Giant theropods overview thread

[theropod]

Most of them are actually Late Cretaceous, mostly Cenomanian (S. aegyptiacus, C. saharicus & iguidensis, G, carolinii, M. roseae, S. pachytholus, T. chubutensis), only Acrocanthosaurus is Lower Cretaceous.

The 13-14m range in them is known from actual fossils and used in many scientific sources, and in a smaller sample than the sample in which the largest T. rex is 12,3m. So if we propose this as a likely size for T. rex (no problem with that) we have to assume these animals to have been even longer.

[Grey]

I tend to confuse early and middle Cretaceous. Of course I referred to the giants of around 90-100 MYA.

Speaking of large T. rex, there is also this maxilla UCMP 118742.

[theropod]

(UCMP 118742) (~12.1-12.4 m, adult) (skull ~1.31 m?) maxilla (810 mm) (Molnar, 1991)
----------------------
According to the theropod database, it is smaller than sue's maxilla (ignore the total lenght, still bases on old 12,8m long tailed sue...).
What some fanboys are making of this is picking some growth rate (highly unreliable if calculated from only 31 specimens, and impossible to account for natural individual variation) and filling in some madeup size figures (I remember one guy who tought this specimen must have a 1,6m skull, because its maxilla is merely 5cm shorter than sue's, and that's the only remain), because they think a 16 year old specimen would have still grown from 12 to 16m...
In fact, it is doubtful it would have grown sigificantly at all, it is not downright typical to just continue growing until some uniform age, regardless of the size already reached. If this specimen was that large at that young age, this implies it had grown differently, so why should it grow like the others from that point on? And 16 years is already counted as adult, its not as if this individual was osteologically immature, just not very old when it died compared to specimens like sue.
You see, I have fanboy-tales of nearly every single T. rex specimen there is lol
Kinda sad, isn't it?

Still, very nice maxilla, the look of it is just fantastic. The teeth are especially impressive, and it seems in a perfect state of preservation, I just whish the photo was better...
there are some other shots available, just use google and type in UCMP 118742

[creature386]

I remember Frank Fang's 16,9 m estimate was often cited. From what I read on CF, he is not even an expert. Appearently, some people treat him like one, so I found it important to post it here.

[theropod]

That's not an estimate, it is more or less completely madeup...

[theropod]

wow, I just searched for frank fang tyrannosaurus. you find things like topix posts and allexperts answers (where palaeontology is a subcategory of archaeology). that guy isn't just absolutely no expert, he is apparently worse than the average carnivora troll. He probably made the formula up completely, it looks like it is made up for sure...

[Grey]

Allexperts : allamateurs.

Although some responses are educated.

[creature386]

By the way, who is Emperor celestial dragon? Is that Frank Fang? Is it the Illiterate Sholar?
I remember Big Al has once mentioned that name.

[theropod]

I know the name celestial fang, i assume that is the same guy as frank fang. The illiterate scholar merely likes to parrot him. Parroting fanboys is always a bad idea...

[theropod]

Just a short tought on the myth of T. rex being taller than Giganotosaurus
The holotype of G. carolinii should be about the same height as FMNH PR 2081 at the acetabulum, possibly a little taller but not dramatically;
mean femur lenght+tibial lenght+(extrapolated( metatarsals (basing on Acrocanthosaurus MOU 8-0-S8 in which the Femur/Metatarsal ratio is 2,13)

Sue has a 131-138cm femur (the lower end is more easily verifiable but let's take the mean which is ~135cm), a 114cm tibia and the longest metatarsal is 67cm .
Mean femur lenght for MUCPv-CH1 would be 140cm (range is 137-143cm), tibial lenght is 112cm and metatarsals based on mean femur lenght 66cm.

In sum the lenght of the three major leg bones combined is 318cm in the MUCPv-Ch1 and 316cm in FMNH PR 2081, hence pretty much the same in both. The largest Giganotosaurus would be 2-8% bigger dimensionally, but not necessarily in terms of height which often doesn't scale isometrically.

The leg lenght with all bones included would be a bit higher for both of them, while I daresay acetabular height wouldn't because in reality all the bones are not forming a straight line. The height above the ilium would be slightly greater still, as would the height of the head.

[creature386]

Mazzetta has listed the of Sue at 120 cm, where is the 114 cm figure from? If that's false (120 cm), could you debunk it please?

P.S. Haven't you messaged me something like that before on carnivora?

[theropod]

Brochu, 2003

The figure in Mazzetta must have been a misquotation, I have no clue were it is from.

HINDLIMB
right femur, length (greater trochanter to lateral distal condyle) 132.1
right femur, midshaft mediolateral width 19.7
left femur, length (greater trochanter to lateral distal condyle) 130.8
left femur, midshaft mediolateral width 19.1
left tibia, length (with tarsus) 124.5
left tibia, length (without tarsus) 114.3
left tibia, mediolateral width, midshaft 16.5
right fibula, length 102.9
right fibula, anteroposterior width, midshaft 7.0
left fibula, length 103.5
left fibula, anteroposterior width, midshaft 14.0
right metatarsal II, length 58.4
right metatarsal II, mediolateral width, midshaft 9.3
right metatarsal II, mediolateral width, proximal condyle 20.0
right metatarsal II, mediolateral width, distal condyle 13.2
right metatarsal III, length 67.1
right metatarsal III, mediolateral width, midshaft (minimum) 4.6
right metatarsal III, mediolateral width, midshaft (maximum) 11.7
right metatarsal III, mediolateral width, proximal condyle 3.5
right metatarsal III, mediolateral width, distal condyle 15.7
right metatarsal IV, length 62.1
right metatarsal IV, mediolateral width, midshaft 12.6
right metatarsal IV, mediolateral width, proximal condyle 18.0
right metatarsal IV, mediolateral width, distal condyle 12.6
right metatarsal V, length 27.5
nght metatarsal V, mediolateral width, midshaft 5.3

Christopher A. Brochu, Osteology of Tyrannosaurus rex: Insights from a Nearly Complete Skeleton and High-Resolution Computed Tomographic
Analysis of the Skull (Jan. 14, 2003), pp. 1-138, Memoir (Society of Vertebrate Paleontology), Vol. 7

Of course astragalus and calcaneum are not part of the tibia and should be excluded from the measurement, we certainly can’t assume them to be included in other tibial-lenght measurements either, unless the description reads "Tibiotarsus" length. Including them however would make the measurements even higher than 120cm.

You can see the same figure reported in the Theropod database. If other sources mention different figures, that is either a typing mistake or a very different measurement, but I would rather trust the ones above.
The lenght of all the height-relevant bones combined would be greater than just these three of course (including the proximal and distal tarsals, as well as articular cartilage and digits and padding distal to the metatarsal), but we can assume both to be similar in both taxa, and in reality the knee and ankle joints are usually bent even in resting pose, which will probably act to offset that.

Not sure, some time has passed since Carnivora's PM system worked and I currently cannot access my outbox. It is possible I wrote something similar, but not the same. I might have simply added femur lenght and tibial lenght (back then 143+112 vs 132 vs 114), but this is more reliable because it includes the metatarsal and uses mean lenghts were there is more than one published figure. This obviously results in two animals of near-equal acetabular height, which makes you wonder why animals in comparisons that obviously were supposed to be MUCPv-95 are no taller, or even shorter, than sue.

[creature386]

May 20, 2013 15:03:27 GMT 5 theropod said:

Not sure, some time has passed since Carnivora's PM system worked and I currently cannot access my outbox. It is possible I wrote something similar, but not the same. I might have simply added femur lenght and tibial lenght (back then 143+112 vs 132 vs 114), but this is more reliable because it includes the metatarsal and uses mean lenghts were there is more than one measurement.

I now found it. Here the part about leg length:
Femur: 1.43m vs 1.32m

Tibia: 1.12m vs 1.14m
This is from the first August, a long time ago.

P.S. I really like the new preview system.

[theropod]

Yeah, that's a bit outdated, by now Giganotosaurus has a lower figure and T. rex once had a higher one. To be more fair, I took into account both animal's upper and lower measurements.

PS: yeah, that's a great WYSIWYG-editor! I love the updates in general.

[theropod]

Why femur circunmference is a bad predictor of body mass among theropods
It has often been claimed as one of the main arguments for T. rex being heavier than G. carolinii, that the former had thicker femora. Femur lenght on the other hand was claimed as an unreliable means to estimate mass.
In fact, I think both are terribly unreliable.


According to Currie & Carpenter 2000, this Acrocanthosaurus specimen should weight 2.4t based on femur circumference, while the T. rex specimen should weigh 4.2t (both are very similar in lenght).*
The scanned MOR 555 from Bates et al. 2009 on the other hand is ~100kg lighter than NCSM 14345 (at roughly 6.07t for the former), and even tough its ribcage is probably inaccurately mounted (making it too narrow), due to the high density in this one and the shrinkwrapped crest in the Acrocanthosaurus model, the relative weights would not look much different from that in reality (which doesn't have to mean I agree with the absolute figures, I think Stan at least was severely overbulked in that study and more likely similar to Wankel and Fran in life).

In any case these two are close to the same weight, in stark contrast to MOR 555 being 75% heavier than NCSM 14345 based on femur circumference.

Possible reasons for this?

-different relative cortical thickness/pneumaticity
-different degree of cursoriality
-different stance

What does it teach us?
-single-bone-measurements are awful predictors of relative masses among rather distantly related animals due to a variety of factors.
-Carnosaur hindlimb proportions differ significantly from Tyrannosaurine ones

This issue is also reflected in reasearch works. In the chapter he wrote for The Tyrant King, Greg Paul remarks the same, noting that limb diameters varied by a factor of 2 in animals of the same body mass. I recall some work (I’ll try to find it again, so don’t cite me on this for now) found femur lenght actually had a better correlation with body mass than those measurements.

*Also note that while tyrannosaurine proximal limb elements are generally thicker, the opposite is true for the calves and pedes. If tibial or metapodial circumference had been used, the results would have likely turned out the complete opposite of those.