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Re: Wukongopterus and Darwinopterus



 More characters, more taxa, brings better resolution.

 David Peters

Not always, see below.

 On Nov 24, 2009, at 7:00 PM, Unwin, David M. (Dr.) wrote:
>
> As mentioned above, I also scored Darwinopterus for the Wang et al.
> 2009 data set. It is isometric with “Wukongopterus” which can thus
> be safely deleted from the analysis. According to Wang et al. 2009
> “Wukongopterus” has missing data for 34 out of the 89 characters
> used in their analysis (and is thus 62% complete). Darwinopterus
> adds data for 28 of these characters and is thus 93% complete. So,
> I reran the Wang et al. 2009 data set using this near complete
> sequence for Darwinopterus/"Wukongopterus". [...] Anyway, one might
> predict, as Kellner’s comment implies, that the better known
> Darwinopterus (compared to “Wukongopterus”) should now fall out as
> a sister group to pterodactyloids. Not so. This more complete data
> set generated a lot more trees (109980), and the strict concensus
> was very poorly resolved, failing, for example, to recover a
> monophyletic Pterodactyloidea. Darwinopterus formed a polytomy with
> many other basal forms and several pterodactyloid clades. The 50%
> Majority Rule tree did recover a monophyletic Pterodactyoidea, but
> “Ornithocheirus” compressirostris was located basal to Dimorphodon.

Adding data can reveal previously hidden character conflict and thus increase the number of MPTs.

This can also happen when previously unordered characters are ordered (Marjanovic & Laurin 2008b).

Of course, the solution isn't to exclude data, it's to include even more -- and to recheck the _quality_ of the data: How many typos are in there? How many correlated characters? Which characters should be ordered or given a stepmatrix, and why? And so on and so forth (Jenner 2001; Marjanovic & Laurin 2008b, 2009; Marjanovic, Germain & Laurin in prep.).

Size does matter (Emmerich 1998), but so does quality (Kitamura 2004).