The Ordovician Period followed the Cambrian and it is recognized as a separate time interval because of differences in the kinds of animals found in each. As we saw in Chapter 3, the Cambrian came to ...

The Earth has gone through many major events over the course of hundreds of millions of years. Some of the most significant are the six mass extinction events that have occurred. These are times when ...

A pair of Sacabambaspis fish, around 35 cm in length, which had distinct, forward-facing eyes and an armored head. No fossils of animals like Sacabambaspis from after the Late Ordovician Mass ...

Since the emergence of diverse animal phyla around 500 million years ago, five major mass extinction events have occurred, each coinciding with abnormal climate changes. We analyzed sedimentary ...

An extraordinary 512-million-year-old fossil site has been discovered in southern China, preserving in vivid detail almost an entire ecosystem from a time shortly after Earth’s first mass extinction ...

The Ordovician is a geologic period of the Paleozoic Era that follows the Cambrian and precedes the Silurian, spanning roughly 485 to 444 million years ago. It is characterized by extensive ...