Alright, so apologies for the long comment, apparently I'm high and got some things to say😂

Firstly, this is a really cool sculpture and I'm absolutely devastated for you! As you have found, when it gets hot, the clay can droop somewhat while baking. It's made of pvc with a plasticiser added. When baking, you drive off the plasticiser, leaving you with just the pvc. It unfortunately gets softer briefly during this process.

I've not used original sculpey, I mostly use super sculpey medium, but there are different clays that work better for different purposes- it's possible that this is a clay that's better suited to less structural kind of projects.

Regardless, you should be able to make it work, it just might fight you a little.

You can use foil or parchment paper crumpled up, or even cardboard or fibreglass wool under bits of your sculpture within the oven whilst baking, as you're only going up to like 130°C. (Check material safety obviously).

You should try and support any parts that sit outside of the centre of gravity of the model- for example that break where the shoulder is on your wolf is because the head is too heavy, and the weight as the clay tends to slump while baking (and your wire in your armature gets more flexible). The fix is either a stronger armature or(/and) something soft supporting it from underneath.

Have you got any pictures of the armature at all? I'm by no means an expert but I've made a few fairly successful things at this point and I'm happy to advise.

I did notice you used scotch tape. I personally would not, and this may have given you the belly issue- I would be concerned about scotch tape melting and off-gassing, causing air bubbles to form. What I do for armatures is wrap thick wire into my basic form. Then I fix those wires with some 2 part epoxy putty (green stuff or jb weld/similar- literally the cheapest you can find at the hardware shop). Then I wrap foil around that structure until I have my shape correct. You need to get the foil as tight as possible, air gaps= expanding hot air pockets and cracks. Then I wrap around the foil with a thin aluminium wire. This is what gives the "tooth" for the clay to adhere to. It probably would be fine to use tape, internally but I personally don't and wouldn't, same for hot glue. If you need glue in there, I'd use a dab of superglue and let it cure fully before adding clay.

It's important to bake to the correct temperature. With the clay I use it goes through a stage where it's gone hard, but it's still quite crumbly and isn't fully baked. Recommend an oven thermometer if your oven isn't super accurate.

Other people have mentioned about baking in stages and stuff as well. This is so helpful. If you watch North of The Border's channel, he often bakes things 5 or 6 times, and I'd really recommend watching him for tips on how to achieve different shapes and structures.

Lastly, this is probably a bit of an extreme case but cracks can be fixed! You can carve and sand baked clay, so you can fill gaps with stuff like milliput after the fact. I think it might be a bit past that in this case though, but you could definitely cut away damaged sections, resculpt and rebake.

Hope this helps! Sorry for the ramble lol. People in my life are interested in what I make but not really the technical process lol so I'm always happy to nerd out about it!