As to the question whether species aged at all before 4000 BC: I don't think that we've ever found an arthritic dinosaur fossil (if I'd ask a paleontologist he'd probably had a good laugh). In nature, aging leads to the animal becoming weaker and more likely to be killed. I don't think that many animals die of old-age diseases in nature.

Could dinosaurs have been immortal?

I think not even creationists go so far to claim this. Bone growth rings indicate that the most long-lived dinosaurs had a life span of 100 years. If there were immortal dinosaurs, we had likely found fossils with 1000 or even more growth rings on bones. Anyway there are a lot of very old species still living - for instance, sharks go back 400 MYA - and we know definitely that they age.

So, aging is still not explained by creationism.

As to offered prizes like a million dollars for creating life in a lab: Well, maybe someone claims this prize some day, who knows? I, jcl, herewith solemnly promise to pay a prize of one A6, A7, and A99 Pro Edition to anyone who can prove that a species was placed on earth by a God. Just contact me with the proof to claim the prize...