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Arthrodire Genera
Arthrodira (Greek for "jointed neck") is an order of extinct armored, jawed fishes of the class Placodermi that flourished in the Devonian period before their sudden extinction, surviving for about 50 million years and penetrating most marine ecological niches. Arthrodires were the largest and most diverse of all groups of placoderms. Description Arthrodire placoderms are notable for the movable joint between armor surrounding their heads and bodies. Like all placoderms, they lacked distinct teeth; instead, they used the sharpened edges of a bony plate on their jawbone as a biting surface. The eye sockets are covered by a bony ring, which supports the eye, a feature shared by birds and some ichthyosaurs. Early arthrodires, such as the genus '' Arctolepis'', were well-armoured fishes with flattened bodies. The largest member of this group, ''Dunkleosteus'', was a true superpredator of the latest Devonian period, reaching as much as 6 m in length. In contrast, the long-nosed '' Ro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Devonian
The Devonian ( ) is a period (geology), geologic period and system (stratigraphy), system of the Paleozoic era (geology), era during the Phanerozoic eon (geology), eon, spanning 60.3 million years from the end of the preceding Silurian period at million years ago (Megaannum, Ma), to the beginning of the succeeding Carboniferous period at Ma. It is the fourth period of both the Paleozoic and the Phanerozoic. It is named after Devon, South West England, where rocks from this period were first studied. The first significant evolutionary radiation of history of life#Colonization of land, life on land occurred during the Devonian, as free-spore, sporing land plants (pteridophytes) began to spread across dry land, forming extensive coal forests which covered the continents. By the middle of the Devonian, several groups of vascular plants had evolved leaf, leaves and true roots, and by the end of the period the first seed-bearing plants (Pteridospermatophyta, pteridospermatophyt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecological Niche
In ecology, a niche is the match of a species to a specific environmental condition. Three variants of ecological niche are described by It describes how an organism or population responds to the distribution of Resource (biology), resources and competitors (for example, by growing when resources are abundant, and when predators, parasites and pathogens are scarce) and how it in turn alters those same factors (for example, limiting access to resources by other organisms, acting as a food source for predators and a consumer of prey). "The type and number of variables comprising the dimensions of an environmental niche vary from one species to another [and] the relative importance of particular environmental variables for a species may vary according to the geographic and biotic contexts". See also Chapter 2: Concepts of niches, pp. 7 ''ff'' A Grinnellian niche is determined by the habitat in which a species lives and its accompanying Behavioral ecology, behavioral adaptations. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Body Plan
A body plan, (), or ground plan is a set of morphology (biology), morphological phenotypic trait, features common to many members of a phylum of animals. The vertebrates share one body plan, while invertebrates have many. This term, usually applied to animals, envisages a "blueprint" encompassing aspects such as symmetry (biology), symmetry, Germ layer, layers, segmentation (biology), segmentation, nerve, Limb (anatomy), limb, and Gastrointestinal tract, gut disposition. Evolutionary developmental biology seeks to explain the origins of diverse body plans. Body plans have historically been considered to have evolved in a flash in the Ediacaran biota; filling the Cambrian explosion with the results, and a more nuanced understanding of animal evolution suggests gradual development of body plans throughout the early Palaeozoic. Recent studies in animals and plants started to investigate whether evolutionary constraints on body plan structures can explain the presence of development ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nature (journal)
''Nature'' is a British weekly scientific journal founded and based in London, England. As a multidisciplinary publication, ''Nature'' features Peer review, peer-reviewed research from a variety of academic disciplines, mainly in science and technology. It has core editorial offices across the United States, continental Europe, and Asia under the international scientific publishing company Springer Nature. ''Nature'' was one of the world's most cited scientific journals by the Science Edition of the 2022 ''Journal Citation Reports'' (with an ascribed impact factor of 50.5), making it one of the world's most-read and most prestigious academic journals. , it claimed an online readership of about three million unique readers per month. Founded in the autumn of 1869, ''Nature'' was first circulated by Norman Lockyer and Alexander MacMillan (publisher), Alexander MacMillan as a public forum for scientific innovations. The mid-20th century facilitated an editorial expansion for the j ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Science Daily
''ScienceDaily'' is an American website launched in 1995 that aggregates press releases and publishes lightly edited press releases (a practice called churnalism) about science, similar to Phys.org and EurekAlert!. History The site was founded by married couple Dan and Michele Hogan in 1995; Dan Hogan formerly worked in the public affairs department of Jackson Laboratory writing press releases. The site makes money from selling advertisements. the site said that it had grown "from a two-person operation to a full-fledged news business with worldwide contributors". At the time, it was run out of the Hogans' home, had no reporters, and only reprinted press releases. In 2012, Quantcast ranked it at 614 with 2.6 million U.S. visitors. Sections As of August 2023, ''ScienceDaily'' mainly has five sections, Health, Tech, Enviro, Society, and Quirky, the last of which includes the top news. References External links * Alexa - ScienceDaily��{{Webarchive, url=https://web.a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Incisoscutum
''Incisoscutum'' is an extinct genus of arthrodire placoderm from the Early Frasnian Gogo Reef, from Late Devonian Australia. The genus contains two species ''I. ritchiei'', named after Alex Ritchie, a ichthyology, palaeoichthyologist and senior fellow of the Australian Museum, and ''I. sarahae'', named after Sarah Long, daughter of its discoverer and describer, John A. Long. The genus is important in the study of early vertebrates as well-preserved fossilized embryos have been found in female specimens and ossified pelvic claspers found in males. This shows that viviparity and internal fertilization was common amongst these primitive jawed vertebrates, which are outside the crown group Gnathostomata. In a study of fossil remains, comparison of the ontogeny of fourteen dermal plates from ''Compagopiscis, Compagopiscis croucheri'' and the more derived species ''Incisoscutum ritchiei'' suggested that lengthwise growth occurs earlier in the ontogeny than growth in width, and that di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rolfosteus
''Rolfosteus'' is an extinct monospecific genus of arthrodire placoderm from the Early Frasnian stage of the Late Devonian period, found at the Gogo Formation of Western Australia. Description ''Rolfosteus'' had a skull reaching , with tough plating on the front of its body. Like other arthrodires, such as ''Coccosteus'' and the giant ''Dunkleosteus'', it had sharp, bony plates on its mouth which formed a turtle-like beak for cutting prey to pieces. ''Rolfosteuss most unusual feature was its highly elongated rostrum (snout), which may have been used to enhance its sense of smell as well as increase its hydrodynamic streamlining, making it well adapted to be a pelagic pursuit predator. Its fast jaw movement and jaw morphology allowed it to effectively capture prey and swallow them whole. Phylogeny ''Rolfosteus'' is a member of the family Camuropiscidae under the superfamily Incisoscutoidea, which belongs to the clade Coccosteomorphi, one of the two major clades within Eubrachy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dunkleosteus
''Dunkleosteus'' is an extinct genus of large arthrodira, arthrodire ("jointed-neck") fish that existed during the Late Devonian period, about 382–358 million years ago. It was a pelagic fish inhabiting open waters, and one of the first vertebrate apex predators of any ecosystem. ''Dunkleosteus'' consists of ten species, some of which are among the largest placoderms ("plate-skinned") to have ever lived: ''D. terrelli'', ''D. belgicus'', ''D. denisoni'', ''D. marsaisi'', ''D. magnificus'', ''D. missouriensis'', ''D. newberryi'', ''D. amblyodoratus'', ''D. raveri'', and ''D. tuderensis.'' However, the validity of several of these species is unclear. The largest and best known species is ''D. terrelli''. Since body shape is not known, various methods of estimation put the living total length of the largest known specimen of ''D. terrelli'' between long and its weight around . Lengths of or more are poorly supported, with the most recent and extensive studies on the body shape a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arctolepis
''Arctolepis'' is an extinct genus of placoderm arthrodire fish which lived during the Early Devonian period (408 – 307 million years ago). Fossils of ''Arctolepis'' have been found in what is now Norway and Michigan. Classification Within Arthrodira, ''Arctolepis'' is considered a member of "Phylctaenii", a paraphyletic grouping within the clade Phlyctaenioidei, basal to the suborder Order () is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized ... Brachythoraci. ''Arctolepis'' is most closely related to '' Heintzosteus'' and '' Dicksonosteus''. ''Arctolepis'' contains the following six species: * ''Arctolepis brevis'' Heintz, 1929 * ''Arctolepis decipiens'' Woodward, 1891 * ''Arctolepis lata'' Heintz, 1929 * ''Arctolepis lewini'' Heintz, 1929 * ''Arctolepis longicornis'' Heintz, 1929 * ''A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ichthyosaurs
Ichthyosauria is an taxonomy (biology), order of large extinction, extinct marine reptiles sometimes referred to as "ichthyosaurs", although the term is also used for wider clades in which the order resides. Ichthyosaurians thrived during much of the Mesozoic era; based on fossil evidence, they first appeared around 250 million years ago (Myr, Ma) and at least one species survived until about 90 million years ago, into the Late Cretaceous. During the Early Triassic Geologic time scale, epoch, ichthyosaurs and other Ichthyosauromorpha, ichthyosauromorphs evolved from a group of unidentified land reptiles that returned to the sea, in a development similar to how the mammalian land-dwelling ancestors of modern-day dolphins and whales returned to the sea millions of years later, which they gradually came to resemble in a case of convergent evolution. Ichthyosaurians were particularly abundant in the Late Triassic and Early Jurassic periods, until they were replaced as the top ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bird
Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a four-chambered heart, and a strong yet lightweight Bird skeleton, skeleton. Birds live worldwide and range in size from the bee hummingbird to the common ostrich. There are over 11,000 living species and they are split into 44 Order (biology), orders. More than half are passerine or "perching" birds. Birds have Bird wing, wings whose development varies according to species; the only known groups without wings are the extinct moa and elephant birds. Wings, which are modified forelimbs, gave birds the ability to fly, although further evolution has led to the Flightless bird, loss of flight in some birds, including ratites, penguins, and diverse endemism, endemic island species. The digestive and respiratory systems of birds are also uniquely a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sclerotic Ring
The scleral ring or sclerotic ring is a hardened ring of plates, often derived from bone, that is found in the eyes of many animals in several groups of vertebrates. Some species of mammals, amphibians, and crocodilians lack scleral rings. The ring is in the fibrous outer layer of the eye, called the sclera. The structure is commonly referred to as the sclerotic ring; but, because the word ''sclerotic'' often implies pathology of the sclera (''see'' " sclerosis", an unrelated medical condition), recent authors have urged avoiding the use of this term, to avoid confusion and to increase the utility of character comparisons. Scleral rings can be made of cartilaginous material (scleral cartilage) or bony material (scleral ossicles), or often a combination of both, that comes together to form a ring. The arrangement, size, shape, and number of ossicles vary by group. They are believed to have a role in supporting the eye, especially in animals whose eyes are not spherical, or which liv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
