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Allosaurus fragilis (Pack of 5) v Spinosaurus aegyptiacus
Topic Started: Oct 25 2012, 09:11 PM (19,014 Views)
DinosaurMichael
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Allosaurus fragilis (Pack of 5)
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).

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Spinosaurus aegyptiacus
Spinosaurus is a genus of theropod dinosaur which lived in what is now North Africa, from the lower Albian to lower Cenomanian stages of the Cretaceous period, about 112 to 97 million years ago. Spinosaurus may be the largest of all known carnivorous dinosaurs, even larger than Tyrannosaurus and Giganotosaurus. Estimates published in 2005 and 2007 suggest that it was 12.6 to 18 metres (41 to 59 ft) in length and 7 to 20.9 tonnes (7.7 to 23.0 short tons) in weight. The skull of Spinosaurus was long and narrow like that of a modern crocodilian. Spinosaurus is thought to have eaten fish; evidence suggests that it lived both on land and in water like a modern crocodilian. The distinctive spines of Spinosaurus, which were long extensions of the vertebrae, grew to at least 1.65 meters (5.4 ft) long and were likely to have had skin connecting them, forming a sail-like structure, although some authors have suggested that the spines were covered in fat and formed a hump. Multiple functions have been put forward for this structure, including thermoregulation and display. Dal Sasso et al. (2005) assumed that Spinosaurus and Suchomimus had the same body proportions in relation to their skull lengths, and thereby calculated that Spinosaurus was 16 to 18 meters (52 to 59 ft) in length and 7 to 9 tonnes (7.7 to 9.9 short tons) in weight. The Dal Sasso et al. estimates were criticized because the skull length estimate was uncertain, and (assuming that body mass increases as the cube of body length) scaling Suchomimus which was 11 meters (36 ft) long and 3.8 tonnes (4.2 short tons) in mass to the range of estimated lengths of Spinosaurus would produce an estimated body mass of 11.7 to 16.7 tonnes (12.9 to 18.4 short tons).

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Dark allosaurus
Oct 25 2012, 08:48 AM
3-6 allosaurus or as much needed vs spinosaurus
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spinosaurus rex
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I find it unlikely for allosaurus fragilis to weigh that much. they're not really very robustly build animals in my opinion. I find 1.5 tons a likely average and maybe more then 2 tons at max. 3 tons will be pushing it, unless this creature is synonymous with epanterias.
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Carcharadon
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An average allosaurus would rather be at least 2 tonnes imo.

1.5 tons is too low for a 9 m theropod. And that's actually how much MOR 693 (big al) was estimated to weigh, but he is only an immature individual.
Edited by Carcharadon, Dec 31 2013, 01:44 PM.
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theropod
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Dec 31 2013, 11:31 AM
theropod
Oct 26 2012, 07:12 PM
The largest of the traditional A. fragilis specimens was 2,3t and the average was 8,5-9m, thus 1,54-1,83t in weight. this is not accounting for giant specimens possibly synonymous with allosaurus.

On average I do think it is close to 50/50 with a slight edge towards the allosaurs because they are simply perfectly adapted for killing large animals, with very sharp dentition, wide gape and great power in the neck muscles.

Larger specimens of allosaurus fragilis would have a relatively good change (60/40-70/30), and 5 epanterias take this easily.
Didnt you say the largest was over 3 tons? I bet 2,3 tonnes is too low even for Allosaurus fragillis.
Check the date. I changed my opinion on theropod weights since then, I relied on theropod-database figures which tend to be extremely low (5.6t for sue...).
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theropod
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@spinosaurus rex:
Volumetric models yielded 1.5t for a small specimen (MOR 693). I think this is a slight overestimation due to issues with the thoracal articulation of the mount, but I presume the slightly slimmed-down version counteracts that sufficiently.
Based on it, a typical adult like DINO 2560 would already weigh 2t, AMNH 680 would weigh 3.3t and NMMNH P-26083 3.6t. AMNH 5767 likely approached 6t.

Note that Greg Paul likely underestimates the bulk of the tail base and neck. Those areas were quite heavily muscled in Allosaurus, as in other theropods.
Edited by theropod, Dec 31 2013, 09:05 PM.
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Spinodontosaurus
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I personally suspect AMNH 5767 was closer to 5 tonnes than 6 tonnes (when scaled directly from MOR 693), although this is sort of besides the point...


Has anyone considered that the pack probably wouldn't be comprised of identical sized individuals? I know it only complicates things, but there could hypothetically be specimens as large as AMNH 680, and as small a MOR 693 in the same group.

Assuming them all to be of similar size to each other is a lot simpler though.
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Megalosauroid
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theropod
Dec 31 2013, 09:02 PM
@spinosaurus rex:
Volumetric models yielded 1.5t for a small specimen (MOR 693). I think this is a slight overestimation due to issues with the thoracal articulation of the mount, but I presume the slightly slimmed-down version counteracts that sufficiently.
Based on it, a typical adult like DINO 2560 would already weigh 2t, AMNH 680 would weigh 3.3t and NMMNH P-26083 3.6t. AMNH 5767 likely approached 6t.

Note that Greg Paul likely underestimates the bulk of the tail base and neck. Those areas were quite heavily muscled in Allosaurus, as in other theropods.
hmmm scaling from DINO 2560 8.8 m and 2000 kg to 10.08 m, AMNH 680 gets as heavy as 3 tonnes, but 3.3?
NMMNH P-26083 at 10.4 m gets a weight of 3.3 tonnes.
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Megalosauroid
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Spinodontosaurus
Dec 31 2013, 10:32 PM
I personally suspect AMNH 5767 was closer to 5 tonnes than 6 tonnes (when scaled directly from MOR 693), although this is sort of besides the point...


Has anyone considered that the pack probably wouldn't be comprised of identical sized individuals? I know it only complicates things, but there could hypothetically be specimens as large as AMNH 680, and as small a MOR 693 in the same group.

Assuming them all to be of similar size to each other is a lot simpler though.
Scaling from Big Al (MOR 693) 7.3-7.5 m and 1.5 tonnes, it yields 6300-6800 kg for AMNH 5767, but we should not only use MOR 693, DINO 2560 is a good specimen too, it yields 5200 kg for AMNH 5767 when scaled from it.
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theropod
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2000kg is for 8.5m. According to blaze 8.5m DINO and 7.5m BIG AL have the same relative tail lenght, thus they should also be comparable in bulk.

Those estimates for DINO 2560 you use are simply more conservative, nothing more. The corresponding figures for MOR 693 are also lower, as would be figures for other theropods. Big Al merely happens to be the one that has been subject to a detailed volumetric study.

I favoured the 12m lenght considering the 25cm height of the referred axis, which seemed significantly smaller in the big-al-based figure. But they were very similar in size, shartman's Big Al merely had a shorter tail.
I don't think it's quite 6t, but closer to 6t than to 5 (~5.7t).
Edited by theropod, Jan 1 2014, 09:59 AM.
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Megalosauroid
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theropod
Jan 1 2014, 09:53 AM
2000kg is for 8.5m. According to blaze 8.5m DINO and 7.5m BIG AL have the same relative tail lenght, thus they should also be comparable in bulk.

Those estimates for DINO 2560 you use are simply more conservative, nothing more. The corresponding figures for MOR 693 are also lower, as would be figures for other theropods. Big Al merely happens to be the one that has been subject to a detailed volumetric study.

I favoured the 12m lenght considering the 25cm height of the referred axis, which seemed significantly smaller in the big-al-based figure. But they were very similar in size, shartman's Big Al merely had a shorter tail.
I don't think it's quite 6t, but closer to 6t than to 5 (~5.7t).
2000 kg is for 8.5 m, Ok, but a 30 cm longer tail is not going to add much, Hartman stated that a longer tail added about a dozen kilograms, and that was for a 15 m Spinosaurus, so a 8.8 m long Allosaurus is not going to weight more than 2000 kg.

Big Al might be as bulky as DINO 2560, but scaled at the same length it becomes a much larger animal because it has a relatively shorter tail, and even if the 7.5 m specimen has a proportionally identical tail to a 8.5 m DINO 2560, It is less plausible than the 7.3 m figure.

But we should not scale from 7.3 to 8.8 m, that simply overestimates the weight, if the 7.5 m long tail reconstruction matches the 8.5 m, we should scale from 7.5 to 8.5 m to obtain a plausible mass estimate, which gives you 2,184 kg for DINO 2560.

12.1/7.5= 1.613333333333"3= 4.1992557037037037 (1500)= 6,298.883 kg

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Spinodontosaurus
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Eh, Hartman's MOR 693 has a 22cm coracoid, and I just scaled from that to AMNH 5767 size (32.8cm is claimed in the Theropod Database, but it may actually be 33.5cm... not that it matters too much in this instance). Like I said, it's sort of besides the point though.

I'm puzzled at how your UUVP-based estimate came out as so much lower than when using MOR 693, when A: estimates for UUVP should be based on MOR 693 in the first place and B: When you actually scale both specimens to the size of AMNH 5767 the main difference is that the UUVP/DINO based version has 70cm of extra tail, the rest (length and depth of other body segments, plus limb length) is essentially the same.

I made the following comparison back in July to illustrate this (although the weight estimate for the UUVP model was a guestimate, and in hindsight may be a bit too generous).
Posted Image

In any case, even if we assume AMNH 5767 is an Allosaurus (which isn't wise to do in my opinion), it clearly isn't representative of the genus in terms of size, so it isn't a factor in this fight.
Edited by Spinodontosaurus, Jan 1 2014, 08:27 PM.
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theropod
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Quote:
 
Big Al might be as bulky as DINO 2560, but scaled at the same length it becomes a much larger animal because it has a relatively shorter tail, and even if the 7.5 m specimen has a proportionally identical tail to a 8.5 m DINO 2560, It is less plausible than the 7.3 m figure.

But we should not scale from 7.3 to 8.8 m, that simply overestimates the weight, if the 7.5 m long tail reconstruction matches the 8.5 m, we should scale from 7.5 to 8.5 m to obtain a plausible mass estimate, which gives you 2,184 kg for DINO 2560.
And that my fried is EXACTLY what I did ;)

Quote:
 
2000 kg is for 8.5 m, Ok, but a 30 cm longer tail is not going to add much, Hartman stated that a longer tail added about a dozen kilograms, and that was for a 15 m Spinosaurus, so a 8.8 m long Allosaurus is not going to weight more than 2000 kg.
This was just a matter of scaling compatibility. Shartman's DINO 2560 is roughly 8.6m long.

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12.1/7.5= 1.613333333333"3= 4.1992557037037037 (1500)= 6,298.883 kg

As I wrote, I used 12m and 1.4t, but apart from that I did it the same way.

Spinodontosaurus is right, this won't have any major impact here since Epanterias is one of many Allosaurus specimens

ps. why 12m? I measured the 25cm tall axis of AMNH 5767 in all ways I could think of. Its proportions, as could be expected, yield somewhat variable results (13-64% bigger than AMNH 5753), but on average it's slightly over 29% larger. Consider AMNH 5753 is at least 8% (based on its ilium lenght) bigger than DINO 2560 (measurements from vertebrae indicate more, but they are somewhat tricky to measure accurately). So I think Epanterias is likely close to 12m TL.
Edited by theropod, Jan 2 2014, 12:26 AM.
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Hatzegopteryx
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As far as I am aware of Allosaurus fragilis is ~2 tonnes, so all the 5 combined weigh 10 tonnes. Spinosaurus' largest estimate is ~13 tonnes which means it still has a size advantage. I'll give it to Spinosaurus even though many bodies attacking him at the same time would be hard to handle. Though I believe Spinosaurus would kill 1-2 or maybe 3 at first giving it an advantage over the remaining others.
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Drift
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spinosaurus rex
Dec 30 2013, 12:03 PM
we're comparing spinosaurus and allosaurus behavior to lions and hyenas because the proportions are just as similar. heck, its even more so. a lion weighs a little more then two hyenas yet they can chase off packs of them. spinosaurus had a weight advantage over five allosaurs combined. and to top it off as a predator with a superior arsenal of weaponry, spinosaurus does in fact has the advantage. and I doubt spinosaurus will really move much. dodging a creature adapted to strike fast is a hard feat to perform for an allosaur who weighs 2 tons themselves. if an allosaurus strikes, it will hang back and unfortunately get within range of the spinosaurus. and when the spinosaur locks on, goodbye allo. and that's what I imagine with the others to the point until they have to give up. I do believe five can take down a spinosaur, but its more likely for the larger, rugged, and more powerful predator to prevail.
I feel we cannot compare behavior of animals because of the size comparisons they share with modern day predators.There are 5 and spinosaurus wasn't an Olympic sprinter nor marathon runner, the speed factor lies with Allosaurus being nimble and slashing or biting at the legs or flanks.Speedily retreating slightly out of reach of being attacked and commencing the attack once more,on top of that there are 5 of them doing this .Undoubtedly one of them will get to close and get chomped but the others will finish the job,IMO
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spinosaurus rex
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your right, he wasn't a marathon runner. he's a extreme heavy weight wrestler with more then enough capability to dispatch an allosaur quickly and continue doing so to the others. how agile do you think allosaurus is? plenty more agile then the spinosaurus, but come in close quarters, they are not nearly agile enough to avoid retaliation strikes. going in and avoiding retaliation is hard to perform for an allosaur that is 2+ tons themselves. you must also remember that spinosaurus was well adapted to strike fast and catch creatures out of the water.

this fight is not going to be easy. and note that I'm not denying the allosaurs capabilities to kill the spinosaurus. I just find it more likely for spinosaurus to win the majority.
Edited by spinosaurus rex, Jan 4 2014, 09:54 AM.
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Vobby
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spinosaurus rex
Jan 4 2014, 09:03 AM
he's a extreme heavy weight wrestler
I tend to disagree with this. Spinosaurus neck doesn't show insertions for big muscles, like the ones it would need to shake/maneuver other multitonnes animals. If you are referring to the forelimbs, I agree more, spinosaurids always show big and muscolar arms but, on the other hand, we haven't any fossil of Spinosaurus arms, so that we can't be completely sure about their strenght after all. Besides that, as far as I know, excluding Coelurosauria, theropod's hands and arms were good at catching/holding preys, but lacked the necessary mobility to be what we would consider a "wrestler", IMO.
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