Can you explain the human skeletal system to me?

OK, well, apparently there are no similar questions to mine so here goes.
I know babies have 300 bones in their bodies, and adults have 206. Why does this happen/Why is this so? Also, does this occur in other animals (less bones when they reach adulthood) such as dogs and cats and rabbits?

HINT HINT 10 points await the person who answers me best. Deadline: ASAP, or whenever question expires

would it be normal for a child who is just getting over diarrhea to have thin yellow stools?

is this just the process of getting normaaly formed stools again? He is also gtting pain after wiping,dont know from where.
thanks katy but does anyone know about the stools,my family say his stools are just starting to form again.is this right? I know in adults it can be bowel obstruction but…

Do babies and toddlers have all the digestive enzymes of adults?

Or does their digestive system mature at a certain age?
Thanks for the answers but could anyone enlighten me as to what age the digestive system would be as an adults with regards to the digestive enzymes involved please? As for the corn, it comes out pretty much as it went in with me and i’m no baby or toddler :-)