I am an agnostic on the question. I must confess that I really don’t care whether animals were formed by evolutionary means or were “pure” creations of God. Such a question does not affect my belief in the Catholic faith in the slightest.
If God chose evolutionary means to form His creatures: Awesome! Through evolution, His wisdom is revealed by his beautiful direction of a natural process to spawn a multitude of different creatures.
If God chose to create His creatures directly: Excellent! His power and omnipotence is shown by His shaping of each individual creature.
Whatever method God chose to achieve the multiplicity of animals on earth, the doctrines of the Catholic Faith remain true in either case. God made man different from animals, gifting man specifically with reason, intellect, and free will, and sent His Son as a human being to redeem us from our sin - this does not change regardless of whether creationism or evolutionary theory is "true."
The question of evolution is of course interesting for scientists, who will (and should) continue to experiment to discover the method God used to achieve the multitude of animals on earth. But the question of whether or not animals were formed by evolutionary means is in some sense an immaterial question for Catholics, at least from a theological standpoint.