The pup is resource guarding which requires a lot of training to change the behavior. Feed them separately, remove all toys and treats from the floor and place their fav toys or treats in the crate with them.
First exercise:
Keep other dog away while you do this.
Hand feed the dog. Feed the dog bits of food at a time so he knows that you are the one that gives the food. I would do this exercise for at least 5 days.
Second exercise:
Keep other dog away while you do this.
While the dog is in sit, fix the food and let him watch. Do not completely fill the bowl. Place the bowl on the floor. Give the dog permission to eat with the word "eat" or point your finger at the food and snap your fingers. I do both with Titan. I say, "eat", and point my finger at the food and snap my fingers.
Once the food is finished, bring the dog to sit and place a little more food into the bowl. Do this exercise for as long as it takes so the dog knows you provide the food and the dog stops the growling/showing teeth while it eats.
Third exercise:
You will need a gate or some type of barrier that the both dogs can see each. Put the gate in place and bring the other dog to the gate. Repeat the exercise with placing the food in the bowl while the other dog is outside of the gate. At any time if the dog growls or shows teeth tell him “no” in calm, stern voice. Bring the dog to sit and remove the food. When the dog is calm while the dog is still outside the gate, place the bowl back down. Repeat this exercise for as long as it takes.
Show the dog what you want them to do. Remain calm and assertive while doing these exercises. Do not show impatience or yell because the dog will feel your impatience causing them to shut down and stop listening. When you become impatient or frustrated, walk away and take some deep breaths. When you return, stand tall with shoulders back and begin again.
FYI: rawhides are not good chew toys because the pups cannot digest them. Make sure the rawhides are not made in China. With bones, make sure the bones are not weight-bearing bones because they can break pup's teeth.
I, personally, had a pup die from a rawhide that lodged in this digestive tract.