Carnivorous dinosaurs other than the famous t-rex and spinosaurus..

[tigerluver]

Firstly, for those interested in the volumetric method this is a great read discussing many of the method's faults. Unfortunately, it is very subjective as the authors decide how fleshy or dense the animal is. This does not happen with isometric comparisons or regression.

While there are a plethora of estimations of therapods, it seems the raw data gets missed in the quest to find the magic formula. Based on the cEq equation of Campione (2014), Scotty has been given the highest weight. Nonetheless, as I stated in another thread, the limitation of the Scotty study is that it only takes into account femoral circumference, not length. The justification is that Campione (2012 and 2014) found femoral circumference to have the strongest correlation to mass. However, while the dataset of Campione is vast, this may bring in some inaccuracies. Animals very different in proportion are being compared and there is a wide confidence interval that indicates that another random dataset may show another measurement, such as bone length, as a stronger predictor. Thus, a combined measurement estimate should at least be considered. Another thing to note is that errors calculated by regression are simply the errors limited to the dataset itself. A better way to test for error is to test the regression in specimens not used to produce it but this has not yet been done.

Here are the femoral measurements of the largest therapods:

*This image is copyright of its original author

Scotty and the holotype Giganotosaurus can be compared by the follow method:

Using measurement X, the amount specimen 1 is larger or smaller in terms of mass than specimen 2  = (Specimen 1/Specimen 2)^3 = Xm

Using measurement Y, the amount specimen 1 is larger or smaller in terms of mass than specimen 2  = (Specimen 1/Specimen 2)^3 = Ym

Overall amount specimen 1 is larger or smaller than specimen 2 in terms of mass = (Xm + Ym)/2

We will put Scotty as specimen 1 and the holotype Giganotosaurus as specimen 2 and substitute in the numbers to the above:

Using femoral circumference, Scotty is Xm larger or smaller in terms of mass than specimen 2  = (590/520)^3 
                                                                                                Scotty is 1.46x heavier than Giganotosaurus.

Using femoral length, Scotty is Xm larger or smaller in terms of mass than specimen 2  = (1330/1365)^3 

                                                                                                Scotty is 0.925x lighter than Giganotosaurus.

Overall amount Scotty is larger or smaller than the holotype Giganotosaurus in terms of mass = (Xm + Ym)/2 = (1.46 + 0.925)/2 
                                                                                                Scotty is 1.1925x heavier than the holotype Giganotosaurus overall.



For the second larger Giganotosaurus cited to be 8% larger by the original work, we can extrapolate this specimen's femoral circumference to be (520 * 1.08) 562 mm and femoral length to be (1365 * 1.08) 1474 mm. We can go through the aforementioned math again as follows with the larger Giganotosaurus as specimen 2:

Using femoral circumference, Scotty is Xm larger or smaller in terms of mass than specimen 2  = (590/562)^3 
                                                                                                Scotty is 1.16x heavier than Giganotosaurus.

Using femoral length, Scotty is Xm larger or smaller in terms of mass than specimen 2  = (1330/1474)^3 

                                                                                                Scotty is 0.735x lighter than Giganotosaurus.

Overall amount Scotty is larger or smaller than the holotype Giganotosaurus in terms of mass = (Xm + Ym)/2 = (1.16 + 0.735)/2 
                                                                                                Scotty is 0.95x lighter than Giganotosaurus overall.

Now I acknowledge Scott Hartman's estimate for the second Giganotosaurus being no more than 6.5% but his reasoning could be better explained before it's taken over the original work's determination. Persons et al. (2019) themselves do acknowledge that the holotype Giganotosaurus they used in their table is likely not the largest specimen for the species. Reply