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Sauropod Upright Feeding

On 12/21/03, Dan Pigdon wrote:

<<All it had to do was reach up momentarily, grab a branch, and 
tearit off. Then it could feed at its leasure with its head at a more
comfortable lower height. Elephants also do this. Why pluck leaves
individually from up high when you can simply rip off a whole branch -
or knock down the tree entirely - and feed more comfortably?>>

On the contrary, why go to the trouble and energy expense of tearing off a 
whole branch when it would be less time-consuming (and energy efficient) to 
your head (read food collecting apparatus) closest to the source most of the 
time, biting off only the most nutritious plant structures (leaves/leaflets) 
from a foliage mass? Even if you could tear down a whole branch elephant-style, 
there would be a lot of non edible material that would make this an 
inefficient gathering strategy. I doubt very much that sauropods went around 
down trees--a lot of possible food trees may have produced their foliage 
intermittantly in seasonally wet/dry climates like the Morrison's; destroying 
trees is a bad idea if they're your primary food source. Elephants usually do 
this in the process of harvesting items which they can't easily get to (like 
baobab bark and twigs), which would have been no problem for a sauropod.  Adult 
macronarians like Brachiosaurus and Camarasaurus had mouths that could 
probably hold somewhere in the order of 1 1/2--2 bushels of foliage per 
mouthful, and 
were cropping off more than a matter of a few leaves with each bite. The 
shelf wear on camarasaurid teeth shows there was sometimes a tearing motion 
involved in foliage cropping, but I think this would be limited to tearing off 
clumps of leaves in an arboreal context. Diplodocids certainly wouldn't adopt a 
branch tearing strategy, since their delicate pencil-like teeth would have 
off from side-shear forces.   

<I've always thought that it would have been handy for diplodocids to
have prehensile tail tips. Then they could use the tail to tear down
branches without ever having to raise their heads (regardless of 
whether they were capable of doing so or not).>

No comment....

--Mark Hallett