Largest sauropods

[theropod]

It’s impressive, for sure. But I think it’s something we have to keep in mind with all sauropods, not just this particular one. Perhaps this one was particularly young (the abstract alone is not very revealing on this matter), but the vast majority of sauropod specimens are likely not fully grown.

[creature386]

Well, let's look deeper in the paper:

Remarkably, multiple lines of evidence indicate that, despite its enormous size, MPM-PV 1156 was not osteologically mature at death. The scapula remains unfused to the coracoid (Fig. 2B, Supplementary Fig. 15), and the posteromedial margin of the coracoid foramen abuts the scapula; both of these morphologies have been cited as indicators of osteological immaturity in sauropods. Moreover, although histological analysis of the humerus indicates that its cortical bone has undergone extensive secondary remodelling, the element retains a thick layer of vascularized fibrolamellar bone between the remodelled inner cortex and the periphery of the periosteal surface (see Supplementary Information). It also lacks lines of arrested growth or an external fundamental system (Fig. 2G), which may indicate osteological immaturity (although Company proposed this as a synapomorphy of Titanosauria rather than an indicator of ontogenetic stage). A similar pattern is observed in the dorsal ribs, which are exten- sively remodelled but retain primary fibrolamellar bone tissue towards the periosteal surface. Recent analyses have suggested that titanosaurs may have developed extensively remodelled tissues after reaching sexual maturity but prior to attaining their maximum size. Thus, the presence of unremodelled fibrolamellar bone in the outer cortex of the MPM-PV 1156 humerus suggests that this massive Dreadnoughtus individual was still growing at the time of its death.

Apparently, this paper differs the studied specimen from other known titanosaurid specimens, therefore, it was probably at an earlier ontogenetic stage, since it lacks some of the features of older titanosaurid specimens. Myhrvold is nowhere cited, so he is not their reasoning.

[theropod]

I see. Looks like it’s really younger then (unfused scapulocoracoid like in the Giraffatitan holotype, which is considered subadult).

[blaze]

Why are you dealing only with the abstract theropod? click the tittle of the quote in my previous post, this paper is open access and they even made available 3d PDFs of several bones and the full articulated skeleton.

[theropod]

Damn, how could I overlook that? Usually I download that kind of thing immediately, I think I confused it with something else and didn’t check. Thanks!

[Grey]

So it's safe to assume Dreadnoughtus could reach at least let's safely add 10 tonnes, 70 metric tonnes and more.

It's kind of refreshing to have a super-massive sauropod known by much more than fragmentary remains

[creature386]

To assume this safely, we'd need a GDI which can yield estimates completely different from the femur based.

[theropod]

The 59.3t estimate bases on propodial circumferences, it’s possible that it’s off by a significant margin.

Based on the femur lenght and the provided skeletal reconstruction, the animal is about 26m long (this includes a pretty long neck but only moderately long tail), the body measured along the neural canal between the first dorsal and the caudal end of the ilium measures about ~5.5m as restored.

I’m a bit sceptical about the weight estimate, if I measured correctly the same trunk-lenght measurement is 5.25m in the G. brancai holotype (Hartman’s skeletal), isometrically scaled, that would suggest a mass just 15% greater. Sure, it’s body is likely wider, but how much wider do you think it is at the same lenght? Enough to make the difference between 59 and 26t, i.e. over twice? I’m not sure of that, that’s why I’ll second that we need a volumetric estimate.

What I find particularly interesting is that it preserves so much of the proportions, almost the entire body, tail and limbs (the neck can be based on other animals, so it’s not tragic). I wonder what implications these data will have for reconstructions of other giant titanosaurs like Argentinosaurus and Puertasaurus…

As regards how much bigger it may have gotten, there’s no way of telling that with any certainty. If you want to enter the realm of speculation, you could use Brachiosaurus or Giraffatitan as an analogy for how much bigger larger (and likely adult) specimens we have are compared to their respective subadult holotypes.

[creature386]

It doesn't have to be wide. Blaze pointed out that it could also have been extremely short tailed like Zach Armstrong's Alamosaurus.

[stomatopod]

I am back here as well, hope you did not miss me too much. If anybody wants a reason PM or E-mail me.

I did a very quick and rough(as I said elsewhere, I do not have time for a more detailed version) GDI of Dreadnoughtus And I got something around 40 tons. Not bad for a subadult, but not record breaking.

[creature386]

Glad to see you back! And of course thanks for your efforts!

[creature386]

BTW, even if the weight was exaggerated, one thing is sure, the appendicular skeleton of that animal is impressive:

The 1.74 m scapula of MPM-PV 1156 (Fig. 2B, Supplementary Fig. 15) is the longest yet reported for any titanosaur (Table 1).

The massive 1.60 m left humerus of MPM-PV 1156 (Fig. 2D, Supplementary Fig. 16) is greater in minimum shaft circumference (785 mm) than that of all other described titanosaurs, and is longer than all other titanosaur humeri except that of Paralititan (Table 1).

[theropod]

Sept 6, 2014 22:20:29 GMT 5 creature386 said:

It doesn't have to be wide. Blaze pointed out that it could also have been extremely short tailed like Zach Armstrong's Alamosaurus.

I was just comparing the lenght of the torso, excluding the tail and neck. Hence the 5.5 and 5.25m measurements.

[blaze]

stomatopod
Hi! I did a rough GDI of the torso and got about 24 tonnes, so probably between 34-40 tonnes for the whole body.

Comparing the 3d reconstruction with Hartman's Futalognkosaurus it appears that they are about the same size though Dreadnoughtus seems to have a longer torso, kinda like Brachiosaurus against Giraffatitan, Dreadnoughtus' preserved D10-D4 series is as long as Futa's D10-D2, the difference being in the length of the centra.

[creature386]

theropod
OK, I am sorry then, I overlooked figure 2.

Since Dreadnoughtus got reconstructed after Futalognkosaurus and both are estimated at roughly 26 m, I'd assume a similar weight.
How much does it actually weigh?
en.wikipedia.org/wiki/Dinosaur_size
They give an upper bound of 50 t+, but I can't even find Futalognkosaurus in their reference paper.