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Re: On rearing in sauropods





Waylon Rowley schrieb:
> A sauropod neck leaves ample room for such 'second heart' cavities, and arterial walls
> are muscular anyways. Evidence? None, sadly!


Since you're speculating, what about this:

Not only are there 'auxilliary hearts', but also lungs. The pneumatic spaces in the cervical vertebrae are covered in respiratory epithelia, with a rich supply of arterial and veinous blood running through it, like a simple lung (lungfish-like), but unpowered. So, as deoxygenated blood flows away from the brain, it gets reoxygenated (partly) in the neck, then shunted into the arterial vessels leading back up to the brain....it doesn't need to travel up the entire neck, reducing pressure demands on the heart. Maybe sauropods could temporarily created a closed loop high up on the head and neck, allowing them to raise the neck suddenly. Thoughts?
This idea - neck = second lung - did indeed crop up in several debates in Bonn. However, we are totally unsure about how much these air sacs were ventilated, leaving the oxygen content in them open for discussion. An interesting model, in any case :)

--
Dr. Heinrich Mallison
Museum fÃr Naturkunde - Leibniz-Institut fÃr Evolutions- und
BiodiversitÃtsforschung an der Humboldt-UniversitÃt zu Berlin
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10115 Berlin


Tel: +49(0)30-2093-8764 Email: heinrich.mallison@mfn-berlin.de