Another straw that creationists might grasp at is the possibility that only a small sample of all living species made it onto the Ark, and the rest perished, all at once, in Noah's flood. Unfortunately, this has the same problems as noted previously. There are at least five mass extinctions in the geological record, not just one. And it also doesn't wash on Biblical grounds. Surely creationists would not dare to contradict their Holy Creationist Textbook.
Extinction makes perfect sense in light of evolution, however.
The dynamics of population growth, resource competition, adaptation, and environmental catastrophes all combine to create situations where some species are more vulnerable to extinction than others. The fossil record displays a relatively clear, chronological history of extinct species. In accord with evolution, these extinct fossils start to look more and more like modern forms of life the higher one goes in the geologic column. Extinction has helped produce the sheer complexity and diversity of life that we see today, because when species die, other animals occupy the vacant niches and evolve to adapt to the new environments. Mass extinction temporarily reduces diversity, but creates opportunities for radical innovation, such as new body plans or modes of life.