Archaea Described In 1981
Archaea ( ; singular archaeon ) is a domain of single-celled organisms. These microorganisms lack cell nuclei and are therefore prokaryotes. Archaea were initially classified as bacteria, receiving the name archaebacteria (in the Archaebacteria kingdom), but this term has fallen out of use. Archaeal cells have unique properties separating them from the other two domains, Bacteria and Eukaryota. Archaea are further divided into multiple recognized phyla. Classification is difficult because most have not been isolated in a laboratory and have been detected only by their gene sequences in environmental samples. Archaea and bacteria are generally similar in size and shape, although a few archaea have very different shapes, such as the flat, square cells of '' Haloquadratum walsbyi''. Despite this morphological similarity to bacteria, archaea possess genes and several metabolic pathways that are more closely related to those of eukaryotes, notably for the enzymes invo ...
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Paleoarchean
The Paleoarchean (), also spelled Palaeoarchaean (formerly known as early Archean), is a Geologic time scale#Terminology, geologic era within the Archean, Archaean Eon. The name derives from Greek "Palaios" ''ancient''. It spans the period of time . The era is defined Absolute dating, chronometrically and is not referenced to a specific level of a rock section on Earth. The Abiogenesis, earliest confirmed evidence of life comes from this era, and Vaalbara, one of Earth's earliest Supercontinent, supercontinents, may have formed during this era. Early life The geological record from the Paleoarchean era is very limited. Due to deformation and metamorphism, most rocks from the Paleoarchean era cannot provide any useful information. There are only two locations in the world containing rock formations that are intact enough to preserve evidence of early life: the Kaapvaal Craton in Southern Africa and the Pilbara Craton in Western Australia. The Pilbara Craton, Dresser Formation, l ...
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