Shop Forum More Submit  Join Login
Malawisaurus 2-view skeletal by palaeozoologist Malawisaurus 2-view skeletal by palaeozoologist
Malawisaurus dixeyi is one of the most complete titanosaur sauropods described in the scientific literature to date. It is known from skull material (which is a rare case for sauropods in general, not to mention titanosaurs), most of the cervical (neck) vertebrae, all the dorsal (back) vertebrae, all the sacral vertebrae and a large portion of the caudal (tail) vertebrae as well as most of the appendicular elements excluding the ilia, pubis and scapula.

Malawisaurus was rather small (for a sauropod). The projection of its length was about 11.05 meters (that is what the apparent length is from snout to the tip of the tail in the top view of the skeletal). However, along the vertebral series it was about 11.25 meters long. This is in comparison to some titanosaurs which reached over 35 meters in length, and at least one poorly known diplodocid sauropod reached a length of 60-70 meters long. It massed around 2.52-2.59 tonnes, compared to the largest titanosaurs which may have massed up to 100 tonnes and the largest sauropod ever, Amphicoelias fragillimus, probably massed close to 200 tonnes. Malawisaurus is even exceeded in mass by a number of living terrestrial mammal species, as Loxodonta africana (African Bush Elephant), L. cyclotis (African Forest Elephant), Elephas maximus (Asian Elephant), Hippopotamus amphibius (Hippo), Ceratotherium simum (White Rhino), Rhinoceros unicornis (Indian Rhino) all of which have members that well exceed 2,500 kg in mass. The largely aquatic (although they breed, fight and rest on land) species in the genus Mirounga (the elephant seals) also can mass well over 2,500 kg.

As for the illustration itself, the gray bones indicate bones and parts of bones that aren't preserved and so are based off of related species. The white bones indicate preserved bones and the pale yellowish colored bones are bones that are preserved but not figured so their shape is conjectural. Finally, the light blue bones are bones that are from another specimen to help fill in some gaps of knowledge in the caudal series.

Finally, I must apologize to Vladimir Nikolov, to whom I told that this skeletal was not going to be too different from my previous skeletal (which was up at my previous, and now defunct, deviantArt account), as it turns out that this is a bit different proportionally due to better info and drawing techniques. Guess he'll have to do another life restoration (sorry!).

Update: Several things were changed in this skeletal. First, the metacarpal configuration of the forelimb was changed; second, the black outline around the forelimb was changed to reflect a more robust musculature; similarly, the black outline around the lower part of the hindlimb was changed to reflect a more robust musculature; also, the size of the ischium is now larger because it was incorrectly scaled in the earlier version; I also changed the length of the pubis to be more similar proportionally to that of Futalognkosaurus with regards the change of the size of the ischium; finally, the black outline of the belly has been extended and the outline around the anterior to mid-caudals has been extended laterally to reflect new thoughts about the tail musculature in dinosaurs. Also, the mass estimate has been revised downward from 3 tonnes to about 2.5 tonnes (changes have been made in the text above this update to reflect that).

The old version that was here will be uploaded to my gallery's "old version" folder in case anyone wants to compare the previous and current versions.
Add a Comment:
 
:iconpaleo-king:
Paleo-King Featured By Owner May 29, 2016  Professional Traditional Artist
Quick question, what is the evidence for the existence of a 13th cervical? Scott Hartman only drew 12 of them.
Reply
:iconpalaeozoologist:
palaeozoologist Featured By Owner May 29, 2016  Hobbyist General Artist
Scott might have more inside information than I do (as he often does), but I based my reconstruction off of the count suggested in the description:

 "Eighteen cervical vertebrae (Figure 8, Figure 9, Table 2), including nine isolated vertebrae and two articulated sets (Mal-278, three vertebrae; Mal-280, six vertebrae), of at least two individuals, are attributed to Malawisaurus. The atlas-axis complex is not represented. Mal-180 (Jacobs et al. 1996, figure 5a), Mal-243, Mal-245, the Mal-278 set, the first four of the Mal-280 set, and Mal-301 are fairly well preserved while Mal-187-1, Mal-193-1, Mal-244, Mal-246, the last two of the Mal-280 set, and Mal-291 (= 89-78, Jacobs et al. 1993, figure 1e) are poorly preserved...Among titanosaurians, articulated cervical vertebrae are known in “Titanosauridae indet. DGM Series A” from Brazil, (12 cervical vertebrae, except the atlas, preserved in articulation with three proximal dorsal vertebrae; Powell 1986, 1987a) and in “Titanosauridae indet., DGM Series B” from Brazil (five cervical vertebrae articulated with 10 dorsal vertebrae; Powell 1986, 1987a). Thus, titanosaurians are considered to have 13 (Powell 1987a) cervical vertebrae. In “Titanosauridae indet. DGM Series A,” the neural spines are low and lean posteriorly in the second to sixth cervical vertebrae (Powell 1986). Based on comparison of the interprezygapophyseal distance, orientation of the neural spines, development of the posterior centrodiapophyseal and postzygodiapophyseal laminae and neural arch fossae, length of the diapophyses, and width/height ratio of centra with “DGM Series A and B,” Apatosaurus (Gilmore 1936), Camarasaurus (Osborn and Mook 1921; McIntosh et al. 1996a, 1996b), and Haplocanthosaurus (Hatcher 1903), the positions of Malawisaurus cervical vertebrae were estimated."

Table two lists the positions of the vertebrae as follows:

"Table 2. Measurements (mm) of cervical vertebrae of Malawisaurus dixeyi, as preserved. Centrum and vertebral widths and heights were measured on the posterior end of the centra. Cervical positions are estimated anatomical positions. + = incomplete.


Cervical position Specimen # Centrum length Centrum width Centrum height Vertebral width Vertebral height 3 Mal-243 207 41 45 63+ 182 +
4 Mal-180 250 61 46 157 187
5 Mal-278-1 320 65 60 153 182
6 Mal-278-2 340 + 76 70 190 162
7 Mal-278-3 363 80 75 147 + 255
8 Mal-280-1 389 110 60 273 180
9 Mal-280-2 415 120 85 295 200
10 Mal-280-3 420 140 90 285 296
11 Mal-280-4 415 125 144 252 310
12 Mal-245 295 175 125 505 3
13 Mal-246 250 165 85+ 2+ 85 +"

Note that it is specially mentioned that the axis-atlas complex is missing. I might add that having only 12 cervicals would be unusual for a neosauropod.

Reply
:iconpaleo-king:
Paleo-King Featured By Owner May 31, 2016  Professional Traditional Artist
Good point. That last sentence pretty much hammers it home for me :D

Just wanted to make sure, since I think Hartman's version is indeed too short-necked, and then there's that odd Malawisaurus vertebra that looks different and SV-POW didn't know where to fit it anywhere in the series. That might be # 13.
Reply
:iconalgoroth:
Algoroth Featured By Owner Jun 25, 2011  Professional General Artist
Beautiful drawing! Superbly executed.

One peeve to be aired, as I've said before...if the black areas are meant to represent a silhouette of the flesh, the front limbs are those of a mummified individual. The back legs, the hinder quarters, the rear supports are a little better, yes, but still under-muscled. Even chameleons have greater muscle to bone volume than this, and most of them are tiny twig climbers.

Since dinosaurs are seen to be relatives/ancestors/whatever of birds, why are so many modern paleo-artists like you, Greg Paul, and Paleo King drawing the upper limbs and the areas where they attach to the bodies as though they were slender limbed lizards?

Just a random thought....
Reply
:iconpalaeozoologist:
palaeozoologist Featured By Owner Jun 26, 2011  Hobbyist General Artist
I guess I'd disagree that chameleons have greater muscle to bone volume, based on intuition, but I've not crunched the numbers, so I can't really comment on it specifically.

True, dinosaurs are birds ancestors, but only a small group of them, the maniraptorans actually were directly involved in that lineage. You may be right that the limbs need some more musculature, though.
Reply
:iconalgoroth:
Algoroth Featured By Owner Jun 26, 2011  Professional General Artist
I'm basing my claims on chameleons I've seen, both photos and live, and pics I've seen of their skeletons. The other animals? Studied them, informally (I like to draw) live a lot, studied them in books, online, in video and still photos. Before I made my remarks, I spent some hours on my computer and on the net to see if I was correct at all.

I'm not trying to give anyone a hard time. You know more about the bones than I do--WAAAAAYYYY more--but I do study the living creatures. Got to, if I want to be any good.

You and Paleo King do such excellent work, but you do ask for critiques. I want to see your work look the best I think it can, so I critique what I do know something about. I'd write to Greg Paul with my opinions (some of his life restorations look almost as though the living legs were thinner than the bones), but the one e-mail experience I had with him was more than enough, no thank you very much.

No need to make changes on my account.

And all my claims can be easily checked out. No mysteries there! It might be salutary to googly elephants walking. Also google human skeletons to see examples of small elbow muscle attachment areas that can have massive muscle, a la Ronnie Coleman. No, I don't want sauropods to look like body builders! Ouch! Just my thoughts.

I hope to upload some of my dino stuff soon. I'm not quite as scientifically accurate as you--I lack many resources--but I think they'll be interesting in an amusingly morbid sort of way. I am what one would call romantic in the creative sense, so you can have a good laugh at any rate.

Yes, some vertebrates do have similar muscle/bone ratios to what is shown here, but most of them are tree climbers. Front views of limbs, as I am sure you are aware, often are a lot slimmer than side views. That is so with elephants, so I imagine it MIGHT have been the same with sauropods in general.
Reply
:iconpalaeozoologist:
palaeozoologist Featured By Owner Jul 2, 2011  Hobbyist General Artist
You bring up a couple of interesting points. However, when I look at the tissue outlines of living animals and compare it to their skeletons, usually their limbs aren't that heavily muscled. Check out this horse diagram to see what I mean: [link]

True, the soft tisse outline for an elephant (see here:[link]) is more thick on the limbs, but elephants also have very saggy, loose skin so I think (I'm not sure) that this might be an illusion. On the other hand, it might depend on the restoration, see this one of an elephant and the limbs have about the same amount of soft tissue as my skeletals does: [link]

It is true of many living animals that the limbs are much thinner than side view, but the opposite is the case in sauropods. Their limbs are tremendously thin from side view, but rather wide in front or back view. Look at the femora of the sauropod Paluxysaurus jonesi here for instance: [link]

I also the same experience emailing GSP, tried it once, got my head bitten off (and I wasn't even be snarky or something... ;) ). Won't try that again....

I too look at modern animals when I do my restorations, but I see relatively lightly muscled ones. Maybe I'm biased. But thanks for the thoughts, I like to have my notions challenged so I don't become overly biased. Keeps me sharp, so thanks :)
Reply
:iconalgoroth:
Algoroth Featured By Owner Jul 2, 2011  Professional General Artist
Cool diagrams, and very useful to artists like me. I've yet to see or say anything is wrong with your lower lower limb restorations. And yes, both the elephants and the horse match those elements in your skeletals perfectly, as well they should. The black and white elephant is a Charles R Knight diagram, if I remember correctly, and he's got it right on the money. A lot of modern paleo artists like to rag on Knight, but the man was a genius, period. Imagine doing the job he did just from the bones and guidance from Cope and Osborne. All the previous restorations I am familiar with basically sucked dirty rugs clean on the accuracy and life front. Believe me, without Knight, a Greg Paul would be unlikely. I know he inspired and influenced me a lot. As far as artistry and bringing life to his subjects, Greg Paul has nothing on Knight. You and Nima do a lot better on that front than he does.

The horse is cursorial. The outline might actually be a tiny bit too thick on the lower limbs. The upper limb outline does not show, which is a pity. Having been around horses and ponies (live as well as pics!), I can vouch for the fact that their upper arms and upper legs are extremely well muscled and rather thick.

Here is an absolutely superb photo of a superb horse...
[link]

I am sure you'll see what I mean.

As for sauropod limb bones: I concede your point. All I am saying is this: there will extremely likely be bulges in the muscles that will show in the outline, whether from the front or the side. The bulges would not likely be big, but they would round out the space between the shoulder and the elbow, as well as between the hip and the knee. Muscles bulge when in use. Tendons? That is another story, but it is muscles we are talking about.

That's my thoughts for now, anyway. Keep up the good work!
Reply
:iconpalaeozoologist:
palaeozoologist Featured By Owner Jul 5, 2011  Hobbyist General Artist
Right, the upper limb muscles in horses are thick, the reason you can't really see that in the outline I provided is because the rest of the body outline and skeleton obscures it mostly. The same thing happens, but to a greater extent, in my sauropod skeletals. There should be large bulging muscles coming from the delta-pectoral crest on the forelimbs, for instance. Unfortunately, I don't have any up-to-date life restoratinos showing this as I haven't uploaded a complete life restoration of a sauropod since last November!
Reply
:iconcommander-salamander:
commander-salamander Featured By Owner Feb 2, 2011  Hobbyist General Artist
There is a mount of Malawisaurus in my local museum, it will be interesting to compare the two!
I am trying to interpret skeletals better for my reconstructions so comparing the 2D with the actual bones (or painted plaster) might be handy :)
Reply
:iconpalaeozoologist:
palaeozoologist Featured By Owner Feb 3, 2011  Hobbyist General Artist
Thanks for the fave, BTW! :)
Reply
:iconpalaeozoologist:
palaeozoologist Featured By Owner Feb 3, 2011  Hobbyist General Artist
That's cool that you live my the museum that houses a mount of the skeleton. Maybe if you visit it, you can take some pictures and upload them here or send them to me, I would be interested in seeing how the mount compares to my skeletal.

There are photos of a mount of Malawisaurus on the internet, but none of them are in a nice direct side view...
Reply
:iconcommander-salamander:
commander-salamander Featured By Owner Feb 3, 2011  Hobbyist General Artist
I have a few photos already, I need to hunt them out on my external hard drive. I kinda want to go and take a few more pictures as the ones I took had a different focus on different bones than the ones I want now. I am well aware that mounts are not the best for reconstruction references but I want an understanding of the 3D nature of them.
I'd be glad to hunt them out and send them to you, I'll upload them to my photobucket account and send you a link via a note :D

The mount itself has the rather horizontal WWD neck if I remember, but if I also recall the ceiling is rather low too. Last time I saw it was a couple of years ago when the museum had a cast of "Sue" on display, in comparison Malawisaurus is teeny and just asking to be lunch.
Reply
:iconpaleo-king:
Paleo-King Featured By Owner Feb 6, 2011  Professional Traditional Artist
I've seen pictures of the mount, but the skull seems to be reconstructed differently to how it was in the paper and Zach's skeletal. Also the neck looked a bit shorter in the mount (not sure if it really was but the photos give that impression). This animal actually seems to have a decent-sized neck for its body, it's not a stumpy little thing like a Saltasaurus neck.
Reply
:iconcommander-salamander:
commander-salamander Featured By Owner Feb 7, 2011  Hobbyist General Artist
From what I remember the mount was rather short necked and the skull was a boxy affair.
Reply
:iconpaleo-king:
Paleo-King Featured By Owner Feb 7, 2011  Professional Traditional Artist
Yeah... I recall the same in the photos. I think that mount has some errors with both the neck and the skull.
Reply
:iconcommander-salamander:
commander-salamander Featured By Owner Feb 7, 2011  Hobbyist General Artist
I just got the photos off the hard drive, I'm just cleaning them up for clarity.It has saggy cervical ribs for a start. I counted the vertebrae in the neck it has the right number, if they are the right shape is another story. The skull is nothing like the skeletal, overly simplified and based on another species. It's like it's pretending to be brontosaurus.

I really need to see it again. And get batteries for my camera.
Reply
:iconpalaeozoologist:
palaeozoologist Featured By Owner Feb 6, 2011  Hobbyist General Artist
Sounds good, keep me posted. :)
Reply
:iconaloxamax:
Aloxamax Featured By Owner Jan 30, 2011
WOW! Amazing! Great representation!

P.D: there is a whole conversation of you and PaleoKing and then nothing (but me)? Why does nobody comments?
Reply
:iconpalaeozoologist:
palaeozoologist Featured By Owner Feb 3, 2011  Hobbyist General Artist
Hey, thanks, glad you like it!

I'm not sure why nobody else has really commented on it...maybe they don't have anything to say?
Reply
:iconpaleo-king:
Paleo-King Featured By Owner Jan 14, 2011  Professional Traditional Artist
Oops, I meant to say, "all of these features are pretty rare to non-existent OUTSIDE the Lognkosauria".
Reply
:iconpalaeozoologist:
palaeozoologist Featured By Owner Jan 14, 2011  Hobbyist General Artist
Yeah, I figured, but thanks for the clarification anyways.
Reply
:iconpaleo-king:
Paleo-King Featured By Owner Jan 13, 2011  Professional Traditional Artist
I took another look at Malawisaurus and it seems that you were correct about it being so small. I re-scaled the Malawisaurus vertebrae and it turns out they are barely any bigger than those of Pitekunsaurus (same with the femur) , so the two were probably around the same size.
Reply
:iconpalaeozoologist:
palaeozoologist Featured By Owner Jan 14, 2011  Hobbyist General Artist
Good to know, thanks.

Yup, Malawisaurus looks like it was pretty small for a sauropod. In fact, I probably over-estimated its weight, because I was working off of a previous version of the skeletal I have above that was incorrectly scaled. It was probably closer to 2.4-2.5 tonnes than to 3 tonnes based off the skeletal restoration above. Although that could change slightly upward since I think I made the soft tissue outline of the belly too narrow and I might have restored the (unknown) pubis proportionally shorter than in some other titanosaurs. Once I make these corrections, I'll probably upload a different version with the corrected outline (and corrected mass) in the near future. This of course reduces extrapolated mass in larger sauropods such as Argentinosaurus, probably closer to 80-84 tonnes if Malawisaurus massed around 2.4 tonnes and assuming they were proportionally similar.

I haven't done a detailed comparison of Pitekunsaurus in comparison to other titanosaur species to see how big it was, but your conclusion seems to be reasonable and accurate to me.
Reply
:iconpaleo-king:
Paleo-King Featured By Owner Jan 14, 2011  Professional Traditional Artist
Thanks! I'm doing the comparisons for a paper I'm writing.
Pitekunsaurus is a funny beast. I think it's literally a key to unlocking the Lognkosauria. It's got extremely wide and "merged" anterior dorsals like Puertasaurus, with diapophyses that have branching ventral laminae similar to those of Malawisaurus, very widely spaced prezygapophyses like Futalognkosaurus, an intrapostzygapophyseal junction like that of Mendozasaurus, and a very rugose femoral head like Ruyangosaurus. All of these features are pretty rare to non-existent

One of the anterior dorsals of Pitekunsaurus also has an unusual rearward-inclined tilt to the centrum, which is a feature I've only seen before in Barrosasaurus. Now THAT titanosaur is a pain in the neck to classify, but it shows a few Lognkosaurian features. If it is a lognkosaur, it would be a very strange and derived one. And Pitekunsaurus might be the key to learning more about it.
Reply
:iconpalaeozoologist:
palaeozoologist Featured By Owner Jan 14, 2011  Hobbyist General Artist
Wow, impressive, what's your paper on (or don't you want to say, if not, I understand for obvious reasons)?

I don't necessarily disagree with your observations from a quick glance, but I'd have to look it over in more detail in order to firmly agree or disagree. It would indeed be nice to see a better review of the Lognkosauria and its members, if that's what you're working on. Surely, SOMEONE needs to, and they need to be illustrated!
Reply
:iconpaleo-king:
Paleo-King Featured By Owner Jan 14, 2011  Professional Traditional Artist
I definitely plan to illustrate them. Starting with Futa (well I already did Puertasaurus so that's one out of the way!). My paper is on Ruyangosaurus... I can't give the specifics but basically I'm compiling as much evidence as I reasonably can from all major lineages of titanosaurs to see if the evidence supports the limited original analysis in the description paper, or if it was something else entirely. I'm pretty confident you won't steal my paper topic lol. Funny thing is, OTHER titanosaurs I'm using for comparison seem to be racking up the lognkosaur points like crazy, and not just Pitekunsaurus. This family seems to have developed a lot of weird new branches and many "indeterminate" titanosaurs are in fact looking more and more like Lognkosaurs. I'm even open to the fact that Isisaurus may be a member, though that's going to be pretty hard to prove for now with all the support for a Saltasaur classification based on the hips.
Reply
:iconpalaeozoologist:
palaeozoologist Featured By Owner Jan 17, 2011  Hobbyist General Artist
Haha, yes, rest assured I will NOT steal your paper's topic, I'm already neck-deep in college courses and my own research interests as it is! Sounds like a very interesting topic, though, and I think the results should be most interesting.
Reply
:iconpaleo-king:
Paleo-King Featured By Owner Jan 17, 2011  Professional Traditional Artist
LOL 'neck deep' is quite ironic as we're both sauropod nuts. :D

Yeah it's a very interesting topic, I think this might become my specialty if I start getting published consistently - making sense of titanosaur taxonomy. Now unlike Wilson and Upchurch, I have no clue how to do a cladistic analysis, does it need a special computer program, etc???? It looks like a pretty complicated math operation to me, so I don't think I'll be including one in my paper. Do you know how it's done? Mainly I'm looking at plesiomorphies across different lineages as compared to Ruyangosaurus.
Reply
:iconpalaeozoologist:
palaeozoologist Featured By Owner Jan 18, 2011  Hobbyist General Artist
Try googling "PAUP", it's a program for generating cladistic analyses; it is sort of expensive, between 85-150 dollars depending on the version. This is the program that I have most seen used in paleontological phylogenetic analyses. Once you get it, 'all' you need to do then is to code the characters for each taxa (which can be quite complicated from what I've heard and read).

If your not willing to spend that much money, google "list of phylogenetics software", this should direct you to a wikipedia article which has a list of a bunch of different software, some of which is free. Keep in mind that all of this software is not created equal and, if I were you, I would do more research on each program to see which program is considered best of the freeware for paleontological phylogenetic analyses. I myself am not particularly interested in phylogenetics itself as a research interest, so I can't help you out much more than that as I don't have any experience in doing phylogenetic analyses. I will say this however: in this day and age, I would say including a phylogenetic analysis when reviewing taxonomic relationships is a necessity in order for your paper to be taken seriously by others in the field.

I would suggest doing research on computational phylogenetics if you are serious in your intentions to do a rigorous phylogenetic analysis.
Reply
(1 Reply)
:iconpaleo-king:
Paleo-King Featured By Owner Jan 8, 2011  Professional Traditional Artist
WOW this is incredible. I mean DAMN! I didn't think I'd ever see a skeletal with so much detail! :D :O

I can tell you really followed the paper closely with this one (since I've been reading many times it myself!), it's on a whole different level than all your other skeletals and even a lot of my Futalognkosaurus stuff. I'm very impressed. I may not agree with the neck and tail posture but for actual images of the bones themselves (at least in side view) this thing outclasses Greg Paul's skeletals and many other artists and then some.

You know I'll HAVE to do my own version based on this now hehe ;) It's that inspiring. BTW did you leave out the other two limbs because there's no material for them or will you add them later? (I tend to forget about the limb material when focusing on vertebrae so much.... Futa is missing the limbs after all...)
Reply
:iconpalaeozoologist:
palaeozoologist Featured By Owner Jan 8, 2011  Hobbyist General Artist
Haha. Glad you like it! I certainly was not expecting such a positive reaction for this, so I really take that as a compliment.

This skeletal took me FOREVER. I've been working on it since November; it would've been sooner but my first version somehow got corrupted and when I went to open it, it was a bunch of colored lines with no image to be found (!). But it finally came all together.

I'm not particularly happy with how the neck and tail posture turned out, but when I followed the bones, this is what I got. There is an odd dip in the anterior part of the caudal series, but I could not figure out if this was an artifact of preservation (like maybe the neural spines were eroded) or something that was 'real' in life. So I decided to leave it. I may attempt a more 'stylized' version in the future, but we'll see.

I am curious to see what your opinion is on the neck posture: too vertical? too straight?, etc.; same with the tail posture.

The limb material is complicated. Four humerii are preserved (of at least two, probably three, individuals). There are two ulnae preserved of significantly differing lengths, so are of two individuals probably. Only one radius is preserved. There is only one femur, tibia and fibula preserved. For simplicity on my part, I left out the right limb elements, but may add them later in a more 'stylized' version.

Thanks for the feedback! It's greatly appreciated. :)
Reply
:iconpaleo-king:
Paleo-King Featured By Owner Jan 8, 2011  Professional Traditional Artist
You're welcome! :) Well here's my take... 8-)

The neck is too horizontal IMO. Several of the cervicals look like they are deflected too far downwards, as is the second dorsal (which seems to be missing the bottom portion of the centrum's rear "lip", if you added this it would become clear that bone needs to be rotated upwards a bit). I would expect a neck posture similar to the one I gave my Futalognkosaurus, maybe a bit more S-curved but a similar angle overall at least.

The tail also looks too stiff... I would say the dip in the anterior caudals is part natural, part erosion/crushing. For one thing, the first bone that shows this dip is semi-dislocated from the cotyle of the one in front of it. I would rotate this "dip" vertebra down, so that there is a bit of a dip in the anterior tail but it has nothing to do with the neural spines. But I would also expect a subsequent gradual upcurve further back in the tail, probably in the middle. I'm not sure if the tip was as long and narrow as you drew it here, but if so a bit of drooping is possible at the end. Like Andesaurus-level drooping, not full on Diplodocus-level drooping. Also I would tilt the chevrons back and not have them so vertical. Just curious, what are those few blue caudals supposed to represent?

Something that really shocks me is the mass. This thing, I always thought, should weigh a LOT more than 3 tons... and that HUGE 1m scale bar.... is that really accurate for the biggest specimens of Malawisaurus? I expected it to be around 45-50 feet long (at least 13 or 14m) not 11m. This thing really was a dwarf! :o

But Pitekunsaurus (which I suspect may be a Lognkosaur - despite some very cursory assumptions and labels, it honestly doesn't look like anything more derived than a Lognkosaur, and its vertebrae are practically a cross between Puertasaurus and Malawisaurus in miniature) is even smaller than Malawisaurus, perhaps only 2/3 to 3/4 as big. So if the 3 tons is accurate, then Pitekunsaurus is maybe only 2 tons? Who knew titanosaurs on large continents could get so small! This isn't like island dwarfism of any sort.

A caveat is that Pitekunsaurus' holotype includes a proximal femur fragment that's in very good shape and has some pretty convincing traces of a growth plate at its head... the sutures are still visible so it's possible this was a juvenile specimen and the adults grew bigger. So do you know if there's any hint that the biggest of the Malawisaurus material may not be fully adult? (aside from the loose coracoid not having a scapula fused to it....)
Reply
:iconpalaeozoologist:
palaeozoologist Featured By Owner Jan 9, 2011  Hobbyist General Artist
Ok, I get what you're saying. Couple of things: the main reason I posed my neck this was was so that the dorsal view of the skeletal would be easier angle-wise and so that a GDI estimate of its volume (and hence, mass) would be easier and more accurate. I certainly think the neck could be held more vertical, this skeletal was not meant to be a commentary on what position the neck or tail was supposed to be. A similar reason for the tail's position: it better enabled me to get the total length.

As for the anterior dorsals' "dip", from the preserved remains, it appears that there is a "sigmoid" curve in the anterior part of the dorsals as indicated by the fossils. For this skeletal, I have tried to do as minimal interpretation as possible with the bones and follow their osteology as strict as possible. This is how I got the articulation for the neck and dorsal column and tail. They are supposed to be in a minimally flexed pose between the articulations of the vertebrae. Obviously, as Talyor et al. (2009) pointed out, this does not necessarily reflect a normal life posture. I can see why some would like to have a skeletal posed in the most likely posture held in life, but as this will always be speculative and based to a large extent on opinion, I felt this minimally flexed pose was probably the best to serve my needs (for length and mass estimates, mainly) and best to serve the needs of those who may wish to use it as a reference for illustrations.

For the caudal vertebrae that you feel is dislocated, I will assume you are talking about the 6th caudal since I think that is the one you are talking about from your description. I can see why you think that, because the bottom part of the cotyle of the preceding (the 5th caudal) vertebrae extends far below the anterior articular surface of the 6th caudal. However, if, as you suggest, I rotate it down to articulate it, the prezygapophyses will not articulate, which is problematic. Otherwise, I would have to change the shape of the vertebrae to make it look like that, something that I am very hesitant to do.

Now if you are talking about the 14th-15th caudal where a similar morphology is present, you may have a good point. I probably could shift those down and angle them a bit more, which would change the outline of the tail.

An upward inclination is possible in the posterior part of the tail, as you suggest. The 30th caudal has a bit of a 'rounded' cotyle. If I changed the succeeding vertebrae to better articulate with that, and upward incline in the posterior part of the tail might result.

The tip of the tail is based on Phuwiangosaurus largely, where the posterior-most caudals are indeed that narrow. As for drooping in the posterior part of the tail, I am ambivalent. I used to draw my sauropods with a large droop like Greg Paul shows, but I am now skeptical of that posture. No living animal does that with its tail; admittedly, no living animal has a long tail that does not drag, either. However, I think that if the interconnecting muscles in sauropod tails were strong enough to hold a mutiple-tonne tail in the largest sauropods out horizontal without dragging (as it seems from footprint evidence), it seems unlikely that the tails drooped like Greg Shows in diplodocids. I think having the tail droop like that would be dangerous, a theropod could easily come and bite the end of the tail off, or it could be stepped on by fellow sauropods if it drooped like that and could possibly even get caught in something. Certainly, if it didn't have the muscles to hold the posterior end of the tail up more-or-less horizontal it probably did not have the muscular control to keep it out of harms way. I probably could show a more downward arch in the last half of the tail, but I tried to show it as straight as possible to get a good idea of its length. I certainly would not object to such a life restoration showing a more downward curve. In fact my own life restoration will probably show a bit of a downward curve in the posterior segment--but probably no "tail droop".

The osteology of the chevrons does not indicate (to me) that they should be angled; however, if you have any further insight into the research on that, I would be interested in hearing it. (BTW, the caudals that are blue, came from another specimen, as explained in artist's comments and were used to model the posterior caudals.)

As for the length and mass, I thought it might shock you, but was not much of a surprise to me. First, the total lengths of the vertebrae do not indicate an animal more than 12.5 meters long at any rate (factoring in the missing vertebrae). When you discount the condyles in the cervicals and dorsals (which would fit into the concave cotyles completely), you shave of about 1-1.5 meters of length. As it is, my tail is more than half of the total length of the tail, and is possibly a little too generous (although not be much, maybe a half-meter too long at most, depending on how you restore the unknown posterior-most caudals).

As for the mass, here are several reasons why I think it should be reasonable. The average functional length (that is, excluding the anterior condyle) of the dorsal vertebrae in Malawisaurus is by my calculation about 14 cm (give or take a couple millimeters). In Argentinosaurus the average functional length of the preserved dorsals is 45 cm (give or take a couple millimeters) by my calculation. Scaling up, we have that Argentinosaurus was about 45/14=3.214 times as long as Malawisaurus. Now, assuming we can scale up Argentinosaurus based off of Malawisaurus, and assuming the latter was 11.05-11.25 meters long, we get a projected length of 35.51-36.15 meters long. Similarly, we get that Argentinosaurus should be about 3.214^3=33.2 times as massive as Malawisaurus which gives a mass estimate of 99.6 tonnes for Argentinosaurus(if this specimen even massed one tonne more (so 4 tonnes) we would get a huge mass estimate of 132.8 tonnes! Similar calculations gives an estimated mass of just over 29 tonnes for Futalognkosaurus, assuming its dorsal column was about 298.4 cm long by my calculation. Puertasaurus's mass based on it's lone preserved dorsal (presumably, the second), about 30.6 cm in functional length based on the drawings in the description, would be about 70.9 tonnes based on the functional length of the second dorsal of Malawisaurus (estimated to be about 10.66 cm in functional length by my calculation). This may be an overestimate, because doing a sole calculation based off of the second dorsal in Futalognkosaurus (the one paper implies a functional length of about 28.7 cm for the 2nd dorsal of Futalognkosaurus) gives a mass estimate for the latter of 58 tonnes (for comparison, the mass estimate from my own skeletal was about 26 tonnes for Futalognkosaurus which compares well with the 29 tonne estimate done by scaling from Malawisaurus; the difference in mass is probably because I restored the dorsal view of the neck in Futalognksaurus too narrow, as you have previously suggested--meaning you probably were right about the neck width). Estimating based off the one dorsal also is misleading because smaller titanosaurs tend to have more variation in the length of their dorsals than the larger titanosaurs based on my own observation (certainly, in Futalognkosaurus most of the dorsals are within 1 cm length of each other--based off my understanding of the paper, admittedly, with which you disagree--and in Argentinosaurus the dorsals are all very similar in length, too).

My guess is that such 'small' sauropods were able to do well because there was limited competition from similar-sized ornithopods in South American and Africa at the time. Remember, this specimen of Malawisaurus is still larger than any native terrestrial animal in North and South America today, so I would hardly call it a dwarf. True, it was dwarfed by other sauropods, but if alive today it would be called anything but a dwarf. I'm sure there were larger individuals, the unfused coracoid being an indication it might not be fully grown. On the other hand, all the neural arches were fused, which indicates it was close to being full grown. None of the specimens described suggest much larger individuals. However, comparing it to the HMN SII specimen of Giraffatitan, which was mostly done growing, there are still specimens of Giraffatitan that suggest individuals 15% longer and 52% more massive. So, there may be individuals of Malawisaurus that were also similarly larger. I think individuals in the 12.7-12.9 meter range and up to 4.6 tonnes were probably fairly common, but we need more remains to be sure.

I think Pitekunsaurus was probably close to being full grown since all of its preserved vertebrae have neural arches that are apparently fused. For some reason, Greg Paul states in his new field guide that it was a juvenile, probably of one of the other Ancleto Formation titanosaurs. (If he's right, this means it's possible its a juvenile of Antarctosaurus wichmannianus!) The measurements give for Pitekunsaurus indicate an animal as large as or larger than Malawisaurus. The posterior cervical is longer than the two posterior-most cervicals in Malawisaurus, also the posterior-most dorsal in Pitekunsaurus is longer than all but two of the dorsals of Malawisaurus.
Reply
:iconpaleo-king:
Paleo-King Featured By Owner Jan 9, 2011  Professional Traditional Artist
Ok I get why you posed the neck and tail the way you did.

Admittedly doing a good top view of the neck is very hard in any pose, in fact I'm revising my Futa skeletal (hopefully for the final time for a while) to reflect a more accurate top view of the neck. I don't know how Greg Paul did it for so many dinosaurs, it's crazy-hard stuff. As for the 6th caudal.... if what you said is correct, then it's probably crushed and hence there is a discrepancy in the centrum articulation and the zygapophyseal articulation.

Now with Pitekunsaurus.... I don't know if it's bigger than Malawisaurus.... The femur seems to have similar dimensions, but I scaled the vertebrae together and Pitekunsaurus has smaller vertebrae overall - not as tall or wide. But they are similar in length, although proportionally much more of that length is made up by the condyle than in Malawisaurus. In the anterior dorsals of Pitekunsaurus, the condyle is 80% as long as the rest of the centrum! So the length is misleading unless you articulate the vertebrae together. I highly doubt that Pitekunsaurus had anything to do with Antarctosaurus or any other lithostrotians. It looks like a lognkosaur through and through, the vertebrae are almost exact miniatures of Puertasaurus in anterior view, and in lateral view they resemble Malawisaurus very closely. There's really only one significant feature I can find which it does not share with other more established lognkosaurs - the rearward incline of the centrum - though this feature IS found in some other titanosaurs which may be lognkosaurs (but not in lithostrotians).

I speculate that the neural arches actually fuse rather early on in the sauropod's life, and other adult features (like femur growth plate fusion and scapulacoracoid fusion) take longer to develop, hence a lot of specimens have one but not the others. So fused neural arches are not by themselves a good indicator of an adult animal, but they do indicate at least large juvenile or a subadult. The femur sutures just look freaky, and the femur head is unusually rugose. Only other place I've seen such a bumpy femur head (that isn't eroded) is in Ruyangosaurus (and neither basal "Andesaurs" nor derived Argyrosaurs and Lithostrotians have nothing like this - their femoral heads, when present, are all pretty smooth). Though if other lognkosaurs' femurs were recovered I think we would see the same bumpy surface on them too.
Reply
Add a Comment:
 
×




Details

Submitted on
January 8, 2011
Image Size
1.1 MB
Resolution
8350×3043
Link
Thumb

Stats

Views
5,792
Favourites
26 (who?)
Comments
37
Downloads
498

License

Creative Commons License
Some rights reserved. This work is licensed under a
Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.
×