Jurassic Park Gave us Vegisaurus; Madagascar Gave us Vegisuchus

L. lateral view of Type Specimen, 2004

The SVP memoir describing the Cretaceous crocodyliform Simosuchus is published! Its magnificent and a great contribution likely full of more data and buried treasure than one person could ever use. Its a frequent problem that weekly Science/Nature articles describing new and amazing fossils never follow up with an adequate description and analysis; not this time, and the authors flaunt this fact. It took a few years, but with new specimens and comprehensive treatment, there’s little one can complain about.

I first saw this specimen being prepped at the Field Museum, jeez like in 99? maybe and said, “wow what kind of amphibian is that!?, Greg Buckley told me “it’s a crocodile” with clear intonations that I was a doofus for thinking otherwise. I thought it looked like a big frog or something in the state it was in. who’da thought? I got to return in 2004 to study the specimen (left).

The memoir has numerous articles about various parts  and phylo analysis of the animal (Turner and Sertich).  I only really care about the skull. But, the phylo analysis chapter has some exquisite comparative pictures of notosuchian skulls, and I REALLY like the way the authors illustrate character #s and their codes directly onto the pictures of the specimens; some specific labels fail a bit, but the thought counts and motif is greatly appreciated. It is such a help for those trying to pair up morphology and coding.The skull chapter is rich with cross-sectional data from the hi res CT scans they have been taunting us with for 7years. Perhaps the next generation of papers like this one will come with a high-res 3D model with codings attached as orbiting comments. A brief scan through the limb chapter (Sertich and Groenke) has muscles mapped onto the limbs, so it must be good!

Fig. 7 From Holliday and Witmer, 2009, JVP

With it’s virtually iguana/ornithischian-like multicusped teeth, short face, and vertical jaw muscles, Simosuchus takes the cake presenting fairly solid evidence of a plant-eating crocodile.  It bears other notosuchian characteristics like enlarged dorsotemporal fenestrae and pterygoideus muscles substantially smaller than your standard-fare flat-headed crocodylian–features that I care about. The rostrally shifted, small pterygoid buttress is way cool and I’m really interested in the ‘more in depth functional analysis to occur elsewhere’ they hint at in the Discussion of the skull.

I was very pleased a few years ago to hear from Nate Kley that our interpretations of an epipterygoid in the taxon in our 2009  JVP Croc Braincase Paper (Top Right) was supported by its presence in some of the additional specimens–it was also appreciated that the Simosuchus team allowed us to figure the specimen in that same paper. There’s a paper on the way out on a Metriorhynchid braincase that also supports our interpretations of epipterygoids in Thallatosuchians, so its a bit of a relief that our findings on croc braincases are making their way into the literature and that they’re being supported.

Trying to interpret the biology of such a unique animal is what paleontology is all about and the Discussion is fun with the authors debating whether the animal could use its head to burrow (probably not) (Nate Kley is an expert on fossorial reptiles) and I assume Justin Georgi taking head posture inferences to task. As for the latter, regardless of how one views the utility and significance of semicircular canals, it’d be nice to see a comprehensive treatment of how crocs hold their heads alertly with respect to ears, and/or occipital muscles, before strongly applying data from Pigeon ears to such a bizarre animal like Simosuchus. Such is life. I wonder if the huge palpebrals might have significantly limited its vision with a down-tilted head. Maybe it didn’t care as long as the Simosuchus-opener Masiakosaurus wasn’t lurking about.

The Discussion also notes that new data from the epipterygoid/braincase paper, and other adductor chamber features should benefit future phylogenetic analyses (hooray?maybe we should resurrect our supermatrix and new characters paper). Croc phylogenetics is a mess challenge with numerous virtually irreconcilable matrices lurking about, so I’m not particularly interested in touching that specific problem with a 10ft, stolen copy of TNT. That said, I’m funded to go to South America this next year to work up the Notosuchian end of my ongoing croc research more fully so stay tuned. Attila Osi is doing something similar, and certainly the local researchers on continuing their work. Maybe we can fold some new characters into “the matrix”; I’ve  played with our specific braincase characters, and they’re not pretty, particularly if you have an aversion to multi-state, non-independent characters, and holes & donuts. I think scoring cranial anatomy into independent 0s and 1s is a ludicrous, albeit, I suppose necessary? exercise.

The use of “glenoid fossa” as the identifier for the jaw joint throughout the paper is the equivalent of nails on a chalkboard with me since the glenoid is really either the scapular structure receiving the humerus, or the mammalian squamosal receptacle of the articular disk and dentary. -That- contextual issue aside, the glenoid fossa of mammals is nonhomologous with the articular fossa of sauropsids, so maybe we can move away from its usage in reptile heads one day. I might just shut up about it.  That said, the jaw joints of Simosuchus and other notosuchians are very interesting given their morphologies consistently suggest to paleontologists that there was propalinal (fore-aft) movement of the jaw. This morphology differs from the heavily buttressed, high-walled, ligament-scarred, articular fossae of torsional feeding, hard-biting crocodylians.

Awesome animal, and absolutely beautiful specimens; so many out of the Mahajanga Basin are.

Screw the Age of dinosaurs, the Mesozoic was the Age of Crocs!

I know we gripe about the use of “living fossil” or the “myth of living fossils” as a hook in the media, and “living fossil” is a lame, naive term and an all-too-common misconception. But I think that even though many people in Paleontology  have been aware of notosuchians, herbivorous crocs, and the Mesozoic explosion of crocs for a while now; they don’t always realize the general public still is not all that aware of them. There aren’t any TV shows on them, no kid’s books, no toys, no stickers, they’re not in cartoons, there’s no Notosuchian Train featuring Dr. Pol or the like. It’s rare that the Gondwanan  taxa get much limelight in the press in Laurasia and when they do, they get cute names.  I wonder if applying cutesy mammalish names to Gondwanan crocs like Dog-croc, cat-croc, rat-croc, boar-croc (ffs pancake croc?! is in its own category) etc are really doing croc evolutionary diversity, outreach, and science a disservice.  I can see how an analogy with mammals may be important to convey the niches we think these crocs occupied, but I think they sometimes fall short and are interpreted as just silly names scientists make up. Ooooo Simosuchus is “Pac-man croc”, like Pac-man frogs. What would you call Iharkutosuchus, which is arguably an even more bizarre Late Cretaceous croc than Simosuchus? Wait until we find monkey-croc, an arboreal, frugivorous croc only represented by a distal tibia whose significance for brain evolution will be hotly debated for years.

It seems to me like it wasn’t just the extinction of non-avian dinosaurs that opened niches to mammals, but the extinction of these crocodyliforms as well–they deserve respect.

From Wired.com: The most widespread of all living fossils, crocodiles have barely changed in the 230 million years since dinosaurs roamed the Earth. (Not!)

So, I’m still ok with “living fossil” for a while longer…some usages are indeed abhorrent and just wrong (Right). Just 2 weeks ago I turned in a talk title and blurb for a University/Town-wide talk & Dissection workshop in Early Feb here at Mizzou:

Inside Alligators: functional anatomy and evolution. The latest discoveries in crocodilians reveal bird-like lungs, dynamic skulls, herbivorous species, and numerous other insights that dispel the myth they are “living fossils”.

So I’m equally guilty, but I think we’re at the stage now where we as scientists and croc enthusiasts, can drive the point home that today’s crocs are indeed a relatively boring tip of a very rich tree, and hopefully be rid living fossil moniker in the near future, but through education, not snark. Maybe Simosuchus will help.

PS, I don’t think extant crocs are boring at all; they still hold alot of secrets as well.


Dec 14th: A follow-up to this post, USA Today had a nice writeup on the discovery and publication of Simosuchus. With it hitchhiked an addendum relating to several of the topics I mention above. Lets be clear that 1) armadillos eat worms and invertebrates, not plants so again, mammalimorphizing crocodiles fails; 2) galloping is not known among fossil terrestrial (ish) crocs particularly since their limb skeletons are largely unknown and certainly have not been studied to the extent necessary to make that sort of claim; 3) burrowing, remains quite unclear as well.

About Casey

I am an Associate Professor of Anatomy at University of Missouri-Columbia. I teach Anatomy for the Medical School. I conduct research on the evolutionary morphology of vertebrates, particularly the structure, function, and evolution of the feeding apparatus. Much of this involves studying the biology of bone, cartilage and muscle. of dinosaurs and fossil crocs. I have a great job.
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2 Responses to Jurassic Park Gave us Vegisaurus; Madagascar Gave us Vegisuchus

  1. Nick Gardner says:

    Some points were made on vrtpaleo that galloping only occurs during duress rather than being a normal locomotor strategy in extant crocs. I forget who said it though and if they had a pub to cite for t heir statement.

  2. hollidaylab says:

    yes, they apparently only gallop as an escape response. John Hutchinson has given some talks over the years about his research on croc locomotion: freshies, cubans, etc. I don’t think he’s published it yet though.

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