Giant theropods overview thread

[Dakotaraptor]

2.6-2.8 tonnes sounds a bit modest for 10 m animal. Although Torvosaurus seems to have relatively narrow torso. But i am not sure how accurate the model is, even though it looks not bad.

Anyway Hendrickx & Mateus included Edmarka as one of the synonyms of Torvosaurus tanneri. So did Carrano et al. Although without detailed analysis in both papers.

[theropod]

Yeah, sounds fairly low. I have my doubts regarding the scientific basis of the body width in that model.

[Fragillimus335]

Apr 30, 2014 1:52:59 GMT 5 Dakotaraptor said:

2.6-2.8 tonnes sounds a bit modest for 10 m animal. Although Torvosaurus seems to have relatively narrow torso. But i am not sure how accurate the model is, even though it looks not bad.

Anyway Hendrickx & Mateus included Edmarka as one of the synonyms of Torvosaurus tanneri. So did Carrano et al. Although without detailed analysis in both papers.

It doesn't sound far off to me, scale it up to 12.3 meters and it's 1.86X 2.8 tons=5.2 tons. Implying Torvosaurus was ~65% as massive as Tyrannosaurus at equal lengths. 3.0-3.2 tons would probably be better though.

[blaze]

You are forgetting that Torvosaurus has an elongated head that "artificially" increases its total length somewhat and a very shallow torso, a 10m long Torvosaurus will have a torso roughly as deep as a 8.6m Allosaurus.

[blaze]

I found something interesting that was recently posted in the DML, there are pictures in all views of a spinosaurinae indet. quadrate from the Kem Kem beds and also the inclusion in a phylogenetic analysis of "spinosaurinae morpho I" and "spinosaurinae morpho II"

btw, Deinocheirus news also belong here right?

[theropod]

Of course. Is there anything new on that matter?

[theropod]

Found it myself, looks interesting: www.infomongolia.com/ct/ci/7787/60/The%20%C3%A2%EF%BF%BD%C5%93horrible%20hand%C3%A2%EF%BF%BD%20%20Deinocheirus%20dinosaur%C3%A2%EF%BF%BD%E2%84%A2s%20fossils%20are%20repatriated%20to%20its%20home%20country

[Grey]

I was reading this article of Mark Witton where he explains how the new Godzilla version displays realistic proportions.

markwitton-com.blogspot.fr/2014/05/godzilla-and-mutos-vs-birds-and-newts.html?m=1

He notes :

"Animals show a disproportionate reduction in skull length with respect to body mass - that is to say, larger animals generally have proportionally smaller heads than smaller ones. Note that this applies to carnivores as well as herbivores (Van Valkenburgh 1990; Christansen 1999)."

I was wondering if this could justify the upper size estimates for Spinosaurus (+15 m) or at least have an implication.

[creature386]

Hasn't Verdugo once brought the argument "larger theropods tend to have proportionally larger heads"? Guess this argument now goes down the toilet.

[blaze]

Van Valkenburg (1990) deals exclusively with extant carnivoran mammals, Christiansen (1999) deals with sauropodomorphs as far as I can read in the preview page on springer, I don't think it applies to theropod dinosaurs but who knows.

[Grey]

Seems like Witton acknowledges reptiles are overall implied :

"What’s more, whatever Godzilla actually is (the new movie, thankfully, doesn’t really concern itself with this), it’s clearly on the reptile branch of the animal tree. Reptile cranial musculature is generally less developed than that of mammals, so their skulls and heads are relatively smaller at a given body mass than equivalently sized mammals (Christansen 1999)."

[blaze]

The heads of prosauropod and sauropod dinosaurs appear to be small, compared with those of extant endothermic mammals. This has been considered inconsistent with the hypothesis, supported by several other anatomical characteristics, that these animals had cellular metabolic rates significantly above the usual reptilian level. However, prosauropods and sauropods had only moderately developed cranial musculature, comparable with that of more typical reptiles. This musculature is plesio‐morphic, in contrast with the specialized and powerful muscles of the mammalian cranium. In feeding, these dinosaurs used their heads exclusively in cropping vegetation, a modest amount of oral processing occurring only in certain sauropods. Thus, the heads of prosauropods and sauropods did not have to be as long, at any given body mass, as those of mammals, for the posterior part of the mammal cranium is expanded to accommodate a food processing apparatus as well as the large brain. Statistical comparisons show that sauropodomorph skulls are significantly shorter, relative to body mass or predicted metabolic rate, than those of mammals of comparable mass. In contrast, the width of the muzzle is subequal to that of mammals at any given body mass and predicted metabolic rate. This suggests that the cropping area was not inadequate in mass to enable these animals to ingest sufficient food to maintain an elevated metabolic rate.

That's the abstract of Christiansen (1999).

[theropod]

That scaling principle appears to be extremely generalised.
Ceratopsians, tyrannosaurs, Crocodylians and Pliosaurs are reptiles with gigantic heads and gigantic jaw musculature (as has been noted, in some instances actually more well-developed than that of mammals). Some pterosaurs, birds and carnosaurs have proportionally huge heads despite rather weak musculature in that region. All of these taxa that his references omit, they deal with carnivorous mammals and with sauropods, not with carnivorous reptiles.

On the whole I think he could be right, because most reptiles don’t chew. That mainly affects herbivores (which is why a T. rex has a proportionally bigger head than a lion, but also why a Brachiosaurus has a proportionally smaller head than an elephant), obviously carnivores don’t only develop huge heads for chewing purposes. Mammals are another matter entirely.

So I think it isn’t applicable to theropods, albeit possibly to lizards (if I’m not mistaken, godzilla was supposed to be a lizard).

But in theropods too, there is variation between clades.

Compared to other theropods of similar size, Spinosaurs have just moderate to short skulls, while tyrannosaurines or giganotosaurines have humungous ones.
And it depends on the sample you use, if just big (multi-ton) theropods are included, one is less likely to find considerable positive allometry in skull size, because there won’t be pronounced clustering of a particular ecology towards one end of the range.
But if one includes small theropods, a bunch of small insectivores, omnivores and herbivores (i.e. all relatively small-skulled animals) will fall within the lower end of the surveyed size range, with obvious results (if you want to see a demonstration of what happens when using that in conjunction with flawed size figures and uncertain estimates, see Therrien & Henderson 2008).

Anyway, I don’t think hypotheses regarding godzilla are very relevant to theropod research. Kaiju aren”t really comparable to theropods regarding the appropriate methodology.

Off Topic: What he writes sounds really good. I guess I should watch Godzilla ASAP.

[Infinity Blade]

"Honestly I'm not convinced either way - the bite marks in the tenontosaur that gave the higher estimate sure look like single puncture bite (i.e. they don't look like repeated attempts to gnaw, or etc.). Dromaeosaurs surely didn't have terribly high bite forces among neotheropods, but it may be that theropods across the board had higher bite forces than mammals (a lot more of the wet head mass seems to be dedicated to jaw closing muscles). I'd like to see a finite element analysis of Deinonychus before I took a stronger stand about what the snout and mandible could handle, but of course the currently published skulls of Deinonychus aren't complete - that's why I had to work so hard to reconstruct it for my skeletal.

So in short I'm not sure, and I don't think anyone else is either."
scotthartman.deviantart.com/art/Terrible-Claw-310579803

Just sayin'.....

[Grey]

Of course, wasn't comparing Godzilla fic research with theropods, only reporting the referral about allometry.

Witton probably has not properly consulted the doc, only the abstracts I guess. Should ask him.

No news of the Spino new material ?

Off topic : yes, go watch the movie, seen it twice, old fashion good monster movie, more like Jurassic Park, Alien or Jaws. Creatures are majestic.