Re: Regarding Spinosaurus

["Adam Britton" <abritton@wmi.com.au>]

From: "Jura" <archosaur@reptilis.net>
Sent: Thursday, January 10, 2002 3:33 PM

>>>Furthermore all large reptiles lack any form of heat acquiring device.<<<

I can immediately think of two than may qualify. Green iguanas extend their
dewlap when they are below preferred body temperature and exposed to radiant
heat. While there may be some social function in doing this, it's clearly
increasing surface area. However, I don't know whether this provides
significant benefit, nor whether it's been looked at experimentally. What
has been tested, though, is the heat-acquiring potential of the dorsal
osteoderms of crocodilians. While they are not a significant extension of
their back in terms of surface area, they do function as solar panels, being
infused with blood vessels that transport warm blood to key parts of the
body more quickly.


>>> Furthermore many small tropical reptiles have developed a variety of
different means to avoid large thermal loss (e.g. shunting, burrowing and
selective sleeping positions, sociality) and rarely need any real long
"activation" period in the morning.<<<

Yes, but tropical species live in an environment which is typically (during
daylight hours at least) at least as warm as preferred body temperature.
Hence the relative abundance of nocturnal reptiles in the tropics. During
the day, most tropical reptiles spend far more time avoiding overheating
during daylight hours, rather than the other way around.

Adam Britton