How does one define a fossil to the species level when there is no genetic material??

Answer 1

"Species" in paleontology are defined following the classical Linnaeus biological system, ie. they are "morphotypes", with reference to type-specimens. We know from modern species what sort of range in morphology to expect within a species.

But the variation within a fossil species has an extra dimension to the range of variation within living populations - time. Often this is not such a big problem as many "species" have a fairly stable morphology through most of their existance. And new "species" tend to appear suddenly at any one locality, often accompanying a slight chance in the paleoenvironment (suggesting migration from an unseen isolated population, or very rapid evolution). The new species and the old species (which may go on existing) are usually easily distinguishable by some modified feature or features.

In other cases, the nature of the geological record, which only preserves a few environments at a time in any one region, can force time gaps in our observations. Perhaps artificially creating separate "species" (as sometimes when fossils from an intermediate stratigraphic level turn up in the basin it can be hard to attribute them one or the other species).

But in some cases, for example, among the planktonic microscopic fossil groups which are very abundant and used for time-correlation, assemblages may be nearly gradational over time from one range in morphology, to a completely different looking morphology. In this case, it is the use of the fossils that dicates how we "split" them in to species. eg. one "species" may be split from the other based on the presence of a certain feature, eg. a ridge. When that ridge first appears in the population, it may seem that it is just variation within a wider, inter-breeding population of the species. Only later may the whole population have that ridge. But splitting off all specimens with the ridge as a separate "species" (=morphotype) is useful as it allows tighter time-correlation.

Basically any species in paleontology is a practical approximation - an hypothesis. Usually fairly accurate, but at high resolution it can be fairly arbitrary.

Answer 2

A fossil species is defined by its appearance, differing from all other similar fossils. It is going to get real interesting in the near future when the new Phylocode classification becomes more popular, because the Phylocodists (to coin a term) haven't taken fossils into account. Because they use genetics in their work they won't be able realistically fit fossils into their system. Incidentally fossils as well as living organisms are placed into species, not as individuals, but as areally-continous groups, hence are (were) able to interact in some way. Isolation from a group speeds up the process of differential mutation (two isolated groups would not be expected to develop the same mutations over time), which is said to cause speciation.

Answer 3

Paleontologists use morphology--that is, a species's general appearance and anatomy--far, far more than they use genetics, precisely because genetic material is almost never available. They define a species as having a certain feature or set of features, and any other fossils sharing them is assigned to that species.

Answer 4

This is a chicken-egg type question. Speciation of fossils are defined by the morphological differences, e.g., the bone structure and arrangement.

This means that whenever paleontologists find a fossil with different bone structures, they'll tend to think that it's a different species.

Answer 5

You are struggling to find any genetic propertys after just a few hundred years, unless the specimen is perfectly preserved, {as in permafrost}..Its skeletal and dental structure that assigns a fossil {no, by fossil, i dont mean a southern senator!..Ohh. i dunno though!} to a specific species!..

Answer 6

Appearance, how it differs from the holotype. that was why there was confusion over brontosaurus / apatosaurus.

Answer 7

From its appearance i guess ?!