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Re: Yonghesuchus, was Shuvosaurus



Strange only because it hasn't been TRIED before. Lay them out on paper. It'll make sense.

Not to me so far... :-)

> DM: Are you sure you've included all proposed
> apomorphies of Archosauriformes as characters in your analysis?

Not necessary, as explained way earlier. Taxon inclusion is all that is necessary after 150 or so characters are used.

What, you have only 150 or so characters in your matrix, and in spite of this you are so certain of your conclusions?!?


You've misinterpreted the "enough is enough" phenomenon. _*For each number of taxa*_ there's a number of characters which is "enough". You have something like 1.2 characters per taxon. This is _nowhere near_ enough. There's a reason why the recent theropod analysis start at 250 characters, which is obviously not enough (judging from the poor resolution of those trees), have doubled that, which is still not enough, and will soon reach four, five, six times as much, _while maintaining similar taxon numbers to your analysis_!
You'll agree that if you have 151 taxa, then having only 150 characters must produce at (the very) least one trichotomy, right? Now what could the chance be that 151 characters would happen to correctly arrange the 151 taxa? Perhaps adding 10 more characters would show that the 151st character evolves convergently as easily as ovovivipary in squamates?


Hey, a ratio of 1.2 characters per taxon is even worse than my bird analysis, which has over 1.31 (or 1.34 if I don't count the allzero outgroup or the hopelessly fragmentary *Alexornis*, or almost 1.37 if I ignore both) and _still_ produces phylogenetic grass (even without *Alexornis*)! New Mesozoic birds keep being discovered faster than I can discover characters. Sorry, but... to quote... "it's hard work".

If you're worried about it though, suggest a character or ten that would attract other (traditional) taxa. Would love to see the list.

I'd like to, but I won't have time for at least, say, a week. But anyway, I don't know which characters there are in your matrix; if I suggest the same ones, that's obviously no use. I hardly have any literature on archosauromorph phylogeny... probably you should try to get Senter's thesis... I think I can send you Müller's paper, probably with its supplementary information. Or do you already have it?


In the Diapsida, if is difficult to find any characters that occur in isolation. The homoplasy index is way higher than I've ever seen elsewhere. Although the "diapsid" middle ear is not visible in the great majority of taxa â?" and so did not make my character list â?" if it evolved twice or more then it would join the great majority of characters that also pop up repeatedly.

Of course, the fewer characters evolve repeatedly, the better... and then of course the evolution of an ear -- a major rearrangement in the function of the stapes -- may be more than one character state change...


And if you have good material on Youngina, please point the way~!

I don't. I was just following Senter and Müller. But from Friday onwards, I'll be in Paris to write my ~ Master's Thesis under the supervision of Michel Laurin. He could well have something.