Only in the movies, and thanks for the ping.
I had read it before, but thoroughly enjoyed reading it again. Asking the questions remains far more important than knowing the answers. Without questions, there can be no answers. What we can be certain of however, are the final six words:
In our world, that can't happen.
The real question: If those kinds of sizes were such a winning ticket for creatures which supposedly dominated the planet for tens of millions of years.... then why in the 70,000,000 years which supposedly has passed since they went away, has nothing else ever re-evolved to such sizes? Evolving to different sizes should be fairly easy.