Sauropod neck posture

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Sauropod neck posture is a subject that is sometimes debated among scientists, who consider horizontal posture, or erect to be how the neck is held routinely.

Video Sauropod neck posture

Biomechanics

Biomechanical skeletons and sauropod neck can help determine at which angle the neck is positioned.

Flexibility

In 2013, a study led by Matthew J. Cobley and published in PLOS ONE focused on sauropod neck flexibility. They compare the ostrich's neck to the genera sauropods to find out how flexible the neck really is. The study notes that earlier biomechanical studies found the neck has been positioned between vertical extremes, and the neck is tilted downward. In conclusion, the study found that sauropod neck flexibility should not be based on osteology alone, and if so, the results should be used with caution. Although there is a lack of preserved muscle tissue that will determine flexibility, the sauropod neck may be less flexible than previously thought.

In 2014, Mike P. Taylor analyzed the flexibility in the neck of Apatosaurus and Diplodocus . He found that Cobley et al. is not true in the fact that the vertebra implies a less flexible neck than reality. Cobley et al. finds the neck to be much lighter than the reality when cartilage is added. It was found that the cartilage between the joints will allow the neck to flex well past 90 Â °. However, Taylor notes that while the neck can flex above the vertical, the osteologically neutral pose will be around horizontally, with a habitual pose of having the head held upwards in a standby position.

Muscle

Sauropods' necks may be very muscular to fit their eating level. Brachiosaurus brancai (now Giraffititan ) is probably a taller browser, so it gets more muscular along the neck than other sauropods such as Diplodocus and Dicraeosaurus which is a low browser. The tail length and feet of B. brancai should also be larger, to compensate for the sloping neck. However, the question of whether sauropods are endothermic or ectothermic plays a major part in how sauropods are muscular, since endotherms have more intestines and stomach than ectotomes. The amount of intestine needed can determine how much food is eaten by sauropods, and therefore at what altitude their heads are held.

Heart and metabolic stress

The previous upright posture of the sauropods neck will require great blood pressure and a strong heart. A 2000 study conducted by Roger Seymour and Harvey Lillywhite found that the blood pressure needed to reach the head with an upright neck would be 700 millimeters of mercury (28Ã, inHg). This can be fatal for endotherms, and also very dangerous for ectotherm. If sauropods are endothermic metabolically, it is certainly not possible for them to survive with a vertical neck, because blood pressure will be too high to live even with muscular muscles that are thicker muscled. Subsequent studies by Seymour concluded that it takes half a certain sauropod energy to pump blood to the head. This will lower the chances of sauropod being a high browser, and instead have a lower neck when breastfeeding than is usually described.

Maps Sauropod neck posture

Hypothesis

Several hypotheses have been produced to resolve disputes about how sauropods hold their necks.

Horizontal pose

Kent Stevens and Michael Parrish are the two main proponents of horizontal neck posture. In 1999, they studied the genera apatosaurus and Diplodocus , found the habitual poses of the genera to be slightly decreased. They claim that both sauropods have a much more pliable neck than previously suspected, with the neck bones of becoming more inflexible than Apatosaurus . Both poses show that sauropods are ground feeders, rather than exploring higher flora. Then, in 2005, Stevens and Parrish again studied sauropodic neck biomechanics, but this time on a wider variety of sauropods, those who inhabit Jurassic. Specifically, Apatosaurus , , Camarasaurus , Brachiosaurus , Dicraeosaurus , Cetiosaurus , and Euhelopus are studied, and each and every one is expressed to have a neck held horizontally by Stevens and Parrish. The couple even says that all but a few have necks curving down toward the head. However, in 2009 some things were found wrong with this hypothesis. Michael P. Taylor et al. Comparing the sauropod neck posture with the remaining reptiles, finding different sauropod habits poses very different from the Stevens and Parrish hypotheses, including the upright neck for Diplodocus . The inaccuracies of Stevens and Parrish largely derive from their thinking about the habitual poses, which they say, the Osteological Neutral Pose (or ONP) of any sauropod. Taylor et al. finds the ONP not being a regular pose, away from it, but only the midpoint between the two extreme structures of the neck orientation.

Leaning base

Another, wider hypothesis supported about the sauropod neck posture is that the neck is held on the slope, but not as straight as it is commonly shown. Daniela Schwartz et al. in 2006 published studies on scapula and coracoids, sometimes fused with scapulocoracoids, genera sauropods. Previously, the sauropodic shoulder girdle was thought to have been positioned horizontally along the torso, but Schwartz et al. found that girdles should not be horizontally positioned, and vice versa, they would be inclined on average from 55 ° to 65 °. This study reconstructs the framework of the , camarasaurus , and the titanosaur opisthocoelicaudia , all known from a complete shoulder belt, with the correct orientation of the scapulocoracoids. For Diplodocus , the 60 Â ° shoulder blades will mean more or less horizontal neck, not too different from horizontal poses. A teenager Camarasaurus discovered by Gilmore was initially described as having a scapulocoracoid in "the right place", but with it oriented at a 45 ° angle, Schwartz et al. criticizing attitude. The framework discovered by Schwartz et al. with a scapulocoracoid angle similar to the previous reconstruction of the genus by Osborn and Mook, and Jensen. Opisthocoelicaudia was found to have two possible poses, both with a tilted scapulocoracoid of about 60 °. No previous reconstruction, unlike with Camarasaurus , has restored Opisthocoelicaudia in the same way.

Upright poses for some sauropods

Euhelopus and Brachiosaurus have been found to be between only a few sauropods to hold their necks at a vertical angle, which is impossible for other sauropods. Many studies have stated that blood pressure and energy spent will be too great to survive, but for Eucelopus and Brachiosaurus it would be more suitable for them. The energy spent by pumping blood to the head may be too great for sauropods, but when they travel a lot, which has been suggested for two genera, it will actually save energy. Biomechanical evidence supports the upright neck when traveling to deploy separate resources. The study found this conclusion also tested how much energy would be released when walking 100 m (330 ft) and standing, both with a straight neck. The conclusion is that the same amount of energy will be exhausted. The elongated cervical rib is a skeletal proof for a strong nucleus to support the neck and limit its movement as it goes. This study supports the idea that during times of drought and famine, upright necks are essential for these sauropods to survive.

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References

Source of the article : Wikipedia