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Re: Resources, energetics and dinosaur maximal size

Jura schrieb:

 McNab goes further with this, by showing that a hypothetical sauropod
 with an "average lizard" metabolism (i.e. the metabolism of a sit and
 wait iguanian), would "need" to grow to 330 tonnes in order to
 consume the same ammount of calories as a large African elephant
 (_Loxodonta africanus_). That no sauropod comes close to this
 estimated size, suggests that sauropods had higher FMRs than this.

Fine so far...

 If they were given a mammalian
 metabolism, and concomitant FMR (as detailed in the paper) then a 56
 tonne _Brachiosaurus altithorax_ would have to digest some 561,000
 calories a day. This is asking a lot for plant productivity of any
 time period.

A 56-tonne *Brachiosaurus altithorax*? OK, a fifteen-tonne one might be too light despite all air sacs, given the reported existence of ten-tonne and apparently even thirteen-tonne elephants. So let's say twenty. OK, thirty. But fifty-six? In an individual that's not grossly obese? Seriously?

Never forget that Godzilla is right: size does matter.

 It is under this assumption that McNab posits that sauropods would
> have been unlikely to have sustained a mammalian level FMR.

The body masses, too, are assumptions.