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| Spinosaurus aegyptiacus v Tyrannosaurus rex | |
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| Tweet Topic Started: Jan 7 2012, 02:16 AM (459,238 Views) | |
| Wolf Eagle | Jan 7 2012, 02:16 AM Post #1 |
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M E G A P H Y S E T E R
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Tyrannosaurus rex Tyrannosaurus is a genus of coelurosaurian theropod dinosaur. The species Tyrannosaurus rex (rex meaning "king" in Latin), commonly abbreviated to T. rex, is a fixture in popular culture. It lived throughout what is now western North America, with a much wider range than other tyrannosaurids. Fossils are found in a variety of rock formations dating to the Maastrichtian age of the upper Cretaceous Period, 67 to 65.5 million years ago.[1] It was among the last non-avian dinosaurs to exist before the Cretaceous–Paleogene extinction event. Like other tyrannosaurids, Tyrannosaurus was a bipedal carnivore with a massive skull balanced by a long, heavy tail. Relative to the large and powerful hindlimbs, Tyrannosaurus forelimbs were small, though unusually powerful for their size, and bore two clawed digits. Although other theropods rivaled or exceeded Tyrannosaurus rex in size, it was the largest known tyrannosaurid and one of the largest known land predators. By far the largest carnivore in its environment, Tyrannosaurus rex may have been an apex predator, preying upon hadrosaurs and ceratopsians, although some experts have suggested it was primarily a scavenger. The debate over Tyrannosaurus as apex predator or scavenger is among the longest running in paleontology. Tyrannosaurus rex was one of the largest land carnivores of all time; the largest complete specimen, FMNH PR2081 ("Sue"), measured 12.8 metres (42 ft) long, and was 4.0 metres (13.1 ft) tall at the hips. Mass estimates have varied widely over the years, from more than 7.2 metric tons (7.9 short tons), to less than 4.5 metric tons (5.0 short tons), with most modern estimates ranging between 5.4 and 6.8 metric tons (6.0 and 7.5 short tons). Packard et al. (2009) tested dinosaur mass estimation procedures on elephants and concluded that dinosaur estimations are flawed and produce over-estimations; thus, the weight of Tyrannosaurus could be much less than usually estimated. Other estimations have concluded that the largest known Tyrannosaurus specimens had a weight exceeding 9 tonnes. ![]() 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).
Edited by Taipan, Apr 24 2015, 10:10 PM.
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| Jinfengopteryx | Feb 17 2013, 02:15 AM Post #2146 |
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Aspiring paleontologist, science enthusiast and armchair speculative fiction/evolution writer
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We could use Irritator, but it's estimates seem to be based on Spinosaurus. |
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| blaze | Feb 17 2013, 02:23 AM Post #2147 |
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Carnivore
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What were the values you used for Baryonyx and Suchomimus? |
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| theropod | Feb 17 2013, 02:24 AM Post #2148 |
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palaeontology, open source and survival enthusiast
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rather on suchomimus or baryonyx, there is only an isolated posterior cranium known of it, and spinosaurus is not a good reference for estimating other animals for obvious reasons... |
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| theropod | Feb 17 2013, 02:25 AM Post #2149 |
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palaeontology, open source and survival enthusiast
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Baryonyx: 9,1m, 0,91m skull Suchomimus: 11m, 1,19m skull (and the explanation for the odd skull lenght in Sereno's scale is that he scaled to the total lenght of 11m, while in life it would end up shorter) |
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| blaze | Feb 17 2013, 02:48 AM Post #2150 |
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Carnivore
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I don't think that actually explains it, Sereno says "total length ~11m" meaning he is not certain and why would he scale to total length if that is an estimated value he just came up with (as in, based on the size of the bones). Measuring the skeletal, it is 11.1m from tip to tip, it might be around 11.5m completely stretched but the scale is not exact, the femur is shown at 108.7mm rather than 1075mm meaning total length is actually ~11.3-11.4m and going by the Sarcosuchus paper, Sereno likes to round down (saying the croc is "~11.5m" when the value he actually means (11.68m) can easily be rounded to 12m). There are also problems with Baryonyx, from where does the 0.91m figure comes from? the skull in the 1997 paper (author's names escape right now) is ~0.96m long and its "short snouted", it looks like the JP Spinosaurus (or rather the other way around) the current long snouted reconstructions are not 0.91m but rather over 1m long. |
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| theropod | Feb 17 2013, 03:00 AM Post #2151 |
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palaeontology, open source and survival enthusiast
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it ended up at 10,9m when using the scalebar, I didn't measure the skull and femur tough |
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| blaze | Feb 17 2013, 03:08 AM Post #2152 |
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Carnivore
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In the one I used, tip to tip length was 1278px, scalebar 115px (there's another pixel there but it looks like an artifact mmm
Edited by blaze, Feb 17 2013, 03:09 AM.
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| Godzillasaurus | Feb 17 2013, 03:56 AM Post #2153 |
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Reptile King
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I see. However, while I would not consider the proportions of spinosaurines to be vastly different, they are possibly differentiated from baryonichines to at least some extent (at least in the realm of skull width and depth). The skulls of animals like spinosaurus and irritator may have been proportionally thicker than animals including baryonyx. Even the teeth are different in the two subgroups. Baryonichines have teeth that were more blade-like that possessedserrations, much like a handful of other theropods. Spinosaurines had teeth that were almost entirely conical, which little to no serrations at all. I really don't think baryonyx and suchomimus are the best contenders for estimating the proportions of spinosaurus. |
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| Jinfengopteryx | Feb 17 2013, 04:00 AM Post #2154 |
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Aspiring paleontologist, science enthusiast and armchair speculative fiction/evolution writer
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Is that "rounding down" maybe an explaination for the relatively low size for the Charcharodontosaurus neotype what is usually cited? |
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| blaze | Feb 17 2013, 04:31 AM Post #2155 |
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Carnivore
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Maybe, but we don't actually have the source of the 12m estimate, remember? all the papers citing it lead to papers that don't say it at all. |
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| theropod | Feb 17 2013, 07:04 AM Post #2156 |
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palaeontology, open source and survival enthusiast
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they're the only contenders...at least unless you want to do it the Therrien&Henderson way and assume the skull size grows allometrically for every single theropod, from a regression equasion containing compsognathus and t. rex, but not a single spinosaur, which alltogether have completely different proportions. @jingoferx: it is not really cited, Sereno doesn'tmention it, neither Currie. Sereno gives a figure nearly 2m higher than that actually (the 45ft might be rounded down, this is not too far from 14m). 12m is simply such a classic, mainstream theropod lenght figure that every newsarticle likes to use it. I don't know about the papers, either there is another paper on the same topic from the same year by Sereno and Currie respectively (I think I and the others here would know about that tough), or they quoted it incorrectly (wouldn't be the first time, remember the skull lenght figures for the Torvosaurus holotype?) Edited by theropod, Feb 17 2013, 07:06 AM.
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| Godzillasaurus | Feb 17 2013, 07:17 AM Post #2157 |
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Reptile King
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I do agree that baryonyx and suchomimus could be considered the best possible contenders. But the proportions of baryonichines. like you said, could be very different from those of spinosaurines. |
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| theropod | Feb 17 2013, 07:06 PM Post #2158 |
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palaeontology, open source and survival enthusiast
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of course, they could. That could either mean Spinosaurus would end up larger or smaller, so lets take the save way and stick to their actual proportions, because we have no indication that spinosaurus' proportions where vastly different. |
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| Spinodontosaurus | Feb 18 2013, 06:11 AM Post #2159 |
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Herbivore
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This might help. Scaled Scott Harman's Baryonyx and Suchomimus skeletals to possess 175cm long skulls.![]() The primary difference between the two is really just leg length and tail length. Of course neither are perfect indicators, Both are sub-adult individuals, which tend to be more gracile than adults (this tends to be the case for adults of smaller species vs adults of larger species anyway), if not big-headed. Furthermore, the 'body' of Spinosaurus would have reached up the neural spines a considerable distance, 1/3 or 1/2 of the height at a stretch, and so it's torso and tail would have been much deeper than the Baryonyx, for example, suggests here. But they are all we have unfortunately. |
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| theropod | Feb 18 2013, 06:18 AM Post #2160 |
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palaeontology, open source and survival enthusiast
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^thanks, that's indeed helpful! |
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