Reptilian Anatomy 101

I'm sure that "Reptoids" are sort of taboo to most, but there are a few who actually believe that ETs are reptilian in nature. I've noticed that a lot of research into the mythology of reptilian beings throughout different cultures have been used as reference evidence, but I haven't really noticed anyone taking much time to examine the hypothetical anatomy and physiology of such a creature, so I thought I'd take a shot.

I'll probably post more later, as is my tendency to analyse things at my leisure over an extended period of time. I just wanted to point something out real quick (and feel free to correct me if I'm wrong, I'm no expert):

To the best of my knowledge, reptiles and mammals have very different spines.

Every reptile that I have ever seen has had a spine that moves from side to side, with a very limited range of movement for bending forward and backwards.

Here's a picture of what I mean (it's not the best illustration, I know):
www-geology.ucdavis.edu...

A mammalian spine, however, moves quite differently than that of a reptile, fish, or amphibian. Instead of curving laterally, a mammal's spine has a dorsal curve... Visualize the way a catepillar moves.

Picture of a cheetah running:
www.millworldwide.com...

As far as I've read, speculation of "Dinosauroids" like what paleontologist Dale Russell concocted never included the modification of a spine. I think that the reason bipedal dinosaurs, such as velosoraptor, never stood fully upright is because of the limitations of their spines. They may have walked on two feet, but the spines stubbornly refused to leave the age of the fish.

Unless the spine is modified to the likeness of a human spine, a reptilian-humanoid would have very stiff, inefficient movements. Imagine being a reptoid with a lateral bending spine trying to tie your shoe-laces.