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 era covers the time period from 541 million years ago to 485.4 million years ago, and is considered by many scientists to be the most important in Earth’s history since it saw the first large-scale diversification of life on our planet. During this time period, many major evolutionary events took place as well as several significant geological and oceanographic changes that would shape the world for millions of years to come.
In terms of atmospheric changes during this era, oxygen levels began rising significantly due to a rise in photosynthesis from primitive plants and algae which produced an abundance of oxygen gas into the atmosphere. This increase would serve as one key factor in allowing more complex organisms to develop over time due to their need for higher oxygen concentrations.