Cambrian Meaning
The Cambrian Period is not to be the most ancient geological period of the Paleozoic Era and the Phanerozoic Eon. The Cambrian lived for 55.6 million years from the completion of the preceding Ediacaran Period 541 million years ago (mya) to the commencement of the Ordovician Period 485.4 mya. The period was authenticated as a "Cambrian series" by Adam Sedgwick, who identified it after Cambria, the Latin title for 'Cymru' (Wales), where Britain's Cambrian rocks are completely revealed.
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Cambrian Distinguished from Extension
Thin mineralized animal fossils, including sponge spicules and likely worm tubes, are distinguished from the Ediacaran Period directly preceding the Cambrian. Some of the unique fossils of the biota from the Ediacaran may also have been animals delegate to living phyla, although this continues a somewhat debatable topic.
Cambrian Period Landscape
The topography of the Cambrian system differed greatly from such of the contemporary day. The geographic reorganisation is based on integrated geologic and biological proof. Fossils in continental-shelf sediments indicate the presence of at least three major faunal territories. This geographic analysis is supported by the presence of thick, warm-water carbonate-platform sediments that accumulated in a broad belt encircling the mainland.
Cambrian Location
The largest Cambrian faunal region is located around Gondwana, which stretched from the low northern latitudes to the high southern latitudes, just bare of the South Pole. The rocks and fossil associations of Gondwana show major changes that correspond to its great size and wide range of climates and environments. The Antarctic and Australian sectors of Gondwana halted in low latitudes through the Cambrian and have extensive carbonate deposits, although these of Antarctica are poorly exposed through the present-day polar ice cap.
Scientific proof states that present-day North and South China were on separate tectonic plates. The fossil assemblies of South China have strong connections with those of both Australia and Kazakhstan, but details of the Cambrian geographic relationships reside unclearly.
At times, two almost reciprocally exclusive ecosystems are separated by temperature and salinity limits in the shallow water on the carbonate floors. Outer open-shelf films are characterized by high-diversity ecosystems that were widely disseminated around the continent. Fossils are usually the most copious and most diverse near the outer boundaries of the carbonate platform. Another Cambrian faunal territory surrounded the small continent of Baltica, which was discovered in middle to high southern latitudes. Cambrian shelf sediments of Baltica are relatively thin, rarely exceeding 250 metres (820 feet) in thickness, and are formed primarily of sandstone and shale. Seemingly as an outgrowth of cool-water environments, carbonate deposits are comparatively minor and very thin.
Cambrian Animals
Flora: The Cambrian vegetation was a little unusual from the Ediacaran. The principal taxa were the aquatic macroalgaeFuxianospira, Sinocylindra, and Marpolia. No calcareous macroalgae are distinguished from the period. Neither land plant (embryophyte) fossils are identified from the Cambrian. However, biofilms and microbial mats were well manifested on Cambrian tidal flats and beaches around 500 mya. Concerning this also microbes forming microbial Earth ecosystems, similar to modern soil crust of desert regions, adding to soil formation.
Fauna: As most animal growth during the Cambrian was aquatic. So all the causes of Fauna in the Cambrian period were Oceanic life. Trilobites were once considered to be the dominant life form at that time, but this has proven to be inaccurate. Arthropods were by far the most authoritative animals in the ocean, but trilobites were only an insignificant part of the total arthropod diversity. What made them so seemingly plentiful was their heavy armour augmented by calcium carbonate.
The period noted a step-change in the diversity and synthesis of Earth's biosphere. The Ediacaran biota experienced a mass extinction at the start of the Cambrian Period, which resembled an increase in the excess and complexity of burrowing behaviour, which converted the seabed ecosystems. The seafloor was incorporated by microbial covers. By the completion of the Cambrian, burrowing animals had destroyed the mats in many domains through bioturbation. As a result, many of those organisms that were conditioned on the mats became obsolete.
Around the same time, there was a rapid presence of delegates of all the mineralized phyla besides the Bryozoa, which emerged in the Lower Ordovician.
Approximately 515 million years ago, the number of species fitting extinct exceeded the number of new species which created mass extinction.
FAQs on Cambrian Period
1. What is the Cambrian Period and when did it occur?
The Cambrian Period is a major division of the geologic timescale, lasting from approximately 538.8 million to 485.4 million years ago. It is the first period of the Paleozoic Era and is renowned for a dramatic burst of evolutionary innovation in life on Earth. Before this period, life was predominantly simple and unicellular, but the Cambrian saw the emergence of most major animal phyla that exist today.
2. What is the "Cambrian Explosion," and what is its importance?
The "Cambrian Explosion" refers to the relatively brief evolutionary event, starting around 538.8 million years ago, during which most major animal phyla first appeared in the fossil record. Its importance lies in the fact that it marked a profound shift from simple organisms to a complex ecosystem filled with diverse, multicellular life forms. This event established the fundamental body plans (e.g., animals with heads, tails, limbs, and shells) for nearly all animal life that followed.
3. What were the dominant life forms during the Cambrian Period?
The oceans of the Cambrian Period teemed with new and diverse life forms. The most iconic animals included:
- Trilobites: Hard-shelled arthropods that are one of the most famous Cambrian fossils.
- Anomalocaris: A large, swimming predator, considered an apex predator of its time.
- Hallucigenia: A peculiar worm-like creature with defensive spines on its back and legs below.
- Archaeocyathans: Sponge-like, reef-building organisms that were crucial to early marine ecosystems.
4. What was the climate like during the Cambrian Period?
The climate during the Cambrian Period was generally much warmer and more stable than in the preceding Ediacaran Period. There is no evidence of widespread glaciation, and polar ice caps were likely small or non-existent. The seas were warm and shallow, especially around the edges of the newly forming continents, creating ideal conditions for the proliferation of marine life.
5. How long did the Cambrian Period last on the geologic timescale?
The Cambrian Period lasted for approximately 53.4 million years. It began at the end of the Proterozoic Eon (around 538.8 million years ago) and concluded with the start of the Ordovician Period (around 485.4 million years ago).
6. Why was there no significant life on land during the Cambrian Period?
Life on land was largely absent during the Cambrian Period primarily due to harsh environmental conditions. The land surface was barren and rocky, and a substantial protective ozone layer had not yet developed in the atmosphere to shield organisms from the Sun's intense ultraviolet (UV) radiation. Furthermore, the complex soils needed to support plant life had not yet formed, meaning all significant evolution was happening in the relative safety of the oceans.
7. How did the breakup of the supercontinent Pannotia influence the Cambrian Explosion?
The breakup of the supercontinent Pannotia is believed to have had a profound influence on the Cambrian Explosion. As the landmasses rifted apart, it created vast new areas of shallow continental shelves and epicontinental seas. These new marine environments were nutrient-rich and offered diverse habitats, which acted as crucibles for evolution. This geological change, altering ocean chemistry and sea levels, is considered a key environmental trigger for the rapid diversification of animal life.
8. What evidence do scientists use to study the animals of the Cambrian Period?
Scientists primarily rely on fossil evidence to understand Cambrian life. This evidence comes from exceptionally well-preserved fossil sites known as Lagerstätten. The most famous of these include:
- The Burgess Shale in Canada.
- The Chengjiang fossil site in China.
9. How does the diversity of life in the Cambrian Period compare to the preceding Ediacaran Period?
The diversity of life in the Cambrian Period represents a quantum leap compared to the preceding Ediacaran Period. Ediacaran life consisted of enigmatic, soft-bodied organisms with simple forms, whose relationship to modern animals is debated. In contrast, the Cambrian introduced organisms with familiar features like bilateral symmetry, hard exoskeletons, jointed appendages, and complex sensory organs. Nearly all modern animal phyla trace their origins to this explosive diversification, marking a transition from a simple biosphere to a complex one.
10. What caused the extinction events at the end of the Cambrian Period?
The Cambrian Period concluded with several extinction pulses, known as the Cambrian–Ordovician extinction events. The leading theories suggest these were caused by significant environmental changes. Key factors include a period of global cooling and glaciation, which lowered sea levels and dramatically reduced the warm, shallow sea habitats where most life thrived. Changes in ocean chemistry, such as a drop in oxygen levels (anoxia), are also believed to have been a major contributing factor.
