Friday, October 8, 2010

"The Princeton Field Guide to Dinosaurs" - The Sauropodomorphs

Part 3 of the review series, I should preface this by saying that sauropodomorphs aren't my speciality.  I don't follow the literature closely, so I don't know if some of Paul's nonstandard ideas have been proposed before, or how likely they are to be correct.

As with the theropods, the reconstructions are plentiful.  My favorites include Massospondylus, Lufengosaurus, Yunnanosarus, Jingshanosaurus, Riojasaurus, Gongxianosaurus, Datousaurus, Cetiosaurus and Atlasaurus.

Among non-sauropods, Paul doesn't follow the consensus in a few areas.  Ammosaurus is listed separately from Anchisaurus, Ruehleia is said to be an adult Plateosaurus longiceps, Efraasia is back to being a juvenile Plateosaurus gracilis and P. longiceps is kept separate from P. engelhardti.  He only does a little lumping, with "Massospondylus (or Plateosaurus = Lufengosaurus) huenei" and "Massospondylus (or Plateosaurus) carinatus".  Plateosaurus is usually not in an exclusive clade with Lufengosaurus and Massospondylus, so this seems like an improper synonymy.  Even synonymizing Lufengosaurus with Massospondylus seems wrong if Adeopapposaurus and Coloradisaurus are retained in their own genera.  In the first of a few examples to be noted here, Paul says Plateosauravus cullingworthi "was Euskelosaurus browni, which is based on inadequate remains."  Argh.  Euskelosaurus can't become Plateosauravus since the former has priority.  According to Yates (2004), Euskelosaurus really is indeterminate and could belong to Plateosauravus or an undescribed prosauropod from the Clocolan District.

Among sauropods, Klamelisaurus is treated as adult Bellusaurus, which I know was suggested, but has anyone actually examined this issue?  The mamenchisaurids suffer quite the deconstruction.  I agree with Paul that the alpha taxonomy on these things needs to be examined, but since Paul's rationale is never explained and even his intent is sometimes ambiguous, I can't say he sheds much light on the issue.  tianfuensis is said not to be Omeisaurus (it is "too different"), while maoianus is placed in the genus with a question mark.  hochuanensis and youngi are both said to be in the same genus and perhaps just different sexes of the same species.  They're also excluded from Mamenchisaurus based in part on M. constructus having a shorter neck, though I was under the impression M. constructus' cervicals were simply incomplete so restored as being short.  Paul also lists (quotation marks his) "Mamenchisaurus" anyuensis, "Mamenchisaurus sinocanadorum" and "Mamenchisaurus jingyanensis."  The latter is said to probably belong to one of the other Shangshaximiao species.  While the quotation marks would seem to indicate Paul doesn't think anyuensis belongs in Mamenchisaurus, I'm not sure what they imply for sinocanadorum and jingyanensis (both were properly described, so are not nomina nuda).

Among diplodocids, Paul lists "Amphicoelias or Diplodocus altus" and says "Status not certain, may be a distinct genus or Diplodocus."  Ack again.  Diplodocus altus can never exist, as Amphicoelias has priority over it.  There's an unnamed species of Diplodocus listed from Utah represented by "two skulls and majority of a few skeletons."  It's illustrated with a complete skeleton and is listed separately from D. longus, D. carnegii, D. hayi and D. halli (wasn't this emmended to hallorum?).  Anyone know if the literature supports this?  Paul seems to place Apatosaurus parvus, A. excelsus and A. louisae in the subgenus Brontosaurus, which contradicts Upchurch et al.'s (2004) study that found parvus and excelsus to be closer to ajax than to louisae.  His statement "Brontosaurus is the shorter, narrower necked version of Apatosaurus from the lower and middle Morrison" wouldn't be agreed on by sauropod experts as far as I know.  It's these kinds of statements which make me cringe imagining kids reading the book, since they're just stated as true despite being found nowhere in the literature.

Paul excludes ruyangensis from Huanghetitan and giganteus from AntarctosaurusPitekunsaurus is said to be "probably a juvenile of one of the other Anacleto titanosaurs."  I have no idea is these things are plausible.  While I can never keep track of the metric crapload of titanosaurs being described these days, things like placing Isisaurus outside Lithostrotia but including Huabeisaurus don't seem to mesh with even the pitiful amount of consensus that has been reached regarding their phylogeny.  I also don't think the evidence justifies synonymizing Opisthocoelicaudia skarzynskii with Nemegtosaurus mongoliensis or placing Quaesitosaurus in the same genus.  It's not like formations with more than one sauropod are uncommon, and I'm doubtful Nemegtosaurus' sister genera have skulls preserved.  Finally, Pleurocoelus is said to be "originally Astrodon johnstoni, which was based on inadequate remains."  But just like with Euskelosaurus, Astrodon has priority over Pleurocoelus so can never become Pleurocoelus.

Next up, ornithischians *yawn* ;)


  1. Hi, thanks for this. I was really curious to see what Greg would do with the basal sauropodomorphs but simply don't have the cash to splash around on books like this.
    Regarding Euskelosaurus, I've matured my views a little bit and seen a heck of a lot more material since I last wrote about it. Euskelosaurus is a real pain. The type isn't Plateosauravus since the tibia lacks a distinctive autapomorphy seen in P. cullingworthi (this autapomorphy is present on more than one specimen of P. cullingworthi so we aren't dealing with an odd individual variation). Nor is it Antetonitrus, Blikanasaurus or apparently Eucnemesaurus (the latter comes closest, differing largely in femoral characters - but the femur of Euskelo is really beat-up). Nor is it likely to be the thing from Clocolan either since it is at least twice the size of that apparently mature specimen.I may have to eat my words and accept Euskelo as a distinct taxon though only diagnosable by lacking the autapomorphies of all its contemporaries.

  2. The arbitrariness what Greg's done to the eusauropods here makes my gut hurt. *sigh*.

  3. Adam, is it possible to diagnose Euskelosaurus on the basis of an unique combination of features that differentiates it from any other known basal sauropodomorph?

  4. Very interesting about Euskelosaurus. Fits into the trend I see of supposed nomina dubia being valid once looked into more closely.

    Btw, Paul has no phylogeny among basal sauropodomorphs, thouh he does say "many researchers consider known prosauropods to be the sister group to sauropods", which even the Galton and Upchurch matrix doesn't agree with now. The division between prosauropods and sauropods in his book is also quite haphazard, with Lessemsaurus, Camelotia and Blikanasaurus as prosauropods and Antetonitrus and Chinshakiangosaurus as sauropods.

  5. Andrea,

    Yes, I think it can. Its still not very satisfying since its unique combination of characters simply point out a poorly known large basal plateosaurian that lacks the distinctive autapomorphies of other taxa. But yes I'm forced to admit yet another sauropodomorph into the rapidly expanding bestiary of the lower Elliot (its getting crowded down there!). I should write this up or something.....

  6. Rexisto

    Mamenchisaurus sinocanadorum 75 tons with a 2.5 meter femur is doubtful, and that has not been formally described the skeleton can be constructed in China and everything is an estimate not well studied. Given the size of the jaw and cervical rib may have been much smaller, perhaps with a femur of 2 meters. The remains are complete and new elements really seem to have been rebuilt and are not real.