Respuesta :
''The Cambrian Period marks an important point in the history of life on Earth; it is the time when most of the major groups of animals first appear in the fossil record. This event is sometimes called the "Cambrian Explosion," because of the relatively short time over which this diversity of forms appears. It was once thought that Cambrian rocks contained the first and oldest fossil animals, but these are now found in the earlier Ediacaran (Vendian) strata.''
Answer:
the appearance of fossils
Explanation:
- the ability to fly
- the ability to swim
- the appearance of hard parts
- the appearance of fossils
