[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

RE: Phylogeny of Basal Iguanodonts



Initially I was excited about this paper, as I do love me some phylogenetic 
analyses.  McDonald adds several taxa and characters and updates several other 
taxa, which is always useful since that can change the topology.  
Unfortunately, after stating these updates, the paper goes quickly downhill.  
The (useless) unordered and ordered analyses both yielded identical poorly 
resolved strict consensus trees, but McDoland doesn't tell us if or how the 
topology differed between taxa that could be resolved with a posteriori 
deletion.  Similarly, the one figure is an agreement subtree, but this only has 
36 of the 66 included taxa.  The four paragraphs of discussion never mention 
the deleted taxa either.  Subsequently, the paper simply doesn't say where 45% 
of the analyzed taxa go.  This includes four of the five newly added taxa.  One 
of these is "NHMUK R3741 (cf. Mantellisaurus in McDonald [2012]; considered to 
represent a possible distinct taxon by Carpenter and Ishida [2010])", which is 
a great idea to include so that rival hypotheses can be tested.  But it was 
deleted a posteriori for lacking a unique character combination and never 
mentioned again, so why propose a test than not answer it?  I completely agree 
with McDonald that fragmentary taxa "might present useful phylogenetic 
information and should not be excluded a priori, but only after rigorous 
application of safe taxonomic reduction and strict reduced consensus methods", 
so it's great he included them, but please tell us what their relationships 
were, even if their placement was poorly constrained.  Not doing so would be 
excusable if the analysis was part of some larger paper, but an analysis is all 
this paper is.  There's nothing else to it, so you'd think the results would 
actually be discussed in detail.  The bottom line is while the matrix does give 
us new data that I'd rather have out there than on McDonald's hard drive, this 
is the first PLoS dinosaur paper I've seen that runs afoul of traditional 
publishers' worry about the consequences of PLOS!
' model o

Mickey Mortimer

----------------------------------------
> Date: Tue, 22 May 2012 15:05:58 -0700
> From: bcreisler@gmail.com
> To: dinosaur@usc.edu
> Subject: Phylogeny of Basal Iguanodonts
>
> From: Ben Creisler
> bcreisler@gmail.com
>
> New in PLoS ONE:
>
> Andrew T. McDonald (2012)
> Phylogeny of Basal Iguanodonts (Dinosauria: Ornithischia): An Update.
> PLoS ONE 7(5): e36745.
> doi:10.1371/journal.pone.0036745
> http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0036745
>
>
> The precise phylogenetic relationships of many non-hadrosaurid members
> of Iguanodontia, i.e., basal iguanodonts, have been unclear.
> Therefore, to investigate the global phylogeny of basal iguanodonts a
> comprehensive data matrix was assembled, including nearly every valid
> taxon of basal iguanodont. The matrix was analyzed in the program TNT,
> and the maximum agreement subtree of the resulting most parsimonious
> trees was then calculated in PAUP. Ordering certain multistate
> characters and omitting taxa through safe taxonomic reduction did not
> markedly improve resolution. The results provide some new information
> on the phylogeny of basal iguanodonts, pertaining especially to
> obscure or recently described taxa, and support some recent taxonomic
> revisions, such as the splitting of traditional “Camptosaurus” and
> “Iguanodon”. The maximum agreement subtree also shows a close
> relationship between the Asian Probactrosaurus gobiensis and the North
> American Eolambia, supporting the previous hypothesis of faunal
> interchange between Asia and North America in the early Late
> Cretaceous. Nevertheless, the phylogenetic relationships of many basal
> iguanodonts remain ambiguous due to the high number of taxa removed
> from the maximum agreement subtree and poor resolution of consensus
> trees.