Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:6406682.

No supports needed. I used 3 perimeters to ensure the hinges are strong, this is much preferred over trying to obtain strength through infill. If you use too high infill, the model may become poorly balanced due to the head being too heavy. If you want to improve stability, use a higher infill for the piece with the legs if you can.

This should move freely right after you take it off the build plate. If you print with hairspray on a glass bed, the Rex may spontaneously jump into a random pose all by itself when it pops off the plate after cooling down. If you need to use force to free the hinges, you still have some optimization work to do on your printing technique.

This is not a demanding print. If this is one of the first things you're printing and it fails, expect other things to fail as well.