When puppies are born, they actually look a lot like toothless blind gophers…
They do not have complete joint formation. The bones and joints are actually not mature until after two years of age. At birth, everything is soft and squishy – otherwise labor & delivery would be a lot harder on both the mother and puppies. You can view some xrays of puppies at one day of age, 8 weeks and 20 weeks here.
Newborn puppies are able to scoot on their bellies, navigating by scent. They have claws for traction. Their ears and eyes are not open yet. Some noses, foot pads and eye rims will be pink, and will turn black gradually over the next four months.
It is not possible to determine the bite on a very young puppy – first, the puppy’s mouth is formed for drinking the mother’s milk, and gradually grows into a more normal shape over the next few weeks. The cranium/upper jaw and the lower jaw do not always grow in unison, so at times during the first 9 months puppies may appear to have a slight overbite. This usually corrects itself.
Ideally, eyes begin to open between the 10th and 14th day. It is a gradual process. Ears open slightly after the eyes. At two weeks of age, puppies still primarily navigate by scent, but are beginning to hear their mother approach as well.
One thing that I have learned to look for during puppy development, and this is a ‘hillbilly’ criteria, is whether they can lift their bellies and stumble around by the time they are two weeks old. If they cannot, this could possibly indicate genetically poor development of the bones and joints (still just cartilage where they connect).