Re: Ceratonykus braincase described

[Jura <pristichampsus@yahoo.com>]

----- Original Message -----

> From: Tim Williams <tijawi@gmail.com>

> Extant myrmecophages are not cursorial, because the energy derived
> from a myrmecophagous diet does not permit high metabolic rates in
> mammals higher than 1 kg mass (McNab, 1984; J. Zool. Lond. 203:
> 485-510).  Termites have higher calorific value than ants, but still
> not great.

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Just a brief aside here: BMR says nothing about the aerobic capacity of an 
organism (e.g. Konarzewski et al 1997), despite the popularity of Bennett and 
Ruben's (1979) initial hypothesis. 

What seems to keep myrmecophages from being cursorial is the fact that an 
exclusive diet of ants and termites is exceedingly low in energy. One needs to 
eat a crap tonne of these guys to make it worthwhile and that requires a nice, 
capacious gut. It's that gut that seems to be in contention with a cursorial 
bauplan.


Jason


Bennett, A. and Ruben, J. 1979. Endothermy and Activity in Vertebrates. 
Science. Vol.206:649-654.


Konarzewski, M., Sadowski, B., Jozwik, I. 1997. Metabolic Correlates of 
Selection for Swim Stress-Induced Analgesia in Laboratory Mice. Am.J. 
Physiol.Regul.Integr.Comp.Physiol. Vol.273(42):R337–R343.