New Material - Australian titanosaurs!

Posted by Nima On Friday, July 24, 2009 10 comments

I know this is a bit late in coming, but as pterosaurs consumed most of my attention, I almost missed this exciting piece of news.

Three new species of dinosaurs have been discovered in Australia and described in a groundbreaking new paper! And two of them are giant sauropods of the titanosaur sort- and they provide a lot of useful information for restoring these often poorly understood giants. Most of all it will be a lot of fun to draw these creatures. Sauropods never cease to fascinate, and titanosaurs are by far the most interesting of them all.

Meet the new giants: (in vertical order)

  • Australovenator wintonensis, an allosauroid possibly close to Carcharodontosauridae;
  • Wintonotitan wattsi, a basal titanosauriform (though the hand material in the paper looks like a true titanosaur);
  • Diamantinasaurus matildae, a lithostrotian titanosaur.

Scale bar = 2m (I think..... so then the Allosaur would be ~30 ft (10m) and the sauropods would both be around 80-90ft. Pretty impressive! Those of you who want to see the entire paper can download it for FREE right here. Of course the guys at SV-POW beat me to it (here's their post on it if you haven't already seen it.)

Now as much as I like these preliminary restorations, I know the artist could have done better. I can do better. There are several anatomical errors in the painting and the titanosaurs don't even look like convincing titanosaurs (not even by the over-simplified standards of Ken Carpenter and many others in the field who assume every titanosaur looked like Saltasaurus [credit: Brian Franczak]).

Now check out some of the gorgeous fossils - here's the hand of Diamantinasaurus:

All four views show the titanosaur's right hand. C and D show it with the associated thumb claw and a mirror-replica of the first metacarpal based on the one found with the left hand (the one for this hand was missing).

Did I just say thumb claw? Yes. The authors of this paper make a convincing argument it's authentic. And the hand includes phalanges. This specimen goes a LONG way towards clearing up the confusion among lithostrotian titanosaurs.

I think we are beginning to see good evidence that highly derived titanosaurs DID indeed retain their thumb claws and phalanges, instead of losing them as was long believed. The enlarged bottoms of the metacarpals indicate that the phalanges were actually quite well-cushioned with cartilage and used to support the creature's weight. Indeed, it may be the loose phalange attachments of titanosaurs that led the phalanges to often be washed away, resulting in things like Opisthocoelocaudia, which APPEARS to have no phalanges, but the type specimen is simply missing them as a result of incomplete sedimentation or decomposition (plus, the skeleton appears to have been scavenged, so it was probably still exposed and the soft tissue was likely decomposing for a while before the whole thing was buried in sediment, which explains the loss of the phalanges and thumb claws...)

This also fits with Janenschia, one of the oldest titanosaurs, having thumb claws (painting by Andrey Atuchin).

Here's the pelvis of Diamantinasaurus. MASSIVE!

By the way, thanks to everyone that participated in guessing the identity of our mystery dinosaur. It is Dacentrurus. Congratulations to Darthsantuzzo for getting it right!

I figured the scale bar would make it pretty obvious, though this creature is not as widely known as I expected - Dacentrurus is the only stegosaur other than Stegosaurus itself to reach a length of 9m (~3o feet). Which is ironic considering that John Sibbick and many other artists often illustrate it as a much smaller dwarf species along the lines of Lexovisaurus or Kentrosaurus (Sibbick's Dacentrurus is the all-spiked creature on the bottom right - the spikes themselves are inaccurate).

The Dacentrurus project is well under way, but first the pterosaurs will have to be finished. Stay tuned for more soon.


Zach Armstrong said...

Okay, here I am. And the first to comment on this post. I feel privileged. Anyways, you were saying...on how I could better restore by Diamantinosaurus? If you could give me some more details, it would be much appreciated.

On another note, I was just re-reading this post, and you talk about Diamantinosaurus's hand claws. Even about eight or nine years ago when I started seriously drawing sauropods (and dinosaurs in general), I always had this nagging feeling that titanosaurs should have hand claws, and it appears that tuition was correct after all (at least in this case). They would have been useful in defense and when males competed for females I think.

Nima said...

Tips on restoring Diamantinosaurus:

1. It needs a longer neck - the artist who did that painting made the neck even stubbier than Saltasaurus. Until they find the neck, this shortness is doubtful at best. Shame, shame...

2. Reduce the amount and mass of armor - this guy for some reason looks like an Edmontonia that got stretched out at both ends. Titanosaur armor was never this massive or "tank-like". The only one that even came close was Ampelosaurus.

3. Fix the ankles - they shouldn't bend so much and the metatarsals should be shorter. The artist seems to have no practical knowledge of sauropod foot anatomy - of course that's not really unusual - most artists with no paleontological background often copy the same old inaccurate museum murals anyway.

4. Put this guy on a diet. Sure titanosaurs were bulky, but most of that bulk was in the torso, not the legs. That guy just piled on the leg flesh like scoops of tiramisu. The leg bones - no matter how thick - only needed relatively light, simple muscles to move them because of their graviportal stance.

5. Some good spa treatments lol! Sauropod skin should not be as rough as the skin on this guy's legs and other un-armored areas. In fact, sauropod skin had VERY few wrinkles and was overall smooth and tight fitting. Sauropods were NOT elephants, and their skin did not have heavy wrinkles.

I think that pretty much covers it.

* PS. As for the thumb claws, I'm in agreement with you. I always had a hunch that most or all titanosaurs had both thumb claws and phalanges in life - they were only "lost" after death, due to loose ligaments and decomposition (such as with Opisthocoelocaudia). What's more, before Diamantinosaurus, so few titanosaur hand remains were known that it's not certain if ANY of them are even close to being perfectly preserved.

The metacarpal for the thumb was enlarged and tapered out at the bottom in titanosaurs - likely to support a movable side-facing thumb claw as you see in diplodocids and mamenchisaurs, but perhaps even more massive.

Based on the "swollen" structure of the bottom of the metacarpals and the loose fit with the phalanges' attachment surfaces, it certainly looks like the thumb claws and phalanges connected to the metacarpals with a MUCH greater amount of cartilage than in other sauropod families. This would help titanosaur support their greater weight on solid ground, and it also explains how the thumb claws could easily get loose and detach from a desiccating carcass, and get swept away by a river or a flood - creating the false impression that titanosaurs "lost" their thumb claws.

Nima said...

BTW, point # 3 also applies to Wintonatitan. The Wintonatitan in the painting also looks WAY too much like a diplodocid.

And thanks for posting, Zach. I can tell you'll be watching this blog very closely :)

Zach Armstrong said...

Haha. Thanks for the tips. I agree with point #1; mostly agree with #2 (usually, the armor is not found in situ, so it is hard to know how extensive and densely packed the armor is. Tracy Ford did an article in Prehistoric Times a while back about this, to show possible, though not definitive, placement of the armor. Having said that, neither of these guys were found with armor, so ANY armor is speculative in this case); I mostly agree with #3, however, I think sauropod ankles were more flexible than most paleontologist and paleo-artists/paleontograophers let on; on #4 I completely agree; on #5 I am somewhat split: I think sauropod skin was a lot "smoother" than it is often restored by non-Paulian paleo-artists/paleontographers, but I sort of disagree on the "not like an elephant" mantra that has taken over.

There are a couple of reasons for this; I realize that dinosaurs did not have mammalian skin, but at the same time, if you look at the skin of modern reptiles you see saggy, wrinkly skin. Now, while it is not quite elephantine, it comes to the reptilian equivalent of elephant skin. Also, no one has discovered a sauropod "mummy"--we are left with bits and pieces to go off of. If we recall, the hadrosaur "mummies" they have wrinkly skin around their neck area (although, admittedly, some experts think this may be an artifact of preservation, but I digress). No one would have guessed this based on the isolated elements of hadrosaur skin from before. Now, I know hadrosaurs are not titanosaurs, they're not even sauropods. BUT, they are the closest thing we can compare them with. I don't think it is unreasonable to give some sauropods wrinkly, saggy skin as there are modern reptiles and dinosaurian examples of wrinkly, saggy skin. I suppose it is up to one's preferences.

I agree with you whole-heartedly on titanosaur thumb claws. Before this discovery, I thought they may have developed keratinous spurs there that resembled the thumb claws in replacement--much like pheasants, chickens turkey and other Galliformes (also, some Anseriformes have developed wing spurs). Now, it appears that is unnecessary, although still a possibility for some in theory.

On another note, in your post, I think you're estimates for the lengths are wrong; at least according to published estimates. Both Wintonotitan and Diamantinasaurus are both estimated to be around 15-16 m in length, and Australovenator is estimated at 5 m in length. Judging from the figure, the scale bar is around 1-1.5 m. Although...these are based off estimates that probably guess-estimated the neck lengths wrongly; but, at maximum, neither of these animals look like they would be longer than 20 or 21 m at that, from the published material, and both probably weighed between 10-15 and 15-20 tons, respectively.

Nima said...

Wow I've never been wrong on so many points.... in fact I was guessing the scale bar was a whole number, and 1m was too small to be realistic so I assumed 2m... though you appear to be correct, 1.5m would make a lot more sense... but ultimately I blame the artist, or whoever it was that FORGOT to include a bloody measurement for the scale bar itself! Now that I think about it, a 60-foot Diamantinosaurus is a lot more believable than a 90-foot one, judging by the centimeter scale bars in the fossil photos. It's a mid-sized sauropod, not a supergiant one.

As for the wrinkles... when I said sauropod skin is not like elephants, I meant that very literally. I'm not using it as a broad-brush "mantra" to reject ANY wrinkles or folds on a sauropod. Rather I think the wrinkles were minimal on most surfaces and even then, they were usually vertical rather than criss-crossing every which way like on an elephant.

I think your reptile comparison may have some merit... if you use monitor lizards as an example, it's obvious that even though their skin is tight, it still has some wrinkles and sags in places... for fine-scaled sauropods this is a good model. Crocodiles on the other hand are HORRIBLE skin models for sauropods (even though they are closer to dinosaurs than a lizard could ever be...)

I suspect that sauropods had more wrinkles at the base of the neck and around the shoulders and upper thighs, but less on the neck, back, and sides of the torso. There were likely skin flaps near the armpits and groin, and these had deeper wrinkles (Greg Paul does this on just about every sauropod).

A less accurate wrinkle job would be that of Mark Hallett, who uses the same extremely thick rope-like rolls on seemingly every dinosaur, not just sauropods. However, a few artists like Raul Martin have so far managed to do a slightly more reasonable form of the "elephant" texture that looks better on sauropods than one might expect. Not necessarily perfect, but far better than the illustrations above.

As for the ankles... they are bent a bit too far IMO, and most experts will agree with me... it's almost a given that the REAL metatarsal section was also nowhere near as long as in the painting. The feet are painted almost like those of an ankylosaur or some other chubby ornithischian. In this respect sauropod hindfeet WERE built a bit like elephants - with short toes, limited ankle rotation and a fatty pad that supported the ankle at all times (i.e. the exact OPPOSITE of the semi-cursorial ungulate posture shown in the painting).

Also with both sauropods (particularly Wintonatitan) the artist mysteriously decided to do away with the triple foot claws and replace them with rhino-like hooves instead. This makes no sense at all - however, he oddly got the hands right!

Zach Armstrong said...

I agree with you on all points. As for the reptilian skin, I wasn't referring to crocs in particular, but I get the point. What made me think of the reptile skin thing is that some iguanids have really loose skin that droops all over the place. As for the ankles, i see you're point.

BTW, I redid my estimates of Puertasaurus's weight and length, and that of Argentinosaurus, too, in line with new data and the new paper that suggested the allometric equations used previously for estimating weight was really off. My new estimates are 120 ft long and 58 tonnes (metric) for Puertasaurus and 118 ft and 44 tonnes for Argentinosaurus. To see the whole shpeal, go to my deviantArt journal.

Nima said...

LOL no no NOOOOO!!! That's too light my friend! Unthinkable! All the concentrated hoodia in the world couldn't bring a Puertasaurus down to 58 tons! The ribs would be sticking out of the skin! It's blasphemy I tell ya!!!!!

Well in any case I'll be sure to check it out :D

Zach Armstrong said...

I was thinking the same thing! But according to the recent paper "Allometric equations for predicting the body mass of dinosaurs" in Journal of Zoology, Brachiosaurus would weigh only 18 tonnes! Now, this seems counterintuitive, but I do not have access to the paper, so I cannot challenge the mathematics (after all, I am going for a B.S. in Math Education)! So, I must accept it, no matter how much I want to challenge it....gah!

I hope you do check out my math :)

Zach Armstrong said...

I pinged the DML (Dinosaur Mailing List) about this topic, and so far have received only one reply....from...guess who? come on....guess who? Yes, Greg Paul himself, in the digital flesh....he said, and I quote,

"You are quite right that there is no way Giraffatitan "SII" was 18 tonnes.
And using the new complete presacral series of Futalognkosaurus I came up
with 50-60 tonnes for the biggest S Amer titanosaurs.

GP ".

This is because I expressed in my email doubt about how Brachiosaurus could be only 18 tonnes. And also gave him my estimate for Puertasaurus at 58 tonnes.

So apparently, he thinks my estimate is reasonable. Go figure.

Samsung A187 Unlocked Phone with QWERTY Keyboard said...

nice blog, good, this is good information for me u can also u know make post about

Post a Comment