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Sauropod head-neck complexes

I have explained why sauropod head mouth-complexes were large enough to feed
a mammalian rate of food consumption, but do not show they had the same.
However, it occured to me that I should not leave things there, because the
complete head-neck complex of sauropods IS most compatible with high
metabolic rates.

In 1980 Russell et al suggested that the sauropod head-neck complex was
comparable in function to the fingers-trunk complex of elephants. This
comparison seems valid. Russell concluded that the feeding power of sauropods
was comparable to that of much smaller elephants. This does not make sense,
because the head-necks of all but the smallest sauropods were obviously many
times larger and more powerful than the trunks of elephants. If anything, in
this view the feeding power of sauropods was greater than that of elephants. 

If a 50 tonne sauropod had a reptilian metabolisms, then it would have had to
eat only about 50-100 kg of food each day, or just a fraction of a percent of
their body mass each day. It is hard to explain why sauropods would have
evolved such extremely tall, powerful head-neck complexes in order to eat
such modest amounts. A tachyaerobic (what most call 
endothermic) sauropod would have to eat about ten times as much. In this case
evolving an extremely tall, strong feeding apparatus makes a whole lot of
sense, in part because it allows access to a whole new resource base. 

The big head-neck complex of sauropods is therefore positive evidence for
high rates of food consumption above those expected in giant reptiles. It is
not definitive, but it sure tells us a lot more about sauropod metabolics
than respiratory turbinates ever will!