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Allosaurus fragilis v Carnotaurus sastrei
Topic Started: Jun 17 2013, 09:04 PM (12,180 Views)
Taipan
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Allosaurus fragilis
Allosaurus (play /ˌælɵˈsɔrəs/) is a genus of large theropod dinosaur that lived 155 to 150 million years ago during the late Jurassic period (Kimmeridgian to early Tithonian). Allosaurus was a large bipedal predator. Its skull was large and equipped with dozens of large, sharp teeth. It averaged 8.5 meters (28 ft) in length, though fragmentary remains suggest it could have reached over 12 meters (39 ft). Relative to the large and powerful hindlimbs, its three-fingered forelimbs were small, and the body was balanced by a long, heavy tail. As the most abundant large predator in the Morrison Formation, Allosaurus was at the top of the food chain, probably preying on contemporaneous large herbivorous dinosaurs and perhaps even other predators (e.g. Ceratosaurus). Potential prey included ornithopods, stegosaurids, and sauropods. Allosaurus was a typical large theropod, having a massive skull on a short neck, a long tail and reduced forelimbs. Allosaurus fragilis, the best-known species, had an average length of 8.5 meters (28 ft), with the largest definitive Allosaurus specimen (AMNH 680) estimated at 9.7 meters long (32 ft), and an estimated weight of 2.3 metric tons (2.5 short tons). In his 1976 monograph on Allosaurus, James Madsen mentioned a range of bone sizes which he interpreted to show a maximum length of 12 to 13 meters (40 to 43 ft). As with dinosaurs in general, weight estimates are debatable, and since 1980 have ranged between 1500 kilograms (3300 lb), 1000 to 4000 kilograms (2200 to 8800 lb), and 1010 kilograms (2230 lb) for modal adult weight (not maximum). John Foster, a specialist on the Morrison Formation, suggests that 1000 kg (2200 lb) is reasonable for large adults of A. fragilis, but that 700 kg (1500 lb) is a closer estimate for individuals represented by the average-sized thigh bones he has measured. Using the subadult specimen nicknamed "Big Al", researchers using computer modelling arrived at a best estimate of 1,500 kilograms (3,300 lb) for the individual, but by varying parameters they found a range from approximately 1,400 kilograms (3,100 lb) to approximately 2,000 kilograms (4,400 lb).

Posted Image

Carnotaurus sastrei
Carnotaurus was a large predatory dinosaur. Only one species, Carnotaurus sastrei has been described so far. Carnotaurus lived in Patagonia, Argentina (La Colonia Formation) during the Campanian or Maastrichtian stage of the Late Cretaceous. Carnotaurus was a large theropod, about 8 metres (26 ft) in length, weighing between 1488 kg and 2626 kg (1.6–2.9 short tons), depending on the method of estimation. The most distinctive features of Carnotaurus are the two thick horns above the eyes, and the extremely reduced forelimbs with four basic digits, though only the middle two of these ended in finger bones, while the fourth was splint-like and may have represented an external 'spur.' The fingers themselves were fused and immobile, and lacked claws. It is also characterized by its unusually long neck (compared to other abelisaurs), and its small head with box-shaped jaws. The eyes of Carnotaurus faced forward, which is unusual in a dinosaur, and may indicate binocular vision and depth perception. There is a rather puzzling contrast between Carnotaurus’ deep, robust-looking skull and its shallow, slender lower jaw. So far no one has worked out what this might imply about its methods of feeding.

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DarkGricer
Jun 16 2013, 10:32 PM
Carnotaurus VS Ceratosaurus dentisulcatus


Ceratosaurus is probably too small, so lets try this first.
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blaze
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XD no problem

Because Epanterias has material that not only can be compared with A. fragilis but is also material that is not diagnostic for anything else other than Allosauridae (thus A. fragilis), Epanterias material also doesn't overlap with Saurophaganax other than a cervical centrum, he notes that they are similar (which will probably apply to Allosaurus too) the preserved dorsals of Epanterias are anterior ones while those of Saurophanax are posterior dorsals, Chure assumes that the diagnostic feature of S. maximus, the horizontal lamina at the base of the neural spines should still be there in a position similar to that of the Epanterias dorsal and thus they are not the same, for now, we'll require more complete fossils of either one to test his hypothesis.

Which one is latter Kimmeridgian? According to Osborn & Mook 1921 Epanterias fossils come from the uppermost beds of the Morrison Formation at Garden Park, according to The Paleobiology database, is Tithonian in age.
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theropod
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I meant Saurophaganax which according to the Palaeobiology database is late Kimmerdigian (OMNH quarry)
http://paleodb.org/cgi-bin/bridge.pl?a=basicCollectionSearch&collection_no=49338

Off-topic: There btw is a really large carnosaur tooth from the Tithonian-Berriasian of Spain, most if not all is crown and over 98cm long. http://estudiosgeol.revistas.csic.es/index.php/estudiosgeol/article/download/632/655
Sadly, again an enigmatic giant only described in spanish. I'll really have to take the DVD-course I have lying around somewhere...
Edited by theropod, Jun 22 2013, 03:43 AM.
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blaze
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I've seen that but in the taxonomic section of Allosaurus it says that the OMNH Quarry 1 is Kimmeridgian/Tithonian and going by how far (or close) is to the top of the formation (just 12m) I think is more likely to be Tithonian.

mmm I wonder what it is, could it be a Carcharodontosaurid? the tooth falls in the range of teeth of Acrocanthosaurus (NCSM 14345) and Carcharodontosaurus (SGM DIN-1).
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theropod
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If so, that would be a pretty large, pretty early form, perhaps even Jurassic. Another possibility, it might belong to a similar animal to the Kimmeridgian Morrocan trackmakers.
here's a comparison: Posted Image
The shape resembles both C. saharicus and A. fragilis, but based on temporal range it is closer to Allosaurus, and based on size closer to Carcharodontosaurus (both are considered the only criteria for the assignment of isolated allosauroid or at least carcharodontosaur teeth).
It is definitely large however. It would be crucial to determine what age it really is, but it always jsut says tithonian-Berriasian. Probably right at the boundary...

http://paleodb.org/cgi-bin/bridge.pl?a=checkTaxonInfo&taxon_no=38590&is_real_user=1
Looking at this, it seems there are other Allosaurus specimens (labeled A. sp) from the Tithonian
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blaze
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Veterupristisaurus milneri is a carcharodontosaurid from Tendaguru, dating from either the latest Kimmeridgian or earliest Tithonian, is large, estimated between 8.5-10m based on comparisons with Acrocanthosaurus specimen Fran, maybe it's not an allosaurid what roamed Africa in the late Jurassic.

The size of the teeth in theropods, can it really be more precise than large, small, medium? in Fran, the largest teeth is maxillary 5 at 107mm in apical length (that of CTP-1980 is 98mm) which is larger than the maxillary 5 of SMG DIN-1 at just 81mm, maxillary 6 is also larger in Fran by 10mm, of the teeth that can be compared, only the maxillary 8 is bigger in Carcharodontosaurus, by 3mm but we both know that Carcharodontosarus had a much bigger skull and a larger body.

The paper says that the Villar del Arzobispo Formation has sediments dating from the middle Tithonian to the Berriasian and the teeth was found at the middle, there's no "early Berriasian" or "middle Berriasian" mentioned so I guess it means all of the Berriasian age, mmm if the Berriasian is 5 million years in duration, middle Tithonian up to the start of the Berriasian will be 3 million years, assuming the deposition was uniform in that time span (unlikely, I think) then the middle of the formation would be in the early Berriasian.

On the subject of Tithonian Allosaurus, the top of the Morrison Formation is early Tithonian, 148 million years old (Kowallis et al. 1998), though, if those dates are still valid, with the new boundaries (ICS 2013) the Tithonian starts at 152ma, making all of the Brushy Basin Member of the Morrison Formation Tithonian in age, encompassing a little bit more than the first half of the age.
Edited by blaze, Jun 22 2013, 08:49 AM.
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theropod
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^No, I guess it doesn't get more precise than small-medium-large with isolated teeth.

I know about Veterupristisaurus. The phylogeny of the Tendaguru theropods is sadly very confusing, but it seems Abelisaurs and Carcharodontosaurs possibly evolved at that location. Apart from that, the fauna is very similar to Lourinha (I'll spend my holidays in Portugal, hopefully I'll have to opportunity to visit some dinosaur localities) or Morrison. "A." tendaguriensis is hardly, if at all diagnosable,l but it looks more Allosaurid than carcharodontosaurian to me (see this: http://www.gutenberg.org/files/19302/19302-h/images/fig010th.jpg , however basal carcharodontosaurs may have looked just like allosaurids...). It is also pretty large.

The teeth of Acrocanthosaurus seem more elongate than C. saharicus or A. fragilis: http://palaeos.com/vertebrates/theropoda/images/AcrocanthosaurusSkull.jpg
http://palaeos.com/vertebrates/theropoda/images/Eddy&Clarke2011-fig2.jpg
At one point the crown is about as long as the dentary is deep.
Edited by theropod, Jun 22 2013, 07:04 PM.
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Makaveli7
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Carnotaurus is alleged to run 70 km/h with its long legs and short tail as speed adaptions.
A headbutt at that speed is its best offense, but even then it's not fatal.
Allosaurus has power, a far deadlier bite with a slicing and chopping ability, durability (judging by how many healed broken bones many Allosaurus specimens have), powerful arms with strong claws that also allow it to get up after being knocked down, and some formidable speed and agility of its own. I have no doubt that Allosaurus wins this.
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Carcharadon
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When did carnotaurus even headbutt using its horns as weapons?
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Ausar
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I sort of doubt it could use its head and horns as a weapon in interspecific conflict. I don't think its skull could withstand such stress if it did.
Edited by Ausar, Aug 27 2013, 08:59 PM.
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Makaveli7
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Just an idea for offense. Not many of its other weapons were deadly.
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BobaF3tt
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https://www.researchgate.net/publication/259010793_Bite_me_Biomechanical_models_of_theropod_mandibles_and_implications_for_feeding_behavior
So, Carnotaurus did have a stronger bite than Allosaurus?
(sorry for revival of thread)
Edited by BobaF3tt, May 9 2016, 12:27 PM.
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Ausar
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Could someone help me out with a few things about the study posted above?

It says that Saurornitholestes' bite force relative to that of the Komodo dragon is 0.118 and relative to that of the American alligator it is 16.96. I've taken 'bite force relative to V. komodoensis or A. mississippiensis' as how many times harder it bites than either of these animals. But if that is the case, then how can Saurornitholestes bite significantly lower than an ora and yet several times harder than an alligator could? Is this a typo or something?

Second, take the figure in the row 'T. rex maximum bite force'. Its bite force relative to A. mississippiensis is 12.432 and the bite force is 235,123N, yet if you actually do the math, it's 235,113, not quite what the study says. Again, is this a typo?

Finally, is this study really a reliable reference for theropod bite forces? You know, considering the fishy stuff I mentioned above, as well as the freaking whopping bite force figure obtained for T. rex.
At any rate, I think Allosaurus wins at similar sizes. Even if it did have an inferior bite force to Carnotaurus, both predators were armed with blade-like slicing teeth, so I'm not sure exactly how much this will matter. Allosaurus may have proportionally larger teeth with a bigger head and longer toothrow. There's also the fact that its forelimbs are of far greater use than those of the abelisaurid, as well as the fact that it was likely more maneuverable (the same oversized m. caudofemoralis and stiffened tail allowing for great speed in Carnotaurus also hampered its turning ability).
Edited by Ausar, Jan 7 2017, 11:05 PM.
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Drift
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Allosaurus has the superior size and weaponry,What is the Carnotaurus really going to do?
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Megasaurus
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SpinoInWonderland
Jun 19 2013, 04:06 PM
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Allosaurus has dinner
Allosaurus bigger head,gape arms with claws,size,axe bite ,sharp teeth.
Carnotaurus-stronger neck
8,5m Allosaurus vs 8m Carnotaurus 70/30 for Allosaurus
9.7 Allosaurus vs Carnotaurus MISMATCH
Edited by Megasaurus, Dec 2 2016, 02:53 AM.
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LionClaws
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Ausar
May 10 2016, 09:14 AM
Could someone help me out with a few things about the study posted above?

It says that Saurornitholestes' bite force relative to that of the Komodo dragon is 0.118 and relative to that of the American alligator it is 16.96. I've taken 'bite force relative to V. komodoensis or A. mississippiensis' as how many times harder it bites than either of these animals. But if that is the case, then how can Saurornitholestes bite significantly lower than an ora could yet several times harder than an alligator could? Is this a typo or something?

Second, take the figure in the row 'T. rex maximum bite force'. Its bite force relative to A. mississippiensis is 12.432 and the bite force is 235,123N, yet if you actually do the math, it's 235,113, not quite what the study says. Again, is this a typo?

Finally, is this study really a reliable reference for theropod bite forces? You know, considering the fishy stuff I mentioned above, as well as the freaking whopping bite force figure obtained for T. rex.
Yeah, there are a couple of typos in that chart. I don't have the study in front of me, but you can get the figures you need straight from the Zx values. 10^(Saurornitholestes Zx)/10^(KD Zx) will give you what you're looking for.

At any rate, the 235 kN figure for rexy's bite is far from unprecedented, IIRC. And, by extension, we can get a pretty confident estimate of the Giganotosaurus holotype's bite force at ~80 kN.

That being said bite force =/= better bite. T-rex had a bite force ~3x greater than Giga's, but the latter had a bigger head and slicing dentition, making for a more damaging bite.
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