How many transitional forms does a fossil record contain?

Answer 1

"Transitional form" is an arbitrary term because every organism, whether living or fossil, is a link in the chain between an ancestral organism and a descendent. The break into new species is gradual rather than sudden. Every fossil is therefore a "transitional form" in the strict sense.

In general, "transitional form" is used specifically to link one modern species with its prehistoric ancestor. In some cases, a form may not be a specific ancestor of an identifiable living species, but it may have general characteristics that indicate the evolutionary path that was being followed. E.g. the bird fossil Confuciusornis may not be ancestral to living birds, but it still indicates the direction of evolution from earlier repties.

There are abundant transitional forms that illustrate e.g. the transition from fish to land animals; the transition from amphibians to reptiles; the transition from dinosaurs to birds; and the transition from early apes to humans.

Because the definition of "transitional form" in the narrow sense (a transition between two set organisms) is variable, it's not possible to give a strict number.

Answer 2

The fossil record contains numerous transitional forms between different species. While the exact number is difficult to determine, paleontologists have identified a substantial number of transitional fossils that provide evidence of evolutionary links between different organisms.