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Re: What did Spinosaurus eat? New species of Lepidotes found

On 3/3/2011 6:37 PM, Augusto Haro wrote:

As far as I know, sails are proportionally larger in the larger taxa
of some non therapsid synapsid groups (pelycosaurs), supporting your
viewpoint. There are, however, "pelycosaurs" without sails which are
much larger than the largest ones with sails.

Yes. Adopting temporarily the assumption that sails served to dump heat, I would expect a lifestyle wherein the main body was usually immersed in warm water and size was an advantage. The thermal conductance of water being much higher than air, a vascularized flat plate sticking up in the breeze to take advantage of evaporative cooling would allow for a larger body w/out overheating.

That would in turn predict that the larger sail-less pelycosaurs were more terrestrial in their habits, and/or lived in climates where the water temps were lower.

I am a little skeptical of the "sail as heat absorber" btw, just because in my experience flat plates w/out insulation make crappy solar collectors (even with liquid tubes), especially when wet, only working well on hot days :).

2011/3/3 David Marjanovic<david.marjanovic@gmx.at>:

>  No, really, there's no evidence for a hump. There just happen not to be any
>  mammals with a sail,

What about the African Elephant? Granted, it's "double-sails" are not based on elongated spines, but they still serve as informative functional analogs. They also serve as communication and display devices in real-time (isn't multi-function the way these things always are?), but the correlations between ear size, body size and climate seem clear in the mammoth to Indian to African spectrum.