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palaeozoologist β Uberabatitan
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Published: 2010-11-23 23:15:36 +0000 UTC; Views: 5675; Favourites: 24; Downloads: 108
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Description
Uberabatitan ribeiroi was a titanosaur sauropod from the Marilia Formation of Minas Gerais, Brazil. It achieved a length of approximately 15-17 meters and a mass of approximately 11-15 tonnes. U. ribeiroi lived in the late Cretaceous of Maastrichtian in age (~70-65 mya).It was unjustly left out of Greg Paul's Princeton Field Guide to Dinosaurs, and thus felt it was in need of its own restoration here.
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Comments: 32
It's nice....then it's Brazil's biggest dinosaur?
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Possibly, either it or Trigonosaurus is the largest known dinosaur from Brazil.
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I love the ALIVE aura you gave the creature, as well as the textures.
Its right arm is fine. What happened to its left arm? The legs are excellent to my eyes.
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Thanks!
The right arm is, *ahem* *coughs*, suffering from an arterial skeletal muscle infarction.
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Thanks, much appreciated!
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Thank you! I really appreciate that, especially coming from you!
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Nice detailed image! I also had some misgivings about the Princeton Field Guide.... namely Daxiatitan, Phuwiangosaurus, and hopes for a full skeletal of Malawisaurus... in any case, this is pretty legit, really like the spiky look on the hands (but I'm not sure if titanosaurs had this).
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Hey, thanks, that means a lot! Glad you like it.
My misgivings with the Princeton Field Guide are also many. Daxiatitan has a relatively complete skeleton (for a titanosaur) and should have had a skeletal restoration done (and its adult size can be determined with a fair amount of certainty au contraire to what the Field Guide states), as should have Phuwiangosaurus and Malawisaurus. I complained about this on the DML, and got a rather nasty reply from Greg Paul. His main reason was that he was reluctant to do a new skeletal restoration if there were not a pelvis known. Of course, this is hogwash since Phuwiangosaurus is actually known from a pelvis, and I do not see why whether having pelvis material present or not makes or breaks the deal for a new skeletal (furthermore, Trigonosaurus is known from a pelvis, as is Epachthosaurus, Argentinosaurus, Isisaurus and some other titanosaurs of which none get skeletal treatments). Oh well, guess I'll have to do them myself.
The spiky hands are based off of spiky impressions known from some footprints that have been referred to Bothriospondylus. It is not known how wide spread these tubercles were, but I speculatively put them on here.
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Maybe you SHOULD do them. Hmmm? How about it?
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I'm sorry, I don't follow. What do you think I should do?
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All of these skeletals! Maybe you should even write a competition to GSP's book...hmmm...?
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Well, I'm afraid my skeletal library will be no where near as large as GSP's for a long time as I simply don't have the technical papers I need to have a skeletal library as big as his. Scott Hartman is getting there, and is a far superior skeletal artist than I am so I'd refer to him if I were you.
As for a book, it is highly unlikely that I'll ever get there...certainly no time soon.
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You'll get there...maayyybe. Hopefully!
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Haha, well, we'll see I guess.
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No pelvis? LOL I've even got pictures of the pelvis of Phuwiangosaurus (and that's not even including the PDF of the paper!) You can find a partial mount (and I DO mean partial) with the hips included just by googling the beast. There are pelvis elements known for Andesaurus and Argyrosaurus, and neither one of those got the Greg Paul treatment either.
Greg Paul did do an Argentinosaurus skeletal back in the 90s (it's not in the book, shocker!!!!) but it's missing the pelvis, the femur, and most of the dorsals. Which is a shame because not all the material was figured in the description paper, and the only skeletal to show all the elements was Ken Carpenter's, which really fudged the proportions of the silhouette as well as the shapes and positions of most of the bones, and worst of all was TINY and lacked reliable detail. For all the stuff that wasn't figured in the description paper, I had to hunt up images on the internet, fortunately I was able to find a diagram of the sacrum and tibia and some decent pics of the femur and a few dorsal verts, which pretty much filled in all the gaps. But not all of the pics were from good angles, so I had to mess around with frontal widths of my diagrams and update my Argentinosaurus.... AGAIN. I only included anterior views for stuff that I had good frontal references for.
As for Trigonosaurus and Isisaurus, why those two didn't get a skeletal in the book is beyond me. Isisaurus is complete enough to restore with almost no margin of error. And Trigonosaurus has a pretty impressive and totally UNCRUSHED spinal column with all the laminae in perfect condition, no distortion or erosion, just like new! Seriously, when when do we EVER see that sort of thing in sauropods? And yet it isn't even placed firmly in a family, much less given a decent skeletal drawing by anyone, not just Greg Paul. And Epachtosaurus has some pretty good remains... any idea which family it belongs in? It looks similar to Argentinosaurus in some ways.
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Felipe Elias has a Trigonosaurus.
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Yeah, but it's hard to tell how accurate his skeletal of Trigonosaurus is.... Elias's skeletals seem a bit "sketchy" and "comic-ized" like those of Paul Sereno. And Paul Sereno has been very wrong with his skeletals before....
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Yeah...but it's an OK reference point. Sort of. They don't look too bad. I've checked them, but I've gotten lazier and lazier as time goes on.
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I know, I thought it was a ridiculous argument. Here is my initial thoughts on the book on the DML . Here is GSP's response and here is my reply , if you're interested.
Yes I have seen his Argentinosaurus skeletal, in fact most of GSP's papers have pdfs now up at his cite in his CV, including one with that skeletal. I'm also somewhat confused by Carpenter's skeletal and I have been meaning to email him to ask him about that. As far as I know, only 7 dorsals are known (not 9 as portrayed) which is one more than described, and a partial ilium , femur and pubis (also not in original description) have been found. I'm not sure where he got refs for the ilium and pubis, though (yes, I know, there are pictures of the mounted skeleton that include that material but I am somewhat wary of the accuracy of the mount).
I concur on your opinion of the lack of skeletals for Trigonosaurus and Isisaurus. I mean, if he includes a skeletal of Cetiosaurus for goodness sakes, those other taxa should have been included.
I'm not sure where Epachthosaurus belongs as it has a hyposphene and hypantrum complex, but otherwise appears to have derived characteristics characteristic of saltasaurs. Your guess is as good as mine.
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Sheesh it looks like these titanosaurs just kept on recycling their old basal genetic material with every new family radiation! Even hip shapes got recycled... there's a huge amount of throwbacks in skeletal design.
At least Greg Paul did a Cetiosaurus, that's a genus that hasn't had a skeletal for a century! But yeah, I'd like to see what he does with those others. O well, more skeletals for us to do...
I'll see if I can download those PDFs, I haven't seen them on his site before.
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I'm not really sure exactly what was going on with Epachthosaurus, whether it was recycling skeletal material or not. In fact, I am starting to think that maybe hyposphene-hypantrum complexes are not necessarily indicative of how derived is a titanosaur. To quote from Martinez et al. (2004), "Although the extremely large titanosaurian Argentinosaurus possesses accessory intervertebral articulations in its dorsal column, they are anatomically distinct from those of Epachthosaurus (Salgado and MartΔ±Β΄nez, 1993; Sanz et al.,
1999). Moreover, Argentinosaurus possesses reduced, non-bifurcate prespinal laminae, implying that this taxon may be more highly derived than Epachthosaurus (Salgado et al., 1997)."
So, they think Argentinosaurus might be more derived. In fact, I know of at least one other study that indicates that Argentinosaurus may actually be fairly derived. It may be that the taxa that retained these basal features had different lifestyles (since the hyposphene-hypantrum complex is thought to have stiffened the vertebral column).
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Yeah I've always wondered about that.... why did some titanosaurs need a stiffer back? I'm sure supporting armor had nothing to do with it, sauropod armor isn't all that heavy relative to the whole animal. I doubt any titanosaurs were flexing their torso sideways, they weren't all that flexible to begin with. Maybe the stiffness was needed for constant rearing or for sex? But then why don't non-titanosaurs have it?
Argnetinosaurus has SOME kind of hyposphene-hypantrum complex, but mainly in the rear dorsals. It's totally absent in the front dorsals. And it's not as extreme as insome other titanosaurs. But how old it Epachthosaurus? It's from the Bajo Barreal formation, which is either Cenomanian or Campanian (BIG difference there...) right now the popular stance is Cenomanian, but I notice that several species tied to Campanian formations are also found in Bajo Barrel which indicates it WAS Campanian. I don't see how Argentinosaurus could be older AND more derived than Epachthosaurus, unless Epachtosaurus is a descendant of a much older line.
I have a feeling that hyposphenes have nothing to do with how basal or derived you are, but rather your lifestyle. I see so many weird things in titanosaurs that are flat-out making it impossible to classify some species. A lot of experts place Isisaurus as a saltasaur. I'm not convinced. IMO it could just as easily be an anomalous lognkosaur or argyrosaur. And what the heck Barrosasaurus is, nobody seems to know. It's so freaky it doesn't fall into any of the known families of titanosaurs, and looks like an odd mix of all of them. So perhaps traits did get recycled and "remixed" every version odder than the last... caudal vertebrae of many titanosaurs are notorious for this.
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Well the vast majority of titanosaurs didn't have a stiffer back because they lacked hyposphene-hypantrum complexes, which means they had more flexible backs in most cases. This might be because they reared up more (supposedly), but there have not been a lot of biomechanical studies on titanosaurs since they aren't well studied as other sauropods (which, in all honesty, get the short shrift in terms of research papers as a larger group too compared to theropods and hadrosaurs), so why some groups had stiffer backs than others is not readily apparent.
Epachthosaurus is from the Bajo Barreal Formation, as you correctly noted, which is thought to be middle Cenomanian to the Coniacian. In the 80s, it was apparently thought that the Bajo Barreal Foramtion was from the Campanian-Maastrichtian, but the modern consensus is that it covers the Cenomanian to Coniacian, which is a period of around 10 million years or so. I am not currently aware of any taxa that hail from that formation that are confidently placed at a younger age of Campanian. So, Argentinosaurus is not much older than Epachthosaurus, and even if it was, that would not preclude it from being more derived than Epachthosaurus since there is no reason to think that Argentinosaurus was an ancestor of Epachthosaurus. I think by "derived" the authors mean that the skeletal features are more derived, not necessarily meaning more derived in a direct ancestral-type way.
I completely agree with you that hyposphene-hypantrum complexes probably have little to do with how basal or derived a titanosaur taxon is or is not, since everything from basal somphospondylians (Daxiatitan) to saltasaurs (Epachthosaurus) have them.
Isisaurus is a complex case. In fact, a comparison with the sacrum of Argentinosaurus reveals striking similarities as do the ilia. However, their dorsals are not very similar at all (however, this may be somewhat misleading since the hyposphene-hypantrum complex of Argentinosaurus appears to be unique to it and are only present in the posterior dorsals apparently and no posterior dorsals have been figured for Isisaurus). So again, each taxon needs a re-description badly with hi-res photos and good anatomical drawings along with a new phylogenetic analysis (although I hear Kristina Curry Rogers and Jeffrey A. Wilson are working on a review of the titanosaur phylogeny so that may help clear things up 
Either titanosaurs did mix and match traits often to deal with new environmental conditions (for instance the calmodulin pathway in Darwin's finches appears to control beak characteristics which have been observed to change morphology back and forth in populations in response to their environment; maybe something similar was happening in titanoasaurs) or our understanding of titanosaurs still has a lot of growth to do (actually, it's probably some of both).
And titanosaur caudal vertebrae are annoying, that's all I have to say on that.
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I don't consider Epachthosaurus a saltasaurid at all, but rather a side branch of titanosaurs that led to things like Trigonosaurus and Barrosasaurus. It seems to be about as derived as the argyrosaurs, but less so than antarctosaurs or saltasaurs. Lognkosaurs probably diverged earlier, so it seems that hypantrum-hyposphene was lost more than once in the history of titanosaurs. That's just my take on it for now...
One other thing is that titanosaurs which lack a hypantrum-hyposphene complex seem to feature a more passive form of interlocking or stiffening of the dorsal column, with the neural arches slanted way back relative to the centrum, and the postzygapophyses being "hugged" in the valley formed by the prezygapophyses. Also the diapophyses are pretty wide in derived titanosaurs, making extreme lateral bending unlikely. The vertebrae passively fit together without hypantrum-hyposphene, as they seem to have more extensive contact surfaces.
As for Ligabuesaurus.... I always thought it was a basal titanosauriform, not a true titanosaur, so it's pretty odd to consider that it DOES resemble Futalognkosaurus in the anterior dorsals.... maybe this was an independently evolved pattern.
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BTW, I know this is a bit late to this comment, but I just came by Curry Rogers (2005) that includes the most complete and detailed phylogenetic analysis to date of the titanosaurs, and it indeed finds Epachthosaurus as a member of the Saltasauridae clade. Also interesting is that Argentinosaurus is part of the Saltasauridae and it itself clades with Opisthocoelicaudia and Alamosaurus, among other interesting things. You can see the cladogram in the preview for the book "The Sauropods: Evolution and Paleobiology" on Google Books (its on page 69; note that the node J indicates Saltasauridae) or as a calibrated phylogeny here .
Obviously this result isn't set in stone, considering the number of titanosaur taxa published since then, but it does give a good general impression of titanosaur relationships.
Ref--
Curry Rogers, K. A., 2005, "Titanosauria: A Phylogenetic Overview" in Curry Rogers and Wilson (eds), The Sauropods: Evolution and Paleobiology pp. 50β103
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Your right that Epachthosaurus isn't a saltasaurid (well, maybe), but I never said it was, I said it was a saltasaur which could mean it was a saltasaurian (although I'm not aware of any definition for a Saltasauria). My point was that it is still quite derived. It was found to be more derived than Rapetosaurus and Nemegtosaurus by Ksepka and Norell (2010). Interestingly, Epachthosaurus was found to be more derived than Rapetosaurus and Nemegtosaurus and the latter of which are outside Saltasaurida however, Opisthoceolicaudia is inside the Saltasauridae, but Wilson (2005) noted that Opisthocoelicaudia and Nemegtosaurus are probably congeneric. If this is true, then Rapetosaurus and Nemegtosaurus would likely be saltasaurids, and since Epachthosaurus is more derived then they, it too would be a saltasaurid in this case.
In the end, titanosaur systematics is a mess, so you might be right that Epachthosaurus is not a saltasaurid, but I might be right too. Future analyses will have to clarify it. Your other hypotheses about who is related to whom are otherwise (as far as I know) untested and not supported by any other current research.
I'm not going to say anything on hyposphene-hypantrum complexes for the moment, but I will note that Epachthosaurus also has strongly swept back neural arches. I don't know what you mean by postzygs being "hugged" though by the prezygs. The diapophyses aren't that wide in Saltasaurus or Rapetosaurus.
I don't think I said Ligabuesaurus was a true titanosaur, if I did, I misspoke. Considering that the posterior dorsal vertebrae of Ligabuesaurus has a hyposphene-hypantrum complex and considering that the parts of the dorsal vertebrae that are preserved are quite wide, I think your implicit suggestion that wide diapophyses were evolved to stiffen the dorsal column in the absence of hypo-hypantrum complexes appears to be falsified.
Refs--
Ksepka, D.T. and Norel, M.A. (2010). "The Illusory Evidence for Asian Brachiosauridae: New Material of Erketu ellisoni and a Phylogenetic Reappraisal of Basal Titanosauriformes." American Museum Novitates, 3700: 1β27.
Wilson, J. A. (2005). Redescription of the Mongolian sauropod Nemegtosaurus mongoliensis Nowinski (Dinosauria: Saurischia) and comments on Late Cretaceous sauropod diversity. Journal of Systematic Palaeontology 3: 283-318.
BONAPARTE JF, GONZΓLEZ-RIGA BJ AND APESTEGUΓA S.2006. Ligabuesaurus leanzai gen. et sp nov. (Dinosauria, Sauropoda), a new titanosaur from the Lohan Cura Formation (Aptian, Lower Cretaceous) of NeuquΓ©n, Patagonia, Argentina. Cret Res 27: 364β376.
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Thanks! It's much appreciated.
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