The biological species concept cannot be applied to fossils. Which alternate approach to identifying species would be most useful for classifying fossil organisms?

The phylogenetic species concept.

Explanation:

The biological species concept states that a species is a group of individuals that can breed together, that is a group of individuals reproductively isolated from other groups of individuals. According to this concept it is impossible to classify fossils since fossils are just traces of any once-living organism (no longer alive). However in order to classify taxonomically fossils, the phylogenetic species concept can be used.

The phylogenetic species concept, which is not based on breeding but in evolutionary relationships. If a fossil group share a common ancestor and are evolutionarily distinct from all other groups, the group then recognized as a species. Morphological and / or genetic analysis of fossils are used to determine the evolutionary relationships and establish if te group is or is not a species.