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| Megatherium v Therizinosaurus | |
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| Tweet Topic Started: Jan 17 2012, 11:19 PM (13,456 Views) | |
| Taipan | Jan 17 2012, 11:19 PM Post #1 |
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Megatherium americanum Megatherium ("Great Beast") was a genus of elephant-sized ground sloths endemic to Central America and South America that lived from the Pliocene through Pleistocene existing approximately 5.3 million years. Its size was exceeded by only a few other land mammals, including mammoths and the even larger Paraceratherium. Megatherium was one of the largest mammals known, weighing up to eight tons, about as much as an African bull elephant. Although it was primarily a quadruped, its footprints show that it was capable of assuming a bipedal stance. When it stood on its hind legs it was about twenty feet (6 m) tall, twice the height of an elephant. This sloth, like a modern anteater, walked on the sides of its feet because its claws prevented it from putting them flat on the ground. Megatherium species were members of the abundant Pleistocene megafauna, large mammals that lived during the Pleistocene epoch. Megatherium had a robust skeleton with a large pelvic girdle and a broad muscular tail. Its large size enabled it to feed at heights unreachable by other contemporary herbivores. Rising on its powerful hind legs and using its tail to form a tripod, Megatherium could support its massive body weight while using the curved claws on its long forelegs to pull down branches with the choicest leaves. Its jaw is believed to have housed a long tongue, which it would then use to pull leaves into its mouth, similar to the modern tree sloth. ![]() Therizinosaurus cheloniformis Therizinosaurus (play /θɛˌrɪzɨnɵˈsɔrəs/; 'scythe lizard', from the Greek therizo meaning 'to reap' or 'to cut off' and sauros meaning 'lizard') is a genus of very large theropod dinosaur. Therizinosaurus lived in the late Cretaceous Period (late Campanian-early Maastrichtian stages, around 70 million years ago), and was one of the last and largest representatives of its unique group, the Therizinosauria. Its fossils were first discovered in Mongolia and they were originally thought to belong to a turtle-like reptile (hence the species name, T. cheloniformis — "turtle-formed"). It is known only from a few bones, including gigantic hand claws, from which it gets its name. Though the fossil remains of Therizinosaurus are incomplete, inferences can be made about its physical characteristics based on related therizinosaurids. Like other members of its family, Therizinosaurus probably had a small skull atop a long neck, and had a bipedal gait and a heavy, deep, broad body (as evidenced by the wide pelvis of other therizinosaurids). Its forelimbs may have reached a length of 2.5 metres (8 feet) or even 3.5 metres for the largest known specimen. Its hindlimbs ended in four weight-bearing toes, unlike other theropod groups, in which the first toe was reduced to a dewclaw. Gregory S. Paul in 2010 estimated the length of Therizinosaurus at ten metres, the weight at five tonnes. It is the largest therizinosaur known and the largest known member of the Maniraptora. The most distinctive feature of Therizinosaurus was the presence of three gigantic claws on each digit of its frontlimbs. These were common among therizinosaurs but especially large in Therizinosaurus, and while the largest claw specimens are incomplete, they probably reached just under 1 metre (3.28 ft) in length. The claws are the longest known from any animal. The claws were relatively straight, only gradually tapering into a point, and extremely narrow, transversely flattened. ![]() _____________________________________________________________________
Edited by Taipan, Jan 17 2012, 11:20 PM.
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| Vobby | Feb 12 2014, 07:52 AM Post #76 |
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Omnivore
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This may be an ignorant question, but are we so sure that Therizinosaurus weighed more than 3-4 tons? |
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| Hatzegopteryx | Feb 12 2014, 08:08 AM Post #77 |
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Unicellular Organism
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Common figures suggest those mass estimates, but they are just common figures. I also wonder if thoe figures are about right. |
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| blaze | Feb 12 2014, 08:11 AM Post #78 |
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Carnivore
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That's a pretty good question, Greg Paul is the only who has estimated its weight, therizinosaurs are said to have wide hips which means they had wide torsos, necessary for their herbivorous diet. Therizinosaurus was big and it has been estimated to have legs 3m long, right there with the largest theropods known.... I don't really remember how much is known of it. more info on the size Megatherium americanum The specimen that's in the London museum and is said to be 5.4m long has a femur 71cm long according to Clift (1834) while the longest known femur is 78cm long, from De Iuliis (1996), assuming isometric scaling the largest specimens known, at least based on the femur, were 5.9m long (essentially 6m long) and some 3.8m tall. What is a surprise for me is the length of the femora of Eremotherium, the largest one is 89.5cm long, 15% longer! but since it is said to only be similar in size to M. americanum, I wonder if it only has proportionally longer legs. |
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| Vobby | Feb 12 2014, 08:29 AM Post #79 |
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Omnivore
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My problem with Therizinosaurus weight is that, even if its legs may have been very long, it had a quite weird posture for theropod standards, so that the tail would have been relatively light, and obviousl the same is even more true for the head and neck, amongst the lightest in non avia theropods, relatively to body weight... I just found that, in this very old post, Cau tried to estimate Therizinosaurus mass too, arriving at 3,2 t (although some other parts of its post are making me think that his opinion may have changed about this matter...): http://theropoda.blogspot.it/2008/03/le-masse-di-deinocheirus.html |
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| Ausar | Feb 12 2014, 08:57 AM Post #80 |
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Xi-miqa-can! Xi-miqa-can! Xi-miqa-can!
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I still believe Therizinosaurus wins easily from the size comparison, though, were that not the case, Megatherium would win. |
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| blaze | Feb 12 2014, 09:18 AM Post #81 |
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Carnivore
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Head and neck don't contribute as much anyway probably around 10% of the body weight based Bates et al. (2009) while the tail is around 20% I do think his opinion has changed, 3 tonnes just because its femur is only 1.1m long, according to femur circumference there's T. rex specimens that have femora that long but were supposedly over 5 tonnes (not that I believe they were really that big) while there's femora that long that only yields a weight of 1.4 tonnes (that of Gigantoraptor). Let's see, he used Neimongosaurus yangi, accoding to Zhang et al. (2001), the femur is 366mm in length, its humerus and radius are 222mm and 180mm respectively, those of Therizinosaurus are 3.42 and 3.06 times bigger so the femur might have been 1.12-1.25m long, it seems he used the most conservative numbers (the 1.07m is probably from the scaling of the other taxon he used), if 1.12m means 3.2 tonnes then 1.25 means 4.7 tonnes. Greg Paul estimates Neimongosaurus at 3m long and 150kg, which corresponds well with what he estimates for Therizinosaurus. Edited by blaze, Feb 12 2014, 09:19 AM.
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| Vobby | Feb 12 2014, 09:57 AM Post #82 |
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Omnivore
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Mmh well, a possible range of weights from 3 to around 4,5-5 (more likely?) tons seems wide enough to be plausible. Pushing it at something like 6 tons seems a little too much, I guess. Now I'm having doubts about Megatherium weight... a very big brown bear or a polar bear could be nearly as tall as this sloth, but wouldn't ever approach weights like 3 or 4 tons. The sloth appears more robust and massive, but that much? More than two times bigger than a black rhino seems too high as a weight estimate to me. |
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| blaze | Feb 12 2014, 10:42 AM Post #83 |
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Carnivore
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You might be up to something, the specimen estimated at 4 tonnes has a humerus 65cm long, transverse diameter is 11cm and anteroposterior diameter is 7cm, distal width is 30cm, for comparison the largest humerus of the largest Arctotherium is 62cm long, 8.4cm in transverse diameter and 9.1cm in anteroposterior diameter, distal width is 18.5cm, the distal width is a lot greater but the width of the shaft is comparable. The biggest difference is in the femur, is 62cm long, it has a transverse diameter of 28cm and a anteroposterior diameter of 7cm, for comparison the largest Arctodus simus femur is 72cm long and 6.4cm in transverse diameter, anteroposterior diameter I don't know, probably comparable to that of the Megatherium. Edited by blaze, Feb 12 2014, 11:07 AM.
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| Ausar | Feb 12 2014, 11:10 AM Post #84 |
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Xi-miqa-can! Xi-miqa-can! Xi-miqa-can!
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Edit: Stupid me, I forgot what I said elsewhere. This shouldn't surprise me that much. Edited by Ausar, Feb 12 2014, 11:14 AM.
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| Ausar | Feb 16 2014, 11:39 PM Post #85 |
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Xi-miqa-can! Xi-miqa-can! Xi-miqa-can!
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Updated size comparison made by blaze.![]() Small sloth gets demolished. Big sloth wins. Then again, the latter is a large specimen, something we haven't found for Therizinosaurus. Edited by Ausar, Feb 16 2014, 11:42 PM.
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| jj5893 | Mar 11 2014, 06:02 PM Post #86 |
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Heterotrophic Organism
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Therizinosaurus claws are very awkward and weak weapons, megatherium wins easy. |
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| Vivyx | Mar 12 2014, 02:17 AM Post #87 |
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Felines, sharks, birds, arthropods
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The megatherium might be smaller than you think. Also, I wouldn't exactly call these weak:![]()
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| retic | Mar 12 2014, 06:27 AM Post #88 |
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snake and dinosaur enthusiast
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based on blazes size comparison i favor therizinosaurus. |
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| Carcharadon | Mar 12 2014, 06:41 AM Post #89 |
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Shark Toothed Reptile
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| ArachnidKid | Mar 27 2014, 04:15 AM Post #90 |
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Heterotrophic Organism
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Megatherium had some type of armour under its fur if i;m not mistaken and that would protect against claws suited to grabbing tree branches imo |
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