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Ekrixinatosaurus novasi v Tarbosaurus bataar
Topic Started: Oct 20 2013, 07:20 PM (5,879 Views)
Taipan
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Ekrixinatosaurus novasi
Ekrixinatosaurus (Explosion-Born Reptile) is a genus of dinosaur which lived during the Late Cretaceous. It was a theropod believed to be one of the abelisaurs. Its fossils have been found in Argentina. The type species, Ekrixinatosaurus novasi, was first described in 2004 by Argentinian paleontologist Jorge Calvo, and Chilean paleontologists David Rubilar-Rogers and Karen Moreno. Ekrixinatosaurus is perhaps the largest abelisaurid known to date, estimated as 10 to 11 metres (33 to 36 ft) long. It was also particularly robust and had a relatively large head, suggesting that it was a powerful predator or scavenger, able to scare other predators away from their kills.

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Tarbosaurus bataar
Tarbosaurus belongs in the subfamily Tyrannosaurinae within the family Tyrannosauridae, along with the earlier Daspletosaurus, the more recent Tyrannosaurus and possibly Alioramus. Animals in this subfamily are more closely related to Tyrannosaurus than to Albertosaurus and are known for their robust build with proportionally larger skulls and longer femurs than in the other subfamily, the Albertosaurinae. Although many specimens of this genus have been found, little definite data was confirmed on the dinosaur as of 1986, though it was presumed to share many characteristics with other tyrannosaurids. The close similarities have prompted some scientists to suggest a possible link between the North American and Eurasian continents at that time, perhaps in the form of a land bridge. As with most dinosaurs, Tarbosaurus size estimates have varied through recent years. It could have been 10 meters long, with a weight of 4 to 5 - 7 tons.

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Daspletosaurus
Oct 20 2013, 08:55 AM
Tarbosaurus vs. Ekrixinatosaurus
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theropod
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Yes, Tarbosaurus definitely has a longer skull, it's 1.1m (average, maximum is ~1.26) vs 0.85 (and shouldn't it be 76cm when based on Skorpiovenator? My memory isn't the best and I'm too lazy to search through posts right now, but I might do a reconstruction and see myself soon.)

But as I noted, a short skull is not always a disadvantage, it is a combination of features that gives a bite its potency.
eg. -Tyrannosaurines typically have a massive, mid-lenght skull and bite force and large teeth especially for puncturing deep and crushing, in combination with a neck musculature allowing for strong lateral and dorsal movements to cause devastating internal damage
-Carcharodontosaurids have a long jaw with rows of sawlike, very sharp teeth and likely used pulling motions to give immense cutting power and chunk-size/wound lenght to the bite
-Allosaurids have strong but narrow, relatively short skulls and dentitions on longish necks, specialized for depressing the skull to drive the dentition deep into the bitten part and rip through tissue by pulling it backwards
-and, as I presume, at least some Abelisaurs used powerful bite forces and torsionally resistant, very short skulls and teeth and shaking as well as possibly pulling while hanging onto a prey item.

All these are very different in their features and often complete opposites, but all (and also combinations or intermediate states) could potentially serve the purpose of causing great amounts of damage to a large prey item (where large as in "a notable precentage of the predators size" whether it's as big as the predator or 5 times that size is not that important here), and can achieve comparable amounts of optimization, all with their respective strenghts and weaknesses.

I hope this wasn't an overdose of my usual "jaw philosophing" and sorry if I bored you ;D

btw where I think Tarbosaurus is in there? Somewhere between the typical tyrannosaurines and the carnosaurs, probably together with many other tyrannosauroids and some other macrophagous coelurosaurs.
Edited by theropod, Oct 27 2013, 08:15 AM.
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Vobby
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About the kinetics of abelisaurids skulls, my source is this:

http://translate.google.com/translate?u=http%3A//theropoda.blogspot.it/2009/04/ad-ognuno-il-suo-morso-i-giunti.html&hl=en&langpair=it|en&tbb=1&ie=UTF-8

It is quite technical, I hope google traslate wont make it too impossible to understand. It clearly says that abelisaurids, at least generally, had the most kinetic jaws. Anyway, I don't want to say that a more rigid skull, with a strong bite, is necessarily the best to fight. Bites are not just stronger or weaker, they are different among species, and so require different strategies.
As I said, here I back Ekrixinatosaurus, basing on the description in Juarez's article.
Edited by Vobby, Oct 27 2013, 08:43 AM.
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Daspletosaurus
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theropod
Oct 27 2013, 07:53 AM
Adductor musculature is the musculature that adducts (= ~it rises or pulls it towards the upper jaw) the lower jaw, ie. adductor force is the force excerted by a simple static bite were the mandible is pulled upwards, with nothing else applied. This is the kind of force usually given in bite force figures. There is a notable difference between this and the force actually excerted on the victim in total, because many predators enhance the power of their bites significantly by cervical or other postcranial motions of pulling, shaking, striking/stabbing etc. (take for example sharks or varanids).
I found the term "adductor force" quite suitable and precise because it makes clear what exactly is being referred to.

It's true some monitor lizards with rather kinetic jaws (as far as I know at least) shake their prey (stuff like rats and such) to kill it. However this only seems to work well on comparatively small prey, not on large prey like what some dog breeds do or Tyrannosaurines may have done. By comparison, for an animal with such traits to attack large prey a pulling bite, like in oras, is a much better attack style.

It's possible Abelisaurs mostly (that is, more than other theropods) fed on small animals, but it doesn't convince me. The skulls seem very resistant and rather akinetic, they don't have the traits of kinetic jaws such as a light, fenestrate built with many gaps, open spaces, thin bones and loose connections. Quite the contrary, the bones are thick and compact, with small fenestrae-not a structure that seems to be built to yield under stress.

Of course this is just an observation based on the primary sources, not the specimens themselves which I of course haven't examined. But in the absence of much conrete data on that, I don't think Abelisaurs in general were small-prey specialists (not saying some of them couldn't have been tough).

Their jaw structure can be explained as that of a specialised macropredator.
Robust, resistant skulls and short teeth to hold onto prey and rip off meat, likely in combination with inertial feeding (perhaps even somewhat crocodile-like?) and maybe gregarious behaviour. As a positive side effect, the relatively small skull may have allowed very quick strikes, which is not just advantageous against small game.

There is not necessarily a perfect extant analogy for every extinct predator and its ecology, its often a jigsaw of various traits. Abelisaurids have a very interesting combination of features (and are obviously difficult to interpret, even just explain).
Thank you I'm glade to know that there are people on this site that are willing to help (and as far as I've seen that's pretty much everyone :) ) others understand things when questions like mine are posed.
Quote:
 
But as I noted, a short skull is not always a disadvantage, it is a combination of features that gives a bite its potency.
eg. -Tyrannosaurines typically have a massive, mid-lenght skull and bite force and large teeth especially for puncturing deep and crushing, in combination with a neck musculature allowing for strong lateral and dorsal movements to cause devastating internal damage
-Carcharodontosaurids have a long jaw with rows of sawlike, very sharp teeth and likely used pulling motions to give immense cutting power and chunk-size/wound lenght to the bite
-Allosaurids have strong but narrow, relatively short skulls and dentitions on longish necks, specialized for depressing the skull to drive the dentition deep into the bitten part and rip through tissue by pulling it backwards
-and, as I presume, at least some Abelisaurs used powerful bite forces and torsionally resistant, very short skulls and teeth and shaking as well as possibly pulling while hanging onto a prey item.
I think what you said in the above quote here makes sence, and I'm inclined to agree with you and others that comparing every newly discovered genus to T.Rex is shear stupidity.
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I hope this wasn't an overdose of my usual "jaw philosophing" and sorry if I bored you ;D
Nope was not at all boring, I appreciate you explaining it, again thank you. :)
Edited by Daspletosaurus, Oct 27 2013, 11:54 AM.
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theropod
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Thanks vobby! That one is actually quite easy to understand, despite the google translator.

One note; he is merely talking about the mandibles, not the crania, and as far as I know the intramandibular joint was movable in the vast majority of theropods. The analogy to snakes is also quite a stretch imo (considering the different morphology in the upper jaws of both), but I can understand what he is talking about.
The morphology of the upper jaw is vastly different tough.

Either way most of it makes sense and fits what I would presume, the hypothesis of shaking and holding onto prey, the only variable is the question of bite force.
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Taipan
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Hatzegopteryx
Jun 28 2014, 04:16 AM
Users do not make match-ups, they are requested in the requests thread.


Yes. Topic closed. Try this!

Hatzegopteryx
Jun 28 2014, 04:16 AM
Users do not make match-ups, they are requested in the requests thread. Anyway, answering your question, the tyrannosaurid wins; it's just too large. Ekrixinatosaurus novasi was actually not as big as many think, the large size estimates come from a mistake which was scaling it from not so related taxa.


Ausar
Jun 28 2014, 04:38 AM
Hopefully when the new giant Kenya abelisaurid becomes better known, it'll be a good abelisaurid match for T.rex (assuming it really was that large).


UnknownDino
Jun 28 2014, 04:45 AM
Hatzegopteryx
Jun 28 2014, 04:16 AM
Users do not make match-ups, they are requested in the requests thread. Anyway, answering your question, the tyrannosaurid wins; it's just too large. Ekrixinatosaurus novasi was actually not as big as many think, the large size estimates come from a mistake which was scaling it from not so related taxa.
Technically it isn't exactly an official match-up. It is not a poll. It is more like a simple debate. Also, I think that Ekrixinatosaurus would win because it was probably more agile, just like its little cousin, Carnotaurus.


Palaeogirl
Jun 28 2014, 12:15 PM
UnknownDino
Jun 28 2014, 04:45 AM
Hatzegopteryx
Jun 28 2014, 04:16 AM
Users do not make match-ups, they are requested in the requests thread. Anyway, answering your question, the tyrannosaurid wins; it's just too large. Ekrixinatosaurus novasi was actually not as big as many think, the large size estimates come from a mistake which was scaling it from not so related taxa.
Technically it isn't exactly an official match-up. It is not a poll. It is more like a simple debate. Also, I think that Ekrixinatosaurus would win because it was probably more agile, just like its little cousin, Carnotaurus.
Ekrixinatosaurus wasn't anywhere near large enough to be a match for T.rex. I wouldn't bet on it being all that agile either, it seems too heavily built for that. How much of its skeleton do we have anyway? I've heard it was proportioned more like Majungasaurus rather than Carnotaurus but I've never seen the bones myself.
Edited by Taipan, Jun 28 2014, 02:27 PM.
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blaze
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As I was writing this the other topic got closed haha

@palaeogirl

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It's fairly complete, actually, but actual photos of the postcranium are pretty much non existent on the web, there's only the drawings of the femur, a neck and tail vertebrae, each in a single view, in Calvo et al. (2004) and photos of a neck vertebrae in Novas et al. (2013), this time in two views and that's all. The skeletal in Calvo et al. (2004) (which I modified a bit above) is all we have.

The pelvis appears similar to that of Aucasaurus and Carnotaurus, albeit more similar to that of the former, the tail vertebrae has those crazy transverse processes like Carnotaurus/Aucasaurus/Skorpiovenator so it had strong leg retractor muscles, the cnemial crest of the tibia, however, doesn't look as developed as that of Carnotaurus/Aucasaurus/Majungasaurus, being closer to what is seen in Skorpiovenator, so it had weaker calve muscles, the neck vertebrae appears more compact (in length) than those of the aforementioned abelisaurids. The size of the legs compared to the body looks similar to that of Carnotaurus/Aucasaurus/Skorpiovenator, and the length of the tibia compared to the femur is also about the same, this is corroborated in Juarez-Valieri et al. (2010).

About the head, the known bones are very similar to those of Skorpiovenator but its size in proportion to the body is greater than in all the previously mentioned abelisaurids but if Greg Paul is right, Ekrixinatosaurus wasn't alone in that, Indosuchus also had a big head for an abelisaurid.
Edited by blaze, Jun 28 2014, 02:35 PM.
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Thalassophoneus
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I've heard that both are believed to have had a maximum length of 12 meters. If this is true then it would be a draw but if Tarbosaurus was 10 meters at maximum and Ekrixinatosaurus 11 meters at maximum, then maybe Ekrixinatosaurus would win this battle.
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Jinfengopteryx
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11 m for Ekrixinatosaurus is rather unlikely, you have a post about that above of yours.
However, 10 m for Tarbosaurus is pretty likely and shall give it the upper hand.
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theropod
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Tarbosaurus would have been between 2 and 4 times the body mass of Ekrixinatosaurus. I don”t think that aside from the obvious effects of size Ekrixinatosaurus was more agile, but I could be wrong. However that wouldn’t really help it anyway when faced with a much larger opponent

We are talking about a tyrannosaur averaging between 9 and 10m, with a skull over a metre long, and an abelisaur between 7 and 8m, with a skull between 70 and 80cm. Needless to say the largest tarbosaurus at closer to 11m would thrash any known Ekrixinatosaurus, but I’m not even taking it into consideration. The forelimbs of both are neglegible, agility never outweighs size, especially if it is a result of size. The most important factors are size, strenght, durability and weaponery (even if the latter three are all resulting from size), all on the Tarbosaurus’ side.
Edited by theropod, Jun 28 2014, 07:08 PM.
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Daspletosaurus
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Going back over this match up one thing I think we have to remember is that with Tarbosaurus we have dozens of specimens and a vastly superior data base of knowledge, where as with Ekrixinatosaurus we have one specimen and to my knowledge very little in the way of data. So on the first hand I agree with Theropod that all the advantages that matter are on Tarbosaurusus side in the matchup. But on the other hand until we find more specimens of Ekrixinatosaurus we can assume very little or a whole lot about its potensial size and weight. My point being that yes as things sit now Tarbosaurus wins hands down but in the future the scales could tip in Ekrixinatosaurus favor as new specimens are recovered and new data becomes available.
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Megasaurus
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11 m Ekrixinatosaurus vs tarbosaurus 50/50
8-9 m Exkrixinatosaurus vs Tarbosaurus-Tarbosaurus wins very easy
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Carnotaur
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According to Grillo and Delcourt(2016),Ekrixinatosaurus' specimen was "only" around 7.4 meters in length,so this is a size mismatch.
Edited by Carnotaur, Dec 4 2016, 09:50 AM.
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Thalassophoneus
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Megasaurus
Dec 4 2016, 05:42 AM
11 m Ekrixinatosaurus vs tarbosaurus 50/50
8-9 m Exkrixinatosaurus vs Tarbosaurus-Tarbosaurus wins very easy
11 m. Ekrixinatosaurus probably never existed.
By the way, guys, if you want you can just delete the Tyrannosaurus VS Ekrixinatosaurus thread. http://carnivoraforum.com/topic/10116002/1/#new And you can remake it if you want, but it will be a mismatch.
Edited by Thalassophoneus, Dec 4 2016, 09:58 AM.
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Soopairik
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Tarbo wins unless they're the same size, in that case I'm not sure.
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