Heck, how to classify even existing living and breathing specimens is not always clear. Genetic sequencing has resolved some, but not all, such questions.
Fundamentally, there is no obvious and unambiguous definition of "species". It is a functional definition that is highly useful, but it is not exactly predictive is every case under the sun. There will always be confusion on the margins, because the natural world is sometimes messy that way.
Fundamentally, there is no obvious and unambiguous definition of "species". It is a functional definition that is highly useful, but it is not exactly predictive is every case under the sun. There will always be confusion on the margins, because the natural world is sometimes messy that way.