1-Why is the Cambrian explosion an important biologic event in Earth’s history?

The Cambrian explosion marks the first appearance of stromatolites.

The Cambrian explosion was the meteor impact that killed the dinosaurs.

The Cambrian explosion marks the first time that organisms developed hard parts.

The Cambrian explosion marks the first evidence of life on Earth.

The Cambrian explosion describes the evolution of humans.

2- What was the Cambrian Explosion?

the introduction of vertebrate animals during the Cambrian period

the expansion of biodiversity that introduced all the major invertebrate groups during the Cambrian period

a mass extinction of many different types of organisms for reasons unknown

the remarkable increase in populations of organisms that already existed before the Cambrian period

a period of heavy volcanism during the Cambrian period that wiped out half of the types of organisms that currently existed

3- Gymnosperms were the dominant ________ of the Mesozoic.

reptiles

algae

trees

mammals

4- What group of reptiles led to the evolution of birds?

pterosaurs

lizards

plesiosaurs

turtles

dinosaurs

5- Following the reptilian extinctions at the close of the Mesozoic, two groups of mammals, the marsupials and ________, diversified.

trilobites

stromatolites

cephalopods

eukaryotes

placentals

6- _______ (flowering plants) came to dominate most terrestrial environments during the Cenozoic.

Allosperms

Angiosperms

Radiosperms

Gymnosperms

7-Most of the evidence related to human evolution has been found in ________.

West Africa

East Africa

Northern North America

Central Asia