Apatosaurus, having long legs, required bone structure in the neck and tail so as to manuver the neck and tail where as the type which it prototyped, being a belly crawler need none, the land surface supporting it's head and entire body. The similarities lie in the appearance of the dorsal, head and tail as previously noted.
The ribs in snakes attach to the thoracic vertebrae, just like in all tetrapods including apatosaurus. The neck and tail of snakes are actually very short, for example the tail vertebrae usually make up less than 20% of the overall length (and just to correct what I previously said, these vertebrae do not possess ribs). This shows that snakes evolved through the elongation of their body, not from an animal with a long neck and tail like Apatosaurus. Some species of snake retain remnants of the pelvis indicating how far along the body the legs were positioned.
Without legs, the snake skeleton must be flexible enough to allow movement for both locomotion and preparing to strike at prey. By contrast the Apatosaur neck only needs to hold its head up and, contrary to oil company logos or indeed 1920s movies, was fairly inflexible.
But it is amusing to see creationists fall back on some form of hyper-evolution to explain the shortfalls in their conjectures, whether its diversification of post flood 'kinds' or dinosaurs becoming snakes.