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Protomelission
''Protomelission'' is a Cambrian fossil taxon of contested affinity. It comprises cataphract arrays of box-like chambers, forming a club-shaped thallus surrounding a hollow central cavity. It was first described from phosphatized microfossils whose individual chambers were interpreted as housing the zooids of a non-mineralized bryozoan, which would make it the only affinity representative of that phylum – implying that all animal phyla originated in the Cambrian period. The subsequent discovery of articulated macrofossils from the Xiaoshiba biota called into question the biological nature of the distal apertures, showing that the surface was instead covered with leaf-like triangular flanges. This has led to the reinterpretation of the fossil material as a "seaweed", strictly as a dasycladalean green alga. History of description ''Protomelission'' was first described by Brock & Cooper in 1993 from limestones in Wirrealpa, Australia. A bryozoan affinity was dismissed o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dasycladales
Dasycladales is an Order (biology), order of large unicellular green algae in the class Ulvophyceae. It contains two families, the Dasycladaceae and the Polyphysaceae. These single celled algae are from 2 mm to 200 mm long. They live on substrates in shallow warm (>20 °C) euhaline tropical marine waters, usually less than 20 meters deep, and protected from waves. They are very large cells. They are able to attain these sizes without numerous internal cell wells because they build calcium carbonate shells around themselves. They contain only one Cell nucleus, nucleus in their vegetative stage, which remains in the bottom of the cell in the holdfast (biology), holdfast at the substrate. Only when they are ready to produce gametes does the nucleus undergo meiosis and then numerous mitosis, mitoses into many nuclei which then migrate into the gametangia at the top of the alga. Because the nucleus is safely hidden in the holdfast, the cells easily regenerate if t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wirrealpa
Wirrealpa Station is a pastoral lease that operates as a sheep station and cattle station in South Australia. The property is situated approximately south east of Leigh Creek and north east of Quorn, on the eastern side of the Flinders Ranges. It occupies an area of and has been owned by the same family for five generations. The lease dates back to the early 1850s, with the station being established in 1856, John Chambers owned the station in the late 1850s and eventually sold it to Philip Levi. Levi had sustained heavy losses through the drought in the 1860s and Wirrealpa was acquired by John Howard Angus in 1871. The shearers quarters were built in 1860, today they are used as accommodation for tourists visiting the area. In 1953 the property occupied an area of and was placed on the market to be sold as one lot or split into four blocks. It was stocked with 16,000 sheep at the time that were not included in the deal. F. H. Fargher and sons acquired a portion of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biological Specificity
Biological specificity is the tendency of a characteristic such as a behavior or a biochemical variation to occur in a particular species. Biochemist Linus Pauling stated that "Biological specificity is the set of characteristics of living organisms or constituents of living organisms of being special or doing something special. Each animal or plant species is special. It differs in some way from all other species...biological specificity is the major problem about understanding life." Biological specificity within ''Homo sapiens'' ''Homo sapiens'' has many characteristics that show the biological specificity in the form of behavior and morphological traits. Morphologically, humans have an enlarged cranial capacity and more gracile features in comparison to other hominins. The reduction of dentition is a feature that allows for the advantage of adaptability in diet and survival. As a species, humans are culture dependent and much of human survival relies on the culture and soc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mudstone
Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from ''shale'' by its lack of fissility.Blatt, H., and R.J. Tracy, 1996, ''Petrology.'' New York, New York, W. H. Freeman, 2nd ed, 529 pp. The term ''mudstone'' is also used to describe carbonate rocks (limestone or dolomite) that are composed predominantly of carbonate mud. However, in most contexts, the term refers to siliciclastic mudstone, composed mostly of silicate minerals. The NASA Curiosity rover has found deposits of mudstone on Mars that contain organic substances such as propane, benzene and toluene. Definition There is not a single definition of mudstone that has gained general acceptance,Boggs 2006, p.143 though there is wide agreement that mudstones are fine-grained sedimentary rocks, composed mostly of silicate grains with a grain size less than . Individual grains this size are too small to be distinguished without a micros ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Burgess Shale
The Burgess Shale is a fossil-bearing deposit exposed in the Canadian Rockies of British Columbia, Canada. It is famous for the exceptional preservation of the soft parts of its fossils. At old (middle Cambrian), it is one of the earliest fossil beds containing soft-part imprints. The rock unit is a black shale and crops out at a number of localities near the town of Field in Yoho National Park and the Kicking Horse Pass. Another outcrop is in Kootenay National Park 42 km to the south. History and significance The Burgess Shale was discovered by palaeontologist Charles Walcott on 30 August 1909, towards the end of the season's fieldwork. He returned in 1910 with his sons, daughter, and wife, establishing a quarry on the flanks of Fossil Ridge. The significance of soft-bodied preservation, and the range of organisms he recognised as new to science, led him to return to the quarry almost every year until 1924. At that point, aged 74, he had amassed over 65,000 s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Small Shelly Fossils
The small shelly fauna, small shelly fossils (SSF), or early skeletal fossils (ESF) are mineralized fossils, many only a few millimetres long, with a nearly continuous record from the latest stages of the Ediacaran to the end of the Early Cambrian Period. They are very diverse, and there is no formal definition of "small shelly fauna" or "small shelly fossils". Almost all are from earlier rocks than more familiar fossils such as trilobites. Since most SSFs were preserved by being covered quickly with phosphate and this method of preservation is mainly limited to the late Ediacaran and early Cambrian periods, the animals that made them may actually have arisen earlier and persisted after this time span. Some of the fossils represent the entire skeletons of small organisms, including the mysterious '' Cloudina'' and some snail-like molluscs. However, the bulk of the fossils are fragments or disarticulated remains of larger organisms, including sponges, molluscs, slug-like halkieri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Taphonomy
Taphonomy is the study of how organisms decay and become fossilized or preserved in the paleontological record. The term ''taphonomy'' (from Greek language, Greek , 'burial' and , 'law') was introduced to paleontology in 1940 by Soviet scientist Ivan Yefremov, Ivan Efremov to describe the study of the transition of remains, parts, or products of organisms from the biosphere to the lithosphere. The term taphomorph is used to describe fossil structures that represent poorly-preserved, deteriorated remains of a mixture of Taxon, taxonomic groups, rather than of a single one. Description Taphonomic phenomena are grouped into two phases: biostratinomy, events that occur between death of the organism and the burial; and diagenesis, events that occur after the burial. Since Efremov's definition, taphonomy has expanded to include the fossilization of organic and inorganic materials through both cultural and environmental influences. Taphonomy is now most widely defined as the study of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambrian
The Cambrian ( ) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordovician Period 486.85 Ma. Most of the continents lay in the southern hemisphere surrounded by the vast Panthalassa Ocean. The assembly of Gondwana during the Ediacaran and early Cambrian led to the development of new convergent plate boundaries and continental-margin arc magmatism along its margins that helped drive up global temperatures. Laurentia lay across the equator, separated from Gondwana by the opening Iapetus Ocean. The Cambrian marked a profound change in life on Earth; prior to the Period, the majority of living organisms were small, unicellular and poorly preserved. Complex, multicellular organisms gradually became more common during the Ediacaran, but it was not until the Cambrian that fossil diversity seems to rapidly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Affinity (taxonomy)
Affinity (taxonomy) – mainly in life sciences or natural history – refers to resemblance suggesting a common descent, phylogenetic relationship, or type. The term does, however, have broader application, such as in geology (for example, in descriptive and theoretical works), and similarly in astronomy (for example, see " Centaur object" in the context of 2060 Chiron's close affinity with icy comet nuclei."Centaur object." Encyclopædia Britannica. Encyclopædia Britannica 2007 Ultimate Reference Suite . Chicago: Encyclopædia Britannica, 2011.) Basis In taxonomy the basis of any particular type of classification is the ''way in which objects in the domain resemble each other''. A resemblance of a type that seems appropriate to the classification that we propose, we may call an ''affinity'', and when we decide how to classify say, a specimen of rock or butterfly, we justify our decision according to the affinities that we observe. Other resemblances we dismiss as being out of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biome
A biome () is a distinct geographical region with specific climate, vegetation, and animal life. It consists of a biological community that has formed in response to its physical environment and regional climate. In 1935, Tansley added the climatic and soil aspects to the idea, calling it ''ecosystem''. The International Biological Program (1964–74) projects popularized the concept of biome. However, in some contexts, the term ''biome'' is used in a different manner. In German literature, particularly in the Walter terminology, the term is used similarly as '' biotope'' (a concrete geographical unit), while the biome definition used in this article is used as an international, non-regional, terminology—irrespectively of the continent in which an area is present, it takes the same biome name—and corresponds to his "zonobiome", "orobiome" and "pedobiome" (biomes determined by climate zone, altitude or soil). In the Brazilian literature, the term ''biome'' is sometimes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phylum
In biology, a phylum (; : phyla) is a level of classification, or taxonomic rank, that is below Kingdom (biology), kingdom and above Class (biology), class. Traditionally, in botany the term division (taxonomy), division has been used instead of phylum, although the International Code of Nomenclature for algae, fungi, and plants accepts the terms as equivalent. Depending on definitions, the animal kingdom Animalia contains about 31 phyla, the plant kingdom Plantae contains about 14 phyla, and the fungus kingdom Fungi contains about eight phyla. Current research in phylogenetics is uncovering the relationships among phyla within larger clades like Ecdysozoa and Embryophyta. General description The term phylum was coined in 1866 by Ernst Haeckel from the Greek (, "race, stock"), related to (, "tribe, clan"). Haeckel noted that species constantly evolved into new species that seemed to retain few consistent features among themselves and therefore few features that distinguishe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
