Ediacaran Period Presentation

The Ediacaran Period

Additional Facts

(635 - 538.8 Mya)

What Was It Like?

The Ediacaran period is the final period of the Proterozoic Eon. During this period, Earth's atmosphere was very rich with oxygen, as the period began with the end of an ice age that caused a swell of photosynthetic life, which produced more oxygen. The climate was generally warm and humid, but would fluctuate somewhat due to minor glaciation events. Besides the single-celled bacteria and photosynthetic life, the Ediacaran period was populated with the first complex multicellular life, which mainly took the form of aquatic plants and soft-bodied marine organisms.

Major Events

1. Trilateral Symmetry

Some organisms from the Ediacaran period exhibited trilateral symmetry, which means portions of their body are mirrored three times total. Fossil records of organisms like tribrachidium (pictured) reveal this type of symmetry that has very rarely been seen in any other time period. For context, humans exhibit bilateral symmetry in the way that the two vertical halves of our bodies are approximate mirror images of each other.

4. Rangeomorphs

In the early 2000s, strange fossils of giant, frond-shaped organisms were discovered in Newfoundland. These organisms are called Rangeomorphs (pictured), and had not previously been well documented by fossils. These organisms grew upwards of 2 meters tall and lived on ocean floors. Strangely, these organisms exhibit a fractal growth pattern, as their branches seem to maintain the exact same shape and pattern as they grow smaller near the top of these organisms.

2. Glacial Activity

Before the Ediacaran period began, Earth went through two glacial events: the Sturtian Glacial; and the Marinoan Glacial. Scientists believe that both of these events were global, and lasted for several million years. The end of these events caused the abundance of oxygen that likely allowed for a flourishing of life to occur during this time.

3. Oxygenated Oceans

Prior to the Ediacaran period, the world's oceans did not have nearly as much oxygen content as they do today, and instead had ample traces of elements like iron. Additionally, there was very little oxygen in the deeper ocean areas. However, potentially as a result of the end of global glacial events and evident by the fact that there was an influx of life in the deep ocean regions, the oceans developed a much higher oxygen content percentage, making its composition grow much closer to what it is today.

1. The Avalon Explosion

The Avalon Explosion was a massive spike in complex multicellular life that occured during the Ediacaran period. This event is very similar to The Cambrian Explosion of the Cambrian period, but this event predates The Cambrian Explosion. The Avalon Explosion is responsible for the very first complex multicellular organisms on the planet.

(Shen Et al. 2008)

2. The Breaking of Pannotia

At the time of the Ediacaran period, the continents were arranged in the supercontinent Pannotia. Due to tectonic movement in this period, however, Pannotia was separated into the landmasses that would next collide to form Pangea. This information has been contested by scientists, but it is theorized that this supercontinent existed as per the supercontinent cycle theory.

(Nance Et al. 2022)

3. End-Ediacaran Extinction Event

The Ediacaran Period ended with a great loss of life referred to as the End-Ediacaran Extinction Event. While it is uncertain the true cause of this event, there are multiple theories to explain this mass extinction: some believe that the loss of Ediacaran life was a gradual and natural transition that came with changing ecosystems; others believe that this is the result of a sudden catastrophic event. Regardless of the cause, the immense loss of life at the end of the Ediacaran period allowed for the eventual rapid growth of life that is the Cambrian Explosion.

(Darroch, 2016)