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Re:prolacertiformes as arboreal leapers,.



At 06.28 23/03/01 -0500, you wrote:
>>>
>>If we accept that Protorosaurus and Prolacerta were primitive
>>prolacertiforms, then they do not look arboreal.
>
>
>I`m not sure I follow the logic here. (Why does "If we accept that they were
>primitive prolacertiformes..."precede they don`t look arboreal???

Problems with language ...sorry.  Anyway,  with "if we accept" I meant that
someone (e. g., Dilkes, 1998) does not consider them as true
prolacertiforms. It was only a premise. 

>At any rate, they do look so to me. 
In general body plan, they appear quite
>lizardlike, and lizards can climb quite well. The divergent toes might have
>been quite capable of grasping cycad bark, and might have been a "specialty"
>for climbing along Cycad branches along the midrib.

True, I have no difficulty to accept that they can climb or stay on
branches like iguanas or many other reptiles;
 what I was meaning was that IMHO there are no skeletal peculiarities of
adept climbers like chameleons, Longisquama or, I would add,
drepanosaurids. The scapula in Macrocnemus and in Langobardisaurus is very
low, unguals are not those of a climber etc. etc.

>surely they must have had smaller family members, that cou;ld have
>been strictly arboreal?? ...(and of course, the smaller representatives are
>less likely to get preserved, especially in an arboreal
>enviornment...unfortunately).
 
the little Cosesaurus  may be the best candidate. I imagine (speculation)
something like this: prolacertiform are primitively terrestrial but then
highly variable and  some advanced and small forms become semi bipedal
runners in some cases and other may have been arboreal, then come
pterosaurs(?) . 
>
>>The mighty Tanystropheus is a weird animal indeed, and very difficult to
>>categorize concerning mode of life.
>
 
>Tanystropheus,....could it have been vegetarian?? Perhaps it`s habit was to
>"climb" up a trunk with it`s forelegs,keeping it`s feet on the ground in a
>bipedal stance, and chest against the trunk in order to reach whatever
>foliage it could with that long neck? 

A sort of gerenuk (giraffe antelope)?
 Nice, but if there is anything **I will put my hand on fire for** is that
Tanystropheus was a carnivore. Teeth are undoubtedly those of a carnivore,
especially in the adult. Conical, sharp and interlocking each others at the
tip of the snout like a  nothosaur. Rupert Wild (1973) suggested a diet of
cephalopods because hooklets of belemnoids(?) were found in the belly area
of some specimens.

                                  Silvio Renesto
-

"Before being enlightened,   hard work; after enlightenment, hard work"
(Guo Yunshen).

Dr. Silvio Renesto
Dipartimento di Scienze della Terra
Università degli Studi di Milano
via Mangiagalli 34
I 20133 Milano
Italy

phone +39-0223698232
fax  +39-02-70638261

e-mail:    renesto@mailserver.unimi.it

or/and     Silvio.Renesto@unimi.it