Shading for a realistic Brachiosaurus

[Mirco]

Hi all!
In the last days i'm started the shading for my brachiosaurus in xsi(showed in the attached in his first rendering test)
http://img375.imageshack.us/img375/5786/11kv9.th.jpg (http://img375.imageshack.us/my.php?image=11kv9.jpg)

I would like to know where I can find more informations to help me with shading settings for a realistic skin of this type(dinosaur,animal like elephant....)
I usually work with a setting of this kind:
http://img78.imageshack.us/img78/4642/immaginejh6.th.jpg (http://img78.imageshack.us/my.php?image=immaginejh6.jpg)


I have many doubts because i'm in a difficoult to find informations on shading of organic creatures for XSI with mental ray.

I would like to know some techniques to set the render tree for a realistic rendering ...I've some video tutorial on render tree and shading with XSI but they aren't specific for creatures and they don't explain in depth the function of all nodes....
CAn you help ne to find some tutorial on shading for creatures please?
Thanks!!!!

P.S. Sorry for my bad english but i'm italian...

Mirco Paolini