This is the Flexi Rex split up into separate parts, intended for making really huge prints where the full model doesn't fit inside the printer.
This needs to be assembled with glue in a specific order. See the Post-printing section for instructions and an animation.
If you merely want to print this model at normal kids-hands-friendly-size scale that fits all printers, by all means use the original print-in-place model because for that one, your printer can do all the hard assembly work for you!
The parts are scaled 200% w.r.t. the original model but you'll probably want to further scale them up to the desired size. The head is the largest part, so use it as a reference if you really want to print as large as your printer can handle.
Given that this is intended to be printed big, you'll probably want to print this with your widest nozzle and thickest possible layers to save time. Do not rely on infill for strength, instead use many perimeters and top layers and the lowest infill that allows to properly seal the top layers. For the split pieces, you don't need many bottom layers because their only purpose is to be glued together.
You can opt to print the head in one piece or split in two like the rest. As shown in the assembly instructions, you need to start assembling with the head, which is why it can be printed as one piece. However if you want the model to have a uniform appearance without having to sand all the parts, you should also print the head in two pieces so it has the same top layer finish at both sides.
Supports shouldn't be needed except maybe for the axle of the hinge on the head, depending on how big you're printing this and how well your printer can bridge gaps.
For stability, use the lowest possible infill for the uppermost 4 pieces, especially the head. Given that most of the model is supported by the piece with the legs, you can maximize stability by making that piece heavier with extra infill and perhaps also the first tail piece behind it.
If you printed the head as one piece, one side will have a different finish than the other side and all other pieces because that side was laying on the print bed. To hide this and give all parts a uniform finish, you could sand their sides.
Order of assembly
Start with the head and piece 1a, then glue piece 1b on top. Then add 2a and glue 2b on top, and so on. Do not apply an excessive amount of glue all over the pieces, you don't want it to squirt out when pushing the parts together. Apply glue near the edges, not at the center. Make sure there is a good amount of glue on the end of the shackles. I would recommend epoxy or another glue that has a curing time longer than a few seconds. I wouldn't use super glue (cyanoacrylate), because if you don't get the alignment right immediately, you risk ending up with a deformed and unusable Rex…
After gluing, you may need to apply a bit of sanding to hide the seam.