The biggest dinosaurs that lived on Earth

[tigerluver]

To start, this is the study that asserted that the simple regression equations provided by Campione and Evans produced overestimates for giant sauropods:
Downsizing a giant: re-evaluating Dreadnoughtus body mass

Their point was that when you model a Dreadnoughtus, there's no way it can realistically carry 60 tons of mass with the given frame. They then estimate a maximum weight of Dreadnoughtus specimen to be 22-38 metric tons. 

Now let's focus on the new Notocolussus. It is estimate to be 60.4 metric tons by the Campione and Evans equations, so slightly heavier than Dreadnoughtus. Using the volumetric method, Notocolussus would likely be estimated to around 24-40 metric tons. Quite a discrepancy between the two methods.

Perhaps there is a way we can visually interpret which estimate was more likely.

First, I scaled an elephant skeleton so that its humeral length equal that of a giant sauropod (Notocolossus in this case).

*This image is copyright of its original author

From this comparison, which do you think will be heavier? To me, the sauropod seems to have a bit more surface area which may result in more weight, but then the pneumatized (hollowed) vertebrae of the sauropod could also undo the added weight. 

Now, we can do a simple isometric comparison. Disclaimer, I highly doubt an elephant and a sauropod scale isometrically whatsoever, but we can get a rough range of possibility from this simple procedure. 

An Asian elephant (ZMUC 1399) from Campione and Evans (2012) weighed 3,534 kg and had a humerus of length 830 mm and midshaft circumference of 310 mm. Notocolossus had a humerus length of 1760 mm and a midshaft circumference of 770 mm. Isometrically relating each corresponding value calculates as follows:

Length-based mass = (1760 mm/830 mm)^3 * 3,534 kg = 33,700 kg
Circumference-based mass = (770 mm/310 mm)^3 * 3,534 kg = 54,200 kg
Averaging to ~44 metric tons.

With the sauropod known to have adaptations to reduce mass for its frame that the elephant lacks, clearly 61 metric tons does seem like a hefty overestimate. Reply