Comments on: Did Sauropods Hold their Heads High? http://blogs.smithsonianmag.com/dinosaur/2009/04/did-sauropods-hold-their-heads-high/ Where Paleontology Meets Pop Culture Sat, 22 Dec 2012 16:48:38 +0000 hourly 1 http://wordpress.org/?v=3.4 By: New Study Suggests That Some Sauropods Reached High for Leaves | Dinosaur Tracking http://blogs.smithsonianmag.com/dinosaur/2009/04/did-sauropods-hold-their-heads-high/comment-page-1/#comment-2139 New Study Suggests That Some Sauropods Reached High for Leaves | Dinosaur Tracking Tue, 08 Jun 2010 12:56:32 +0000 http://blogs.smithsonianmag.com/dinosaur/?p=1148#comment-2139 [...] sauropod dinosaurs hold their heads? It is a simple question, but for years it has been part of an ongoing controversy about the evolution and habits of these long-necked, large-bodied vegetarians. [...] [...] sauropod dinosaurs hold their heads? It is a simple question, but for years it has been part of an ongoing controversy about the evolution and habits of these long-necked, large-bodied vegetarians. [...]

]]> By: The Sauropod Posture Debate, Part Eleventy | Dinosaur Tracking http://blogs.smithsonianmag.com/dinosaur/2009/04/did-sauropods-hold-their-heads-high/comment-page-1/#comment-617 The Sauropod Posture Debate, Part Eleventy | Dinosaur Tracking Mon, 01 Jun 2009 14:19:25 +0000 http://blogs.smithsonianmag.com/dinosaur/?p=1148#comment-617 [...] have been debating their posture for years. Indeed, last month a short communication in Science suggested that the ancient giants held their heads low to the ground, but a new paper published in Acta [...] [...] have been debating their posture for years. Indeed, last month a short communication in Science suggested that the ancient giants held their heads low to the ground, but a new paper published in Acta [...]

]]> By: Roger Seymour http://blogs.smithsonianmag.com/dinosaur/2009/04/did-sauropods-hold-their-heads-high/comment-page-1/#comment-555 Roger Seymour Sat, 02 May 2009 08:31:51 +0000 http://blogs.smithsonianmag.com/dinosaur/?p=1148#comment-555 Steve, The upward sloping vertebrae in Brachiosaurus and others has a simple explanation other than to 'aim' the neck upwards. Because the work of the heart is related to the absolute distance between the heart and the head, by raising the chest on long front legs, the animal could reach higher without getting into cardiovascular problems. The giraffe does this. It raises its heart on legs so long that it is difficult for them to drink. The giraffe neck is about 2 meters above the heart. This is about the distance in large bipedal tyrannosaurs too. I suggest reading the Science note and a longer paper in Biology Letters to learn that to raise the head 9 meters above the heart would have cost the sauropods about half of their food energy. Steve,
The upward sloping vertebrae in Brachiosaurus and others has a simple explanation other than to ‘aim’ the neck upwards. Because the work of the heart is related to the absolute distance between the heart and the head, by raising the chest on long front legs, the animal could reach higher without getting into cardiovascular problems. The giraffe does this. It raises its heart on legs so long that it is difficult for them to drink. The giraffe neck is about 2 meters above the heart. This is about the distance in large bipedal tyrannosaurs too.
I suggest reading the Science note and a longer paper in Biology Letters to learn that to raise the head 9 meters above the heart would have cost the sauropods about half of their food energy.

]]> By: Steve http://blogs.smithsonianmag.com/dinosaur/2009/04/did-sauropods-hold-their-heads-high/comment-page-1/#comment-516 Steve Fri, 17 Apr 2009 10:46:00 +0000 http://blogs.smithsonianmag.com/dinosaur/?p=1148#comment-516 Hi Zach, the point I was trying to get across was that the sauropods with steeply inclined backs and long straight necks don’t look comfortable in a low browsing pose. Look at this image I knocked together. It’s traced from Scott Hartman skeletal reconstruction of Mamecnhisaurus Youngi. The straight neck is articulated in the neutral pose, as it is in Scott’s reconstruction. The bottom neck is it showing its neck at heart level. Now, I don’t know how flexible the neck is, so the way I have posed it could be wrong, (I didn’t try and get it precise, I did it quickly) but to me it looks awkward. It could be that the base of neck is more flexible that what I have shown and it wouldn’t look as weird. http://i208.photobucket.com/albums/bb186/Steveoc_86/mamenchisaurus_youngi_hartman_NECKc.jpg Hi Zach, the point I was trying to get across was that the sauropods with steeply inclined backs and long straight necks don’t look comfortable in a low browsing pose. Look at this image I knocked together. It’s traced from Scott Hartman skeletal reconstruction of Mamecnhisaurus Youngi. The straight neck is articulated in the neutral pose, as it is in Scott’s reconstruction. The bottom neck is it showing its neck at heart level. Now, I don’t know how flexible the neck is, so the way I have posed it could be wrong, (I didn’t try and get it precise, I did it quickly) but to me it looks awkward. It could be that the base of neck is more flexible that what I have shown and it wouldn’t look as weird.

http://i208.photobucket.com/albums/bb186/Steveoc_86/mamenchisaurus_youngi_hartman_NECKc.jpg

]]> By: John http://blogs.smithsonianmag.com/dinosaur/2009/04/did-sauropods-hold-their-heads-high/comment-page-1/#comment-514 John Fri, 17 Apr 2009 02:00:12 +0000 http://blogs.smithsonianmag.com/dinosaur/?p=1148#comment-514 It would make sense that the sauropods would be able to hold their heads in a high vertical position because they used their tail as a defensive weapon. To be used in this fashion, the tail would have to be fully visible and therefore, the head would have to be elevated. It would make sense that the sauropods would be able to hold their heads in a high vertical position because they used their tail as a defensive weapon. To be used in this fashion, the tail would have to be fully visible and therefore, the head would have to be elevated.

]]> By: Zach Miller http://blogs.smithsonianmag.com/dinosaur/2009/04/did-sauropods-hold-their-heads-high/comment-page-1/#comment-513 Zach Miller Thu, 16 Apr 2009 22:22:24 +0000 http://blogs.smithsonianmag.com/dinosaur/?p=1148#comment-513 Steve, as long as sauropods kept their heads level with or below their hearts, they'd be fine. The higher body of Brachiosaurus would have allowed it to habitually graze on higher vegetation than its diplodocoid contemporaries. This would avoid competition and spur the evolution of a greater diversity of sauropods. It's not like these animals were forced to munch on plants at their toes. I'm sure there was a great many plants, all of which had different hights. Steve, as long as sauropods kept their heads level with or below their hearts, they’d be fine. The higher body of Brachiosaurus would have allowed it to habitually graze on higher vegetation than its diplodocoid contemporaries. This would avoid competition and spur the evolution of a greater diversity of sauropods. It’s not like these animals were forced to munch on plants at their toes. I’m sure there was a great many plants, all of which had different hights.

]]> By: Steve http://blogs.smithsonianmag.com/dinosaur/2009/04/did-sauropods-hold-their-heads-high/comment-page-1/#comment-506 Steve Wed, 15 Apr 2009 12:05:28 +0000 http://blogs.smithsonianmag.com/dinosaur/?p=1148#comment-506 I haven’t read the study in question, but the idea of all sauropods being low browsers ignores the anatomy of some of these animals. It ignores the variety of sauropod anatomy. I think the neutral posture can tell you something about these animals, like what they might be biased towards interims of foraging preference. Brachytrachelopan and Dicraeosaurus with their downward sloping backs and short necks seem to be biased towards low browsing. However a lot of the longer necked forms seem to be biased towards medium to higher browsing. They nearly all have horizontal and often upwardly inclined backs. Take Mamenchisaurus youngi, I strongly doubt it was primarily a low browser; its neck is inclined up nearly 40 degrees, in neutral position. (Check out Scott Hartmans restoration.) It doesn’t make any sense for that animal to evolve an upward inclined back and neck which is really long if it’s a primarily a low browser. Brachiosaurus is similar, why evolve an upward sloping back (with a shoulder height of nearly 6m!) if your munching on the ground?? Why not have a horizontal back, or a downward sloping back with a shorter, cheaper (in energy terms) neck? I haven’t read the study in question, but the idea of all sauropods being low browsers ignores the anatomy of some of these animals. It ignores the variety of sauropod anatomy. I think the neutral posture can tell you something about these animals, like what they might be biased towards interims of foraging preference. Brachytrachelopan and Dicraeosaurus with their downward sloping backs and short necks seem to be biased towards low browsing. However a lot of the longer necked forms seem to be biased towards medium to higher browsing. They nearly all have horizontal and often upwardly inclined backs. Take Mamenchisaurus youngi, I strongly doubt it was primarily a low browser; its neck is inclined up nearly 40 degrees, in neutral position. (Check out Scott Hartmans restoration.) It doesn’t make any sense for that animal to evolve an upward inclined back and neck which is really long if it’s a primarily a low browser. Brachiosaurus is similar, why evolve an upward sloping back (with a shoulder height of nearly 6m!) if your munching on the ground?? Why not have a horizontal back, or a downward sloping back with a shorter, cheaper (in energy terms) neck?

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