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Giganotosaurus carolinii
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I thought these might be a helpful addition to this thread.
Here are some conversations I have had with Scott Hartman regarding the validity of his original estimates for Giganotosaurus compared to the significantly larger estimates I have outlined above from GetAwayTrike, Greg Paul, and SpinoInWonderland. The messages in these screenshots should be very important to consider for anyone who thinks the estimates in this thread that make the animal quite a bit larger than Scott's original estimates are inaccurate just because they are larger.  *This image is copyright of its original author  *This image is copyright of its original author EDIT 04/22/2021: As can be seen in the above images, Hartman suggests that the ribcage would probably be narrower regardless of the pectoral girdle. I didn't really notice this until somebody elsewhere pointed it out, so I went and asked Hartman what he meant. Here is that conversation.  *This image is copyright of its original author  *This image is copyright of its original author  *This image is copyright of its original author  *This image is copyright of its original author  *This image is copyright of its original author  *This image is copyright of its original author Given that he doesn't think my inflating the ribcage based on Acrocanthosaurus' proportions is unreasonable, I see no reason to think so either. At this point, anyone who wants to use estimates lower than the ones in this thread will have to justify that very, very well.
As of late, it has come to my attention that there may be more mistakes underestimating Scott Hartman’s Giganotosaurus than just the shallowness of the chest from the incomplete pectoral girdle that earlier posts in this thread have went over.
Specifically, because he assumed the pectoral girdle was complete as preserved, the dorsal view for his Giganotosaurus is quite slender and has since been known well for being such, especially compared to T. rex. He talks of this on his website, and what he states may even lead some to believe his dorsal view isn't slender enough. Quote:Tyrannosaurs have almost comically wide abdomens (and mine is not as broad as some other workers and some mounts show), while Giganotosaurus has the typical allosaur-grade torso. Quote:I'm sure that some will claim that Giganotosaurus should have a wider torso or head, but the skull is already substantially wider than in Acrocanthosaurus and matches up with more recent reconstructions of the skull, like the one you see here. Also note that if anything the torso should be smaller up front due to the diminutive pectoral girdle. Perhaps unsurprisingly to those that follow the thread, this is not in accord with the anatomy of more complete relatives. How do I know this, you may ask? A combination of three factors: phylogenetic bracketing, the proportions of the animal used for this phylogenetic bracketing, and how Giganotosaurus' estimated complete pectoral girdle length would affect its proportions. What is being used for the phylogenetic bracketing? I will be using Acrocanthosaurus (specifically, NCSM 14345) as a means for the phylogenetic bracketing, as it preserves a complete pectoral girdle, complete ribs, has a publication and measurements for both, and is the most closely related animal to Giganotosaurus that has all of these preserved and/or published. What are the proportions of this Acrocanthosaurus? Currie & Carpenter (2000), on page 8 of their publication, give a length of 118 cm for the specimen's complete pectoral girdle. This together with its 130 cm wide ribcage gives us a ribcage width to pectoral girdle length disparity of about 10.2%. Its femoral length is also probably about 120 cm as per the comments of here, which will come in handy for the next point. Quote:Is it possible that the legs were shorter? I just noticed that the often mentioned femur lengths of both Fran and the holotype are estimates, with the later being criticized as too long by Harris (1998), that the femora are incomplete, I also just noticed in photos of the mount and the digital scans presented in several of Karl Bates publications that the femur is reconstructed there at ~120cm long, which is roughly what you'll get from isometric scaling comparing the circumference of Fran's femur with that of the only complete (sic) Acrocanthosaurus femur (SMU 74646). How does Giganotosaurus' estimated complete pectoral girdle length affect its proportions based on this? The change is bigger than some might think. As the link in the second point for ribcage width said, Scott Hartman's Giganotosaurus is 134 cm wide, and that would mean an estimated complete pectoral girdle of 121.6 cm assuming isometry with Acrocanthosaurus. Problem is, Giganotosaurus' complete pectoral girdle ends up longer than that based on Acrocanthosaurus. For instance, SpinoInWonderland has restored the pectoral girdle in his Giganotosaurus based almost entirely on Acrocanthosaurus as well as used its proportions to help do so. Quote:The shoulder girdle is reconstructed based on Mapusaurus (which barely helped, but it's incorporated here anyway) and Acrocanthosaurus, with the length of the scapula based on the scapula:femur ratio found in Acrocanthosaurus. Given the 136 cm femur length of the Giganotosaurus holotype from Carrano et al. (2012) that SpinoInWonderland used in his skeletal (as per the top of the comments section), this gives us a pectoral girdle length of 133.7 cm based on Acrocanthosaurus, and the ribcage would therefore be about 147.3 cm wide instead of 134 cm assuming isometry. The resulting ribcage is about 9.9% wider than what Scott Hartman restored, and while it's not barrel chested like a tyrannosaurid, neither is it the very slender animal some like to claim, instead being roughly intermediate between slender and barrel chested. In fact, directly to the contrary to what Scott Hartman's blogpost implies, known specimens of Giganotosaurus do not appear to have had ribcages any narrower than known T. rex individuals of the same size class (average, maximum, minimum). For one, the extrapolated width for MUCPv-95's ribcage of 162 cm (147.3x1.1) is right on par with or slightly greater than that of Sue (150 cm from Asier Larramendi to 160 cm from Scott Hartman, which I will be assuming the 155 cm mean of). That's not all - because the size difference between the estimates for Sue and MUCPv-95 (maximum vs maximum) is relatively less (8200 kg vs >11100 kg) than the size difference between the estimates for average vs average (6000 vs >9700 kg) or minimum vs minimum (<4000 kg vs >8320 kg), Giganotosaurus' ribcage would be decisively wider than that of T. rex when those size classes are compared. What's more, Scott Hartman himself does not think my inflating the ribcage is unreasonable, as can be clearly seen in the post above this. So there really isn't any justification at this point that I'm aware of to be using the original version over the 9.9% wider version. Of course, this fix to the ribcage would also bring all the Giganotosaurus size estimates in this thread and others up somewhat. Large as they already are compared to Scott Hartman's original estimates, they are based on that slender dorsal view, and I wasn't aware of the above issues with it at the time I made the estimates. @GuateGojira I believe previously you have made points (->, ->) about how slender/lightly built these animals supposedly were. Quote:These animals were long but relatively light in its composition. That is why even the hypotetical Giga of over 13 meter was just close to the 8 tons and not more. Quote:The weights are always inflated, none Carcharodontosaurid weighed more than 7 maybe 8 tons, they were long but more slender than the T. rex. As such, you may find the information in this post useful if you still stand by the above. In fairness, just as you said and as stated above, they do not appear to be barrel chested like tyrannosaurids. However, they are almost certainly not as slender or lightly built as you might think. 
Well Giganotosaurus wasnt normally described, so we cant really know ribcage width. Also, MUCPV-95 appears to be from animal ~6% longer and ~21% heavier
@Anchiornis
Quote:Well Giganotosaurus wasnt normally described, so we cant really know ribcage width. I never claimed my estimate for the ribcage width was set in stone or the only possibility. The entire premise of my post above was that the dorsal view of Scott Hartman's Giganotosaurus was not consistent with the ribcage proportions of related, well-preserved, well-described animals, and what it would be like when based on the proportions of said animals. Furthermore, what you are saying is by no means news to me. Take a look at what Scott Hartman told me in the final Twitter screenshot about how well preserved the ribs are in the 1st place. Quote:Also, MUCPV-95 appears to be from animal ~6% longer and ~21% heavier If you can show how this was reached and why it may be a better option than my demonstrated estimate on Post #7 leading to an animal 10% larger in linear dimensions and 1/3 heavier, then I would love to see that. But, until or unless you can do so, I consider 10% the more likely option than 6%. This is because (as I explained in Post #10) I can easily replicate 10% while not being able to do so with 6%.
I think now would be a good time to explain why size estimates from 2 other rather popular (both old and new) Giganotosaurus reconstructions are most likely incorrect, and to reveal some more information about SpinoInWonderland's Giganotosaurus GDI, as I finally found sufficient and appropriate time to do so.
As of late, a Giganotosaurus skeletal reconstruction by Dan Folkes has become rather popular. It is the following, and the size estimate from it is 8300 kg for MUCPv-95 (2.2%), resulting in 7780 kg for MUCPv-Ch1. (Side note: since it is in the link, I don't know how to get 9700 kg for Sue without overinflating the ribcage. I would therefore advise to use my 8200 kg estimate instead as it corrects for this problem). In all fairness, it seems to be a well done skeletal aside from the issues I will discuss from here on. Those issues are, perhaps somewhat interestingly, just the same as some of those from Hartman's skeletal: a likely too narrow ribcage, and a likely too small size difference between MUCPv-Ch1 and MUCPv-95. First of all, the ribcage. As per post #16, it was most likely 147.3 cm wide. However, the ribcage in Dan Folkes' Giganotosaurus is considerably narrower than that (I got 125.1 cm using the 136 cm femur as scale). Therefore, as is, the skeletal is likely to be underestimated because its ribcage is 17.7% narrower than the probable actual width. At this point you may be wondering just how large MUCPv-Ch1 would be with a 147.3 cm wide ribcage. This is where the part about revealing more information on SpinoInWonderland's Giganotosaurus GDI comes into play. As per my personal communication with him, the total volume of his skeletal is 8507 liters - and even this is with a 134 cm ribcage instead of a 147.3 cm ribcage (he was not aware of the potential for the 134 cm width to be too narrow at the time he did the GDI, so he used it). He also has told me the torso segment of that model is 5329 liters. And since we know the proportional torso mass, we can know what a Giganotosaurus with the probable 147.3 cm wide ribcage would weigh. So: 5329x1.099=5857. 5857-5329=528, therefore we can add 528 liters to the 8507 liter estimate, which would give us 9035 liters. Multiplying this by 0.95 (as proposed for terrestrial theropods by Asier Larramendi and Greg Paul) gives us 8580 kg for SpinoInWonderland's MUCPv-Ch1 estimate adapted to fit the probable ribcage width of MUCPv-Ch1, which is somewhat larger than the narrow-bodied estimate from Dan Folkes. This also has an implication for the size of MUCPv-95 (which from post #7, as will come in handy later, was most likely 10% larger. I consider this more likely to be correct than the 2.2% that Folkes has used because MUCPv-95 is proportionally >2.2% deeper than MUCPv-Ch1 on the whole - such as with the 10% - while being more eroded). When accounting for both this problem and the ribcage problem, we get 11420 kg for MUCPv-95 instead of 8300 kg (8580x1.1^3=11420). Of course, like stated before, Dan Folkes' skeletal isn't the only popular skeletal that is most likely incorrect. Franoys' is the other one, and despite its popularity it suffers from the same issue with the ribcage width outlined above. It comes out to a volume of 7467 liters (obviously quite lower than the 9035 liters of SpinoInWonderland's skeletal) because of that. The difference in ribcage width between it and my estimate is also notable - I got 128.7 cm using (as like before) the 136 cm femur as scale, so it comes out to 14.4% narrower than 147.3 cm. Consequently, I'd trust the estimate from SpinoInWonderland over that from Franoys. Hopefully this is clarifying enough, but if anyone has any questions they can feel free to ask. |
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