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Re: New findings Support Spinosaurus Sail as thermal regulator (My own theory)
Aygusto Haro wrote:
<Can they also function as "fixed dorsal fins"?
Or, if meatier at the base, give the body a piranha-like laterally
compressed profile, for whatever hydrodynamic reason?
Or to increase the mass of epaxial musculature useful in undulate swimming?>
Ronald Orenstein wrote:
<I gather that the sail is folded own during rapid swimming, so
steering may not be a likely function.>
I don't understand this argument. Is this implying a foldable sail in
*Spinosaurus aegyptiacus*, or just in billfish?
Further, is the first set of quotes suggesting some form of lateral
undulation? If so, the vertebral structure as described by von Stromer
does not indicate lateral undualtion would really be possible. A firm
adherence of vertebrae to one another, in the form of flattening
central articulations in the middle and posterior of the back braced
by narrow zygapophyses with subvertical facets would prevent such
mobility. There is some, it should be there to help distribute load
while walking, but to undulate as a means of locomotion, as in
crocodile sculling? Highly, highly improbable.
On Sun, Sep 14, 2014 at 9:06 PM, Ronald Orenstein
> I gather that the sail is folded own during rapid swimming, so steering may
> not be a likely function.
> Ronald Orenstein
> 1825 Shady Creek Court
> Mississauga, ON L5L 3W2
> From: Augusto Haro <firstname.lastname@example.org>
> To: Ronald Orenstein <email@example.com>
> Cc: "firstname.lastname@example.org" <email@example.com>; "DINOSAUR@usc.edu"
> Sent: Monday, September 15, 2014 11:38 AM
> Subject: Re: New findings Support Spinosaurus Sail as thermal regulator (My
> own theory)
> Can they also function as "fixed dorsal fins"?
> Or, if meatier at the base, give the body a piranha-like laterally compressed
> profile, for whatever hydrodynamic reason?
> Or to increase the mass of epaxial musculature useful in undulate swimming?
> However, I mostly bet on its fuction on display.
> Dr. Augusto Haro
> Museo de Paleontología
> Universidad Nacional de Córdoba
> Vélez Sársfield 249
> Córdoba, Argentina
> 2014-09-14 20:54 GMT-03:00 Dr Ronald Orenstein <firstname.lastname@example.org>:
> In living sailfish, from what little I have read on the subject, the sail may
> serve multiple functions, from sexual signaling and (possibly)
> thermoregulation to herding prey. The same could have been true in
> sail-bearing tetrapods - there is no reason to suppose that there is only one
> "right" explanation for their sails (any more than there is for bird wings),
> and the proximate cause of their evolution could have shifted as they grew
>>1825 Shady Creek Court
>>Canada L5L 3W2
>>> On Sep 15, 2014, at 7:05 AM, Dann Pigdon <email@example.com> wrote:
>>>> On Sun, Sep 14th, 2014 at 12:14 PM, Vlad Petnicki
>>>> <firstname.lastname@example.org> wrote:
>>>> I'll throw something out to the professional scientists out there that
>>>> dawned on me today:
>>>> The sail could not only have been added ballast, it may indeed have served
>>>> a heat regulatory
>>>> purpose. I think this is
>>>> rather than a hump - the easier to warm the blood that courses through the
>>>> vessels just under the
>>>> Think about this: Crocs need to get out of the water to sun themselves
>>>> (yes, I KNOW that
>>>> Spinosaurus was most likely NOT (as) cold-blooded as Crocs are), but
>>>> regardless of how
>>>> "warm-blooded" it was, if the water ever got too cold, the swimming/wading
>>>> Spinosaurus could
>>>> turn the sail towards the sun - and voila - thermal regulation that does
>>>> not require it to leave
>>>> the water.
>>> The problem with thermoregulatory explanations for dorsal sails is that
>>> often there were closely
>>> related species living in the same part of the world at the same time that
>>> lacked them completely.
>>> Large dorsal sails tend to be extremely rare amongst dinosaurs in general,
>>> and when they do occur
>>> it's usually in a species that is far from representative of their
>>> particular group (Ouranosaurus,
>>> Armargasaurus, Spinosaurus, etc).
>>> The various sizes and shapes of dorsal sails amongst the spinosauridae
>>> might suggest that species
>>> recognition was their main purpose. Spending a lot of time wading in deep
>>> water might have
>>> obscured other clues, such as differences in colouration or bodily
>>> proportions. Dorsal sails of
>>> different sizes and shapes (and perhaps colours) that stuck out of the
>>> water might have helped to
>>> advertise what species animals belonged to, allowing them to easily tell a
>>> potental ally (or mate)
>>> from a competitor.
>>> Dann Pigdon
>>> Spatial Data Analyst Australian Dinosaurs
>>> Melbourne, Australia http://home.alphalink.com.au/~dannj
Jaime A. Headden
The Bite Stuff: http://qilong.wordpress.com/
"Innocent, unbiased observation is a myth" - P. B. Medawar (1969)