I WAS WRONG ABOUT GIGANOTOSAURUS (not clickbait!)
I WAS WRONG ABOUT GIGANOTOSAURUS (NOT CLICKBAIT)
Reconstructing entire skeletons of extinct animals can be tough, especially when our picture of these animals is fragmented by the inherent nature of the fossil record. This task becomes even more challenging when much of the material has not been figured or measured in the literature – this is the case with Giganotosaurus carolinii, one of the largest terrestrial carnivores to ever exist and the largest carcharodontosaurid theropod that we currently know of.
My latest Giganotosaurus skeletal. Why the change? I explain below…
Here's a little bit of context:
Giganotosaurus was first described in 1995 by two scientists, Rodolfo Coria and Leonardo Salgado, two “giants” in Palaeontology, and instrumental in understanding the extinct dinosaurs and animals of the southern hemisphere, which even at this fairly recent time was not so well understood. The holotype specimen of Giganotosaurus is known from a considerable portion of the skeleton, from the vertebral column to limbs and many elements of the skull – brilliant for creating a skeletal reconstruction, right? Well, here’s where the problems begin. The original description contains a low-res images of elements of the skull, and an abstract skeletal showing the known material in black and white – not great for reconstructing the skeletal in a detailed manner (BTW, this is by far not the only published literature for notable genera which lacks much of an in depth description of the material including measurements, which for making skeletal diagrams is very helpful, but is understandably not a priority for many researchers.) Luckily, there are many subsequent papers from a number of different authors which include images and measurements of a few select elements of Giganotosaurus material, and so far (2022) we have no osteology for this taxon.
So, you may ask, “what has this got to do with your skeletals?” and “WHY DO YOU HAVE SO MANY VERSIONS?!” and these are both good questions which I’d like to discuss below. So, how many versions of Giganotosaurus have I made? 4, with my 4th being the latest (so 3 before this). Here’s why:
1. Learning
My first Giganotosaurus skeletal was made back in late 2020 early 2021. During that time period I’ve learned a whole bunch about Giganotosaurus, and many of the choices I made for reconstructing Giganotosaurus back then I don’t agree with now I’m more knowledgeable on the subject. Then there’s Meraxes, published this year, Meraxes is a carcharodontosaur with a wonderful description consisting of a number of beautiful figures and measurements (including for Giganotosaurus!) which are incredibly useful when filling in the gaps which before I was filling in with more basal taxa like Allosaurus and Acrocanthosaurus (which aren’t very fitting in some cases). This brings us on to our next point:
2. I’M A PERFECTIONIST
Of course after seeing the publication of Meraxes, I couldn’t not update my Giganotosaurus. When something becomes outdated, especially with an animal I’m very passionate about, I just had to update it – I almost feel a duty to do so, especially as many people are using my work as reference for a variety of beautiful projects. As such, my 3rd version was born – and here I swore I wouldn’t change this skeletal until an osteology was released: famous last words. This brings us on to my final point:
3. You found measurements from what paper???
About a month or so ago, I was alerted by a discord user to a few measurements of Giganotosaurus they discovered – in the Murusraptor description no less?? (though, this is a Coria paper so it does make sense). The reported measurement was that of a sacrum – the sacrum of the holotype as measured from the skeleton mount. This one measurement was the catalyst for an entire update that, well, needed to happen. You see, one of the references that is helpful for the general proportions of this animal is a lovely lateral image of the mount – I know a few notable skeletal makers that have used this for their skeletal. So, why is this significant? Well, the sacral measurement was taken right from the mount – and was larger than in my previous versions (1090 mm). This may not sound significant, but even a slight size change means a whole lot for such a large animal – and this was no slight size change in relative terms – there was over a 10 cm increase in size for the sacrum alone. So – I dug further – it turned out the COM (centre of mass) of my 3rd version was far too far forward, so I went looking for images and measurements. Myself, with the help of others on discord, managed to find a whole lot of images and measurements for the skull. It turns out, my skull was also slightly too small in previous versions (before I had used the original scale bar from the 1995 description, which is slightly too small – I’d been referencing from other skeletals too and they seemed to share this size). Finally, my tail was obviously way too small – looking at images of the floor mount of Giganotosaurus (which consists of the original material) I was able to verify that indeed, the tail was too small and needed to be scaled up. This had repercussions size wise.
The brilliant model by Toxic Midget which was used for a volumetric and COM analysis
Thanks to the incredibly talented Toxic Midget on discord, who performed a COM analysis of my new model (as well as a weight estimate) we were able to verify that the new model was also stable – and bigger. The measurements for the new model are as follows:
For the holotype:
Length along the centra: ~12.7m
Weight (0.97 density): 8839 kg
“ “ (0.99 density): 9021 kg
For the dentary specimen (if 2.2% larger):
Length along the centra: ~13 m
Weight (0.97 density): ~9400 kg
“ “ (0.99 density): ~9600 kg
We can safely say, Giganotosaurus was big. Bigger than Tyrannosaurus? Length wise, probably. Weight wise? Currently, T.rex still holds the heavyweight title by a decent amount (much to our surprise).
That about sums it up. I thought that describing my process in detail would make my work more transparent, and hopefully let you guys peak behind the scenes at how I make skeletals (and that I’m not a freaking sweet steampunk machine pumping out random garbage). I truly apologise to those who have used my skeletals before and are frustrated at the amount of changes, for that I am sorry. However, for me updating my diagrams to make them as good as possible is paramount. I hope you understand.
SPECIAL THANKS TO SAID DISCORD USERS:
Toxic Midget
4LPH48
derpy.stego
Greyback
Giganotosaurus
For their help with this project and acting as my other brains in this matter.
