6. How does the study of
fossils strengthen the theory
of evolution?

Gap-fill exercise

Fill in all the gaps, then press "Check" to check your answers. Use the "Hint" button to get a free letter if an answer is giving you trouble. You can also click on the "[?]" button to get a clue. Note that you will lose points if you ask for hints or clues!
The study of fossils ancient and
extinct species many similar
structures to of the present and
the past. Fossils still radioactive
dating to estimate periods during
which species and to establish a
relationship between
them. Those strengthen the
hypothesis of and common
origin among and that their
features modified gradually until
the of the current species.