Yeah, for sure I've always found Terryl Whitlatch's 'Animals: Real and Imagined' as my go-to book for animal anatomy. She has pages and pages of things like these, all drawn beautifully. There's also 'Science of Creature Design', it's got some good explanations, but the pages are much more bare bones than the previous.
And for really creative design the 'Monster Hunter Illustration' book have always had some great creatures inside them. I highly recommend
Anyway, I did some Metal studies last night. Thought I'd share!