Write a short essay (~ 5 paragraphs, or ~1000 words) about the geological and biological changes and conditions taking place during the Cambrian era. Be sure to list the years covered, atmospheric and oceanographic changes, if any, and any major evolutionary events (e.g., the first amniotic egg or the first angiosperm, etc.), and important extinctions. If there is a mass extinction, make sure to list the percentage of species lost as well as the types of organisms lost. Important geological events would include things such as orogenies (mountain-building events), plate movement (especially supercontinents converging or breaking apart), important occurrences of volcanoes and meteorite impacts, and marine transgressions and regressions.
Sample Solution
The Cambrian period, which lasted from 541 to 485.4 million years ago, was a time of major evolutionary change in the history of Earth. During this era, atmospheric and oceanic conditions were mostly consistent with modern times; however, there were some notable changes such as a decrease in oxygen levels due to the presence of anaerobic bacteria during this time. This era is also known for its dramatic geological events, including orogeny (mountain-building) events that created significant shifts in topography and climate across the globe; plate movement resulting in supercontinents breaking apart or coming together; and marine transgressions and regressions that changed shorelines dramatically.