Giant theropods overview thread

[stomatopod]

Cau makes some pretty good arguments: theropoda.blogspot.de/2015/10/sigilmassasaurus-awakens.html

[Deleted]

A new paper about theropod gapes just turned up: rsos.royalsocietypublishing.org/content/2/11/150495

It turns out that while Tyrannosaurus' gape is outmatched by that of a carnosaur, it could still open it's mouth wider than an alligator, a therizinosaur, or a buzzard.

Also, Tyrannosaurus used sustained force to crush bone, not that "one bite crush kill" that many still believe lol

"In T. rex, however, the muscle strain curves for the majority of the different muscles lie on a narrow trajectory (figure 6c,d). This suggests that these muscles had a homogenous muscle performance and provided a sustained bite force, as necessary to crush bone and dismember prey."

[theropod]

Already posted that here:
theworldofanimals.proboards.com/post/24933/thread
The findings are fairly consistent with Bakker 1998’s figures and his finding that the specialized joint morphology in Allosaurus allowed gapes in excess of 90° without dislocation.

This had me wondering though, if Allosaurus (79-92° gape angle based on muscle constraints) requires these specializations (antarticular, backwards-bent quadrate, spiral grove and enlarged quadrate condyles) to prevent dislocation, may the joint morphology generally be the more limiting factor?

And yes, crushing takes time. Crocodiles vs turtles is a great example.

[Infinity Blade]

I still don't really understand what sustained bite force is. Either that or I forgot.

[creature386]

Looking at how broly explained it, it refers to a bite that does not instant kill, but where it is necessary to sustain the grip for some time until the prey dies.

EDIT: Theropod explained it elsewhere, so you can feel free to ignore this.

[stomatopod]

Sustained force: force sustained over a period of time. Basically T. rex bites and keeps excerting force till the wanted result.
Nothing more than a few seconds.

Imagine cracking a nut with a nut cracker instead of a hammer.

[Deleted]

Cau's post about Spinosaurus spine positions

[Grey]

What is the current status regarding the biggest/heaviest theropod ?

Giganotosaurus and Tyrannosaurus are still topping at the same body mass ?

[spinodontosaurus]

Tyrannosaurus is comfortably the largest when talking about near-complete specimens.

When talking about largest known (or average) specimens, including fragmentary material, the situation becomes a hell of a lot less clear especially when you consider the low sample size of some of the species involved.

The exact ordering will vary depending on who you ask. In my opinion, based on largest known specimen, the top bunch goes something like:

Tyrannosaurus (8,400 kg; Hartman)
Giganotosaurus (~8,200 kg; Hartman)
Mapusaurus (>8,000 kg)
Tyrannotitan (~7,600 kg; femur circumference)
Carcharodontosaurus (~7,200 kg; skull length)
Sauroniops (~7,200 kg; assumed to be same size as C. saharicus)
Deinocheirus (~7,200 kg; mean of two Campione et al. femur circumference equations)

If MSNM V4047 does indeed turn out to be a Spinosaurus after all then it might be slightly larger than Tyrannosaurus. If we just base it on the type specimen instead then it doesn't really make the cut, ending up at roughly the same sort of size as Acrocanthosaurus.

I have previously made a very rough GDI of Spinosaurus - I used the chest width I estimated from the ribs and vertebrae figured in Stromer's plates, narrowed Scott Hartman's Giganotosaurus dorsal view based on this width estimate, modified the proportions of it's body segments to match his Spinosaurus, then performed a GDI and got an estimate of ~7,200 kg (making it the fourth theropod I estimated at that exact mass... for some reason).
However, that is based on old data now, with a normal-sized pelvic girdle and Tyrannosaurus-sized hindlimbs. I shrunk down the pelvis and hindlimbs to try and match Ibrahim et al.'s specimen, and re-did the GDI achieving an estimate of ~6,200 kg.
Hartman restores MSNM V4047 as 11.4% bigger than the type specimen, meaning an estimated mass of ~8,600 kg.

I don't consider any of the Jurassic theropods known from actual skeletal remains to be big enough. The largest is, in my opinion, Epanterias, which I estimate at only ~4,800 kg based on both MOR 693 and DINO 2560.



Of course this is all based on the largest known specimen of each. Average size is a better comparison but we don't really know how big the average specimen of each is. We could try to estimate it though.

The average Tyrannosaurus femur is something like 121 cm long, suggesting a mass of ~6,600 kg. However, this excludes several quite large and a couple of very small specimens - I have postulated in the past that including these in the sample could suggest an average individual actually had a femur around 127 cm long (~7,600 kg), but that is a rough estimate at best.

The average of the two Giganotosaurus specimens is ~7,500 kg.

Mapusaurus is known from a bone bed of many specimens, at least one of which is juvenile. The range of adult size is thus near impossible to estimate. Some potential adult specimens probably weighed under 6,000 kg (femur length 130 cm), the very largest may have exceeded 8,000 kg, so perhaps ~7,000 kg can be used as a very, very rough estimate of the average? 

The paratype of Tyrannotitan has a femur 141 cm long, the holotype 127 cm long. The average of these two can thus be estimated at ~6,500 kg.

The holotype of Carcharodontosaurus is some ~15% smaller than the neotype. The average of these two can thus be estimated at ~6,000 kg.

Only one specimen of Sauroniops is known, and it is comparable in size to the Carcharodontosaurus neotype specimen, so ~7,200 kg.

The holotype of Deinocheirus is ~6% smaller than the largest specimen, the average of these two can thus be estimated at ~6,600 kg. Another much smaller specimen is known, but is probably sub-adult.

As noted above I estimated the holotype of Spinosaurus at 6,200 kg. If MSNM V4047 truly is a Spinosaurus then we can average the two specimens out to ~7,400 kg. This means there are bundles of other specimens we could include too, but most of those are probably sub-adult based on them being smaller than the sub-adult Ibrahim et al. specimen.

So I guess based on my estimated average sizes the list would be as follows:

?(Tyrannosaurus; ~7,600 kg)
Giganotosaurus; ~7,500 kg
?(Spinosaurus; ~7,400 kg)
Sauroniops; ~7,200 kg
?(Mapusaurus; ~7,000 kg?)
Tyrannosaurus; ~6,600 kg
Deinocheirus; ~6,600 kg
Tyrannotitan; ~6,500 kg
Spinosaurus; ~6,200 kg
Carcharodontosaurus; ~6,000 kg

I haven't included Sigilmassasaurus or Bahariasaurus in this because I don't know how big I think they are but both are known from vertebrae rivalling Spinosaurus and Tyrannosaurus in size, so both are clearly enormous.

[Grey]

Thank you for this very good post.

There are uncertainties if the Milan snout is Spinosaurus now ?

None of the reported fragmentary Tyrannosaurus are reliable so far ?

How large are the vertebra of Sigilmassasaurus and Bahariasaurus ?

[spinodontosaurus]

Of course the lists I gave are far from definitive, and I know for sure that say Theropod would give a very different list that wouldn't necessarily be any more or less correct than my own (although I would probably disagree with it).

Evers et al. (2015) caution against referring isolated remains to Spinosaurus given there was several spinosaurids alive at the time (at least 3, 4 by my reckoning). Ibrahim et al. (2014) employed a different approach and simply synonymised virtually every spinosaurid from Cenomanian North Africa into Spinosaurus aegyptiacus, but we know now that at the very least Sigilmassasaurus was distinct, Stromer's "Spinosaurus B" is too. Analyses of teeth, quadrates and vertebrae from the Kem Kem Formation show two forms of each, meaning at least two spinosaurids were present in that formation alone, a formation that S. aegyptiacus might not even be known from.



The Sigilmassasaurus material is various isolated vertebrae, mainly from the neck and a few from the very front of the torso. The largest one appears to be a centrum possibly from the fifth cervical vertebrae, it measures 212 mm long which is actually ridiculously big. I had in my mind that it rivalled Spinosaurus' vertebrae in size, but I've just realised that one of the cervicals preserved in the Spinosaurus type is restored as the fifth by Hartman and it is 'only' 185 mm long, a difference of 14.6%.
Whether or not the Spinosaurus cervical is really a fifth or not I don't know - Evers et al. do change the positions of the known Baryonyx vertebrae after all, and the difference in size between it's vertebrae just 1 position apart is drastic. The sixth cervical is 26% longer than the fifth cervical, which is in turn 28% longer than the fourth. Even so, if we instead assume that the Spinosaurus cervical is a sixth, there is also a Sigilmassasaurus sixth cervical known and it measures 184 mm, identical to Spinosaurus. Quite how big Sigilmassasaurus was is unclear, but calling it Spinosaurus-sized (or larger) seems pretty reasonable.

The Bahariasaurus type specimen preserves two dorsal vertebrae; 200 mm and 180 mm long. The Spinosaurus type preserves several partial dorsal vertebrae, 4 of which can have their centra measured; 170 mm, 190 mm, 195 mm and 210 mm. The dorsals in even the largest Tyrannosaurus specimen (Sue) are shorter than Spinosaurus', albeit much more heavily built.


The only fragmentary Tyrannosaurus specimen that I think could possibly be larger than Sue is MOR 1126, a.k.a. 'Celeste'. But all we have to go on is Horner's original field guess of it being 10% larger than Sue, and a scale bar from Longrich et al. (2010) implying one of it's phalanges to be ~5% larger. But the other scale bars in that paper are not accurate (e.g. showing the UCMP 137538 phalanx at 18 cm long instead of the actual 13 cm), so who knows how big it really is.

A more reasonable estimate for the skull of MOR 008 is, in my opinion, ~136 cm. This is still one of the largest known Tyrannosaurus skulls, but is smaller than MOR 555, UCMP 118742 (probably) and FMNH PR2081. The four specimens Scott Hartman have restored yield drastically different total length estimates for MOR 008; 11 meters (Sue), 11.7 meters (Stan) 12.1 meters (AMNH) and 12.9 meters (Type), which average out to a very reasonable 11.9 meters. A large specimen (est. 7,600 kg), but not record-breaking.

I put this together a while back showing why I think UCMP 137538 is Sue-sized:


I'm not aware of any other 'giant' Tyrannosaurus specimens out there.

[Grey]

In short, maybe the only valid Spinosaurus is the type specimen.

If I read further, could the Milan snout even be Sigilmassasaurus ?

How robust are the vertebra of Sigilmassasaurus and Bahariasaurus compared to the large carcharodontosaurids and Tyrannosaurus ?

Yes I had read your analysis of the alleged big toebone compared with Sue.
Anyway this is an internet myth, no tyrannosaurid expert has ever claimed this one to be >Sue.

It would be good that something more substantial comes from Celeste now...

[spinodontosaurus]

I doubt MSNM V4047 is a Sigilmassasaurus, there is no overlapping material so the referral couldn't be made anyway but MSNM V4047 appears to be spinosaurine, Sigilmassasaurus does not.

[EDIT:A mere day or so after I posted this a new study came out assigning a spinosaurine quadrate to Sigilmassasaurus - see post below this]

The length of Sigilmassasaurus' cervical vertebrae is a little miss-leading, at least when comparing it to Tyrannosaurus. Unfortunately the big C5 is not very complete, so comparing it to Tyrannosaurus visually doesn't work too well. However, the holotype specimen of Spinosaurus maroccanus is a well preserved C6 vertebrae, and since it is now recognised as a specimen of Sigilmassasaurus I used it instead. It's still big too, centrum length of 183 mm. I also up-scaled it to 212 mm to give us a vague idea of how a 212 mm long Sigilmassasaurus cervical will compare to a Tyrannosaurus one.


Click text for full-sized version.

The vertebrae is extremely long but is dwarfed in every other aspect by Tyrannosaurus. This is pretty much the case with all spinosaurids though.

[Deleted]

A new paper about spinosaurid morphotypes

Sigilmassasaurus (spinosaurine morphotype 2) is found to be a spinosaurine and a closer relative to Irritator than to Spinosaurus.

[Cross]

A Carcharodontosaurus with a 1.62m long skull and proportions intermediate between Acrocanthosaurus and Giganotosaurus would be 13.7m and 9,100kg. 
Whereas one with proportions exactly like Giganotosaurus would be 13m and ~8,000kg. 

The composite skeleton from Ibrahim et al. (2014) of Spinosaurus seems to be rather shrink-wrapped, though. So I'm really skeptical of their 6-7 tons figure. 
If I had to guess, a properly fleshed-out version of their composite skeleton with the larger caudofemoral musculature and flesh in the dorsal neural process that are mentioned in the paper and in other recent publications should be around or over 8,000kg. 
If you square-cube their 15-meter, 7,000kg reconstruction to 16m (since they wrote that their reconstruction was "over 15 meters"), you get an animal that's ~8,500 kg. So if my math is correct, Spinosaurus really does appear to be the largest. But this is assuming that MSNMv-4047 does belong to Spinosaurus, which is debatable (Evers et al. 2015; Hendrickx et al. 2016). So we should probably include Sigilmassasaurus in this thread  

There's also that purported giant Kem Kem theropod Osteoporosia (Oh GOD, why did they name it that?) which was said to be 14m. 

Can we start a petition to rename it to something cooler like Kemkemovenator or Moroccodromeus or something? Anything BUT Osteoporosia. Except, no one is allowed to suggest "Theropod Mctheropodface" because I'm afraid some of us have already heard of Boaty Mcboatface.