HOME
*



picture info

Conodont
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 eviden ...
[...More Info...]      
[...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]  


picture info

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 s ...
[...More Info...]      
[...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]  


picture info

Agnatha
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 s ...
[...More Info...]      
[...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]  




Prioniodinida
Prioniodinida is an extinct order of conodonts, a jawless vertebrate. Families Families are: * † Bactrognathidae * † Chirognathidae * † Ellisoniidae * † Gondolellidae * † Prioniodinidae References * Sweet, W. C; P. C.J Donoghue (2001). "Conodonts: past, present, future". Journal of Paleontology 75 (6): 1174. External links * Prioniodinida at biolib.cz(retrieved 22 April 2016) Prioniodinidaat fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database, a large relational database assembled by hundreds of paleontologists from around the world. History Fossilworks was crea ....org (retrieved 22 April 2016) Prehistoric jawless fish orders {{Conodont-stub ...
[...More Info...]      
[...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]  


Wilhelm Eichenberg
Wilhelm Eichenberg (fl. 1930s) was a geologist and zoologist known for having described the class Conodonta of prehistoric jawless fish 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, cyclostome ... in 1930.Conodonten aus dem Culm des Harzes. W Eichenberg, Paläontologische Zeitschrift, 1930, page 177-182, References * Eicheberg, W. 1931. Die Schichtenfolge des Herzberg-Andreasberger Sattelzuges. iNeues Jahrbuch für Mineralogie, Geologie und Paläontologie, Beilage-Band B 65i, 141-196. * Eichenberg, W. 1934. Die Erforschung der Mikroorganismen, insbesondere der Foraminiferen der norddeutschen Erdölfelder. Teil I. Foraminiferen der Unterkreide. 3. Folge. Foraminiferen aus dem Hauterive von Wenden am Mittellandkanal. Erscheinungsdatum * Eicheberg, W. (date unknown) Mikrofaunen-Tafeln zur B ...
[...More Info...]      
[...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]  


picture info

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. I ...
[...More Info...]      
[...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]  


Heinz Christian Pander
Heinz Christian Pander, also Christian Heinrich Pander ( – ), was a Russian Empire ethnic Baltic German biologist and embryologist. Biography In 1817 he received his doctorate from the University of Würzburg, and spent several years (1827–1842), performing scientific research from his estate in Carnikava (german: Zarnikau) on the banks of the Gauja River near Riga. In 1820 he took part in a scientific expedition to Bokhara as a naturalist. In 1826 he became a member of the Saint Petersburg Academy of Sciences. Research Pander studied the chick embryo and discovered the germ layers (i.e., three distinct regions of the embryo that give rise to the specific organ system). Because of these findings, he is considered by many to be the "founder of embryology". His work in embryology was continued by Karl Ernst von Baer (1792-1876), who expanded Pander's concept of germ layers to include all vertebrates. Pander performed important studies in the field of paleontology, being ...
[...More Info...]      
[...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]  


Conodont Biostratigraphy
Conodonts are an extinct class of animals whose feeding apparatuses called ''teeth'' or ''elements'' are common microfossils found in strata dating from the Stage 10 of the Furongian, the fourth and final series of the Cambrian, to the Rhaetian stage of the Late Triassic. These elements can be used alternatively to or in correlation with other types of fossils (graptolites, trilobites, ammonites, ...) in the subfield of the stratigraphy named biostratigraphy. Paleozoic conodonts Cambrian conodonts It is suggested that '' Eoconodontus notchpeakensis'' can be a marker of the Stage 10 of the Furongian, the fourth and final series of the Cambrian. In 2006, a working group proposed the first appearance of '' Cordylodus andresi''. Currently the first appearance of ''E. notchpeakensis'' is favored by many authors because it is globally widespread and is independent of facies (known from continental rise to peritidal environments). The ''Eoconodontus notchpeakensis'' proposal would ...
[...More Info...]      
[...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]  




Ozarkodinida
Ozarkodinida is an extinct conodont order. It is part of the clade Prioniodontida, also known as the "complex conodonts". Name Ozarkodinida is named after the Ozark Mountains of Missouri Missouri is a state in the Midwestern region of the United States. Ranking 21st in land area, it is bordered by eight states (tied for the most with Tennessee): Iowa to the north, Illinois, Kentucky and Tennessee to the east, Arkansas t ..., United States. Elements The feeding apparatus of ozarkodinids is composed at the front of an axial Sa element, flanked by two groups of four close-set elongate Sb and Sc elements which were inclined obliquely inwards and forwards. Above these elements lay a pair of arched and inward pointing (makellate) M elements. Behind the S-M array lay transversely oriented and bilaterally opposed (pectiniform, i.e. comb-shaped) Pb and Pa elements. References External links * * Prehistoric jawless fish orders {{Conodont-stub ...
[...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, a large relational database assembled by hundreds of paleontologists from around the world. History Fossilworks was crea .... org (retrieved 30 ...
[...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, a large relational database assembled by hundreds of paleontologists from around the world. History Fossilworks was crea .... org (retrieved 30 ...
[...More Info...]      
[...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]  


picture info

Index Fossil
Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock 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 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 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 help identify biozones, as they make up the basic biostratigrap ...
[...More Info...]      
[...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]  


picture info

Cambrian
The Cambrian Period ( ; sometimes symbolized 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 Cambrian ...
[...More Info...]      
[...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]