Carcharodontosaurids: bulkier than you think

GIGADINO - This is a very neat and well-presented topic! Indeed, it is quite possible that the Carcharodontosaurids were heavier than they've been presented in more recent publications. It wouldn't surprise me if such massive animals were proportionately heavy! Thank you for sharing this thought provoking notion! :)

Look at its neural spines. They appear to be very long. The fact that Giganotosaurus had long neural spines is mentioned on several sources. And, if Giganotosaurus had long neural spines, well, Acrocanthosaurus are even longer. It means that Giganotosaurus spinal column carried quite high mass.

Evidence for this?

Acrocanthosaurus' neural spines have never really had a definitive reason stuck to them. But, anchoring for muscle attachments is widely accepted atm...

Clicky Click here: Acrocanthosaurus atokensis, a new genus and species of lower cretaceous theropoda from Oklahoma

Let's compare the two:

Harman's most recent acro - 

2013 giga - 

Acro's are significantly taller, and form the prominant "ridge". This feature is not duplicated in Giganotosaurus, so it's safe to say they did not have the same function.the neural spines of Tyrannosaurus are tall as well:

Not as tall as those of Giga or Acro, but their decently sized.

Also, that cladogram you used is outdated(missing tyrannotitan, among other issues) Is it pre- novas 2013?

Here's after Novas et. al:

Cladogram after Novas et al., 2013[3]

Allosaurus

Neovenator

Eocarcharia

Concavenator

Acrocanthosaurus

Shaochilong

Carcharodontosaurus

Tyrannotitan

Mapusaurus

Giganotosaurus

Take note that i'm not saying Carcharodontosaurids aren't bulky, it's just the notions you've put forward have no scientific backing behind them.

CARNOSAUR - As I've come to rely on you as a very credible source for dino info, would you be so kind as to answer a quick question? Was Mapusaurus larger than Carcharodontosaurus? I will greatly appreciate any information you can provide! :)

With pleasure!

Carchy has always been one of the dinos that has had size estimates fluctuate hugely over the last few decades. 

We don't really have a whole lot to go off of for Carchy( Giganotosaurus, isn't a good base, despite common belief. It's within the subfamily Giganotosaurinae, which carchy is not) so i tend to use A. atokensis here for my estimates

But, to put it more simply we look at skull measurements, and the use of what i like to call "the 8ths rule".

SGM-DIN 1 has a skull length of ~1.56 meters

1.56 x 8 ~ 12.4 meters

Now, basing off of the  A. atokensis holotype (OMNH 10146) we get ~7.32 tons. Off of "fran"(NCSM 14345) we get 7.63 tons

Mapusaurus is a bit iffy, really. An animal (again, that catalogue number eludes me -.-) known from a pubic shaft is estimated to measure 13.6 meters in length, and be ~27% more massive then the Giganotosaurus holotype. Which would put it easily at 8+ tons. But, the other individuals we have of Mapusaurus are generally in the 10 -11.5m mark. Acrocanthosaurus, Being of comparible length, measured in at 4 - 5 tons. For those individuals, i usually put the estimate at 5 tons. the 12 meters and up though (3 individuals) i put at 6 - 7.5 tons. 

To end my rambling manner, their pretty similar in overall size...Mapu might be larger overall once this pubic shaft gets an official estimate on it

CARNOSAUR - Thank you ever so much! That actually helps to clarify quite a misconception I've had concerning Mapusaurus! :)

Interesting

I agree with you giga, I do think carcharadontosaurids were a lot bulkier then given credit for.

The cladogramm was outdated indeed, I had two of them and I didn't remember wich the most updated one was.

You're right even abput Acrocanthosaurus.

But no, Giganotosaurus being the best basis for C.saharicus isn't a common belief. G.carolinii and C.saharicus are much closer than A.atokensis and C.saharicus. It doesn't matter if C.saharicus doesn't belong to Giganotosaurinae. Using A.atokensis is liberal, and would produce a freaking ~13.9~14.3 m (so ~14 m +), ~9~10 t thing. ~12.4 m is possible indeend, if we use Carrano's estimates, A such thing would actually weight around to ~6.8 t (~6~7 t), as Hartman estimated the equally long MUCPv-ch1 at ~6.8 t.

And that Mapusaurus pubic shaft is pretty doubtful if you ask. The difference between G.carolinii's holotype and that Mapusaurus specimen is pretty small, and we know that G.carolinii and M.rosae didn't share the same proportions, so its pubic shaft may be proportionally thicker. Imo the safest thing to say is that that specimen was around the same size as the largest Giganotosaurus specimen.

Scaling from Giganotosaurus holotype is better, as Carcharodontosaurus was likely more strongly built than Acrocanthosaurus, like G.carolinii. As I've already pointed out, the whole thing will get somewhere between ~7 and ~8 t.

Yes, I meant more bulky.

I have a very high belief in Charcarodontosaurs being bulky, but agile. They were active sauropod hunters and had to be able to get to the tricky spots to kill what it needed to.

Yes, but more derivated Carcharodontosaurids appear to be even more bulky. Acrocanthosaurus is pretty gracile if compared to derivated Carcharodontosaurids.