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Conodont Specialists
Conodonts (Greek ''kōnos'', "cone", + ''odont'', "tooth") are an extinct group of agnathan (jawless) vertebrates resembling eels, classified in the class Conodonta. For many years, they were known only from their tooth-like oral elements, which are usually found in isolation and are now called conodont elements. Knowledge about soft tissues remains limited. They existed in the world's oceans for over 300 million years, from the Cambrian to the beginning of the Jurassic. Conodont elements are widely used as index fossils, fossils used to define and identify geological periods. The animals are also called Conodontophora (conodont bearers) to avoid ambiguity. Discovery and understanding of conodonts The teeth-like fossils of the conodont were first discovered by Heinz Christian Pander and the results published in Saint Petersburg, Russia, in 1856. The name ''pander'' is commonly used in scientific names of conodonts. It was only in the early 1980s that the first fossil evidence o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambrian
The Cambrian Period ( ; sometimes symbolized C with bar, Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million years ago (mya) to the beginning of the Ordovician Period mya. Its subdivisions, and its base, are somewhat in flux. The period was established as "Cambrian series" by Adam Sedgwick, who named it after Cambria, the Latin name for 'Cymru' (Wales), where Britain's Cambrian rocks are best exposed. Sedgwick identified the layer as part of his task, along with Roderick Murchison, to subdivide the large "Transition Series", although the two geologists disagreed for a while on the appropriate categorization. The Cambrian is unique in its unusually high proportion of sedimentary deposits, sites of exceptional preservation where "soft" parts of organisms are preserved as well as their more resistant shells. As a result, our understanding of the Ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Index Fossil
Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock Stratum, strata by using the fossil assemblages contained within them.Hine, Robert. “Biostratigraphy.” ''Oxford Reference: Dictionary of Biology'', 8th ed., Oxford University Press, 2019. The primary objective of biostratigraphy is ''correlation'', demonstrating that a particular Horizon (geology), horizon in one geological section represents the same period of time as another horizon at a different section. Fossils within these strata are useful because sediments of the same age can look completely different, due to local variations in the Sedimentary depositional environment, sedimentary environment. For example, one section might have been made up of clays and marls, while another has more chalky limestones. However, if the fossil species recorded are similar, the two sediments are likely to have been laid down around the same time. Ideally these fossils are used to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydroxylapatite
Hydroxyapatite, also called hydroxylapatite (HA), is a naturally occurring mineral form of calcium apatite with the formula Ca5(PO4)3(OH), but it is usually written Ca10(PO4)6(OH)2 to denote that the crystal unit cell comprises two entities. Hydroxyapatite is the hydroxyl endmember of the complex apatite group. The OH− ion can be replaced by fluoride, chloride or carbonate, producing fluorapatite or chlorapatite. It crystallizes in the hexagonal crystal system. Pure hydroxyapatite powder is white. Naturally occurring apatites can, however, also have brown, yellow, or green colorations, comparable to the discolorations of dental fluorosis. Up to 50% by volume and 70% by weight of human bone is a modified form of hydroxyapatite, known as bone mineral. Carbonated calcium-deficient hydroxyapatite is the main mineral of which dental enamel and dentin are composed. Hydroxyapatite crystals are also found in pathological calcifications such as those found in breast tumors, as w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lagerstätte
A Lagerstätte (, from ''Lager'' 'storage, lair' '' Stätte'' 'place'; plural ''Lagerstätten'') is a sedimentary deposit that exhibits extraordinary fossils with exceptional preservation—sometimes including preserved soft tissues. These formations may have resulted from carcass burial in an anoxic environment with minimal bacteria, thus delaying the decomposition of both gross and fine biological features until long after a durable impression was created in the surrounding matrix. ''Lagerstätten'' span geological time from the Neoproterozoic era to the present. Worldwide, some of the best examples of near-perfect fossilization are the Cambrian Maotianshan shales and Burgess Shale, the Silurian Waukesha Biota, the Devonian Hunsrück Slates and Gogo Formation, the Carboniferous Mazon Creek, the Jurassic Posidonia Shale and Solnhofen Limestone, the Cretaceous Yixian, Santana, and Agua Nueva formations, the Eocene Green River Formation, the Miocene Foulden Maar and Ashfall F ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agnathans
Agnatha (, Ancient Greek 'without jaws') is an infraphylum of jawless fish in the phylum Chordata, subphylum Vertebrata, consisting of both present (cyclostomes) and extinct (conodonts and ostracoderms) species. Among recent animals, cyclostomes are sister to all vertebrates with jaws, known as gnathostomes. Recent molecular data, both from rRNA and from mtDNA as well as embryological data, strongly supports the hypothesis that living agnathans, the cyclostomes, are monophyletic. The oldest fossil agnathans appeared in the Cambrian, and two groups still survive today: the lampreys and the hagfish, comprising about 120 species in total. Hagfish are considered members of the subphylum Vertebrata, because they secondarily lost vertebrae; before this event was inferred from molecular and developmental data, the group Craniata was created by Linnaeus (and is still sometimes used as a strictly morphological descriptor) to reference hagfish plus vertebrates. While a few scientist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mineralized Tissues
Mineralized tissues are biological tissues that incorporate minerals into soft matrices. Typically these tissues form a protective shield or structural support. Bone, mollusc shells, deep sea sponge ''Euplectella'' species, radiolarians, diatoms, antler bone, tendon, cartilage, tooth enamel and dentin are some examples of mineralized tissues. These tissues have been finely tuned to enhance their mechanical capabilities over millions of years of evolution. Thus, mineralized tissues have been the subject of many studies since there is a lot to learn from nature as seen from the growing field of biomimetics. The remarkable structural organization and engineering properties makes these tissues desirable candidates for duplication by artificial means. Mineralized tissues inspire miniaturization, adaptability and multifunctionality. While natural materials are made up of a limited number of components, a larger variety of material chemistries can be used to simulate the same propertie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Notochord
In anatomy, the notochord is a flexible rod which is similar in structure to the stiffer cartilage. If a species has a notochord at any stage of its life cycle (along with 4 other features), it is, by definition, a chordate. The notochord consists of inner, vacuolated cells covered by fibrous and elastic sheaths, lies along the anteroposterior axis (''front to back''), is usually closer to the dorsal than the ventral surface of the embryo, and is composed of cells derived from the mesoderm. The most commonly cited functions of the notochord are: as a midline tissue that provides directional signals to surrounding tissue during development, as a skeletal (structural) element, and as a vertebral precursor. In lancelets the notochord persists throughout life as the main structural support of the body. In tunicates the notochord is present only in the larval stage, being completely absent in the adult animal. In these invertebrate chordates, the notochord is not vacuolated. In all ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Myomere
Myomeres are blocks of skeletal muscle tissue arranged in sequence, commonly found in aquatic chordates. Myomeres are separated from adjacent myomeres by connective fascia (myosepta) and most easily seen in larval fishes or in the olm. Myomere counts are sometimes used for identifying specimens, since their number corresponds to the number of vertebrae in the adults. Location varies, with some species containing these only near the tails, while some have them located near the scapular or pelvic girdles. Depending on the species, myomeres could be arranged in an epaxial or hypaxial manner. Hypaxial refers to ventral muscles and related structures while epaxial refers to more dorsal muscles. The horizontal septum divides these two regions in vertebrates from cyclostomes to gnathostomes. In terrestrial chordates, the myomeres become fused as well as indistinct, due to the disappearance of myosepta. Shape The shape of myomeres varies by species. Myomeres are commonly zig-zag, " ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Promissum
''Promissum'' is an extinct genus of conodonts, primitive chordates, that lived during the Upper Ordovician period. A conodont, ''Promissum'' had a primitive mouth under its eyes with mineralized teeth, which are both typical for conodonts. It had a primitive backbone and probably looked like a small eel or large worm, lacking any kind of fins except for perhaps a small one on the tail. It was relatively large for a conodont, reaching about 40 cm (16 inch) in length. Well-preserved specimens were discovered in the Soom shale of South Africa in 1994. ''Promissum'' was probably capable of maintaining a cruising speed, but not of bursts of speed. References External links ''Promissum''at fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals .... org (retrieved 30 A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Promissum NT Small
''Promissum'' is an extinct genus of conodonts, primitive chordates, that lived during the Upper Ordovician period. A conodont, ''Promissum'' had a primitive mouth under its eyes with mineralized teeth, which are both typical for conodonts. It had a primitive backbone and probably looked like a small eel or large worm, lacking any kind of fins except for perhaps a small one on the tail. It was relatively large for a conodont, reaching about 40 cm (16 inch) in length. Well-preserved specimens were discovered in the Soom shale of South Africa in 1994. ''Promissum'' was probably capable of maintaining a cruising speed, but not of bursts of speed. References External links ''Promissum''at fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals .... org (retrieved 30 A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sarah Gabbott
Sarah Gabbott is a palaeobiologist from the University of Leicester. She is known for her research on decomposition and fossilization. Her focus is soft-bodied animals, details of which are often lost during decay. Early life and education Gabbott received an undergraduate degree in geology from the University of Southampton. She went on to receive a doctorate in paleobiology from the University of Leicester on the topic of Soom Shale fossils. She remained at the University of Leicester as a post-doctoral researcher before being appointed lecturer. Career Gabbott leads a paleobiology lab at the University of Leicester which studies the way primitive vertebrates, such as hagfish or rag worms, decompose. This work sheds light on the process of fossilization by determining which types of tissues are preserved and which of them rot away rapidly. The findings can improve the quality of modern reconstructions or restorations based on fossils. In particular, features that evolved ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jan Zalasiewicz
Jan, JaN or JAN may refer to: Acronyms * Jackson, Mississippi (Amtrak station), US, Amtrak station code JAN * Jackson-Evers International Airport, Mississippi, US, IATA code * Jabhat al-Nusra (JaN), a Syrian militant group * Japanese Article Number, a barcode standard compatible with EAN * Japanese Accepted Name, a Japanese nonproprietary drug name * Job Accommodation Network, US, for people with disabilities * ''Joint Army-Navy'', US standards for electronic color codes, etc. * ''Journal of Advanced Nursing'' Personal name * Jan (name), male variant of ''John'', female shortened form of ''Janet'' and ''Janice'' * Jan (Persian name), Persian word meaning 'life', 'soul', 'dear'; also used as a name * Ran (surname), romanized from Mandarin as Jan in Wade–Giles * Ján, Slovak name Other uses * January, as an abbreviation for the first month of the year in the Gregorian calendar * Jan (cards), a term in some card games when a player loses without taking any tricks or scoring a mini ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
