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Allosaurus fragilis v Megalosaurus bucklandii
Topic Started: Jun 28 2013, 03:59 PM (6,232 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).

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Megalosaurus bucklandii
Megalosaurus (meaning "Great Lizard", from Greek, μεγαλο-/megalo- meaning 'big', 'tall' or 'great' and σαυρος/sauros meaning 'lizard') is a genus of large meat-eating theropod dinosaurs of the Middle Jurassic period (Bathonian stage, 166 million years ago) of Europe (Southern England, France, Portugal). It is significant as the first genus of dinosaur (outside of birds) to be described and named. n many ways, Megalosaurus was your garden-variety theropod dinosaur, indistinguishable from a host of other big-headed, large-toothed carnivores of the late Jurassic period. What really sets this predator apart is the fact that it was the first dinosaur ever to be discovered and named: a fossilized femur of Megalosaurus was dug up in England in 1676, but it wasn't until 150 years later--after further discoveries--that it was given its name, Greek for "great lizard," by the early paleontologist William Buckland. Size about 30 feet long with weight estimates varying from 700 kg (1,500 lbs) to 1,100 kg (2,400 lbs).

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Edited by Taipan, Dec 27 2016, 10:29 PM.
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theropod
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^Yeah, a railroad spike seems to fit it pretty well, also in terms of the edges.
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The Reptile
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You technically can; they are much thicker than what you would find in allosaurs for example, but at the same time they are distinctly recurved and, at the same time, serrated.

Something that one would consider a "spike" structure is a spinosaurus tooth or a crocodile tooth, as they are fundamentally straightened and lack true serrations (even though similar structures are found in the teeth of both, they aren't considered true carination).

So no; tyrannosaurid dentition is still not, in this case, "spike-like". When comparing it to animals with notably thin, knife-like teeth like various varanids, sharks, and allosaurs, then adjectives relating to spikes can be used
For Dave's comparison, sarcosuchus and deinosuchus possessed teeth that can, for all intents and purposes, be considered "spikes", as they are designed for puncturing, gripping, and crushing all at the same time.

Those of tyrannosaurids, as thick and robust as they are, are a completely different case
Edited by The Reptile, Dec 13 2014, 07:22 AM.
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theropod
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I was talking about functionality, not appearance (although by any means there’s little those teeth have in common with knifes). A tyrannosaurus tooth, for all intends and purposes, would behave much more similar to a spike with a triangular or quadrangular crossection than to a blade, considering their absolute thickness and the aspect ratios of almost 0.7.

As I’ve posted countless times, the serrations of its carinae have functional effects most similar to a smooth-edged blade, and a pretty dull one, with a large edge angle too. So their presence is not very important for the tooth’s cutting ability, and may as well be ignored. What remains is a recurved shape, but that alone doesn’t mean its function isn’t similar to a spike. It’s merely built to work with different force vectors.
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The Reptile
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By that logic, they also have nothing in common with spikes either. A spike, like one would find in a crocodilian or spinosaurus, is fundamentally a straight(er) structure that is thick in cross-section and also lacks carination. The main function is stabbing.

In tyrannosaurus, we rather see thicker teeth than those of allosaurus that are, simultaneously, serrated and recurved. So this implies that they are neither "spikes" nor "knives" but rather something that can be defined as "in between" for a function that is aside stabbing or cutting.

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As I’ve posted countless times, the serrations of its carinae have functional effects most similar to a smooth-edged blade, and a pretty dull one, with a large edge angle too. So their presence is not very important for the tooth’s cutting ability, and may as well be ignored. What remains is a recurved shape, but that alone doesn’t mean its function isn’t similar to a spike. It’s merely built to work with different force vectors.

Thickly-edged or not, they were still much better adapted for tearing (even if they weren't so in the general sense) than the tooth of a crocodilian like deinosuchus or spinosaurus.
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theropod
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The railroad spikes I’ve seen don’t have a round crosssection, they have a rectangular one, hence also edges.
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TheBeast
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Allo wins.
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Megasaurus
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Spinodontosaurus
Dec 7 2014, 04:40 AM
The Reptile
Dec 6 2014, 08:44 AM
they still possessed some rather allosaur-like characteristics (despite being unrelated) including a rather gracile skull construction and sharply-serrated dentition adapted for cutting.
With such a vague 'characteristic' you could just as easily say that baryonychine theropods possessed some 'allosaur-like characteristics'.

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Full size version.

They aren't alike.
Ihtink allosarus wins DIno 2560 55 percentages
NMMNHP-26083 wins very easy
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Carnotaur
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I usually would favor a megalosaur over an allosaurid at similar sizes(mostly because of the more muscular built and much thicker limb elements),and this probably wouldnt be an exception.
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Soopairik
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Big Al takes this one because it is slightly larger, I think. And it has strong claws and bite.
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GallirallusAustralis
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Megalosaurus has stronger jaws and maybe more robust and has moer deadly claws. Megalosaurus should win.
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