New, strange, and HUGE titanosaurs!

Posted by Nima On Wednesday, February 16, 2011 4 comments

While everyone's busy preparing for Europasaurus month and the International dinosaur illustration contest in Spain, here's a heads up on some new titanosaur discoveries.

Traukutitan - a new midsize to large titanosaur, probably a Lognkosaur. Read the paper HERE.

It's not breaking any size records, but still, that is one seriously big femur. And gorgeous too, the thing's almost perfectly preserved.

Tapuiasaurus - a rather small titanosaur from Brazil, tapuiasaurus is the oldest known member of nemegtosauridae, dating all the way back to the Albian epoch of the Early Cretaceous. That's a pretty big deal, because up until now it was believed nemegtosaurs only emerged at the end of the Late Cretaceous. Since nemegtosaurs are pretty much the most advanced titanosaur family known, that means all the other more primitive families are probably even OLDER than the Albian (and most of them are only known from Late Cretaceous species too!) This amazing specimen has a complete skull and hyoid (throat) bones, not to mention explaining the whole crazy defiance-of-continental-drift problem previously present in the nemegtosaurid fossil record. Interestingly, the skull is "bleached white", much like remains of its Mongolian relatives... probably has to do with the sediment mineral content. Read the paper HERE.

Lastly, there's a huge new specimen of a titanosaur that's been known for a long time - Alamosaurus. This sole sauropod of the North American Maastrichtian age is known from several juvenile and adolescent specimens of different ages and sizes, and it was long thought that the adults were around 50 ft. long.... until a specimen popped up a few years ago that was more like 80 ft. long. So that must be the full grown adult? NO. Now there's a specimen whose neck vertebrae were apparently just as big as those of Puertasaurus. Which means - yeah, we're looking at an Alamosaurus that topped 100 feet. Easily the biggest titanosaur of the northern hemisphere. And one of the three or four biggest dinosaurs of all time, by the looks of it. Read the paper HERE.

Here's a scale diagram of the Alamosaurus neck fragment on top, and the 9th neck vertebra of Puertasaurus below. At right is a femur from a smaller (though still gigantic) individual of Alamosaurus. Is the new giant specimen finally an adult? I'd think so, but wait until the next one turns up!

And on an unrelated note, there are rumors that a new planet may have been found in the deep reaches of the solar system. And it's downright huge. All you 2012 conspiracy buffs probably don't need to hold your breath though. It will take two years to sift through the data, which may or may not prove the existence of this theoretical "Planet X". And it's not going to be anywhere near us next year, assuming it exists. We're talking about an orbit 15,000 times farther from the sun than we are, for a planet that's too far away to see or even be lit by the sun, at least in visible wavelengths. Still, finding a new planet out there would rock, no question.

FORGOTTEN GIANTS, #2: Argentinosaurus

Posted by Nima On Saturday, February 5, 2011 21 comments

It has been a LONG time, dino-fans. But after SVP 2010, its aftermath, writing and working on tons of other projects, I thought I'd show you all something that's already been making the rounds on DeviantArt.

My second installment of the Forgotten Giants series, Argentinosaurus!

Argentinosaurus huinculensis is widely considered to be the biggest dinosaur. Though Amphicoelias fragillimus would have been far larger, and even today, Puertasaurus is the biggest dinosaur known from currently existing remains, that still doesn't reduce the fact that Argentinosaurus still holds many records.

* The largest femur currently known
* The tallest dorsal vertebrae currently known
* The longest tibia currently known (no, Bruhathkayosaurus doesn't count. Here's why.)
* Possibly the largest sacrum ever discovered
* The largest replica/speculatively sculpted fiberglass skeleton mount anywhere (there's one copy in the Fernbank Museum, another in Germany's Senckenberg Museum, and another at Museo Carmen Funes in Plaza Huincul, near the site of the dinosaur's discovery).
* The longest dorsal column of any titanosaur
* The largest (and possibly only) dinosaur to have a museum built on-site specifically to house its remains
* The biggest dinosaur named for a country

So it's almost a forgone conclusion that this giant would be #2 in my series. It's not really "forgotten" at all, but it's still a very important member of the titanosauria, and still not very well-understood. The remains uncovered and described by Dr. Jose Bonaparte and Dr. Rodolfo Coria are pretty limited, but the size of them is astounding. Vertebrae over a meter tall. A femur 8 feet long. And hips as wide a car.

Within a few years it had become an international sensation. Finally, Ultrasauros was out and Argentinosaurus was the new biggest dinosaur. By the late 90s, its name was well known, and it became the subject of a number of long-forgotten TV specials with badass music but dismally high narrator turnover rates.

Ahh yes, the 90s. Good times...

Argentinosaurus is today still famous as the "biggest dinosaur" despite Supersaurus being longer, Sauroposeidon being taller, and the legendary Amphicoelias fragillimus being far longer and far heavier. Even since 2005, when the even more massive Puertasaurus was discovered, Argentinosaurus is still the iconic "record holder" in the eyes of the public. So even though it's pretty popular and far from forgotten, it's still a very important titanosaur, so you knew I was going to give it the Paleo-King treatment sooner or later!

However, there was a bit of a challenge - though huge, the known bones of Argentinosaurus comprise only a small portion of the skeleton. Several dorsal vertebrae, a tibia, a referred femur shaft, a partial sacrum, parts of the ilia and a fragment of pubis. There's also a second referred femur which may be from Argentinosaurus but I've never seen it figured.

This scarcity of fossil remains hasn't stopped people from trying to fill in the huge gaps. The Fernbank Museum's Argentinosaurus mount in Atlanta, Georgia, which is made of mostly speculative fiberglass models along with a few casts of the original bones, is one such attempt. But it's got a host of mistakes in the speculative parts.

Fernbank Museum mount

Senckenberg Museum mount (Frankfurt, Germany)
Museo Carmen Funes mount (Plaza Huincul, Argentina)

These three mounts are all identical, and even have similar poses, but are photographed from different angles. See if you can find the following errors in them (there may be even more that I didn't catch):

* Abnormally angular nasal arch
* Lower jaw looks strangely too much like that of Giganotosaurus - huge side hole and all!
* Teeth are far too few and thin, appear to be made of wire
* Neck is too horizontal (probably a result of the designers and welders reading too much Kent Stevens...)
* Most neck vertebrae are just clones/recasts of one another; three in a row identical, then the next three...
* Cervical ribs are drooping down at the ends instead of overlapping snugly in double rows along the base of the neck.
* Ribs are excessively deep in the chest region to shorten far too rapidly as you go back to the hips - a 'triangular pan-pipe' rib cage profile not seen in any sauropods.
* Ilia are curved inward toward the backbone at their front tips, big mistake! In titanosaurs (and all macronarians for that matter) they are curved OUT. Titanosaurs had a wide belly, flared-out hips make sense. For that matter, the rib cage is also a bit too narrow!
* Sacrum is missing large portions of the front two sacral ribs (the original fossil was missing them too -why didn't the preparators account for this and reconstruct the missing portions?)
* Sacrum is not fused to the ilia - in fact there are huge gaps separating it from them. The reason for these garish gaps can only be guessed at.
* The radius and ulna are improperly aligned in both arms. They should be one in front of the other, not side by side like the tibia and fibula. A little knowledge of vertebrate anatomy could go a long way here...
* The hands lack phalanges and thumb claws. The reasons for NOT getting rid of them are actually quite strong for titanosaurs, especially basal ones like Argentinosaurus. Suffice it to say that even derived titanosaurs like Diamantinasaurus had thumb claws - they just don't get preserved in most titanosaur hands because of the loose cartilage connections in the phalanges, which dessicated easily, allowing the thumb claws to be washed away.
* The feet are far too large and have an excessive fourth claw. This is not found on most sauropods.
* The metatarsals and toes are arranged in an almost linear pattern, rather than the semi-columnar, circular pattern that they would normally articulate in. And yet we criticize Chinese museum workers for making the exact same mistake with their sauropods... sheesh.
* The ankles have an extra "squashed mound of dough" bone beneath the real ankle bones, the Astralagus and the Calcaneum (both of which are too large anyway). This squashed mass is not a real bone at all, nor is it based on anything found in real fossils. One can only assume it represents ossified cartilage, but the ankle cartilage of sauropods NEVER ossified!

Those awful feet ! Linear arrangement of the digits, extra 4th claw, no vestigial 5th phalanx, 4th metacarpal is mysteriously thicker than the 3rd one, ankle bones WAY too big to match the tibia and fibula, and the feet are practically the size of Texas for a dinosaur that was only 110 ft. long!
You could probably sleep under those feet at night!

As for illustrations of Argentinosaurus.... some are great, some are okay, and most are downright terrible. The terrible ones are too many to list. But here is a sample of some of the better ones out there:

Aldo Chiappe. While his version isn't necessarily the most accurate, I do like how he really gives it the feeling of taking up a LOT of space. Great shading and the texture just draws you in...

Unknown artist. Neck needs a bit of work, but the head is unmistakably macronarian.
Illustration from the "Gigasaurier" German exhibition at the Senckenberg Museum (artist unknown). Neck is far too horizontal, but the head is definitely macronarian, which is a plus. Furthermore, I like the fact that the legs are not so "overbulked" with this one.

Fabio Pastori. Although I'm not a huge fan of his textures for either Argentinosaurus or Mapusaurus, he did get the basic shapes generally right.
Dinoraul. This is a 3D model, that is apparently available for sale. Probably the best 3D render of Argentinosaurus, though the neck seems a bit short and stocky. The head is excellent, nice big nose, but I can't help noticing the head's remarkably familiar "squashed" appearance - I suspect this guy must have ripped off my Puertasaurus' head in some capacity... (I'm NOT making any money off of this model, I guarantee you that).

Steve Kirk. This painting was done for one of the later editions of Dougal Dixon's Dinosaurs, which was probably one of the best dinosaur books a kid could ask for back in the 90's (the early editions didn't include Argentinosaurus). Very good size effect, if not the best leg/neck proportions. Thumbs up for the vertical neck! Unfortunately I can't post a larger image, but here it is if you want to see it close up.

Unknown artist. Nice long neck, though too horizontal, and the torso seems too short for Argentinosaurus. The pose, the juvenile, and the incorrect diplodocid-like head, give away that this artist probably copied Mark Hallett's famous Mamenchisaurus painting to some extent. A wonderful painting by the way, though outdated.
Greg Wenzel. He's is definitely working in the style of Greg Paul. Very nice and all around realistic painting of Argentinosaurus. Good skin texture, nice plant life, long semi-vertical neck, and macronarian head typical of basal titanosaurs. Skin color is a bit bland, but at least the shape and perspective have no problems. I just wish there was a bigger version online...

Greg Wenzel, different portion of the same painting. Though this scan is of very bad quality and distorted color, the painting itself looks pretty good anatomically. Nice big belly, long torso, legs not overbulked, and a long, near-vertical neck. The flock of birds really gives an idea of this animal's huge size and scale.

Wikidino image by Timothy Bradley. These digital paintings of many dinosaurs are all over internet forums. Most are actually pretty good. Though the neck may be a bit too short, the posture is excellent. Large torso, boxy head, tail high in the air. Massive, but not overbulked. It LOOKS like an Argentinosaurus, errors or no errors.

But what of the scientific illustrations? I mean actual skeletal diagrams...

Well, there are only really two. Greg Paul's, and Ken Carpenter's....

Modified from Paul (1994) and Carpenter (2006), respectively.

It is not a mistake that Greg Paul's skeletal shows fewer bones than Ken Carpenter's - it was done earlier, just one year after after Bonaparte and Coria's description paper came out (it didn't have diagrams of a couple of the vertebrae, or the femur shaft, which was dug up and referred to Argentinosaurus later). Though why he left out the sacrum is a mystery, as it was in the original paper.

The main difference aside from the bones, is obvious - the shape. Carpenter's version has much shorter arms and a very short thing neck. It's almost embarrassingly small... it's basically a scaled up Saltasaurus! In 2006 there seems to have been a trend towards "re-sizing" Argentinosaurus. Paul's version was considered by many in the field to be too brachiosaur-like, with its long vertical neck and tall arms. Carpenter proposed a radical re-interpretation of Argentinosaurus based on very late, derived titanosaurs like Saltasaurus - which reduced the length of Argentinosaurus to only about 80-90 feet or so. But this revision is not as reliable as it seems. Saltasaurus (which lived in the Maastrichtian epoch) was one of the last titanosaurs to evolve, millions of years after Argentinosaurus (Cenomanian epoch) was long extinct. It's not very likely that the early titanosaurs looked exactly like the last ones. Additionally, Saltasaurus was a small species, far smaller and shorter than Argentinosaurus, and specialized for low-grazing like a diplodocid or dicraeosaurid. The skulls of other small, short-necked titanosaurs like Bonitasaura bear this out - the teeth have become crowded in the front of the mouth and very thin, much like Diplodocus, in a wild case of convergent evolution. But something as huge and massive as Argentinosaurus must have been a treetop feeder - and it would have needed a very long neck. This is true of most if not all of the big basal titanosaurs. But that doesn't mean all of the late stage saltasaur-type titanosaurs were little short-necked grazers. There were some, like Alamosaurus, that had far longer necks, longer arms, and grew much larger than Saltasaurus. Very long necks and long arms didn't die with Brachiosaurus - they survived well into the end of the Cretaceous.

Alamosaurus sanjuanensis. Modified (by Matt Wedel) from Lehman and Coulson (2002) It punches a hole in the notion that all late-evolving titanosaurs were small-armed and short-necked. Of course, that tells us practically nothing about more basal titanosaurs.

Rapetosaurus as well, had an insanely long neck, and was a rather small saltasauroid/nemegtosaurid. And of course there were already several non-saltasauroid titanosaurs known by the time Carpenter wrote his paper that likely had huge necks. Puertasaurus, Phuwiangosaurus, possibly Huabeisaurus.... Yet from all the available reference taxa, Carpenter chose to use little puny low-grazing Saltasaurus as the silhouette shape for Argentinosaurus. Now I know preparing a paper has a lot of time strain and difficult decisions to make, and Ken Carpenter is a very knowledgeable and busy paleontologist with a lot of research going on (I actually met him at SVP, the guy's immensely accomplished). But I just don't understand why he picked Saltasaurus as the ideal body morph for a far larger and more primitive animal. I would have used something a bit closer to the basal end of titanosauria or titanosauriformes, something whose dorsal vertebrae actually resembled those of Argentinosaurus a bit... like Euhelopus, Phuwiangosaurus, Paluxysaurus, Sonidosaurus, heck, even Giraffatitan would be useful here. And they all had very long, probably vertical necks. In subsequent years, Futalognkosaurus turned up, a transitional titanosaur more advanced and younger than Argentinosaurus but more primitive and older than Saltasaurus - and it's a huge beast, with a completely preserved neck that even most brachiosaurs would have envied.

Small neck? I'll show YOU! Futalognkosaurus dukei, from Calvo, et. al. (2008)

So maybe using a "brachiosaur-like" model for Argentinosaurus isn't so bad after all. Monster necks seem to have been the rule rather than the exception in titanosauriforms both before and after its time. And Greg Paul's version of Argentinosaurus doesn't look all that much like a brachiosaur. It's something different. It's actually not copied from any other animal the way Carpenter's version is copied straight from Saltasaurus.

I had a hunch that Paul's version was generally correct. But that long whiplash tail bugged me. It's too diplodocid-like, and even the whip-tails wound on later titanosaurs weren't so thin and limp at the end. Also, Ken Carpenter's version does have two major advantages that Greg Paul's doesn't - it's got ALL the bones currently known (though it heavily distorts their shapes) and it gives an idea of the shape of the pelvis. It's also got a bit of pubis, which wasn't mentioned in the original description paper, but which may be present in some grainy internet photos. This was the clue for dissecting the actual number and shape of the missing bones.

The original bones on display in Plaza Huincul, Argentina.

Most problematic of all was the pelvis - how do you restore it when it's only known from a broken central piece of sacrum and slivers of ilium and pubis that aren't even documented? You do it very carefully.

Argentinosaurus partial sacrum (ventral view) and tibia (medial view) ...taken (and mysteriously flipped) by someone on the net, from Bonaparte and Coria (1993)

That stripe-shaded region is the first sacral vertebra's centrum, which is badly eroded but still visibly much larger than the other sacral centra. The sacrum, even though missing most of the 1st sacral ribs, much of one side, and the entire 6th vertebra, is still as long and almost as wide as the tibia. A rear as wide as your shin? That's a really big butt. Probably the biggest butt on record when complete, though there are some serious challengers to that title.The rough patch at right is a sort of articular surface to both the ilium and the hip socket. Replicating the other half of the sacrum digitally was pretty easy.

 Next, adding the ilia and the 6th sacral vertebra, and fixing up the 1st sacral ribs.

Then, some modding, slimming the ilia, and cleanup of the remaining bones...

On second though, the wider ilia of the earlier version make more sense. They should be more flared out than the ilia of a brachiosaur, but a bit less than in a saltasaur.

Okay, that's the basic hip structure for now. Turns out that it was flipped backwards (the original paper has it the other way around and I didn't realize this when I had first found the diagram online) - no problem, I fixed it later as you will soon see. Next came the actual walking profile of the dinosaur itself. Despite the apparent similarity, I did not look at Greg Paul's version for direct reference here - I simply started my own from scratch (and facing the other direction).
 This early sketch needed a lot of work, but it's a good start. The 12 dorsal vertebrae may be too many. Most titanosaurs had 11, a few even had just 10. There's some droop to the tail tip, but its far less thin and whip-like than the Greg Paul version. Remember, early titanosaurs like Argentinosaurus were basically evolutionary nephews of Euhelopus and Brachiosaurus. They weren't even close to mimicking diplodocids like the much later saltasaurs did. And most titanosaur whip-tail endings that have been discovered are of the late-stage saltasaur variety.

 The drawing, shaded, wrinkled, and patterned. The top of the neck patterned similar to the way David Peters painted it in Don Lessem's book, Supergiants. Great book by the way (and beautifully illustrated), if you're interested in the biggest dinosaurs (or at least the ones that were considered the biggest back in the 90s).

From the original skeleton sketch and using Greg Paul and Ken Carpenter's skeletals as references, a rough skeletal diagram of the known parts took shape, with the left leg separated from the hips.

Then I refined it and shaded the missing portions....
 And fixed the sacral count to six.... sort of.

 First stage cleanup  - captions, bone diagrams, scale bar, and human figure. The dorsal count is also reduced to 11. Probably a more accurate number.

 Next, the tail was extended, and a front view of the dinosaur and the sacrum in ventral view (now correctly flipped) were added. I also added the sliver of ilium, which based on the sacrum's state of preservation, actually does appear to be the right ilium, not the left ilium as in Carpenter's skeletal. To get a good approximation of the sacrum's correct shape (and that of the ilia) from various angles, I referred to these diagrams:

Titanosauriform/titanosaur ilia and pubes, from Lehman and Coulson (2002). (Back then Isisaurus was known as "Titanosaurus" colberti.)

Sacra and ilia of Neuquensaurus, Saltasaurus, Opisthocoelicaudia, and strangely enough, Camarasaurus. From Salgado (1997). All of these hips show the ilia flared out at the front, and very strongly flared out in titanosaurs - unlike the warped speculative ilia of the Fernbank mount, which oddly curve inwards...

 Then the pubis was shortened and thickened a bit, using Ken Carpenter's rather fuzzy interpretation of the fragment, and the pubis of Andesaurus for some reference. Though the classification of Argentinosaurus as an "andesaurid" is increasingly under attack these days, it does have several basic features in common with Andesaurus, and is about the same age. So I did not make the pubis identical, just similar.

 Some lateral details of the vertebrae were altered using the description paper diagrams for anterior reference, and a posterior dorsal pic from Andesaurus for posterior reference.

 A wider torso in front view, and modifying a Wikipedia image of the partial femur for a front-view diagram. The picture was from a bad angle, but another one from a different angle in Mazzetta, et. al. (2004) helped give a fuller idea of the femur's 3D form. Also front and rear views of some vertebrae are added, based on the description paper's drawings.

 Next I made the limbs a bit thicker in both views and re-scaled the femur ends to conform more with complete titanosaur femurs. This diagram from Lehman and Coulson (2002) was very useful:

 Next, it became clear that many of the dorsal vertebrae still had mistakes. So I looked back to the description again:

 Anterior and three posterior dorsals. Cut and pasted from Bonaparte and Coria (1993)

 Eventually it turned out that the diapophyses got much taller and more buttressed at the rear of the dorsal column than I had though, and the neural spines also seemed to go retrograde and tilt forward in the posterior dorsals. So pretty much every detail of the vertebrae had to be revised.

Some cheap anonymous photos of the dorsals floating around on the net were also useful.

Also the sacral neural spines were revised, to look more natural and closer to the fossil (the only halfway decent view of the top of the original sacrum is this):

(Notice the bit of right ilium on the sacrum. Another fragment of it lies in front of the near end of the femur.)
The sacral spines are very squashed, so in life they would have been a bit taller. Though maybe not as heightened as the ones in the Fernbank replica: 

Yeah, those sacral spines look a bit too tall... like almost diplodocid-tall... I still can't get over the fact that the 1st sacral ribs are 90% missing in this cast (hence the huge unnatural gaps in front of the sacrum), the 6th sacral is missing entirely, that the sacrum isn't flush with the ilia anywhere along its length, and that the speculative (and somewhat too long) ilia are curving in at the front instead of out. It's like they just casted the sacrum raw, without restoring any of the missing parts and worn edges first, and wrung the ilia through a giant vise! Who gave the orders to do this horrible mutilation of such a grand dinosaur?

So in the end, after all the revision and rants, you get massively revised buttressed dorsals, and a scalloped sacrum ridge with some cool wavy lines. And one more rear view of a vertebra. With every possible bit of visual data extracted from the 1993 description paper and every photo available on the web, I'd say it's done!

 This is it, the final product.

Feel free to comment on any part of this process. Or, feel free to challenge my arguments if you're one of the sculptors for the Fernbank mount. I'd really appreciate their side of the story. Enjoy :)

P.S. I've never heard of the skull of Argentinosaurus being found, but there is a mysterious skull that has popped up on the internet from time to time, that has no name but is rumored to be Argentinosaurus.

If anyone has information on what this strange skull really is, by all means let me know.

Guess what? It's Draw a Dinosaur Day!

Posted by Nima On Tuesday, February 1, 2011 0 comments

Well, I almost forgot to say that Draw a Dinosaur Day was on January 30th, but they are still taking submissions. Mad props to Trish over at ArtEvolved for getting the word out!

You don't have to be a paleo-Michelangelo or even an artist, period! Just sketch, doodle, or engrave a dinosaur, real or not, and send it in! Here's the submission link:

When you click there, there's an easy upload window and you can write a quick caption about your dinosaur. Fill out your email, click "submit" and you're done!

They'll review it and post it usually within a few hours, so check back often (they absolutely won't reject your drawing based on skill or quality, trust me - the "reviewing" is just a formality to make sure it's not porn or spam). It's just a fun excuse to relax, bust out the pencils and.... draw a dinosaur!

I sent mine in today. And it's already generating some attention. Click HERE to see it on their site.