How many missing links are there in evolution?

Answer 1

First of all, let me explain why the term 'missing link' is inaccurate and misleading. It suggests that there is something wanting from the fossil record, where it really isn't. Some intermediates have been projected but have not yet been found; however, hundreds of transistional fossils have been found without having been projected, nevertheless confirming phylogenies established on the basis of morphology alone. And, of course, some intermediates have been specifically projected and subsequently found.

The definition of 'transitional fossil' is any form that is morphologically intermediate between the basal form of a clade, and a more derived form within that clade. Since the number of morphological intermediates between one ancestral form and its remote descendants is potentially as high as the number of generations between these two forms, it's virtually impossible to project how many intermediate forms we should expect to find even in a single lineage. Moreover, evolution is not a linear or well-ordered process, but a chaotic one, which complicates such deliberations.

In the end, the question itself is irrelevant to our determinations, since however many transitional fossils remain missing, every fossil that we do find confirms common descent and helps clarify various phylogenies.