[Geography Notes] on Cambrian Period Pdf for Exam

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. 

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.