The Cambrian Period [Paleozoic Era]

-- 𝐂𝐚𝐦𝐛𝐫𝐢𝐚𝐧 𝐏𝐞𝐫𝐢𝐨𝐝 --

The first geological period of the Paleozoic Era, The Cambrian Period lasted from 541 to 485.4 million years ago.  This period was after the Precambrian Time, and before the Ordovician period. The Cambrian Period was divided into four epochs and ten ages.

Cambrian comes from Cambria, known as the Latin name for Wales, Cymru. Many preserved organisms have been discovered here due to its sedimentary deposits.

Paleogeography

During this period, the supercontinent Pannotia was in the process of breaking up. Most continental land was clustered in the Southern Hemisphere, but was drifting North. (You can view this on the youtube video above at around three minutes in.) 

There was a lack of sea ice, the great glaciers of the Marinoan Snowball Earth had melted long ago, and sea levels remained high despite fluctuations.

Climate

As the Earth recovered from a long ice age (snowball Earth), it eventually warmed and averaged about 22 °C or 72 °F.  Compare this to today's national average of 15 °C or 59 °F.

Flora

There are no known land plant fossils from this period. Life on Earth resided underwater. However, biofilms and microbial mats did develop on tidal flats and beaches. This was comparable to modern desert regions.

Oceanic Life

Most animals during this period were aquatic with arthropods being the most dominant life form at the time. 

At the start of the Cambrian Period, there was an increase in burrowing behavior, destroying the microbial mats covering the sea floors. This led to the extinction of organisms that were dependent on these mats and other species adapted to the changes.

While the early Cambrian Period was known as the Cambrian Explosion due to the diversification. We can see vertebrates, hard-shells, and jawless fish come from this evolutionary explosion. The later period did experience a sharp drop in biodiversity, because the number of species going extinct exceeded the number of species appearing.

The Cambrian fauna was also majorly restricted, living close to the sea floor. Free-floating organisms or mineralizing animals were rare. However, there is evidence of a slug-like organism having ventured onto land, leaving fossil trackways. 

Charts

Sources:

Eric Ralls (n.d). Supercontinents 101: Pannotia, Gondwana, and Pangea. Earth.com. https://www.earth.com/earthpedia-articles/supercontinents-101-pannotia-gondwana-and-pangea/

Woudloper (2010, October 30). Geologic Clock with event and periods.svg. Wikimedia Commons. https://en.m.wikipedia.org/wiki/File:Geologic_Clock_with_events_and_periods.svg

Flannery, T. Fridtjof (2024, March 1). Cambrian explosion. Encyclopedia Britannica. https://www.britannica.com/science/Cambrian-explosion

Crick, R. E. , Johnson, . Markes E. and Robison, . Richard A. (2024, April 12). Cambrian Period. Encyclopedia Britannica. https://www.britannica.com/science/Cambrian-Period

Solar System Temperatures. (2024, January 25) The National Aeronautics and Space Administration.  https://science.nasa.gov/resource/solar-system-temperatures/