Early Paleozoic (Cambrian and Ordovician periods) By Kevin Poitra

Cambrian Continents Cambrian 542 – 488.3 million years ago Most continents were still merged together, forming the super-continent “Gondwana”. Some smaller continents had yet to merge with Gondwana, which were warmer than the rest (since Gondwana was closer to the South Pole).

Ordovician Continents 488.3 – 443.7 million years ago Some smaller continents began to split off of Gondwana (Laurentia, Baltica, Siberia). It was the coldest time period recording within Earth’s history, with most of Gondwana being covered in ice.

Cambrian Climate Generally a warm temperature held, being around 21°C almost worldwide. No landmasses were to be found at the poles, leaving oceans able to develop currents freely.

Most continents are away from the pole (surrounding the South pole, not shown on image)

Cambrian Seas Seas levels were at a all time low of 30 meters, but rose up to 90 meters fairly quickly. Due to the rise in sea levels, the temperature slowly increased, making most of the polar ice age become nonexistent by the end of the period.

Ordovician Climate Carbon dioxide levels are believed to have been 8 to 20 times from their current day status. Sea temperatures were found to be of extreme lows, with the highest temperatures just barely reaching 24°C. Info from http://palaeos.com/Paleozoic/Ordovician/Ordovician.htm#climate

Ordovician Seas The average sea level was at 180 meters, and feel down to 140 meters by the end of the Ordovician period. With the drop in sea levels, and the hot temperatures, a greenhouse effect was created, and as the climate got cooler later on, current day oceans were formed.

Cambrian Life The most advanced creatures of the time were the Trilobites, who had developed eyeballs, which could pick up visions of light rather than sensing motion like the rest of the animals. The largest of all animals was the Anomalocarids, which measured to 45 to 60 cm, and some reaching 1 or 2 meters. All other animals were still slug-like, and underdeveloped.

Pictured is what most people think the life was like back then Pictured is what most people think the life was like back then. Still very undeveloped, eyes were just beginning to form on some animals.

Ordovician Life The Trilobites were much more advanced, with newly developed spines and larger eyes. Most other animals that began to form eyes had lost their eyes if they lived in a colder ocean. Some Trilobites developed snouts to burrow through mud to aid in food hunting.

Pictured is the newly advanced Trilobite with it’s new snout.