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| Spinosaurus aegyptiacus v Tyrannotitan chubutensis | |
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| Tweet Topic Started: Nov 1 2014, 07:47 PM (5,493 Views) | |
| Taipan | Nov 1 2014, 07:47 PM Post #1 |
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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). ![]() Tyrannotitan chubutensis Tyrannotitan is a genus of huge bipedal carnivorous dinosaur of the carcharodontosaurid family from the Aptian stage of the early Cretaceous period, discovered in Argentina. It is closely related to other giant predators like Giganotosaurus and Carcharodontosaurus. Its fearsome appearance is reflected in the meaning of its name, "Tyrant titan". Tyrannotitan chubutensis was described by Fernando E. Novas, Silvina de Valais, Pat Vickers-Rich, and Tom Rich in 2005. The fossils were found at La Juanita Farm, 28 kilometres (17 mi) northeast of Paso de Indios, Chubut Province, Argentina. They are believed to have been from the Cerro Castaño Member, Cerro Barcino Formation (Aptian stage) around 112.2 - 121 million years ago. The length of the animal is estimated to be on average at 12.2 metres (40 ft). Little information has yet been released about Tyrannotitan. Only a very brief description of the fossils has been published (four pages). The teeth are less blade-like than those of its kin, and possess odd, lumpy denticles (there is a barely distinguishable groove in the center, dividing each denticle into two parts). ![]()
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| Teratophoneus | Nov 4 2014, 11:25 PM Post #16 |
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Herbivore
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He only gave two examples: he was talking about Carcharodontosaurids, not just about Acrocanthosaurus and Carcharodontosaurus. |
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| Jinfengopteryx | Nov 4 2014, 11:46 PM Post #17 |
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Aspiring paleontologist, science enthusiast and armchair speculative fiction/evolution writer
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Well, I don't think both examples are optimal. The extremely low estimates for Acro based on bone robusticity have been criticized here and IIRC, the Carcharodontosaurus holotype was not fully grown (at least that's what some other members said before), so it being more frail is anything, but surprising. |
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| Ceratodromeus | Nov 5 2014, 01:19 AM Post #18 |
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Aspiring herpetologist
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what's the reasoning behind that? everything i've seen suggests it was fully grown |
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| Jinfengopteryx | Nov 5 2014, 01:33 AM Post #19 |
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Aspiring paleontologist, science enthusiast and armchair speculative fiction/evolution writer
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No idea, maybe it's small size: http://carnivoraforum.com/single/?p=8429376&t=9675429 But I have no time to search for old stuff that long now. |
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| Ceratodromeus | Nov 5 2014, 01:43 AM Post #20 |
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Aspiring herpetologist
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with that logic, specimens like Black beauty aren't fully grown just because “sue” is larger then them. size variation is great in species, and i highly doubt that Tyrannosaurus is the only specie of theropod we have that shows such variation. Considering how little we have of carchy, i think it's best to chalk it up to individual variation. that's just imo, though |
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| theropod | Nov 5 2014, 03:32 AM Post #21 |
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palaeontology, open source and survival enthusiast
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Cau is comparing overall size, not bulk. He also talks about the lenght of the femur in that post. It should be common knowledge by now that what he’s making are comparisons of size, not bulkiness. Heck, most of the parts actually relevant for bulkiness aren’t even known for Tyrannotitan (i.e. the ribs). The Carcharodontosaurus holotype was an adult (Why? Stromer states so.). But the Tyrannotitan paratype has a 1.41m femur (just as a rough indicator of longitudinal dimensions), as compared to 1.26m in the holotype of Carcharodontosaurus and 1.28m (probably less, see @blazes comments on the matter) for the largest individual of Acrocanthosaurus. It’s absolutely normal on more than one account that these have less massive skeletal elements. Since for none of the other carcharodontosaur specimens presumed to be similar in size or larger than MPEF-PV 1157 the relevant body parts are described (or even known in some) how can someone claim them to be less bulky? It’s the same situation as with, or even worse than, the baseless claims that Mapusaurus was less bulky than other carcharodontosaurs. Tyrannotitan being bulkier than other carcharodontosaurs of comparable size is baseless speculation, and Cau doesn’t even propose it (doesn’t the translation explicitely say which theropods he is comparing it to? Are you proposing he has access to the Giganotosaurus and Mapusaurus materials without telling anyone?). Perhaps the schematic skeletal reconstruction (click here→ for an explanation on what that is) in the description paper is what continues to give people that erraneous impression. Don’t let it fool you, it’s showcasing ridiculous proportions, and can never have been intended to be accurate in that regard. Fun fact: The humerus of Tyrannotitan isn’t so short after all. In fact, if Canale et al.’s reconstruction is correct, the holotype’s humerus is about 387mm long, that’s actually more than in Acrocanthosaurus. References: Canale, Juan I.; Novas, Fernando E.; Pol, Diego: Osteology and phylogenetic relationships of Tyrannotitan chubutensis Novas, de Valais, Vickers-Rich and Rich, 2005 (Theropoda: Carcharodontosauridae) from the Lower Cretaceous of Patagonia, Argentina. Historical Biology: An International Journal of Paleobiology, Vol. 27 (2015); 1; pp. 1-32 Currie, Philip J.; Carpenter, Kenneth: A new specimen of Acrocanthosaurus atokensis (Theropoda, Dinosauria) from the Lower Cretaceous Antlers Formation (Lower Cretaceous, Aptian) of Oklahoma, USA. Geodiversitas, Vol. 22 (2000); 2; pp. 207-246 Stromer, Ernst: Ergebnisse der Forschungsreisen Prof. E. Stromers in den Wüsten Ägyptens. II. Wirbeltier-Reste der Baharije-Stufe (unterstes Cenoman). 10. Ein Skelett-Rest von Carcharodontosaurus nov. gen. Abhandlungen der Königlich Bayerischen Akademie der Wissenschaften, Mathematisch-Naturwissenschaftliche Abteilung, Neue Folge, Vol. 9 (1931); pp. 1-23 Edited by theropod, Nov 5 2014, 03:51 AM.
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| Teratophoneus | Nov 5 2014, 03:47 AM Post #22 |
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Herbivore
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He actually talked about bulkyness. The traslation only translated the word 'Massiccio' (=bulky) into massive. I don't know why. |
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| blaze | Nov 5 2014, 03:56 AM Post #23 |
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Carnivore
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Sue is the only T. rex specimen in which an external fundamental system has been found in its long bones (of course not all T. rex specimens have been analyzed) so is the only specimen we can be sure is full grown, Black Beauty is supposedly an 18 year old so its small size might be related to that but there must surely be other factors. Femur circumference of the Tyrannotitan paratype is 541mm for a femur length of 141cm while the type is 514mm for a femur length of 127cm according to the supplemental of Canale et al. (2014), circumference/length ratios of ~38.4% and ~40.5% respectively. However Campione et al. (2014) reports a circumference for the type of 500mm instead which will bring its ratio to ~39.4%. For comparison the the type of Giganotosaurus has a femur either 143cm long (Coria and Salgado, 1995), 137cm (Carrano et al. 2012) or 132cm (Benson et al. 2014 supplemental) and a circumference of either 521mm (Campione et al., 2014) or 525mm (Benson et al. 2014 supplemental). Ignoring the original measurement, best case scenario is a ratio of ~39.8%, worst case ~38%. |
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| Jinfengopteryx | Nov 5 2014, 04:01 AM Post #24 |
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Aspiring paleontologist, science enthusiast and armchair speculative fiction/evolution writer
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OK, but I think the point doesn't change, since (as I think you said) a smaller animal has logically a shorter femur. |
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| theropod | Nov 5 2014, 05:13 AM Post #25 |
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palaeontology, open source and survival enthusiast
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@teratophoneus: maybe because that word can also mean "massive", or is used in the sense of "massive", as in "large", not as in "robust in built"? http://www.wordreference.com/iten/Massicci I don’t actually speak Italian, but a certain morphological similarity is hard to overlook. I’m not a native english speaker either, but I think even bulky could be used in this sense (overall mass, not proportions), even though it seems uncommon. @blaze: This Benson et al 2014?: http://www.plosbiology.org/article/info%3Adoi%2F10.1371%2Fjournal.pbio.1001853 Edited by theropod, Nov 5 2014, 05:20 AM.
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| DinosRule | Nov 5 2014, 06:00 AM Post #26 |
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Unicellular Organism
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Poor dead Tyrannotitan |
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| Spinodontosaurus | Nov 5 2014, 09:42 AM Post #27 |
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Herbivore
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Although he does make mention of how the C. saharicus holotype has a femur "significantly more frail" than that of Tyrannotitan. It's a pretty vague claim though, and may not even be comparing them in relative terms, but in absolute terms. |
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| blaze | Nov 5 2014, 09:50 AM Post #28 |
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Carnivore
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@theropod Yes |
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| The Reptile | Nov 5 2014, 11:59 PM Post #29 |
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Herbivore
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For one "teradactyls" don't exist; they are known scientifically as pterosaurs. Second, I cannot understand what you are trying to say. Suchomimus would only be a good indicator for spinosaurus' weight if it possessed the same leg-body proportions, which it apparently did not. Not to mention how they were actually quite distant from each other phylogenically (or at least more-so than what you would expect from two proportion-indentical animals) |
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| theropod | Nov 6 2014, 09:38 PM Post #30 |
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palaeontology, open source and survival enthusiast
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Tetradactyl, not "teradactyl" or "pterodactyl". It has been suggested that Spinosaurus feet were tetradactyl, the increased surface area helping with swimming and walking on muddy ground (although then I find it all the more strange that its whole hindlimb, including the pes is so atrophied in every dimension). |
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