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Micropaleontology
Micropaleontology (American spelling; spelled micropalaeontology in European usage) is the branch of paleontology (palaeontology) that studies microfossils, or fossils that require the use of a microscope to see the organism, its morphology and its characteristic details. Microfossils Microfossils are fossils that are generally between 0.001mm and 1 mm in size, the study of which requires the use of light or electron microscopy. Fossils which can be studied by the naked eye or low-powered magnification, such as a hand lens, are referred to as macrofossils. For example, some colonial organisms, such as Bryozoa (especially the Cheilostomata) have relatively large colonies, but are classified by fine skeletal details of the small individuals of the colony. In another example, many fossil genera of Foraminifera, which are protists are known from shells (called "tests") that were as big as coins, such as the genus '' Nummulites''. Microfossils are a common feature of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Foraminifera
Foraminifera ( ; Latin for "hole bearers"; informally called "forams") are unicellular organism, single-celled organisms, members of a phylum or class (biology), class of Rhizarian protists characterized by streaming granular Ectoplasm (cell biology), ectoplasm for catching food and other uses; and commonly an external shell (called a "Test (biology), test") of diverse forms and materials. Tests of chitin (found in some simple genera, and ''Textularia'' in particular) are believed to be the most primitive type. Most foraminifera are marine, the majority of which live on or within the seafloor sediment (i.e., are benthos, benthic, with different sized species playing a role within the macrobenthos, meiobenthos, and Benthos, microbenthos), while a smaller number float in the water column at various depths (i.e., are planktonic), which belong to the suborder Globigerinina. Fewer are known from freshwater or brackish conditions, and some very few (nonaquatic) soil species have been id ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microfossil
A microfossil is a fossil that is generally between 0.001 mm and 1 mm in size, the visual study of which requires the use of light or electron microscopy. A fossil which can be studied with the naked eye or low-powered magnification, such as a hand lens, is referred to as a macrofossil. Microfossils are a common feature of the geological record, from the Precambrian to the Holocene. They are most common in deposits of marine environments, but also occur in brackish water, fresh water and terrestrial sedimentary deposits. While every kingdom of life is represented in the microfossil record, the most abundant forms are protist skeletons or microbial cysts from the Chrysophyta, Pyrrhophyta, Sarcodina, acritarchs and chitinozoans, together with pollen and spores from the vascular plants. Overview A microfossil is a descriptive term applied to fossilized plants and animals whose size is just at or below the level at which the fossil can be analyzed by the naked e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holocene
The Holocene () is the current geologic time scale, geological epoch, beginning approximately 11,700 years ago. It follows the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene together form the Quaternary period. The Holocene is an interglacial period within the ongoing Ice age, glacial cycles of the Quaternary, and is equivalent to Marine isotope stages, Marine Isotope Stage 1. The Holocene correlates with the last maximum axial tilt towards the Sun of the Earth#Axial tilt and seasons, Earth's obliquity. The Holocene corresponds with the rapid proliferation, growth, and impacts of the human species worldwide, including Recorded history, all of its written history, technological revolutions, development of major civilizations, and overall significant transition towards urban culture, urban living in the present. The human impact on modern-era Earth and its ecosystems may be considered of global significance for th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrrhophyta
The Dinoflagellates (), also called Dinophytes, are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered protists. Dinoflagellates are mostly marine plankton, but they are also common in freshwater habitats. Their populations vary with sea surface temperature, salinity, and depth. Many dinoflagellates are photosynthetic, but a large fraction of these are in fact mixotrophic, combining photosynthesis with ingestion of prey ( phagotrophy and myzocytosis). In terms of number of species, dinoflagellates are one of the largest groups of marine eukaryotes, although substantially smaller than diatoms. Some species are endosymbionts of marine animals and play an important part in the biology of coral reefs. Other dinoflagellates are unpigmented predators on other protozoa, and a few forms are parasitic (for example, '' Oodinium'' and '' Pfiesteria''). Some dinoflagellates produce resting stages, called dinoflagellate cysts ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossils
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, hair, petrified wood and DNA remnants. The totality of fossils is known as the ''fossil record''. Though the fossil record is incomplete, numerous studies have demonstrated that there is enough information available to give a good understanding of the pattern of diversification of life on Earth. In addition, the record can predict and fill gaps such as the discovery of '' Tiktaalik'' in the arctic of Canada. Paleontology includes the study of fossils: their age, method of formation, and evolutionary significance. Specimens are sometimes considered to be fossils if they are over 10,000 years old. The oldest fossils are around 3.48 billion years to 4.1 billion years old. Early edition, published online before print. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protist
A protist ( ) or protoctist is any eukaryotic organism that is not an animal, land plant, or fungus. Protists do not form a natural group, or clade, but are a paraphyletic grouping of all descendants of the last eukaryotic common ancestor excluding land plants, animals, and fungi. Protists were historically regarded as a separate taxonomic kingdom known as Protista or Protoctista. With the advent of phylogenetic analysis and electron microscopy studies, the use of Protista as a formal taxon was gradually abandoned. In modern classifications, protists are spread across several eukaryotic clades called supergroups, such as Archaeplastida ( photoautotrophs that includes land plants), SAR, Obazoa (which includes fungi and animals), Amoebozoa and " Excavata". Protists represent an extremely large genetic and ecological diversity in all environments, including extreme habitats. Their diversity, larger than for all other eukaryotes, has only been discovered in rece ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kingdom (biology)
In biology, a kingdom is the second highest taxonomic rank, just below domain. Kingdoms are divided into smaller groups called phyla (singular phylum). Traditionally, textbooks from Canada and the United States have used a system of six kingdoms (Animalia, Plantae, Fungi, Protista, Archaea/Archaebacteria, and Bacteria or Eubacteria), while textbooks in other parts of the world, such as Bangladesh, Brazil, Greece, India, Pakistan, Spain, and the United Kingdom have used five kingdoms (Animalia, Plantae, Fungi, Protista and Monera). Some recent classifications based on modern cladistics have explicitly abandoned the term ''kingdom'', noting that some traditional kingdoms are not monophyletic, meaning that they do not consist of all the descendants of a common ancestor. The terms ''flora'' (for plants), ''fauna'' (for animals), and, in the 21st century, '' funga'' (for fungi) are also used for life present in a particular region or time. Definition and associated terms Whe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prehistoric Life
The history of life on Earth traces the processes by which living and extinct organisms evolved, from the earliest Abiogenesis, emergence of life to the present day. Earth formed about 4.5 billion years ago (abbreviated as ''Ga'', for ''gigaannum'') and evidence suggests that life emerged prior to 3.7 Ga. The similarities among all known present-day species indicate that they have diverged through the process of evolution from a common ancestor. The earliest clear evidence of life comes from biogenic Δ13C, carbon signatures and stromatolite fossils discovered in 3.7 billion-year-old metasedimentary rocks from western Greenland. In 2015, possible "remains of biotic life" were found in 4.1 billion-year-old rocks in Western Australia. There is further evidence of possibly the oldest forms of life in the form of fossilized microorganisms in hydrothermal vent precipitates from the Nuvvuagittuq Belt, that may have lived as early as 4.28 billion years ago, not long after the Origin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chrysophyta
Chrysophyta or golden algae is a term used to refer to certain heterokonts. It can be used to refer to: * Chrysophyceae (golden algae), Bacillariophyceae (diatoms), and Xanthophyceae (yellow-green algae) together. E.g., Adolf A. Pascher, Pascher (1914). * Chrysophyceae (golden algae) E.g., Lynn Margulis, Margulis et al. (1990).Lynn Margulis, Margulis, L., J.O. Corliss, M. Melkonian, D.J. Chapman. ''Handbook of Protoctista''. Jones and Bartlett Publishers, Boston, 1990. Chrysophyta has some characteristics which includes their possession of the photosynthetic pigments which are chlorophylls a and c, they also possess a yellow carotenoid called fucoxanthin, this is responsible for their unique and characteristic color. They also store food as oil and not starch, their cells contain no cellulose and are often impregnated with silicon compounds. Each species has its own special markings. References Ochrophyta {{Heterokont-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sarcodina
An amoeba (; less commonly spelled ameba or amœba; : amoebas (less commonly, amebas) or amoebae (amebae) ), often called an amoeboid, is a type of cell or unicellular organism with the ability to alter its shape, primarily by extending and retracting pseudopods. Amoebae do not form a single taxonomic group; instead, they are found in every major lineage of eukaryotic organisms. Amoeboid cells occur not only among the protozoa, but also in fungi, algae, and animals. Microbiologists often use the terms "amoeboid" and "amoeba" interchangeably for any organism that exhibits amoeboid movement. In older classification systems, most amoebae were placed in the class or subphylum Sarcodina, a grouping of single-celled organisms that possess pseudopods or move by protoplasmic flow. However, molecular phylogenetic studies have shown that Sarcodina is not a monophyletic group whose members share common descent. Consequently, amoeboid organisms are no longer classified together in on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
