Regarding the subject of dinosaurs, the bible is rather limited in the information it provides. This question has been the subject of much scientific research and speculation.

Some believe that dinosaurs became extinct long before man appeared on the earth. Others claim that dinosaurs were included as part of the creation of sea creatures, birds and land animals on the 4th and 5th days of creation found in Genesis chapter 1. If this is true, it would mean dinosaurs existed at the time Adam and Eve were created. Some believe this is exactly what took place and they teach that dinosaurs existed right up to the time of the flood but that the flood destroyed them all. Some point to Job chapter 40 and 41 and say that these chapters present a description of dinosaurs. If these are descriptions of dinosaurs, then some species of dinosaurs must have survived the flood. If dinosaurs did survive, how did Noah get them onto the ark? Some Christians teach that Noah may have carried both male and female baby dinosaurs onto the ark with him. This would have made it possible for dinosaurs to continue their existence after the flood and would account for the creatures described in Job chapter 40 and 41.

Christians and secular scientists don’t agree on much of anything but one thing they seem to agree on is that this earth experienced a worldwide catastrophic event that destroyed much of the life that existed on the earth. Christians point to the flood of Genesis as the source of this catastrophic event while secular scientist’s wrestle with a variety of different theories. Many bible scholars and teachers believe the bible shows that the Genesis flood caused a dramatic change in the climate and environment, which made conditions less favorable for life. If dinosaurs did survive the flood, it is speculated that the change in environmental conditions led to their ultimate demise. It can be clearly seen in scripture that the change in conditions caused a dramatic decrease in the lifespan of man.

God's Word tells us the following:

a] The flood of Genesis occurred and it was a worldwide catastrophic event.

Genesis 7:18-23
18)    The waters prevailed and greatly increased on the earth, and the ark moved about on the surface of the waters.
19)    And the waters prevailed exceedingly on the earth, and all the high hills under the whole heaven were covered.
20)    The waters prevailed fifteen cubits upward, and the mountains were covered.
21)    And all flesh died that moved on the earth: birds and cattle and beasts and every creeping thing that creeps on the earth, and every man.
22)    All in whose nostrils was the breath of the spirit of life, all that was on the dry land, died.
23)    So He destroyed all living things which were on the face of the ground: both man and cattle, creeping thing and bird of the air. They were destroyed from the earth.

b] Prior to the flood the lifespan of man was long with many living in excess of 500 years. Read Genesis chapter 5 for an example of lifespan prior to the flood.

c] Following the flood, we see the lifespan of man becoming shorter and shorter. Read Genesis Chapter 11 for an example of the decreasing lifespan following the flood.

Many believe that if the flood caused a significant change in the environment, this change may be the event that affected dinosaurs and made it impossible for them to continue to reproduce and exist.

In summary:
Everything I have presented contains speculation, which only seems to lead to more speculation. If you want to do further research on this subject, the following books serve as excellent sources of information.

1] Unlocking the Mysteries of Creation Dennis R. Peterson
2] Scientific Creationism Henry M. Morris
3] The Genesis Record Henry M. Morris

As I search through all of the speculation I come to the place where I ask myself the question, even though I am curious to know more about the subject, how important is it for me to understand exactly what happened to the dinosaurs? I believe that God's Word is an excellent tool for determining that which I should focus my time and attention upon. When I look at the bible, I see certain themes and subjects emphasized on a continual basis. In comparison to what is presented regarding dinosaurs, God's Word devotes much more attention to the subject of how I should live, love God and love my neighbor and how I should strive to fulfill the great commission, just to name a few. If God has given more attention to these areas, shouldn’t I do the same?