The cambrian Period 541 mya - 485.4 mya

References

The cambrian Period 541 mya - 485.4 mya

1. The Oceans during the Cambrian had a high level of Calcium and other similar ions, and is the reason for the development of skeletons and armor2. Almost every major group of animals that exists today, developed during the first 40 million years of the Cambrian explosion.3. The explosion has a few potential explanations for its origin: Increased atmospheric oxygen levels, the snowball earths, and a Carbon isotopic anomaly at the Precambrian/Cambrian boundry

The environment during the Cambrian Period was quite warm. Along with this, sea levels were high, leaving many continents covered in shallow seas. In the atmosphere, there was a high concentration of Carbon Dioxide, and as a greenhouse gas, it played a big role in creating the warm climate. Also, there were fluctuations in the levels of oxygen throughout the period, which is what likely made the period so conducive to complex life.

• The Cambrian Explosion: The explosion began early into the Cambrian period as a result of rapid increases in the number of phytoplankton in Earth’s oceans. This led to a steep rise in oxygen levels which allowed complex life to flourish. Due to the massively increased biodiversity, the way organisms interacted with each other and the environment became more complex. Organisms developed predator-prey relationships, higher mobility, armor and shells, skeletons, and sensory organs. Unfortunately, the Cambrian Explosion came to an end toward the end of the period, with the Cambrian-Ordovician Extinction Event. This event wiped out a large majority of mollusks and trilobites.

Although small amounts of life existed in the fossil record before the Cambrian period, it was during the Cambrian explosion in which we saw a massive spread of biodiversity among marine-based environments. This completely shifted the development of organisms at this time and is shown by the multitude of different traits that began to appear. We began to see Arthropods like Trilobites, Mollusks like Wiwaxia, and even early renditions of fish like the vertebrate Pikaia. There were even predatory arthropods like the Anomolocaris, which had grasping appendages and toothy mouthparts.

Facts

Environment

Organisms

Major event

References

Marshall, C. R. (2006). Explaining the Cambrian “explosion” of animals. Annu. Rev. Earth Planet. Sci., 34(1), 355-384.https://cs.brynmawr.edu/Courses/cs361/spring2008/Readings/Marshall2006.pdfPruss, S. B., & Gill, B. C. (2024). Life on the edge: the Cambrian marine realm and oxygenation. Annual Review of Earth and Planetary Sciences, 52.https://www.annualreviews.org/docserver/fulltext/earth/52/1/annurev-earth-031621-070316.pdf?expires=1758824682&id=id&accname=guest&checksum=E3CAFD457EA96DB46D982FCA2500123D"From the Cambrian explosion to the Great Dying" Lecture Video