Reddit reviews Dinosaur Origami (Dover Origami Papercraft)

Depends on how much experience you have I suppose...

I found a lot of John Montroll's books to be beginner-friendly, with one or two models aimed at more intermediate levels. I had a real soft spot for his dinosaur book.

Moving up a tier, maybe works of Hideo Komatsu? Satoshi Kamiya's books are always good too.

If you're feeling up to it, Shuki Kato's Nature Study book has some impressive looking models, but working through them makes me depressed on accounts of them being insanely difficult to fold.

Thanks! They're from this book, which my friend borrowed for me at our local library!