Which of the following is richest in fossils?

Age of fossils in the past was generally determined by the radio-carbon method and other methods involving radioactive elements found in the rocks. More precise methods,which were used recently and led to the revision of the evolutionary periods for different groups of organisms,include:

Fossils are studied for:

The flippers of penguins and dolphins are an example of ...........

Which of the following is the most acceptable method for determining the age of recent fossils?

Who noted that embryos never pass through the adult stages of other animals?