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RE: Holotype of Sunosuchus cf. thailandicus ?!
Jocelyn Falconnet wrote-
> Is there anyone able to tell me what it means ?
> Holliday et al. (In press) just referred PIN 4174-1 to "Sunosuchus" cf.
> thailandicus Buffetaut, 1980... and treat it as a new species (p. 2).
> This specimen is explicitely designated as a holotype and there are
> information about the the type locality and horizon, as well as a diagnosis.
The issue here seems to be that the specimen is the holotype of Sunosuchus
shartegensis (Effimov, 1988) and was intended to be described as such, judging
by the abstract, introduction, phylogenetic analysis, etc.. But instead, the
authors decided to improperly call it "Sunosuchus" cf. thailandicus part way
through editing, only replacing the name sometimes, and kept the rest of the
information the same. thailandicus of course has a different holotype, a
mandible from Thailand.
> And later, in the same paper:
> "There is no diagnostic feature that separates it from
> the extremely fragmentary S. thailandicus, suggesting that
> PIN 4174‒1 could be considered a synonym of S. thailandicus." (p. 7)
> Excuse my French*, but... what the heck !?
So they think shartegensis could be a junior synonym of thailandicus. This is
fine and interesting, but you can't make a cf. species a senior synonym of a
named species. In any case, if there are no diagnostic differences (and a
detailed comparison would be better than a single statement to show this), does
thailandicus share shartegensis' apparent mandibular apomorphy of "mandibular
symphysis is inclined dorsally"? If so, that would be good grounds for
synonymization, but we're never told that.
> options are defendible, given the data and results that are presented in
> the paper, so the final decision needs to be made by the taxonomist. By
> the authors.
The sad thing is the authors didn't test this in their analysis. They
originally include both thailandicus and shartegensis, but then delete
thailandicus and Turanosuchus because at least one of these taxa causes a
polytomy at the base of Eosuchia. What they should have done is run the full
analysis, then delete Turanosuchus from the trees to see if thailandicus is
better resolved. Currently, we don't know if it's just Turanosuchus messing
things up. Finally, the authors make the common mistake of deleting poorly
constrained taxa THEN rerunning the analysis, instead of letting their
information influence the tree but deleting each from the tree a posteriori.
So basically, partway through the editing process the authors decided to run
with a new hypothesis without completely fixing the manuscript, but didn't
present all of the work needed to test this hypothesis.