Marine invertebrates were still the predominant life forms and the seas harbored the earliest vertebrates, primitive fish with bony armor plates.
During this geologic period, the climate was warm and humid in much of present-day North America and Eurasia but colder in the southern continents, the South Pole of the time being centered in what is now Algeria. Marine invertebrates were still the predominant life forms and the seas harbored the earliest vertebrates, primitive fish with bony armor plates. Graptolites, corals, crinoids, bryozoans, and clams first made their appearance in this period, named for an ancient Welsh tribe and spanning from about 500 million to 430 million years ago. FTP, name this second period of the Paleozoic Era.
During this geologic period, the climate was warm and humid in much of present-day North America and Eurasia but colder in the southern continents, the South Pole of the time being centered in what is now Algeria.
Ordovician