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2021 In Paleoichthyology
This list of fossil fish research presented in 2021 is a list of new taxa of jawless vertebrates, placoderms, acanthodians, fossil cartilaginous fishes, bony fishes, and other fishes that were described during the year, as well as other significant discoveries and events related to paleoichthyology that occurred in 2021. Jawless vertebrates Jawless fishes research * A study on the phylogenetic relationships of cyathaspidids is published by Elliott, Lassiter & Blieck (2021). * Miyashita ''et al.'' (2021) report larval and juvenile forms of four stem lampreys from the Paleozoic era ('' Hardistiella'', '' Mayomyzon'', '' Pipiscius'' and ''Priscomyzon''), including a hatchling-to-adult growth series of ''Priscomyzon'', and report that the studied larvae display features that are otherwise unique to adult modern lampreys, and lack the defining traits of ammocoetes. * A study on the anatomy and likely feeding ecology of ''Mesomyzon mengae'', based on data from new, well-preserved s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossil
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''. Paleontology is the study of fossils: their age, method of formation, and evolutionary significance. Specimens are usually considered to be fossils if they are over 10,000 years old. The oldest fossils are around 3.48 billion years old to 4.1 billion years old. Early edition, published online before print. The observation in the 19th century that certain fossils were associated with certain rock strata led to the recognition of a geological timescale and the relative ages of different fossils. The development of radiometric dating techniques in the early 20th century allowed scientists to quantitatively measure the abs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silurian
The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago (Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozoic Era. As with other geologic periods, the rock beds that define the period's start and end are well identified, but the exact dates are uncertain by a few million years. The base of the Silurian is set at a series of major Ordovician–Silurian extinction events when up to 60% of marine genera were wiped out. One important event in this period was the initial establishment of terrestrial life in what is known as the Silurian-Devonian Terrestrial Revolution: vascular plants emerged from more primitive land plants, dikaryan fungi started expanding and diversifying along with glomeromycotan fungi, and three groups of arthropods ( myriapods, arachnids and hexapods) became fully terrestrialized. A significant evolutionary milestone d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hardistiella
''Hardistiella montanensis'' is a fossil fish and extinct species of lamprey found, dating from the Carboniferous period, at the Bear Gulch Limestone site in the U.S. state of Montana Montana () is a U.S. state, state in the Mountain states, Mountain West List of regions of the United States#Census Bureau-designated regions and divisions, division of the Western United States. It is bordered by Idaho to the west, North .... P. Janvier and R. Lund. 1983. Hardistiella montanensis n. gen. et sp. (Petromyzontida) from the Lower Carboniferous of Montana, with remarks on the affinities of the lampreys. ''Journal of Vertebrate Paleontology'' 2(4):407-413 References {{Taxonbar, from=Q60431263, from2=Q60431365 Lampreys ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paleozoic
The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ''zōḗ'' (), "life", meaning "ancient life" ). It is the longest of the Phanerozoic eras, lasting from , and is subdivided into six geologic periods (from oldest to youngest): # Cambrian # Ordovician # Silurian # Devonian # Carboniferous # Permian The Paleozoic comes after the Neoproterozoic Era of the Proterozoic Eon and is followed by the Mesozoic Era. The Paleozoic was a time of dramatic geological, climatic, and evolutionary change. The Cambrian witnessed the most rapid and widespread diversification of life in Earth's history, known as the Cambrian explosion, in which most modern phyla first appeared. Arthropods, molluscs, fish, amphibians, reptiles, and synapsids all evolved during the Paleozoic. Life began in the ocean bu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crown Group
In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor. It is thus a way of defining a clade, a group consisting of a species and all its extant or extinct descendants. For example, Neornithes (birds) can be defined as a crown group, which includes the most recent common ancestor of all modern birds, and all of its extant or extinct descendants. The concept was developed by Willi Hennig, the formulator of phylogenetic systematics, as a way of classifying living organisms relative to their extinct relatives in his "Die Stammesgeschichte der Insekten", and the "crown" and "stem" group terminology was coined by R. P. S. Jefferies in 1979. Though formulated in the 1970s, the term was not commonly used until its reintroduction in 2000 by Graham Budd and Sören Jensen. Contents of the crown ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyathaspididae
Cyathaspididae is an extinct family in the Heterostraci, heterostracan order (biology), order Cyathaspidiformes.The Classification and Evolution of the Heterostraci. L. Beverly Tarlo, Acta Palaeontologica Polonica, 1962 Cyathaspididae contains most of the genera originally contained within Cyathaspididae, as well as those genera contained within Irregularaspididae, and Poraspididae. In addition to the type genus, †''Cyathaspis'', Cyathaspididae contains the following genera: †''Americaspis'', †''Archegonaspis'', †''Capitaspis'', †''Dikenaspis'', †''Dinaspidella'', †''Homaspidella'', †''Irregulareaspis'', †''Nahanniaspis'', †''Pionaspis'', †''Poraspis'', †''Ptomaspis'', †''Seretaspis'', †''Steinaspis'', †''Torpedaspis'' and †''Veronaspis''. References External links * Cyathaspidida Prehistoric jawless fish families {{Pteraspidomorphi-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eugaleaspidiformes
Eugaleaspidiformes (from Latin, "Helmet shield shapes") is an extinct order of jawless marine and freshwater fish, which lived in East Asia from the Telychian to the Lower Devonian period. The order was first named by Lui in 1965. Examples *''Nochelaspis'' *''Shuyu'' * Falxcornus *Dunyu * Xitunaspis *Yongdongaspis ''Yongdongaspis'', colloquially known as the Binhai Yongdong, is an extinct genus of galeaspid within the monotypic family Yongdongaspididae. The type species is ''Y. littoralis'' and it was found in the Silurian-aged Huixingshao Formation of Ch ... *'' Qingshuiaspis'' *'' Anjiaspis'' References Galeaspida Early Devonian extinctions Prehistoric fish orders {{paleo-jawless-fish-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
