6.6 Paleozoic Era and Extinction Events

What is the approximate time span of the Paleozoic Era?

• 4.6 billion - 2.5 billion years ago

• 541 - 252 million years ago

• 252 - 66 million years ago

• 66 million years ago - present

Which of the following was a key environmental trigger for the Cambrian Explosion?

• A sudden decrease in ocean oxygen levels

• A boom in phytoplankton leading to increased oxygen

• The appearance of dinosaurs

• A global ice age

Which ancient organisms, known for their ability to swim using a flexible rod of cartilage, are considered the ancestors of vertebrates?

• Anomalocaris

• Arthropods

• Pikaia and Haikouella

• Ostracoderms

What combination of factors is believed to have caused the devastating Ordovician-Silurian Extinction Event?

• Increased volcanic activity and rising sea levels

• A global ice age and dropping marine oxygen levels

• The emergence of land plants and increased carbon dioxide

• The appearance of jawed fish and new predators

What significant development in terrestrial life occurred during the Silurian Period?

• The first large predatory organisms appeared on land

• The first land plants, like Cooksonia, began to spread

• Terrestrial life was limited to microbes

• Dinosaurs first appeared on land

What type of fish were considered the "true kings" of the Devonian Period?

• Early sharks

• Lobe-finned fish

• Jawed, armored fish

• Filter-feeding fish like Titanichthys

What significant development occurred on land during the Devonian Period, forming the first major terrestrial ecosystems?

• The emergence of large mammals

• The diversification of arthropods and the rise of trees

• The appearance of shelled eggs

• The formation of vast deserts

What crucial adaptation allowed amniotes to thrive on land during the Carboniferous Period?

• Developing gills for breathing air

• Laying eggs with shells

• Growing to enormous sizes

• Adapting to cold, icy conditions

How did the formation of the supercontinent Pangaea impact the climate and ecosystems during the Carboniferous Period?

• It led to increased humidity and widespread rainforests.

• It caused a severe drop in humidity and temperature, leading to forest collapse and deserts.

• It resulted in a stable, temperate climate across the entire landmass.

• It created new oceans, increasing marine biodiversity.

What percentage of marine species were wiped out during the Permian-Triassic Extinction Event?

• 50%

• 70%

• 85%

• 96%