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Re: surface/volume ratio and water loss in smallest amniotes

This is a research project that is begging to be done.

Many eons ago, I measured the water loss from a leopard frog, using a 
high-precision electronic scale.  He was very cooperative, which allowed a 
precision down to 0.0001 grams.
The largest abount of error was introduced by his breathing pattern....which 
modulated his weight around +/-0.1 grams per breath cycle.

With pteros, you won't have to worry about your subject breathing, but your 
biggest unknown will be the gas-exchange characteristics of ptero skin.  You 
could model a variety of different skin characteristics to get a range of 

All-in-all, a very do-able project.


---------- Original Message ----------
From: David Peters <davidpeters@att.net>
To: Jocelyn Falconnet <j.falconnet@gmail.com>
Cc: dinosaur mailing list <dinosaur@usc.edu>
Subject: Re: surface/volume ratio and water loss in smallest amniotes
Date: Wed, 10 Feb 2010 07:54:00 -0800 (PST)

Wingspan is one way to measure. That's surface area.

I was considering standing height and volume which is more consistent across 
the three smallest flyers.

Question is: Whether or not the smallest pterosaurs were adults or hatchlings, 
if they were in the airstream, were they evaporating at a dangerous rate?

David Peters


--- On Wed, 2/10/10, Jocelyn Falconnet <j.falconnet@gmail.com> wrote:

> From: Jocelyn Falconnet <j.falconnet@gmail.com>
> Subject: Re: surface/volume ratio and water loss in smallest amniotes
> To: davidpeters@att.net
> Cc: "dinosaur mailing list" <dinosaur@usc.edu>
> Date: Wednesday, February 10, 2010, 9:00 AM
> Not so consitent, David
> (wingspan/length):
> Birds => 6,5/5 cm for *Mellisuga helenae*, the Bee
> Hummingbird
> Bats => 16/3 cm for *Craseonycteris thonglongyai*, the
> Kitti's
> Hog-nosed Bat or Bumblebee Bat
> Pterosaur => 25/7 cm for *Nemicolopterus crypticus*
> (length estimated
> after a composite reconstruction by John Conway).
> Note also that:
> 1. The Bumblebee Bat is one of the main compettitors for
> the title of
> the world's smallest mammal with the longer but lighter -
> terrestrial
> - Etruscan Shrew.
> 2. The holotype of *Nemicolopterus* may be a juvenile
> *Sinopterus*
> according to Darren Naish (see Tetrapod Zoology).
> 3. *Nemicolopterus*, if an adult, is quite larger than the
> others
> (especially the wingspan).
> 4. Be small is not a problem at all for winged insects, so
> if there is
> indeed a relation between flight and lower size limit in
> amniotes, it
> should thus be inherent to the animal (metabolism,
> physiology,
> anatomy, reproduction, ...) rather than to flying weather
> conditions.
> 2010/2/10 David Peters <davidpeters@att.net>:
> > Speaking of 2/3, 3/4...
> >
> > I ran across this article and a few others like it
> that describe the world's smallest extant amniotes and their
> desiccation troubles whenever removed from their moist leaf
> litter environments.
> >
> > On a similar note, there seems to be a lower size
limit (for adults) for pterosaurs, birds and bats that's
> pretty consistent even though each has different 'surface'
> characteristics. Anyone know of any papers along these
> lines?
> >
> > Would the lack of smaller birds/bats/pterosaurs be
> more of a flight problem (too small for windy conditions or
> incoming rain drops)?
> >
> > Or a water-loss problem?
> >
> > Baby bats have smaller wings, but embryo pteros do
> not, as we know.
> >
> > Ref below
> >
> > David Peters
> >
> > Caribbean Journal of Science, Vol. 37, No. 3-4,
> 168–173, 2001
> > At the Lower Size Limit in Amniote Vertebrates: A New
> Diminutive
> > Lizard from the West Indies
> -- 
> Jocelyn Falconnet

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