Iguanodon bernissartensis vs Tyrannosaurus rex (small adult)

[Deleted]

Iguanodon bernissartensis

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Tyrannosaurus rex (small adult individuals, around Bucky or B-rex level size or so)


Art by Alexanderlovegrove

[Infinity Blade]

There's a species of frog (Hypsiboas rosenbergi) that uses spiky pseudothumbs for intraspecific combat. In particular, they stab each other's eyes and ear drums, leaving lethal injuries.
blogs.discovermagazine.com/notrocketscience/2012/10/19/more-wolverine-frogs-japanese-species-uses-bony-thumb-spikes-to-fight-and-hold-onto-mates/#.VkT0Mno8KrV

I wonder if Iguanodon was the same and could have used such a tactic against predators. That said, I'm not necessarily saying it wins here.

Also, isn't Tarbosaurus in the same weight range as Iguanodon or the smallest adult Tyrannosaurus specimens? If so, couldn't it have worked too?

[Infinity Blade]

Would anyone else like to give their input? This is a bit interesting IMO.

[creature386]

Lost most of my experience/knowledge related to animal combat, but I'll try:

A bit difficult. First of all, T. rex would have it hard to perform a bite that is continuous enough to kill its opponent, due to the injuries a struggling Iguanodon can deliver. While T. rex was not exactly suited for a really quick, yet lethal bite, I still somehow think that such an encounter would bring more harm to Iguanodon than to Tyranno. Injuring the opponent is equally difficult for both IMO. Iguanodon has to aim well and Tyrannosaurus has to get close with its jaws. As I said, difficult, and I frankly forgot a lot of my "expertise" on animal combat (if I ever had that), but I see Tyrannosaurus winning more often than not at length parity (I assume Iguanodon would have a slight weight advantage there, but probably nothing decisive), though it is dubious if it could still hunt after such a battle.

[Infinity Blade]

I think a Tyrannosaurus could injure an equally-sized Iguanodon rather quickly. But obviously the amount of time it takes will depend on where it bites. If on a less vital area, if Iguanodon really did employ a vulnerable region-jabbing method of fighting and performed it successfully not long after being bitten, I'm not sure how much of a condition the theropod would be in to continue fighting.

Actually, I think both opponents here will have to fight close-quarters, which isn't so appealing for either. Getting in close to bite will mean risks of getting jabbed for the theropod, and being close enough to jab also means being close enough to get bitten (if Thomas R. Holtz Jr.'s word in his dinosaur encyclopedia is anything to go by).

[Deleted]

I think Bucky would be thrashed around, stabbed, and overpowered by an average Iguanodon, but B-rex would probably win ~45-55% of the time.

[spinodontosaurus]

An average Iguanodon? As in 10 meters and 3 tonnes? I don't see it standing much of a chance against even the smallest specimens of Tyrannosaurus, which are all >4 tonnes. Bucky was probably 5-6 tonnes based on femur length.

If large Iguanodon really could reach 13 meters - something I've never been able to verify - they they might weigh 6.6 tonnes, which is far too large for smaller Tyrannosaurus specimens.

[Deleted]

Nov 14, 2015 14:55:52 GMT 5 spinodontosaurus said:

As in 10 meters and 3 tonnes?

A ~10-meter Allosaurus would have been in the ~3-tonne ballpark. Iguanodon was far bulkier than Allosaurus, or even a tyrannosaurid of the same length. Unless Iguanodon was severely anorexic, then it would likely have been closer to maybe ~5 tonnes or so, considering it's bulk.

[theropod]

Nov 14, 2015 14:55:52 GMT 5 spinodontosaurus said:

An average Iguanodon? As in 10 meters and 3 tonnes?

It seems rather hard to believe that an Iguanodon would be that much lighter than a T. rex at equal length. I’d expect it to be somewhat heavier at equal length, being not just bulkier in built but also far denser.

I don't see it standing much of a chance against even the smallest specimens of Tyrannosaurus, which are all >4 tonnes. Bucky was probably 5-6 tonnes based on femur length.

I can’t help but wonder where Mortimer’s femur length figure came from.
Neal Larson (2008) doesn’t list a femur among the known elements and explicitely writes that "no […] major leg bones were found with the skeleton". Neither Peter Larson (2008) nor the bhi catalog entry of the replica (http://www.bhigr.com/catalog/product_pages/BHIGR_BUCKY-Tyrannosaurus.pdf) hint at the existence of a femur. I also didn’t find any mention of a femur, let alone a measurement thereof, in the chapter Mortimer cited, which focuses on the scapula (https://books.google.de/books?id=Mr16gm7VRCAC&pg=PA247&dq=Furcula+of+Tyrannosaurus+rex+larson+%26+rigby&hl=en&sa=X&redir_esc=y#v=onepage&q=Furcula%20of%20Tyrannosaurus%20rex%20larson%20%26%20rigby&f=false) and there are only 2 pages which I can’t access (251 and 253). So unless a data table was hidden on one of those pages, which both Larsons and the museum itself ignored, Bucky doesn’t have a femur.

Other measurements of the specimen reported by Larson also imply it is much smaller than that (e.g. ulna, scapula, ilium…).

–––References:
Larson, Neal L. (2008): One Hundred Years of Tyrannosaurus rex: The Skeletons. In: Larson, Peter; Carpenter, Kenneth: Tyrannosaurus rex the Tyrant King. Bloomington, pp. 1-56.
Larson, Peter (2008): Variation and Sexual Dimorphism in Tyrannosaurus rex. In: Larson, Peter; Carpenter, Kenneth: Tyrannosaurus rex the Tyrant King. Bloomington, pp. 103-128.

[spinodontosaurus]

Strange, maybe Mortimer merely estimated it based on some other measurement? Looking at Bucky's entry again, 'femur' and the measurement are both enclosed in brackets, same with the Tarbosaurus holotype's femur, we know the latter does not preserve a femur so I'm now convinced the listed measurement is indeed just an estimate.

[Deleted]

Scaling using the ilium and comparison with Stan puts Bucky at roughly ~9.3 meters long with a probable mass a little bit over ~3.6 tonnes assuming that Stan had a mass of ~6.5 tonnes.

[theropod]

Ulnae:
l[ength](2001.90.1)/l(pr2081)=176/220=.80
.80³=.512
Tl[est.]=9.84m
Mass[est.]=4.3t

c[ircumference](2001.90.1)/c(pr2081)=96/121=.79
.79³=.50
Tl[est.]=9.76m
Mass[est.]=4.3t

Scapulae:
l(2001.90.1)/l(pr2081)=940/1140=.82
.82³=.56
Tl[est.]=10.14m
Mass[est.]=4.7t

c(2001.90.1)/c(pr2081)=196/205=.96
.96³=.87
Tl[est.]=11.76m
Mass[est.]=7.3t

Ilia:
l(2001.90.1)/l(pr2081)=1275/1480=.86
.86³=.64
Tl[est.]=10.6m
Mass[est.]=5.4t

d[epth](2001.90.1)/d(pr2081)=490/590=.83
.83³=.57
Tl[est.]=10.22m
Mass[est.]=4.8t

Sacra:
l(2001.90.1)/l(pr2081)=897/980=.92
.92³=.77
Tl[est.]=11.26m
Mass[est.]=6.4t

I think we can readily dismiss the scapular circumference as an outlier (and we know similar cases resulting from aberrant conditions such as pathology, if I recall correctly e.g. in Arctotherium’s humerus). That’s further supported by the fact that the BHI’s commercially available cast is stated to be 10m in standing length.
That being said, and even though this is certainly not a large specimen, and most likely a small one, it’s not necessarily smaller than B-rex.

[Deleted]

theropod

Um, why did you use Sue? Isn't Bucky only around ~16 years old or so, thus it would be better to use a specimen closer to it in age?

[theropod]

For the sake of making apples to apples comparisons, and because it’s the most complete specimen, I always use Sue first of all.

[blaze]

The supplementary material of Allan et Al. (2012) has the ilium of Sue at 1670mm, which is more consistent with the digital scans of the mount.

Anyway, as far as I know the only volumetric estimates for I. bernissartensis is 3.2t for an ~8m specimen, RBINS R51 (also known as IRSNB 1534), I don't know of any larger individuals save for the I. "seeleyi" specimen which has a femur with a circumference 30% greater (490mm vs 640mm).