Discuss the difficulties experienced in classifying extinct organisms.

The number of fossils found, the fact that fossils are oftentimes just a cast/mold of the organism with no real remains, and no interbreeding.

As time moves forward, we still strive towards better methods to answer questions about extinct organisms.

Little or no DNA available.
Lack of morphological features in the case of invertebrates

Ithink its c hope it : )