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Re: Support for Enigmosauria



Another part of the problem is, well, where else would they go? The thing is, no, I don't think the support for an oviraptorid-therizinosaur grouping is terribly strong, but it's better than for any other arrangement, considering that therizinosaurs are about as birdlike as the oviraptorids in most features of the anatomy and in some instances, moreso (e.g. posterodorsal process of the ischium, elongate digit IV of pes, tapered posterior iliac blade, terminal placement of the obturator process, opisthopuby), it seems like both groups may have lost (or convergently evolved) a number of derived features. The only times I've had therizinosaurs fall out anywhere besides with oviraptorosaurs (in some earlier versions of my analysis), they fell out *closer* to birds than did oviraptors, probably because of these characters.
This is also where the consistency index thing is misunderstood. Some researchers seem to feel that it's a good thing to have a CI of .9 (for the non-cladists, CI is a measure of homoplasy, if a character either evolves twice or evolves once and is lost once, its CI becomes .5 e.g.). However, if you are looking at a group which has been evolving for a very long time (say, the whole Mesozoic), and has many members, your CI is going to be a lot lower- the longer these taxa evolve and the more taxa are included, the more convergence and reversal is going to up. Getting a CI anywhere near .9 for a large, diverse group of long-evolving animals is preposterous and indicates a fundamentally flawed method, possibly including problems in biased selection of OTUs, biased selection of characters, biased coding of characters, or most likely, all three. The point isn't to get a low CI, but rather the lowest CI relative to everything else out there. If .45 is the lowest CI you get out of several billion trees linking dozens of taxa, then that's the simplest answer. So therizinosaurs and oviraptorosaurs being related ain't simple- but no one has yet come up with a simpler possibility, given our current (poor) understanding of the anatomy of both groups.