Why the focus on dinosaurs? What about trilobites? They existed even before dinosaurs and became extinct before dinosaurs did. What about Anomalacaris?
http://www.trilobites.info/gallery2.html
And do you have any idea how many different species of dinosaurs there were?
There was lots of extinction of many kinds of plant and animal life before humanity existed. That is simply a fact. Remember, theology does not get to say what reality is. God determines reality; theology is a believers' response to that reality. Denying the reality is not doing theology. It is calling God a liar.
What is an appropriate theological response to the fact of death before human existence? There are several. One is that death was not a curse until it was entangled with sin. Another is that the death associated with the fall is spiritual and not relevant to animal death. After all, Adam did not literally die physically in the day he ate the fruit. He lived, according to the text, another 930 years. But he did, immediately, die spiritually, for now he was cut off from God.
Here is still a third take on the theological possibilities.
http://www.asa3.org/asa/PSCF/2006/PSCF6-06Phillips.pdf