The Ordovician period is a theorized second period in the theorized Paleozoic era. It is posited that it started approximately 500 million years ago after the end of the theorized Cambrian era. Most of the phyla which are living today are posited to have existed at the beginning of the Ordovician period by those who assert that the earth is billions of years old. Evolutionary scientists assert by the end of the Ordovician period, the first land plants, bryophytes, evolved and began to colonize the land. The Ordovician also is claimed to have seen the evolution of fish. The Ordovician is posited to have preceded by the Cambrian era and succeeded by the Silurian era.
Young earth creation scientists view
Young earth creationist scientists state that there are numerous lines of evidence pointing to a young earth and that the old earth paradigm is errant and has many anomalies. (For details please see: Geologic system and Young Earth Creationism.)