So while technically it's not my first sketch (it's my second), the first one was lost in a computer crash.

I wanted to get an idea of how the spine would continue into a tail, as well as where the tail would go and at what angle and stuff, since I'm sorta designing a cybernetic/prosthetic tail and wanted a way to visualize how/where it would go.

I would really, really like critique on this piece, even redlining. Please. Anatomy has always been my weakest point and I didn't have a ref for this or anything so I drew it completely from scratch.
I think the thigh is too log, and the head is totally butchered, but what else did I do wrong? All you real artists can probably tell me all the stuff I'm missing XD