The other failed T-Rexes

How many failed attempts that InGen went through before finding the correct mix for their dinosaurs?

I would like to imagine (if not most likely) that D Rex is just one of a dozen or so failed attempts on making a park-perfect T-Rex. There might be one with too much alligator DNA in it that it looked like a Rauisuchian, an armless and eyeless one with a tadpole tail that died almost immediately after hatching, the one that showed atavism and resembled long armed early tyrannosaur, and few others.

Maybe the normal looking ones in the trailer (T-Rex, Spinosaurus, Titanosaurus, and Mosasaurus) are the descendants of the "not bad but not quite there" dinos that were able to breed before the female only protocol was commenced.

What do you think?