Giganotosaurus versus Tyrannosaurus Rex.....

Date : 23 June, 2015
Version: 0.1
By: Albert van der Sel
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Giganotosaurus versus Tyrannosaurus Rex




Fig 1. Up: skeleton of T Rex ("Sue"). Below: skeleton of Giganotosaurus.
Sources: Wikimedia Commons (public, free media).

1. Why Giganotosaurus versus Tyrannosaurus Rex?

Maybe it's boring stuff, but I like to compare Giganotosaurus and Tyrannosaurus Rex. I will explain "the why".
Ofcourse, TRex was a very powerful Predator, possibly the strongest of all. But.., what about Giganotosaurus?

Everybody knows T Rex. Maybe Giganotosaurus is slightly lesser known.

Choosing Giganotosaurus is a bit "risky", since the data on Giganotosaurus is quite scarce,
and estimations of it's dimensions vary quite a bit.
Still, many think that it is one of the largest (maybe the largest after Spinosaurus) land Predators.

Quite a few folks would believe that the following "ranking" in "raw power", from low to high, would (more or less) hold
for prehistoric land Predators:

Carcharodontosaurus, Sarcosuchus, Deinosuchus, Spinosaurus, Giganotosaurus, and T Rex.

(the "true" sea or marine predators are not included in the list)

Spinosaurus was the largest predator, in terms of length and weight. But, T rex is often seen as
the most likely candidate in terms of pure power...,
Or was it not...? Some say that the first place should go to Giganotosaurus instead.

Note:
About the list: A few would say that Mapusaurus and some other "croc-like" (other than "Deinosuchus") are missing.
Also, Allosaurus (especially Espanterias Amplexus), Acrocanthosaurus, Tarbosaurus (bataar) are missing too, and some folks
would absolutely insist that these were great candidates too. Those folks might be right.
It's true. For example the found specimem AMNH 5767 (Espanterias Amplexus) is estimated to be 12m of length.

Sure, not everybody keeps (or likes) the listing, or same "ordering", ofcourse.

Most of the animals were seperated by millions of years, so most have never met the other one. However, some did!

Yes, but quite some other mysteries remain too, and I would say that nothing is fully certain yet. Let's go into a few
some of those intruiging uncertainties.

But first, here are some arguments why I like the discussion to be focussed on Giganotosaurus and T Rex only.

Note: this text deals on large prehistoric "predators" only, and not herbivorous large dino's (not the vegetation eaters).

1.1 Why I like to put "Spinosaurus" out of the discussion:

Viewed from the perspective of weight and length, Spinosaurus is "King". It might have been up to 17m, with a weight
of well over 9 tons. Some paleontologist would go for a slightly shorther lenght, like 15m.
At the same time, remarkably, some voices speak of 17m and a weight even close to 20 tons. It's a bit confusing indeed,
that those numbers "fluctuate" a bit, but really, most consensus seems to hover at about 15m and 9 tons.

However, from about 2000 up to 2014, paleontologist made it quite plausible that Spinosaurus was largely adapted
for an aquatic live, and it may even have dived for prey. So, the original picture as Spino as a landanimal
that converted to an real aquatic animal (that hardly came to land anymore), means that I like to leave Spino out of the equation.
It mainly roamed in lakes, rivers, and possibly tidal waters, in North Africa.
I have to admit, that Spino still is my all-time favourite amongst all of the land Predators...
The latest "interpretation" is even better compared to the original one.

1.2 Why I like to have "Deinosuchus" and "Sarcosuchus" out of the equation too:

Several prehistoric "super" croc-like predators walked/swimmed the Earth, most notably "Deinosuchus" and "Sarcosuchus".
If somebody would claim that "Deinosuchus" was the most powerful non-(sea)marine Predator ever..., I could not
find much arguments against that claim. However, both are largely aquatic, so I like to leave them
out of the discussion as well.

"Deinosuchus", "Sarcosuchus", and "Spinosaurus", were non-marine animals, meaning not inhabitants of the oceans and large seas.
Ofcourse, all three visited rivers, lakes, and other small waters, and both the croc-like animals, all sorts of swamps too.

1.3 Powerfull large (non-marine) Predators, but is it a good listing anyway?:

From low to high:

Carcharodontosaurus, Sarcosuchus, Deinosuchus, Spinosaurus, Giganotosaurus, and T Rex.

Or possibly the more extended listing:

Espanterias Amplexus, Acrocanthosaurus, Carcharodontosaurus, Tarbosaurus (bataar),
Sarcosuchus, Deinosuchus, Spinosaurus, Giganotosaurus, and T Rex.

Who was strongest?

We already have skipped Deinosuchus, Sarcosuchus, and Spinosaurus from the equation (because they are largely aquatic,
but that's ofcourse not a fully satisfying argument, ofcourse).

Now, Espanterias Amplexus, Carcharodontosaurus, Tarbosaurus (bataar),
were indeed very large, and a lenght of up to 12m and a weight of 4, 5 tons (or so) are serious numbers. But it's fair to say that
they are really a class below Giganotosaurus and Tyrannosaurus Rex.

But do I really have all candidates (from prehistoric land predators) in sight here?

Probably not.

For example "Mapusaurus" was a close relative of "Giganotosaurus", and the data on this animal is not fully complete.
From Mapusaurus, and some other predators, bone fragments were found which possibly (?) suggest a slightly larger size than the
comparable bone pieces from Giganotosaurus. Does that mean that larger predators existed than the heavy
Giganotosaurus and Tyrannosaurus Rex? (Spinosaurus not counted in the discussion)
Most experts would say 'no', since conclusive evidence is absent.

I guess that I only want to say that the jiggsaw puzzle is not completely solved yet !

Anyway, for now, I will compare two really "established" champions, that is, Giganotosaurus and Tyrannosaurus Rex.
Ofcourse, this has been done by others millions of time before. But I like the subject, and that's mainly "the why".
Besides that, I was really amazed by the fact that many folks, did not knew Giganotosaurus at all.

2. The "data" of Giganotosaurus and Tyrannosaurus Rex.

2.1 Findings of Tyrannosaurus Rex.

T Rex lived in a period from 70, to 65 millions years ago, in an area now called "North America".

In total maybe around 20 (or so) skeletons have been found, of varying degrees of completeness.
Ofcourse, it all depends on what you understand to be "varying degrees of completeness".
Other interpretations go into the direction of possibly 50 or so, but no doubt, quite a few of them are
are just collections of fragments.

Already in the late 1800s and during the 1900s, some fragments were found, that together lead to an
a certain overall impression of T rex, but which was not fault free.

The holotype of T Rex was a partial skull and partial skeleton first labeled as AMNH 973, discovered in 1902, in Montana.
The lenght was measured to be 11.9 m, and it's weight was estimated to be 7.3 tons.

A few later highlights are the following (not complete). They lead to a more accurate picture of T Rex.

- In 1987, Stan Sacrison discovered in South Dakota, a rather complete specimen (about 63%) of T rex. The complete excavation
was difficult and the restoration took years to complete. Somewhere in the process it was realized that about 63% was
truly genuine. The specimen (BHI 3033) was nicknamed "Stan", and even was used as "the template" to fabricate replica's
for musea's, or Natural History displays etc..

- In 1988, Kathy Wankel discovered another Tyrannosaurus rex in Montana.
This specimen was excavated by the "Museum of the Rockies" (paleontologist Jack Horner), and constitues about 85 % of the skeleton
including a complete skull. The specimem (MOR 555) was later nicknamed the "Wankel Rex" (or Devil Rex).

- In august 1990, Susan Hendrickson discovered (by accident) a rather complete T rex (about 73%) skeleton, in South Dakota.
The later reconstructed animal, was nicknamed "Sue".
Here too, the restoration took years to complete and again in the process it was determined that about 73% of the specimem
(FMNH PR 2081) was genuine.

A few other similar nice stories happened too. Here is a small listing of the major findings:
  1. 1987: T Rex "Stan", 63% complete.
  2. 1988: "Wankel" T Rex, 80-85 % complete.
  3. 1990: T Rex "Sue", 73% complete (other sources say up to 90%).
  4. 1998: T Rex "Bucky", 34% complete.
  5. 2001: T Rex "Jane", 50% complete.
About Jane, some controvery exists. It's probably a juvenile (small) T rex, however some believe it's acually
a specimen of "Nanotyrannus", a smaller predator which might have been T Rex worst enemy, since Nanotyrannus
is believed to have operated in packs, and presumably targeted on T rex juveniles.
But many paleontologist do not agree, and they say that the socalled Nanotyrannus, is just a juvenile T Rex.
This puzzle is not completely solved.

Something else exciting is going on right now. The USA (Montana) agreed to sell a real T rex specimen for about 5 million euros's,
to the 'Leidse Natural Museum' "Naturalis", located in the city of Leiden, The Netherlands.
Sounds like a lot of money. Well, it is, but don't forget that the manpower and labour needed during the excavation and restoration,
is enormous. Secondly, something which is quite rare, is also quite valuable.
The further preparation and restoration is under the supervision of the "Black Hills Institute" (Montana).
It's estimated that for about 50% of the specimen was recovered up to now. That makes it one of the best specimens ever,
except for Stan, Wankel and Sue.

Hopefully it all works out ! If so, it will be at display at "Naturalis" maybe as early as 2016, or possibly in 2017.
For sure, I will be one the first visitors.
Then, next to the USA, only "The Dutch" will be able to show a real T Rex to the public, which is great indeed !

2.2 Findings of Giganotosaurus.

Generally, it is quite accepted among the scientific community, that Giganotosaurus lived about 100 million years ago.
That's way more back in time compared to T Rex, which roamed around in the period 70 - 65 million years ago.

Paleontologist say that T Rex is actually pretty well documented, compared to many other dino's like Spino.

Indeed, also the number of findings of "Giganotosaurus" are absolutely quite a bit "smaller" than those of T Rex.
The data of Giganotosaurus is very low, as we will see below.

The first (relevant) findings were found in 1993 by Ruben D. Carolini, in Patagonia, Argentina.
It's estimated that a little over 50% of the specimen was ultimately recovered, which makes it likely (to some degree),
to get "some sort" of a reasonable impression of the animal. However, some paleontologist say that "a good impression"
is out out of the question with this sort of low volume of data.
Other sources are more "optimistic" and speak of a 70% recovery. (This sort of variation never stops to surprise me.)

Just before (1988), parts of another skull was recovered, especially a large part of the lower jaw.

So, up to now, only two discoveries were made.

Possibly, in 1998, more fragments of fossils of different sizes were found in the same Patagonian regions of Argentina.
But I could not find further confirmation on this. I wonder if that is true.

A few different algolrithems were applied to those two confirmed findings, especially the part of the lower jaw,
to try to calculate the dimensions of Giganosaurus, which would then also be in compliance with other bone fossiles
like those of the limbs and backbone.
Several results goes around, typically ranging in a length of about 12m to slightly over 14m.

That analysis can be very difficult proves the estimations of the skull dimensions.
Those findings ranges from about 1.53 m to 1.95 m.

All considering, most consensus seems to converge to an animal of about 8 tons in weight, and having a total
length of about 13m.
If true, then Giganotosaurus would be, in general, slightly larger than T Rex.
But the latter statement is doubted by many scientists.

Next, let's compare all known (or extrapolated or even guessed) data of T Rex and Giganotosaurus, like possible hunting habits,
bite force, what we can learn from the jaws, and other properties like those of the skull and orientation.

2.3 Data and hypothesis on T Rex and Giganotosaurus.

2.3.1 T Rex:

=> Theropods (like T Rex) were likely to be "energetic" and "warm blooded" animals.

One important hypothesis on the larger dinosaurs was, that they were "warm blooded". If we say that e.g. T Rex
had quite an active live style (as we really think it had), then an ectothermic (cold blooded) physiology could not sustain that.
Or at least, they had some sort of intermediate physiology, named 'mesothermic'. But they were not cold blooded.
Ofcourse we do not now exactly how the larger theropod dinosaur (like T Rex) spend most of it's day, but many
believe it was quite an active one.

Besides that, the larger theropods, just had too much mass for not to be endothermic (or mesothermic), otherwise
they could not perform enough to sustain themselves.

It's actually pretty save to say that our large predators were fairly quick, muscular, and could perform as good as you
might expect from a large mammal.

Thus, Spinosaurus, Carcharodontosaurus, Giganotosaurus, T Rex, and other theropods, were very likely to be warm-blooded animals,
with a high performance.

This hypothesis however, is not fully accepted yet by all the experts in the field. It seems that quite a few are "contra".

=> General statement on the dimensions of T rex.

Since dozens of T Rex fossiles were found, and rather complete specimens too (e.g. Stan, Sue etc..),
some fairly accurate statements can be made on T Rex's dimensions.

Here is a generalized statement on an average healthy adult T Rex:

An average healthy adult T Rex could reach (at least) a length of 12m and (at least) a weight of 6, 7 tons.

=> Some data about T-Rex:

Period: Late Cretaceous period, at about 70 (or maybe 67) to about 65 million years ago.
Location fossiles: North America.
weight: An healthy adult could be at least 6 tons. Some folks sit higher like 7 tons.
Length: An healthy adult was at least 12 m.
Bite force: Some say 3 to 4 tons. Might even be as high as 5 to 6 tons.
Measured Adult Specimens:
The holotype: AMNH 973 Found in 1902. Length 11.9 m, weight was estimated to be 7.3 tons
T Rex "Stan": BHI 3033 Found in 1987. Length 10.9 m, weight was estimated to be 5.8 tons
The "Wankel" T Rex: MOR 555 Found in 1988. Length 11.6 m, weight was estimated to be 6.3 tons
T Rex "Sue": FMNH PR2081 Found in 1990. Length 12.3 m, weight was estimated to be well over 7 tons

=> Did T Rex hunted in "packs"?

A few scientists (Curie) proposed that T Rex actually might have hunted in groups or "packs".
This was mainly based on the fact that occasionally, multiple skeletons (or fragments of different animals),
were found in close proximity.

Although still no absolutely convincing proof has been found, the fact that in 2014 "T rex trackways"
might have been identified, is a strong point in favor of the "pack" behaviour of T Rex.

If true, then the most powerful animal on the land has finally been identified: T rex.

2.3.2 Giganotosaurus:

=> Some data on Giganotosaurus:

Period: Late Cretaceous period, at about 100 (or maybe 99) to about 97 million years ago.
Location fossiles: South America, Patagonia, Argentina.
weight: An healthy adult is often estimated to reach 8 tons.
Length: An healthy adult is often estimated to have a length up to 13 m.
Bite force: Possibly a few tons. Very likely to be significantly lower than T Rex (see below)
Found Specimens (might not be complete):
The holotype: MUCPv-Ch1 Found in 1993. Length ?, weight ? But estimated to be slightly larger than T Rex.
Lower jaw finding: MUCPv-95 Found in 1988. Based on MUCPv-Ch1 & MUCPv-95 together: length 12m - 13m, weight approximately 8 tons.

Although Giganotosaurus was a very large Predator, probably slightly larger than T Rex, it had some "serious" shortcomings
compared to T Rex.
It lacked 28 millions of years of "additional evolution", compared to T Rex.
The brain was only half as big as T-rex (or even only 1/3), even though the mass of the dinosaur was (somewhat) larger.
The teeth were slightly shorter and certainly narrower, and it's skull was more "slender".

However, the forearms (or claws) of Giganotosaurus were longer, and contained six large "fingers", whereas the arms/claws
of T-rex were practically useless in a hypothetical "fight" between the two animals.

If you take a look at figure 1 again, I choose two 'similar' pictures, but which shows some distinct features of those
two animals. Note how both bodies are almost horizontal, balanced by the large tails.
However, note how the skull of T Rex slightly points downwards. For Giganotosaurus, it is strongly suspected that
his head was slightly oriented upwards, due to the overall physiology of the animal.

=> Comparison of the skulls of Giganotosaurus and T Rex:

Both skulls are gigantic ofcourse. However, there are some differences.

T Rex teeth and jaws, seemed to be "optimized" for a horrible bite at it's victim, deeply crushing bones and tissues.
I would not be surprised when (an individual) T Rex blasted this horrible blow, and then waited a few moments for it's
victim to pass away.

(I tell you, this whole text is especially fitted for 8,9 year old boys.)

Giganotosaurus it's jaws and teeth, althoug impressive, seemed to be more optimized for slice and dice.
I would not be surprised when (an individual) Giganotosaurus used several blows on a medium sized victim.

Giganotosaurus it's skull, is estimated to have length from about 1.53 m to 1.95 m.
The largest known Tyrannosaurus T Rex skull measures up to 1.5 m in length.
So, Giganotosaurus "wins" here.

However, since more data exists on T Rex, the bonestructure, and physiology of all skull tissues and muscles
is largely known, and in combination with the large supporting muscles in the back, can only result in
possibly the most powerful biteforce that can be attributed to a land animal.

Fig 2. Comparison of the skulls of T Rex and Giganotosaurus.



We already discussed how the skull of T Rex slightly points downwards. Contrary, for Giganotosaurus, it is strongly suspected that
his head was slightly oriented upwards, due to the overall physiology of the animal.
I think that this fact will not help Giganotosaurus in a "hypothetical fight" with T Rex (yes..., text for 8,9 years old, like me).
I am not saying that Giganotosaurus stared into space all the time, but striking slightly downwards (in a natural way) enables you
to put almost all your weight into the blow, like T Rex could do.

3. Conclusion (if at all possible).

No, it's not possible, really.

We have seen some facts on both animals. The question was: who was strongest?
It's a silly question, but still an interesting one, I think....(I hope, actually).

I don't know the answer, ofcourse. Giga would have a certain chance measuring up to T Rex, especially if it indeed was 14m and 8 tons.
Who knows? Ofcourse the animals were seperated by at least 28 millions of years, but maybe, in a "hypothetical encounter"
both would be scared so much of each other, that both took off in opposite directions as fast as they could ;-)

But all in all, I think (but not fully convinced) that I would put my bets on T Rex.


Some other remarks....

Remark 1: Were females bigger that male TRexes?

This was indeed suggested by two 'morphs' found. One was called the 'robust' morph, while the other one was termed the 'gracile.'
The 'robust' morph can be identified as the female TRex.

However, still various doubts exist whether this was indeed true, or that geographical or different time spans
were actually responsible for the different morphs.

Remark 2: Trix finally in "Naturalis" (Leiden, The Netherlands)

Remark october 2016:

Excavated in 2013 in Montana (US), the T.Rex called "Trix", finally started her display early September 2016,
at "Naturalis" (Leiden, The Netherlands).

Yes..., Trix is a "real" one, and not just some replica.

Trix is likely to be a female (robust morph) and probably lived for over 30 years, which is often regarded as
a rather long lifetime. Experts say that about 75% to 80% of the skeleton was recoverd, which is a lot
compared to many other specimens.
"Trix" is estimated to have had a length of 12m to 12.5m, and she is a tiny bit smaller than Sue.
In the restoration proces, some slightly rescaled parts of Sue served as an example for rebuilding "Trix".

By the way, Trix refers to "Beatrix", who was the former Queen of The Netherlands.

Recently, I have visited "Trix", and it was absolutely fantastic. But that was to be expected from a TRex fan.



TRex "Trix" at display in museum "Naturalis" (Leiden, The Netherlands).