“How does one reproductive system evolve into another, as with amphibians to reptiles?”
Even more ridiculous......dinosaurs to birds.
Dinosaurs were cold-blooded, dense-boned and had no sound producing organ.
Birds are warm-blooded, hollow-boned and have a sound-producing organ.
Wrong, wrong and wrong. (Although I'm not quite sure what you mean by "sound producing organ". Birds don't have any special "sound producing organ" apart from what any other terrestrial vertebrate has.)
To just focus on your error about dense bones. Not only did many dinosaurs have hollow bones, for a genus described last year, there is specific evidence that these bones possessed the same special respiratory function they (otherwise uniquely) do in birds! Full article is online at the link:
Sereno PC, Martinez RN, Wilson JA, Varricchio DJ, Alcober OA, et al. (2008) Evidence for Avian Intrathoracic Air Sacs in a New Predatory Dinosaur from Argentina. PLoS ONE 3(9): e3303.
In this YouTube video you can see one of the authors holding one of the hollow bones.
The following figure from the article shows some of the pneumatopores (where the air sacs entered the bones) in the fossils from this dinosaur, which btw is named Aerosteon, Greek for "air bone":
So, we find a very specialized adaptation, otherwise utterly unique to birds, in a group of dinosaurs which were previously identified (about 150 years ago, btw) as closest to modern birds. Coincidence? For creationists, I suppose it has to be.
“Dinosaurs were cold-blooded, dense-boned and had no sound producing organ.
Birds are warm-blooded, hollow-boned and have a sound-producing organ.”
That is incorrect. Dinosaurs are characterized by being warm-blooded. [Regular reptiles like the ancestors of crocodiles were indeed cold-blooded and are not called dinosaurs.]
T. Rex had a high metabolic rate and moved like birds. They were big, strong and fast. Many dinosaurs had feathers that were mostly used to preserve internally generated warmth. Their descendants are birds.
Feathers and fur would be useless for cold-blooded animals; their skin must be naked so they can absorb externally generated warmth. Their descendants are lizards.
Accepting this does not mean that Jesus did not die for your sins.