The Silurian drew to a close with a series of extinction events linked to climate change; however, these were relatively minor compared with those of other geologic periods.

although it’s unclear if whether that amounts to a sixth mass extinction. The Ordovician-Silurian mass extinction event may have wiped out some 85 percent of species, including many of the ...

In place of oxygen, the ocean was full of hydrogen sulfide, which the researchers believe may have caused the organism to fossilize inside out. Read More: A New 450-Million-Year-Old Arthropod Was ...

although it’s unclear if whether that amounts to a sixth mass extinction. The Ordovician-Silurian mass extinction event may have wiped out some 85 percent of species, including many of the ...

Our planet’s first known mass extinction happened about 440 million years ago. Species diversity on Earth had been increasing ...