anthonissen and Ogg, 2012), which we specify as a minimum age for the last common ancestor of Tetraodon and Takifugu.
  node maximum age
56 Ma
We propose a soft maximum for Tetraodon -Takifugu divergence based on the Ypresian London Clay of southeast England and Calcari nummulitici of Bolca, Italy (Ellison et al., 1994; Papazzoni and Trevisani, 2006) These deposits yield a diversity of gymnodont tetraodontiforms, including triodontids, diodontids, and stem tetraodontids (Tyler and Patterson, 1991; Tyler and Santini, 2002; Santini and Tyler, 2003; Arcila et al., in press), implying that crown tetraodontids would have been sampled were they present. The base of the Ypresian is dated to 56.0 Ma, defining an estimated soft maximum for the divergence between Takifugu and Tetraodon. We apply this as our minimum estimate for the time of divergence between Tetraodon and Takifugu.
 primary fossil used to date this node 
PIN 3363/111+111a
rchaeotetraodon winterbottomi, Tyler and Bannikov, 1994
Location relative to the calibrated node: Crown

[show fossil details]
     Locality: north Caucasus, Russia
     Stratum: Pshekhsky Horizon of the lower Maikop Formation
     Geological age: Oligoene, Paleogene, Cenozoic

  phylogenetic justification
Archaeotetradon winterbottomi is described in detail by Tyler and Bannikov (1994) and Carnevale and Tyler (2010). Formal cladistic analyses (Santini and Tyler, 2003: fig. 4) and verbal arguments (Carnevale and Tyler, 2010: p. 297-298) based on morphology suggest the exact position of Archaeotetraodon winterbottomi to other Tetradontidae is unclear. However, combined analysis of morphological and molecular data nests Archaeotetradon winterbottomi high within the tetraodontid crown as the sister lineage of a clade comprising Tetraodon, Canthigaster, Monotrete, Auriglobus, Chonerhinos, Chelonodon, and Arthrodon (Arcila et al., in press).
  phylogenetic reference(s)
The linked fossil has no phylogentic references.
 tree image (click image for full size) 
tree image
Figure 6 from Benton et al. (2014).