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DrScottHartman In reply to Brad-ysaurus [2011-06-16 15:54:16 +0000 UTC]

My gut reaction is that Saturnalia is indeed more "prosauropod-like" than Panphagia, but that doesn't mean they couldn't clade together, just that the there was a parallel evolution of that body style.

That said, we're still in the early days of studying basal sauropodomorph phylogeny, and several of the taxa are not very compete. So I wouldn't over-analyse what you can infer from these studies just yet.

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DrScottHartman In reply to SwordSaint001 [2011-06-14 18:20:51 +0000 UTC]

Panphagia was described in 2009, and was presented as the most basal sauropodomorph. Subsequent studies (e.g. Galton's late 2010 paper on Panytdraco) find Pahphagia as a part of Guaibasauridae, which would make it tied with several others for the more primitive sauropodomorph.

If Eoraptor ends up as a sauropodomorph it would presumably be even more primative. If not (and it may be that Eoraptor really is a theropod) then we'll have to see how well Guaibasauridae holds up over time.

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SwordSaint001 In reply to DrScottHartman [2011-06-14 23:02:48 +0000 UTC]

thank you for that information. helps to keep me up to date on what i've been missing lately.

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DrScottHartman In reply to RedinTooth [2011-06-14 18:24:21 +0000 UTC]

Oops, let me back walk back that comment on Eoraptor a little bit. I still give it about even odds of ending up as a basal sauropodomorph, but I think for the time being that Nesbitt's recent phylogenetic analysis of archosaurs has to be considered the the current best word on the issue until more specimens/analyses come out.

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DrScottHartman In reply to RedinTooth [2011-06-14 00:40:50 +0000 UTC]

I think it's pretty well supported at this point; it's even less specialized than Panphagia (and that's saying something) but I'd give it better than even odds for ending up on the sauropodomorph branch.

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DrScottHartman In reply to Afrovenator [2011-06-14 17:09:27 +0000 UTC]

Agreed. Now I want a really good Pisanosaurus specimen, or something similar, so we get an example of an ornithiscian that is similarly close to the root of the dinosaur family tree.

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DrScottHartman In reply to pilsator [2011-06-14 00:39:11 +0000 UTC]

Thanks. The skeletal that shipped with the original paper is what I charitably refer to as "a schematic diagram".

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pilsator In reply to DrScottHartman [2011-06-14 02:08:09 +0000 UTC]

Well, that it didn't encompass your amount of work and anatomical knowledge was plain to see. Interesting to note the fifth metatarsal with a nubbin of the first phalanx. Out of interest (and continuing RedinTooth's thoughts), is the fully developed 5th toe in GSP's Eoraptor skeletal actually preserved or rather conjecture?

And nice to hear your thoughts about its proposed sauropodomorphhood. Although being an armchair paleoartist at best, I was actually surprised how much debate this result of Martinez et al. (2011) fueled on the DML.

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DrScottHartman In reply to pilsator [2011-06-14 04:06:43 +0000 UTC]

I wasn't really trying to rag on them for not "using mine" (since I can't do them all...yet). But honestly a lot of authors really do mean for their skeletal diagrams to be schematic rather than literal representations of animals, which is a problem in the post-Paulian period, as artists assume that skeletal diagrams are meant to be literal.

I should note that schematic diagrams are frankly a useful and reasonable mode of communicating data (e.g. completeness), the problem is that authors aren't more transparent in their labeling. This might be a good topic for the blog now that I think about it...

Anyhow, there aren't toe bones known for Panphagia, while there are for Eoraptor (Greg gets it right). Given the somewhat more advanced condition of Panphagia I followed the original papers assumption that the toe claw is lost (a condition seen in later sauropodomorphs) but this is just an unconstrained assumption at the moment.

As for the DML and the Martinez study...I admit, I get most of my DML mail on my smartphone, and start to skim (or skip) comments of threads that get particularly long and argumentative (there's only so many hours in the day). Still, I think it's easy to see why this was such a big deal. First, the placement of Eoraptor (and Herrerasaurus) has long been a simmering bit broad disagreement, and it was then put through a lot of rapid back-and-forth. When Panphagia was described several people publicly speculated that Eoraptor might get dragged from it's basal saurischian position to a basal sauropodomorph. Then the papers on Tawa (and related studies) seemed to shore up the theropod credentials of Eoraptor quite strongly, only to be followed by the Martinez study (which included Sereno, as a sort of emotional "kick" of plausibility) yanking it back to being a basal sauropodomorph (albeit with limited support). With everyone getting teased that their pet hypothesis might be correct, you're inevitably going to get conflict in public forums.

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DrScottHartman In reply to theblazinggecko [2011-06-14 00:37:33 +0000 UTC]

Technically "prosauropod" is an adaptive grade rather than a natural group, but I think you sum it up nicely with "pre-prosauropod".

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