There are actually many fossils of transitional forms, which are fossils that show the evolution of one species into another. These fossils document the gradual changes in anatomy and features over time, providing evidence of evolutionary lineages.

Here are some examples:

* Archaeopteryx: This fossil is a classic example of a transitional form between dinosaurs and birds, showcasing features of both.

* Tiktaalik: This fish-like creature with limbs suggests the transition from aquatic to terrestrial life.

* Australopithecus afarensis: This hominin fossil shows the evolution of bipedalism in humans.

It's important to remember that the fossil record is incomplete. We don't have fossils for every single organism that has ever lived. However, the fossils we do have provide strong evidence for evolution and the existence of transitional forms.