Shop Mobile More Submit  Join Login
The Evolution of Gigantism in Tyrannosaurinae by Sketchy-raptor The Evolution of Gigantism in Tyrannosaurinae by Sketchy-raptor
Despite my online pseudonym Sketchy-raptor, it shouldn’t come as a surprise to anyone that Tyrannosauridae is my favourite dinosaur family. I have no qualms about how cliché this may seem, as I find them absolutely fascinating.

Here’s an illustration showing the gradual evolution of gigantism in the sub-family Tyrannosaurinae over the course of about 12 million years. Note than the species depicted aren’t necessarily directly ancestral/descended from one another, but are instead intended to be representative of the evolutionary trend observed within this clade.

I hope that you find this both interesting and informative!

References are listed at the end of this post.

Lythronax argestes ~80Ma

The stratigraphically oldest and debatably one of the most basal Tyrannosaurines, the 7 metre long Lythronax may seem fairly unimpressive next to its much larger descendants – but all of the basic features of its later kin are present. Most notable of these is the extreme widening of the skull towards the back due to an outward flaring of the jugals (cheekbones) – leading to a larger area in which jaw muscles could attach. This culminated in a much more powerful bite than other predatory dinosaurs (including other Tyrannosaurids) and is a diagnostic feature of the sub-family Tyrannosaurinae.

Daspletosaurus torosus ~77-74Ma

The 9 metre, 2.5 tonne Daspletosaurus actually shared its environment with the similarly large but more gracile Tyrannosaurid genus Gorgosaurus, but despite what may have been the case with their ultimate descendants (see Tyrannosaurus), the two genera do not appear to have been in direct competition. This situation is a testament to what made the two major branches of Tyrannosauridae different – the more gracile Albertosaurines (of which Gorgosaurus is a member) were likely better adapted to hunting more nimble prey such as Hadrosaurs, and the Tyrannosaurines were inversely more suited to tackling larger more powerful animals such as Ceratopsians.

Tarbosaurus bataar ~70Ma

Tarbosaurus is perhaps the first truly gigantic Tyrannosaurine, with a body length of about 10 metres and a mass of 4 tonnes. This Asian genus shares a branch of the subfamily Tyrannosaurinae with the stratigraphically younger Tyrannosaurus, and may be a directly ancestral taxon to the latter.

Tarbosaurus also represents a migration in massive derived Tyrannosaurines from North America to Asia sometime during the late Campanian – Early Maastrichtian, suggesting that sea levels in the latest Cretaceous were lower (or at least less static) than has previously been suggested (this would also explain many similarities in Asian and North American late Cretaceous fauna).

Tyrannosaurus rex ~68-66Ma

Measuring in at 12 metres in length and 7 tonnes in mass, Tyrannosaurus is the largest and most derived member of the subfamily Tyrannosaurinae, as well as being the most famous. While Tyrannosaurus can ultimately trace its evolutionary history back to North America, recent studies suggesting possible direct descendance from the Asian Tarbosaurus imply that Tyrannosaurus was actually an invasive genus. It’s therefore likely that Tyrannosaurus may have contributed to the downfall (and ultimate extinction) of diverse Tyrannosaurids and other predators abundant in North America prior to its arrival.

The stratigraphically oldest Tyrannosaurus rex specimens are extremely large and robust, but it is highly likely that the species slightly decreased in body size throughout the Late Maastrichtian, transitioning into a more gracile animal just prior to the K-Pg boundary. Some have even go so far as to claim that this transition actually represents the genus Tyrannosaurus branching into multiple different species over the course of ~2 million years (as opposed to the singular species T.rex), but a formal study investigating these ideas has yet to be published.

References

Brusatte, SL and Carr, TD (2016) The phylogeny and evolutionary history of tyrannosauroid dinosaurs. Sci. Rep. 6, 20252; doi: 10.1038/srep20252

Loewen MA, Irmis RB, Sertich JJW, Currie PJ, Sampson SD (2013) Tyrant Dinosaur Evolution Tracks the Rise and Fall of Late Cretaceous Oceans. PLoS ONE 8(11): e79420. doi:10.1371/journal.pone.0079420

Paul, GS (2016) The Princeton Field Guide to Dinosaurs 2nd Edition. Princeton University Press

(Image illustrated with reference to my own 3D models, which were created with reference to skeletal and muscular diagrams by Scott Hartman :iconscotthartman: and Gregory S. Paul)

Add a Comment:
 
:iconhublerdon:
HUBLERDON Featured By Owner Feb 13, 2017  Hobbyist General Artist
Cool!
Reply
:iconbackocean:
BackOcean Featured By Owner Jan 22, 2017  Hobbyist Artist
simply beautiful
Reply
:iconkirkseven:
kirkseven Featured By Owner Jan 13, 2017
modern estimates suggest T.rex was more like 8 tonnes
Reply
:iconspinoinwonderland:
SpinoInWonderland Featured By Owner Jan 13, 2017
Except only a few specimens at best, maybe only one known, actually reaches it. The ~7 tonne figure used is pretty much right.

Can people please stop using Sue to represent all members of it's species?
Reply
:iconkirkseven:
kirkseven Featured By Owner Jan 13, 2017
it originally said 6 tonnes when i commented.

i was referring to a Stan based UCMP 118742 silly ;)
Reply
:iconsketchy-raptor:
Sketchy-raptor Featured By Owner Jan 13, 2017  Student General Artist
Agreed - just an error I've forgotten to correct (that will be amended promptly).

I'd wager that a mass of 8 tonnes is probably close to the upper bounds of an "average" adult Tyrannosaurus, with only exceptionally large individuals such as FMNH PR 2081 exceeding it. (The value I originally quoted at best represents the lower bound).  
Reply
:iconkirkseven:
kirkseven Featured By Owner Jan 13, 2017
ah i didn't read that sry
Reply
:iconrobertfabiani:
robertfabiani Featured By Owner Edited Dec 14, 2016  Professional Digital Artist
t-rex ankles are way to high. Tarbos feet are too forward but other then that good work :)
Reply
:iconsketchy-raptor:
Sketchy-raptor Featured By Owner Jan 13, 2017  Student General Artist
Thanks for the feedback!

Yeah, those ankles have been really bugging me recently. I think the erroneously long appearance of them may also be due in part to the fact that I've under-muscled them to quite an extent. 
Reply
:iconrobertfabiani:
robertfabiani Featured By Owner Jan 13, 2017  Professional Digital Artist
np :) that too almost all paleoart is undermuscled
Reply
:iconjahmirwhite:
jahmirwhite Featured By Owner Nov 29, 2016  Hobbyist Artist
t's like Lythronax is one of the smallest Tyrannosaurines ever.
Reply
:iconsketchy-raptor:
Sketchy-raptor Featured By Owner Jan 13, 2017  Student General Artist
Seeing as the known Teratophoneus remains come from an individual that isn't fully grown, I'd wager this to be true, with only Nanuqsaurus currently known to be smaller. 
Reply
:iconjahmirwhite:
jahmirwhite Featured By Owner Jan 13, 2017  Hobbyist Artist
It's so true.
The more larger they increase, the less smaller they become.
Reply
:iconkronosaurus82:
Kronosaurus82 Featured By Owner Edited Nov 24, 2016  Professional Artist
I really like your depiction of these animals. :)
I don't personally think there's that much difference in size between Tyrannosaurus and Tarbosaurus, but "size matters" are actually more "delicate" things than most people think. Thus, that difference doesn't compromise the quality of your job. ;) :)
Reply
:iconsketchy-raptor:
Sketchy-raptor Featured By Owner Nov 24, 2016  Student General Artist
Thank you very much!

It's fair to say that I'm definitely being somewhat conservative with the general size of Tarbosaurus. There are definitely individuals (such as the holotype) that do approach the size of Tyrannosaurus. 
Reply
:iconkronosaurus82:
Kronosaurus82 Featured By Owner Nov 25, 2016  Professional Artist
You're welcome. ;)

Since huge Hadrosauridae of over 12 meters in length could be found both in North America and China/Mongolia/Russia, and since we know that Tyrannosaurus hunted such preys, I think it's fairly reasonable to say that also in China/Mongolia/Russia there were Tyrannosaurinae of the same size of T. rex; if not T. bataar itself, a very close relative of this genus. :)
I always found the differences between Tyrannosaurus and Tarbosaurus a really interesting matter: the two probably had different life habits and hunting techniques because of those differences. :)
And because Tarbosaurus it's actually slightly "older" than its American cousin, it could even represent an earlier evolutive stage of Tyrannosaurus (though this is highly speculative, IMHO).
Reply
:iconsketchy-raptor:
Sketchy-raptor Featured By Owner Nov 25, 2016  Student General Artist
Given Brusatte and Carr's recent study, I think that it's a very compelling idea! They're very likely to be at least sister taxa, so I don't think that it's beyond reasonable thought to consider T.bataar as directly ancestral to T.rex, seperate genera or not. 
Reply
:iconkronosaurus82:
Kronosaurus82 Featured By Owner Nov 26, 2016  Professional Artist
When I was younger I was convinced they were the same genus; then I studied Tarbosaurus anatomy more deeply and I found out that their differences are more substantial than many people think... :)
Reply
:iconspinosaurus14:
Spinosaurus14 Featured By Owner Nov 23, 2016
The woman as portrayed here is actually quite gigantic.
Reply
:iconsketchy-raptor:
Sketchy-raptor Featured By Owner Edited Nov 24, 2016  Student General Artist
To summarise some discussions I've already had on this image:

The woman is actually about 6 foot. Apparent scaling issues here are simply due to perspective/viewpoint - this isn't drawn from a technical plan view, it's drawn from a "real world" perspective of a rendered 3D scene. Therefore it's definitely not a suitable image to take measurements from, nor is it intended to be. 

To get a better idea of how big everything in this image actually is, see this plan view render of the draft 3D scene: orig05.deviantart.net/464e/f/2….

The woman is scaled to the 6 foot red pole.  I can guarantee that no relative sizes were changed in any way before the reference image for this illustration was rendered from the 3D camera. Also, please bear in mind that the 3D scene is just a draft used to setup the approximate sizes and shapes, and not a final interpretation of the exact proportions of the animals.
Reply
:icongrisador:
grisador Featured By Owner Nov 18, 2016
Lythronax is utterly Adorable for a Killer ! Awww :D


Also; ıt could be an awesome pet to ride to a battle :o
Reply
:iconsketchy-raptor:
Sketchy-raptor Featured By Owner Nov 18, 2016  Student General Artist
Indeed so! That deep skull gives Lythronax quite a cute short-faced look. 

Though I'd imagine that an attempt to ride one would result in severe loss of limb ;) 
Reply
:icongrisador:
grisador Featured By Owner Nov 25, 2016
Pug - o - saurus Rex; that sounded more adorable than I thought ! :D


Oh; that would be severe :o
But could be worth it to think that person will be portrayed as The Tyrannosaurus rider/tamer
Reply
:iconcrowford210:
Crowford210 Featured By Owner Nov 22, 2016  Student Artist
Most large predators today kinda give a cute impression, wouldn't be too surprised if the king of the reptiles turns out to be a cutie.
Reply
:icongrisador:
grisador Featured By Owner Nov 25, 2016
I didn't get Cute-Adorableness from a Komodo Dragon (monitor lizard in general) , Saltwater crocodile neither from an Eagle or Vulture.


Only cute predators I could think're Mammalian ones; Like Wolves (yes I think wolves're adorable), Lions, Dingos and such. :D
Reply
:iconcrowford210:
Crowford210 Featured By Owner Nov 26, 2016  Student Artist
I actually find the komodo to adorable in kinda a weird way, but I do agree with you on the crocs and the birds. Maybe it's just an archosaur thing. :)
Reply
:icongrisador:
grisador Featured By Owner Dec 3, 2016
Maybe :B
Reply
:iconzhombah:
Zhombah Featured By Owner Dec 2, 2016  Hobbyist Digital Artist
As far as cute predators go, I think that sharks are the cutest. Except goblin sharks. They're cool, but far from cute.
Reply
:icongrisador:
grisador Featured By Owner Dec 3, 2016
Goblin Sharks are monsters :o
Reply
:iconzhombah:
Zhombah Featured By Owner Dec 3, 2016  Hobbyist Digital Artist
Ugly, pink, projectile-jawed monsters.
Reply
(2 Replies)
:iconsketchy-raptor:
Sketchy-raptor Featured By Owner Edited Nov 25, 2016  Student General Artist
Imma just leave this here ;) 

moonlightwolf39.deviantart.com…
Reply
:icongrisador:
grisador Featured By Owner Dec 3, 2016
Owls are a whole another level; I can't believe how calm she is ! :D  www.youtube.com/watch?v=FBgLyt…
Reply
:iconevodolka:
Evodolka Featured By Owner Nov 17, 2016  Hobbyist Artist
i love this picture so much
tyrannosaurs are my favorite dinosaur species and it makes me happy to see them drawn in such a great way
well done :hug:
Reply
:iconfranoys:
Franoys Featured By Owner Edited Nov 16, 2016
Are you sure about the mass stimates that you provide? Scott Hartman himself stimated the mass of sue at 8400 kgs.

www.skeletaldrawing.com/home/m…

Me and brolyeuphyfusion9500 have done GDI of both CM 9380 and AMNH 5027 using a high fidelity mathematical script, and they seem to cluster around 7 tonnes (CM 9380 was between 7150 kgs (the result broly got) 7600 kg (the result I got)) and AMNH 5027 massed at 6950 kgs aprox, which is the same result another deviant here (blaze) got. Futhermore, Hutchinson et al had CM 9380 mass at 7400 kgs, and bates et al stimated the mass of BHI 3033 at a similar number. Hutchinson et al also had minimal model for Sue at 9500 kgs in mass.

journals.plos.org/plosone/arti…

journals.plos.org/plosone/arti…

journals.plos.org/plosone/arti…
Reply
:iconsketchy-raptor:
Sketchy-raptor Featured By Owner Edited Nov 16, 2016  Student General Artist
The masses quoted here are cited directly from Paul, 2016. However, it must be said that Greg Paul is often very minimal in his mass estimates - they often end up at the absolute lowest end of reasonable ranges.

(Being less conservative, I find Hartman's GDI analysis to be most agreeable, and suspect that the computational analysis of Hutchinson et al. 2011 leads to figures that are a little too large, in part due to overall scaling errors that can result from the way the digitally scanned mounts are actually mounted. Hutchinson et al. do however quote 6000kg as their minimum mass for adult Tyrannosaurus in general, so the mass quoted here is agreeable with their paper if taken as a minimum.)
Reply
:iconfranoys:
Franoys Featured By Owner Edited Nov 16, 2016
Hutchinson et al also provided 7,4 tonnes as the minimum mass sugested for CM 9380, they list 6 tonnes as a minimum for Stan and MOR 555, which are on the small side of the spectrum, however Bates et al had stan at 7,6 tonnes.

GSP figures are not only minimum but also he has not done vollumetric stimates for any T rex specimen that isn't AMNH 5027, and his AMNH 5027 skeletal is just plain wrong, while the scanned mount of it and Scott's restoration of AMNH 5027 is 11.8 m long, his AMNH 5027 is horribly compressed and barely pushes 10.5 meters.

Most stimates of 6 tonnes as an upper bound for Tyrannosaurus are based of allometry equations on femur length.

I think I alredy told you about the stimates that I myself made but since you seem to ignore them...

If you want another GDI that puts Tyrannosaurus above 8 tonnes, here: 

asier-larramendi.deviantart.co…
Reply
:iconsketchy-raptor:
Sketchy-raptor Featured By Owner Edited Nov 16, 2016  Student General Artist
A fair point on Paul's AMNH 5027 reconstruction, it does appear somewhat squashed.

Re-reading my description, I realised that I had initially misphrased it and quoted 6 tonnes as an upper bound - a mistake on my part, this was not the intention.

The mass estimate I've given reflects the lower bounds of the general mass range in adult Tyrannosaurus as quoted by Hutchinson et al. 2011 in their abstract (which does still agree with Paul's most recent minimal figure, despite possible flaws in Paul's methodology) :

"...we conclude that adult T. rex had body masses around 6000–8000 kg, with the largest known specimen (“Sue”) perhaps ∼9500 kg."

journals.plos.org/plosone/arti…

While I do have some issues with the study (as already mentioned), I find it mostly agreeable.

FYI: Your GDI results that cluster around 7 tonnes seem reasonable to me.
Reply
:iconfranoys:
Franoys Featured By Owner Edited Nov 16, 2016
I think you might want to provide a mass range given that 6 tonnes is the lowest stimate for the smaller specimens, because it is really impossible to get less than 8 tonnes for FMNH PR 2081 if you follow the proportions suggested for it by Brochu et al 2003 and do a GDI afterwards. I alredy did a restoration of the skeleton from lateral view and I'm currently working on a dorsal view to allow for a GDI in the future. I used Scott's dorsal view provisionally and got almost 9 tonnes for it.
Reply
:iconsketchy-raptor:
Sketchy-raptor Featured By Owner Nov 16, 2016  Student General Artist
That's a pretty good point you make to be fair, especially given the fact that the description is intended to about the genus in general as opposed to a singular specimen.

Quoting a range does seem to be the better option in hindsight.
Reply
:iconfranoys:
Franoys Featured By Owner Edited Nov 17, 2016
Anyway, I forgot to tell you how much of a wonderful artistic job you did with the models, which is the point of deviantart really (mostly).
Reply
:iconsketchy-raptor:
Sketchy-raptor Featured By Owner Nov 17, 2016  Student General Artist
Thank you very much! :D 
Reply
:iconxstreamchaosofficial:
XStreamChaosOfficial Featured By Owner Nov 13, 2016  Hobbyist Traditional Artist
Awesome!
Reply
:iconfragillimus335:
Fragillimus335 Featured By Owner Nov 13, 2016  Hobbyist General Artist
Ummm, your girl is like 8 feet tall in this scale, unless they aren't meant to be to scale.
Reply
:iconsketchy-raptor:
Sketchy-raptor Featured By Owner Nov 13, 2016  Student General Artist
Just in case there was any doubt in my previous statement, here's the aformentioned 3D draft reference scene in a lateral view with no perspective implemented. The woman in the final illustration is scaled almost exactly to the red pole, which is 6 feet in height: orig05.deviantart.net/464e/f/2… (Also note that in the original 3D model, the Daspletosaurus arms were too large, something corrected in the final drawing)
Reply
:iconnwfonseca:
nwfonseca Featured By Owner Nov 14, 2016  Professional General Artist
The average woman measures about 5'4" in height. That's an above average height woman ;)
Reply
:iconsketchy-raptor:
Sketchy-raptor Featured By Owner Nov 14, 2016  Student General Artist
Taller than average but still realistic ;) 
Reply
:iconnwfonseca:
nwfonseca Featured By Owner Nov 14, 2016  Professional General Artist
In America anyway haha
Reply
:iconsketchy-raptor:
Sketchy-raptor Featured By Owner Nov 13, 2016  Student General Artist
I can assure you that this is not the case.

The scene is based on a draft 3D render - all of the models in which were precisely scaled. The Lythronax is about 2 metres at the highest point of the hip, making the woman ~1.8 metres tall. For reference, the Tyrannosaurus in this scene is 12 metres long. Any apparent issues in scale that may arise are simply due to perspective (The animals are standing in a slight diagonal line relative to camera position).
Reply
Hidden by Owner
Add a Comment:
 
×




Details

Submitted on
November 13, 2016
Image Size
897 KB
Resolution
2483×802
Submitted with
Sta.sh
Link
Thumb
Embed

Stats

Views
6,465 (2 today)
Favourites
306 (who?)
Comments
66
Downloads
81
×