These are all looking pretty good, but I think you're concentrating too much on the contours, and not enough on the underpinning structure: skeleton, muscular system etc. With a little practice in those areas, your art skills could really take off to new heights. But good stuff over all. Keep at it. Peace.
you're concentrating too much on those contours, esp. in the life drawing, when you're doodleing from life, how many pencils are you using and what kinda paper are you drawing on? nowadays when i'm doing so i don't use less than 3 pencils and i usually draw on rives BFK printmaking paper.
who do you look at as inspiration for your concepts?? if you haven't checked him out i'd recommend Yoshitaka Amano of Final Fantasy fame... he draws some really slick reptiles...
true.. im trying to work on anatomy lately..im just using regular cheap sketchbook paper.. im using a brush pen and a water-soluble pencil... seen amano's stuff but never reptiles, hmm ill check them out