Four hundred and fifty (450) million years ago, during the Late Ordovician, most of Ohio was under water. At that time, the Oxford, Ohio area was part of a large inland sea that stretched from the Gulf of Mexico to the Arctic. This sea teemed with marine life, its abundance and diversity rivaling modern-day sea life. However, in the Ordovician, the creatures were invertebrates, or organisms lacking a backbone, such as brachiopods, trilobites, and corals.

These organisms were perfectly suited to survive in the warm waters of the ancient ocean and a climate similar to the climate of the Caribbean today.

Why Was It So Warm?

There are 2 reasons:

• Global climate during the Ordovician was generally warmer (compared to the present).
• The area that would later become southwestern Ohio was about 20° south of the equator at that time.

A Great Place to Collect Fossils

Due to the abundance of life in the Ordovician ocean, southwestern Ohio is one of the best Ordovician fossil collecting sites in the world. The great number of fossils shows the nature of life in benthic communities in the Ordovician ocean.