130-412: The long-tailed ground roller ( Uratelornis chimaera ) is a species of bird in the ground roller family Brachypteraciidae, placed in the monotypic genus Uratelornis . Endemic to arid spiny forests near the coast in southwestern Madagascar , this ground roller occurs at extremely low population densities throughout its habitat. This species requires shade and a deep layer of leaves on
260-456: A bony enclosure around the brain of a vertebrate . In some fish , and amphibians , the skull is of cartilage . The skull is at the head end of the vertebrate. In the human the skull comprises two prominent parts: the neurocranium , and the facial skeleton . which evolved from the first pharyngeal arch . The skull forms the frontmost portion of the axial skeleton and is a product of cephalization and vesicular enlargement of
390-423: A mutation–selection balance . It is predicted that a viral quasispecies at a low but evolutionarily neutral and highly connected (that is, flat) region in the fitness landscape will outcompete a quasispecies located at a higher but narrower fitness peak in which the surrounding mutants are unfit, "the quasispecies effect" or the "survival of the flattest". There is no suggestion that a viral quasispecies resembles
520-400: A "classical" method of determining species, such as with Linnaeus, early in evolutionary theory. However, different phenotypes are not necessarily different species (e.g. a four-winged Drosophila born to a two-winged mother is not a different species). Species named in this manner are called morphospecies . In the 1970s, Robert R. Sokal , Theodore J. Crovello and Peter Sneath proposed
650-424: A 'smallest clade' idea" (a phylogenetic species concept). Mishler and Wilkins and others concur with this approach, even though this would raise difficulties in biological nomenclature. Wilkins cited the ichthyologist Charles Tate Regan 's early 20th century remark that "a species is whatever a suitably qualified biologist chooses to call a species". Wilkins noted that the philosopher Philip Kitcher called this
780-428: A connected series of neighbouring populations, each of which can sexually interbreed with adjacent related populations, but for which there exist at least two "end" populations in the series, which are too distantly related to interbreed, though there is a potential gene flow between each "linked" population. Such non-breeding, though genetically connected, "end" populations may co-exist in the same region thus closing
910-994: A cranial capacity about 10 percent less than that of the male. However, later studies show that women's skulls are slightly thicker and thus men may be more susceptible to head injury than women. However, other studies shows that men's skulls are slightly thicker in certain areas. Some studies show that females are more susceptible to concussion than males. Men's skulls have also been shown to maintain density with age, which may aid in preventing head injury, while women's skull density slightly decreases with age. Male skulls can all have more prominent supraorbital ridges , glabella , and temporal lines . Female skulls generally have rounder orbits and narrower jaws. Male skulls on average have larger, broader palates , squarer orbits, larger mastoid processes , larger sinuses , and larger occipital condyles than those of females. Male mandibles typically have squarer chins and thicker, rougher muscle attachments than female mandibles. The cephalic index
1040-432: A different species from its ancestors. Viruses have enormous populations, are doubtfully living since they consist of little more than a string of DNA or RNA in a protein coat, and mutate rapidly. All of these factors make conventional species concepts largely inapplicable. A viral quasispecies is a group of genotypes related by similar mutations, competing within a highly mutagenic environment, and hence governed by
1170-508: A genetic boundary suitable for defining a species concept is present. DNA barcoding has been proposed as a way to distinguish species suitable even for non-specialists to use. One of the barcodes is a region of mitochondrial DNA within the gene for cytochrome c oxidase . A database, Barcode of Life Data System , contains DNA barcode sequences from over 190,000 species. However, scientists such as Rob DeSalle have expressed concern that classical taxonomy and DNA barcoding, which they consider
1300-509: A human observer, it either freezes or runs away. As its short wings suggest, the species rarely flies, but it is a powerful runner. While largely terrestrial, it roosts in low trees and bushes, and sings from low perches. Long-tailed ground rollers are solitary outside the breeding season. Although diurnal , it does occasionally forage at night unlike most other ground rollers. When calling, this ground roller bobs its head and raises its tail. The long-tailed ground roller also raises its tail when it
1430-509: A large amount of tension on the "obstetrical hinge", which is where the squamous and lateral parts of the occipital bone meet. A possible complication of this tension is rupture of the great cerebral vein . As growth and ossification progress, the connective tissue of the fontanelles is invaded and replaced by bone creating sutures . The five sutures are the two squamous sutures , one coronal , one lambdoid , and one sagittal suture . The posterior fontanelle usually closes by eight weeks, but
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#17327809680641560-504: A larger area outside the breeding season. This species' prime habitat is spiny forest, a mix of sub-arid thorn-scrub and deciduous woodland that only receives on average 500 millimeters (20 in) of water a year and is covered in sandy soil. The dominant plants in these spiny forests belong to the cactus-like family Didiereaceae (especially Didierea madagascariensis ) and more tree-like family Euphorbiaceae (especially Euphorbia stenoclada ). Baobab trees are also prevalent. It
1690-465: A lineage should be divided into multiple chronospecies , or when populations have diverged to have enough distinct character states to be described as cladistic species. Species and higher taxa were seen from the time of Aristotle until the 18th century as categories that could be arranged in a hierarchy, the great chain of being . In the 19th century, biologists grasped that species could evolve given sufficient time. Charles Darwin 's 1859 book On
1820-407: A mate or defend a territory. The bird pumps its tail while giving this call. One territorial call is a series of soft boo notes, typically coming in sets of six to ten and descending in volume near the end. Another call, given by both sexes, is a series of chuckling tu-tuc sounds lasting between 10 and 40 seconds that occasionally ends in a loud snapping sound produced by the wings. This call
1950-492: A misnomer, need to be reconciled, as they delimit species differently. Genetic introgression mediated by endosymbionts and other vectors can further make barcodes ineffective in the identification of species. A phylogenetic or cladistic species is "the smallest aggregation of populations (sexual) or lineages (asexual) diagnosable by a unique combination of character states in comparable individuals (semaphoronts)". The empirical basis – observed character states – provides
2080-449: A particular species, including which genus (and higher taxa) it is placed in, is a hypothesis about the evolutionary relationships and distinguishability of that group of organisms. As further information comes to hand, the hypothesis may be corroborated or refuted. Sometimes, especially in the past when communication was more difficult, taxonomists working in isolation have given two distinct names to individual organisms later identified as
2210-400: A perfect model of life, it is still a useful tool to scientists and conservationists for studying life on Earth, regardless of the theoretical difficulties. If species were fixed and clearly distinct from one another, there would be no problem, but evolutionary processes cause species to change. This obliges taxonomists to decide, for example, when enough change has occurred to declare that
2340-401: A sandy buff crown and dark brown upperparts with black streaks. Its supercilium is a pale buff color, while the ear- coverts are brown. The eyes are brown, while the short and stout beak is black. Its tongue is long with a brush-like tip to help it collect insects. A white stripe is present at the base of the bill and is surrounded by brown and black malar stripes. These malar stripes and
2470-403: A series of only loosely connected bones. Lampreys and sharks only possess a cartilaginous endocranium, with both the upper jaw and the lower jaws being separate elements. Bony fishes have additional dermal bone , forming a more or less coherent skull roof in lungfish and holost fish. The lower jaw defines the chin. The simpler structure is found in jawless fish , in which the cranium
2600-400: A short way of saying that something applies to many species within a genus, but not to all. If scientists mean that something applies to all species within a genus, they use the genus name without the specific name or epithet. The names of genera and species are usually printed in italics . However, abbreviations such as "sp." should not be italicised. When a species' identity is not clear,
2730-404: A specialist may use "cf." before the epithet to indicate that confirmation is required. The abbreviations "nr." (near) or "aff." (affine) may be used when the identity is unclear but when the species appears to be similar to the species mentioned after. With the rise of online databases, codes have been devised to provide identifiers for species that are already defined, including: The naming of
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#17327809680642860-523: A species as groups of actually or potentially interbreeding natural populations, which are reproductively isolated from other such groups. It has been argued that this definition is a natural consequence of the effect of sexual reproduction on the dynamics of natural selection. Mayr's use of the adjective "potentially" has been a point of debate; some interpretations exclude unusual or artificial matings that occur only in captivity, or that involve animals capable of mating but that do not normally do so in
2990-400: A species as determined by a taxonomist. A typological species is a group of organisms in which individuals conform to certain fixed properties (a type), so that even pre-literate people often recognise the same taxon as do modern taxonomists. The clusters of variations or phenotypes within specimens (such as longer or shorter tails) would differentiate the species. This method was used as
3120-491: A species. All species definitions assume that an organism acquires its genes from one or two parents very like the "daughter" organism, but that is not what happens in HGT. There is strong evidence of HGT between very dissimilar groups of prokaryotes , and at least occasionally between dissimilar groups of eukaryotes , including some crustaceans and echinoderms . The evolutionary biologist James Mallet concludes that there
3250-685: A species. Generally the term includes the unknown element of a distinct act of creation. Many authors have argued that a simple textbook definition, following Mayr's concept, works well for most multi-celled organisms , but breaks down in several situations: Species identification is made difficult by discordance between molecular and morphological investigations; these can be categorised as two types: (i) one morphology, multiple lineages (e.g. morphological convergence , cryptic species ) and (ii) one lineage, multiple morphologies (e.g. phenotypic plasticity , multiple life-cycle stages). In addition, horizontal gene transfer (HGT) makes it difficult to define
3380-528: A taxonomic decision at the discretion of cognizant specialists, is not governed by the Codes of Zoological or Botanical Nomenclature, in contrast to the PhyloCode , and contrary to what is done in several other fields, in which the definitions of technical terms, like geochronological units and geopolitical entities, are explicitly delimited. The nomenclatural codes that guide the naming of species, including
3510-517: A traditional biological species. The International Committee on Taxonomy of Viruses has since 1962 developed a universal taxonomic scheme for viruses; this has stabilised viral taxonomy. Most modern textbooks make use of Ernst Mayr 's 1942 definition, known as the Biological Species Concept as a basis for further discussion on the definition of species. It is also called a reproductive or isolation concept. This defines
3640-447: A variation on the morphological species concept, a phenetic species, defined as a set of organisms with a similar phenotype to each other, but a different phenotype from other sets of organisms. It differs from the morphological species concept in including a numerical measure of distance or similarity to cluster entities based on multivariate comparisons of a reasonably large number of phenotypic traits. A mate-recognition species
3770-515: A variety of reasons. Viruses are a special case, driven by a balance of mutation and selection , and can be treated as quasispecies . Biologists and taxonomists have made many attempts to define species, beginning from morphology and moving towards genetics . Early taxonomists such as Linnaeus had no option but to describe what they saw: this was later formalised as the typological or morphological species concept. Ernst Mayr emphasised reproductive isolation, but this, like other species concepts,
3900-438: Is "an entity composed of organisms which maintains its identity from other such entities through time and over space, and which has its own independent evolutionary fate and historical tendencies". This differs from the biological species concept in embodying persistence over time. Wiley and Mayden stated that they see the evolutionary species concept as "identical" to Willi Hennig 's species-as-lineages concept, and asserted that
4030-420: Is a monogamous species, and it defends a territory during the breeding season of October to February. It digs a tunnel in the sand, at the end of which is a wider chamber where it makes its nest out of leaves and earthy pellets. Two to four eggs are laid. After the chicks fledge , the birds continue living in family groups until at least February before dispersing more widely across the scrubland . This bird
Long-tailed ground roller - Misplaced Pages Continue
4160-400: Is a group of sexually reproducing organisms that recognise one another as potential mates. Expanding on this to allow for post-mating isolation, a cohesion species is the most inclusive population of individuals having the potential for phenotypic cohesion through intrinsic cohesion mechanisms; no matter whether populations can hybridise successfully, they are still distinct cohesion species if
4290-444: Is a phenomenon wherein intense intracranial pressure disfigures the internal surface of the skull. The name comes from the fact that the inner skull has the appearance of having been beaten with a ball-peen hammer , such as is often used by coppersmiths . The condition is most common in children. Injuries to the brain can be life-threatening. Normally the skull protects the brain from damage through its high resistance to deformation;
4420-452: Is a population of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring , typically by sexual reproduction . It is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity . Other ways of defining species include their karyotype , DNA sequence, morphology , behaviour, or ecological niche . In addition, paleontologists use
4550-458: Is a set of organisms adapted to a particular set of resources, called a niche, in the environment. According to this concept, populations form the discrete phenetic clusters that we recognise as species because the ecological and evolutionary processes controlling how resources are divided up tend to produce those clusters. A genetic species as defined by Robert Baker and Robert Bradley is a set of genetically isolated interbreeding populations. This
4680-403: Is between 9,500 and 32,700 birds and declining. As the long-tailed ground roller is remarkably silent and difficult to see during the non-breeding season, the local inhabitants of Madagascar once believed that this bird hibernated in its burrows. While not particularly tasty, this species is hunted for food due to its large size and the relative ease of capture compared with arboreal birds. In
4810-414: Is called speciation . Charles Darwin was the first to describe the role of natural selection in speciation in his 1859 book The Origin of Species . Speciation depends on a measure of reproductive isolation , a reduced gene flow. This occurs most easily in allopatric speciation, where populations are separated geographically and can diverge gradually as mutations accumulate. Reproductive isolation
4940-412: Is called the specific name or the specific epithet (in botanical nomenclature , also sometimes in zoological nomenclature ). For example, Boa constrictor is one of the species of the genus Boa , with constrictor being the species' epithet. While the definitions given above may seem adequate at first glance, when looked at more closely they represent problematic species concepts. For example,
5070-508: Is classified as vulnerable by the IUCN and is threatened by habitat destruction . Since the arid, spiny forests in which it lives are not protected by the Malagasy government, it is losing habitat to slash-and-burn agriculture, charcoal collection, and logging . It is also hunted by the native peoples of Madagascar . British banker and naturalist Walter Rothschild first described
5200-591: Is derived from the Ancient Greek word oura "tail," and atelornis in reference to another genus of ground roller. Atelornis comes from the Ancient Greek words ateles "indeterminate or incomplete," and ornis "bird." The specific name , chimaera , is a reference to the Ancient Greek mythological creature known as the chimera . The long-tailed ground roller is placed in the ground roller family, which gets its common name due to its similarity to
5330-403: Is described formally, in a publication that assigns it a unique scientific name. The description typically provides means for identifying the new species, which may not be based solely on morphology (see cryptic species ), differentiating it from other previously described and related or confusable species and provides a validly published name (in botany) or an available name (in zoology) when
Long-tailed ground roller - Misplaced Pages Continue
5460-532: Is excited. This species forages almost exclusively from the ground, where it alternates between remaining still and watching attentively and actively searching for it by rummaging through deep leaf litter. It eats a wide range of invertebrates, including ants, beetles, butterflies, caterpillars, cockroaches, grasshoppers, woodlice, and worms, and occasionally small vertebrates. Despite the long-tailed ground roller's poor flying abilities, it has been seen catching butterflies in midair. The breeding season coincides with
5590-671: Is further weakened by the existence of microspecies , groups of organisms, including many plants, with very little genetic variability, usually forming species aggregates . For example, the dandelion Taraxacum officinale and the blackberry Rubus fruticosus are aggregates with many microspecies—perhaps 400 in the case of the blackberry and over 200 in the dandelion, complicated by hybridisation , apomixis and polyploidy , making gene flow between populations difficult to determine, and their taxonomy debatable. Species complexes occur in insects such as Heliconius butterflies, vertebrates such as Hypsiboas treefrogs, and fungi such as
5720-413: Is given when birds are close to each other either on the ground or on low perches, and it does not carry over long distances. The use of wing-snapping to produce a sound is a rare phenomenon in birds, and in the order Coraciiformes only one other family, the todies , is known to do it. Low gu notes are given by mates as they come in contact with each other. Endemic to the island nation of Madagascar,
5850-726: Is hard or even impossible to test. Later biologists have tried to refine Mayr's definition with the recognition and cohesion concepts, among others. Many of the concepts are quite similar or overlap, so they are not easy to count: the biologist R. L. Mayden recorded about 24 concepts, and the philosopher of science John Wilkins counted 26. Wilkins further grouped the species concepts into seven basic kinds of concepts: (1) agamospecies for asexual organisms (2) biospecies for reproductively isolated sexual organisms (3) ecospecies based on ecological niches (4) evolutionary species based on lineage (5) genetic species based on gene pool (6) morphospecies based on form or phenotype and (7) taxonomic species,
5980-403: Is no easy way to tell whether related geographic or temporal forms belong to the same or different species. Species gaps can be verified only locally and at a point of time. One is forced to admit that Darwin's insight is correct: any local reality or integrity of species is greatly reduced over large geographic ranges and time periods. The botanist Brent Mishler argued that the species concept
6110-405: Is no space for the brain to expand; this can result in significant brain damage or death unless an urgent operation is performed to relieve the pressure. This is why patients with concussion must be watched extremely carefully. Repeated concussions can activate the structure of skull bones as the brain's protective covering. Dating back to Neolithic times, a skull operation called trepanning
6240-414: Is normally represented by a trough-like basket of cartilaginous elements only partially enclosing the brain, and associated with the capsules for the inner ears and the single nostril. Distinctively, these fish have no jaws. Cartilaginous fish , such as sharks and rays, have also simple, and presumably primitive, skull structures. The cranium is a single structure forming a case around the brain, enclosing
6370-478: Is not valid, notably because gene flux decreases gradually rather than in discrete steps, which hampers objective delimitation of species. Indeed, complex and unstable patterns of gene flux have been observed in cichlid teleosts of the East African Great Lakes . Wilkins argued that "if we were being true to evolution and the consequent phylogenetic approach to taxa, we should replace it with
6500-423: Is one seventh of the size of the calvaria . (In the adult it is half the size). The base of the skull is short and narrow, though the inner ear is almost adult size. Craniosynostosis is a condition in which one or more of the fibrous sutures in an infant skull prematurely fuses, and changes the growth pattern of the skull. Because the skull cannot expand perpendicular to the fused suture, it grows more in
6630-586: Is similar to Mayr's Biological Species Concept, but stresses genetic rather than reproductive isolation. In the 21st century, a genetic species could be established by comparing DNA sequences. Earlier, other methods were available, such as comparing karyotypes (sets of chromosomes ) and allozymes ( enzyme variants). An evolutionarily significant unit (ESU) or "wildlife species" is a population of organisms considered distinct for purposes of conservation. In palaeontology , with only comparative anatomy (morphology) and histology from fossils as evidence,
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#17327809680646760-408: Is sometimes an important source of genetic variation. Viruses can transfer genes between species. Bacteria can exchange plasmids with bacteria of other species, including some apparently distantly related ones in different phylogenetic domains , making analysis of their relationships difficult, and weakening the concept of a bacterial species. Skull The skull , or cranium , is typically
6890-534: Is supported by DNA evidence. It has been suggested, but not widely accepted, that ground rollers are closely related to the puffbirds and jacamars . It has been speculated that the ancestor of the long-tailed ground roller was an arboreal roller that crossed over from Africa to Madagascar and developed a terrestrial lifestyle before moving from the rainforests into the long-tailed ground roller's arid scrubland. No fossils have been found for this genus, and genetic analysis suggests that this bird's closest relative
7020-468: Is the scaly ground roller . The long-tailed ground roller has no subspecies. The long-tailed ground roller's silhouette is highly distinctive due to its long tail and plump silhouette. The bird is 34 to 47 centimeters (13 to 19 in) long, although its tail can contribute up to 30 centimeters (12 in) of the length, which makes it the longest tail of any of the ground rollers. This ground roller has short wings and long, pinkish-brown legs. The male has
7150-452: Is the bone structure that forms the head in the human skeleton . It supports the structures of the face and forms a cavity for the brain . Like the skulls of other vertebrates, it protects the brain from injury. The skull consists of three parts, of different embryological origin—the neurocranium , the sutures , and the facial skeleton . The neurocranium (or braincase ) forms the protective cranial cavity that surrounds and houses
7280-431: Is the ratio of the width of the head, multiplied by 100 and divided by its length (front to back). The index is also used to categorize animals, especially dogs and cats. The width is usually measured just below the parietal eminence , and the length from the glabella to the occipital point. Humans may be: The vertical cephalic index refers to the ratio between the height of the head multiplied by 100 and divided by
7410-594: Is threatened by hybridisation, but this can be selected against once a pair of populations have incompatible alleles of the same gene, as described in the Bateson–Dobzhansky–Muller model . A different mechanism, phyletic speciation, involves one lineage gradually changing over time into a new and distinct form (a chronospecies ), without increasing the number of resultant species. Horizontal gene transfer between organisms of different species, either through hybridisation , antigenic shift , or reassortment ,
7540-428: Is unknown. After the young fledge, they live in a family group of four to five birds until approximately February, at which point the family disperses. Classified as vulnerable by the IUCN due to ongoing habitat destruction and a decline in the quality of the remaining habitat, the long-tailed ground roller is believed to be the most threatened species of ground roller. Thirty percent of its already small habitat area
7670-530: The ICZN for animals and the ICN for plants, do not make rules for defining the boundaries of the species. Research can change the boundaries, also known as circumscription, based on new evidence. Species may then need to be distinguished by the boundary definitions used, and in such cases the names may be qualified with sensu stricto ("in the narrow sense") to denote usage in the exact meaning given by an author such as
7800-403: The facial skeleton (14) are the vomer , two inferior nasal conchae , two nasal bones , two maxilla , the mandible, two palatine bones , two zygomatic bones , and two lacrimal bones . Some sources count a paired bone as one, or the maxilla as having two bones (as its parts); some sources include the hyoid bone or the three ossicles of the middle ear , the malleus, incus, and stapes, but
7930-738: The facial skeleton and splanchnocranium with the mandible being its largest bone. The mandible articulates with the temporal bones of the neurocranium at the paired temporomandibular joints . The skull itself articulates with the spinal column at the atlanto-occipital joint . Functions of the skull include physical protection for the brain, providing attachments for neck muscles , facial muscles and muscles of mastication , providing fixed eye sockets and outer ears ( ear canals and auricles ) to enable stereoscopic vision and sound localisation , forming nasal and oral cavities that allow better olfaction , taste and digestion , and contributing to phonation by acoustic resonance within
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#17327809680648060-399: The fly agaric . Natural hybridisation presents a challenge to the concept of a reproductively isolated species, as fertile hybrids permit gene flow between two populations. For example, the carrion crow Corvus corone and the hooded crow Corvus cornix appear and are classified as separate species, yet they can hybridise where their geographical ranges overlap. A ring species is
8190-405: The frontal bone ). The bones of the roof of the skull are initially separated by regions of dense connective tissue called fontanelles . There are six fontanelles: one anterior (or frontal), one posterior (or occipital), two sphenoid (or anterolateral), and two mastoid (or posterolateral). At birth, these regions are fibrous and moveable, necessary for birth and later growth. This growth can put
8320-423: The introduced black rat is a nest predator. This ground roller is capable of tolerating some habitat disturbance, but requires a suitable amount of shade and leaf litter to continue living in the area. Although it was fairly common at the beginning of the twentieth century, its population went into decline and it was considered rare by the 1960s. As of 2012, the estimated population of the long-tailed ground roller
8450-507: The jaguar ( Panthera onca ) of Latin America or the leopard ( Panthera pardus ) of Africa and Asia. In contrast, the scientific names of species are chosen to be unique and universal (except for some inter-code homonyms ); they are in two parts used together : the genus as in Puma , and the specific epithet as in concolor . A species is given a taxonomic name when a type specimen
8580-402: The rainy season , which lasts from October to January. During this period this bird abandons its solitary habits to find a mate, with which it remains monogamous . Males form territories during the breeding season, and they defend their area with territorial calls. These calls are given from a perch up to 6 meters (20 ft) off the ground for an hour after sunrise and occasionally throughout
8710-404: The rollers and its largely terrestrial nature. Until recently the ground rollers, cuckoo roller , and rollers were all placed in a single family, Coraciidae, in which each of the three groups formed a subfamily. In 1971, Joel Cracraft proposed a separate family for the ground rollers based on significant differences in behavior, plumage, and post-cranial anatomy between the groups. This position
8840-421: The skull base and its fossae , the anterior , middle and posterior cranial fossae changes rapidly. The anterior cranial fossa changes especially during the first trimester of pregnancy and skull defects can often develop during this time. At birth, the human skull is made up of 44 separate bony elements. During development, many of these bony elements gradually fuse together into solid bone (for example,
8970-404: The zygomatic processes . The fenestrae (from Latin, meaning windows ) are openings in the skull. The jugal is a skull bone that found in most of the reptiles, amphibians and birds. In mammals, the jugal is often called the zygomatic bone or malar bone. The prefrontal bone is a bone that separates the lacrimal and frontal bones in many tetrapod skulls. The skull of fish is formed from
9100-406: The "cynical species concept", and arguing that far from being cynical, it usefully leads to an empirical taxonomy for any given group, based on taxonomists' experience. Other biologists have gone further and argued that we should abandon species entirely, and refer to the "Least Inclusive Taxonomic Units" (LITUs), a view that would be coherent with current evolutionary theory. The species concept
9230-626: The Origin of Species explained how species could arise by natural selection . That understanding was greatly extended in the 20th century through genetics and population ecology . Genetic variability arises from mutations and recombination , while organisms themselves are mobile, leading to geographical isolation and genetic drift with varying selection pressures . Genes can sometimes be exchanged between species by horizontal gene transfer ; new species can arise rapidly through hybridisation and polyploidy ; and species may become extinct for
9360-630: The U.S., researchers replaced a large percentage of a patient's skull with a precision, 3D-printed polymer implant . About 9 months later, the first complete cranium replacement with a 3D-printed plastic insert was performed on a Dutch woman. She had been suffering from hyperostosis , which increased the thickness of her skull and compressed her brain. A study conducted in 2018 by the researchers of Harvard Medical School in Boston, funded by National Institutes of Health (NIH), suggested that instead of travelling via blood , there are "tiny channels" in
9490-405: The abbreviation "sp." in the singular or "spp." (standing for species pluralis , Latin for "multiple species") in the plural in place of the specific name or epithet (e.g. Canis sp.). This commonly occurs when authors are confident that some individuals belong to a particular genus but are not sure to which exact species they belong, as is common in paleontology . Authors may also use "spp." as
9620-570: The amount of hybridisation is insufficient to completely mix their respective gene pools . A further development of the recognition concept is provided by the biosemiotic concept of species. In microbiology , genes can move freely even between distantly related bacteria, possibly extending to the whole bacterial domain. As a rule of thumb, microbiologists have assumed that members of Bacteria or Archaea with 16S ribosomal RNA gene sequences more similar than 97% to each other need to be checked by DNA–DNA hybridisation to decide if they belong to
9750-428: The anterior fontanel can remain open up to eighteen months. The anterior fontanelle is located at the junction of the frontal and parietal bones; it is a "soft spot" on a baby's forehead. Careful observation will show that you can count a baby's heart rate by observing the pulse pulsing softly through the anterior fontanelle. The skull in the neonate is large in proportion to other parts of the body. The facial skeleton
9880-474: The biological species concept, "the several versions" of the phylogenetic species concept, and the idea that species are of the same kind as higher taxa are not suitable for biodiversity studies (with the intention of estimating the number of species accurately). They further suggested that the concept works for both asexual and sexually-reproducing species. A version of the concept is Kevin de Queiroz 's "General Lineage Concept of Species". An ecological species
10010-505: The biological species concept, a cladistic species does not rely on reproductive isolation – its criteria are independent of processes that are integral in other concepts. Therefore, it applies to asexual lineages. However, it does not always provide clear cut and intuitively satisfying boundaries between taxa, and may require multiple sources of evidence, such as more than one polymorphic locus, to give plausible results. An evolutionary species, suggested by George Gaylord Simpson in 1951,
10140-421: The black breastband frame a white throat. The tail has 15 to 20 dark brown bars marking it, while the outer rectrices are sky blue; this sky blue is also present on the wing-coverts. In flight, the bird's two black and white bands on the primaries and secondaries are conspicuous. The underparts are a light gray, and the breast white. The toes are zygodactylous , with the first and fourth toes turned outwards and
10270-466: The bones either absent or wholly or partly replaced by cartilage. In mammals and birds, in particular, modifications of the skull occurred to allow for the expansion of the brain. The fusion between the various bones is especially notable in birds, in which the individual structures may be difficult to identify. The skull is a complex structure; its bones are formed both by intramembranous and endochondral ossification . The skull roof bones, comprising
10400-416: The bones of the facial skeleton and the sides and roof of the neurocranium, are dermal bones formed by intramembranous ossification, though the temporal bones are formed by endochondral ossification. The endocranium , the bones supporting the brain (the occipital, sphenoid , and ethmoid ) are largely formed by endochondral ossification. Thus frontal and parietal bones are purely membranous. The geometry of
10530-428: The boundaries between closely related species become unclear with hybridisation , in a species complex of hundreds of similar microspecies , and in a ring species . Also, among organisms that reproduce only asexually , the concept of a reproductive species breaks down, and each clone is potentially a microspecies. Although none of these are entirely satisfactory definitions, and while the concept of species may not be
10660-462: The brain and brainstem . The upper areas of the cranial bones form the calvaria (skullcap). The facial skeleton (membranous viscerocranium) is formed by the bones supporting the face, and includes the mandible . The bones of the skull are joined by fibrous joints known as sutures— synarthrodial (immovable) joints formed by bony ossification , with Sharpey's fibres permitting some flexibility. Sometimes there can be extra bone pieces within
10790-492: The brain, with several special senses structures such as the eyes , ears , nose , tongue and in fish specialized tactile organs such as barbels near the mouth. The skull is composed of three types of bone : cranial bones, facial bones and ossicles , which is made up of a number of fused flat and irregular bones . The cranial bones are joined at firm fibrous junctions called sutures and contains many foramina , fossae , processes , and sinuses . In zoology ,
10920-584: The branch while producing a "ripping and crackling sound" with its wingbeats. From the perch the bird releases a stream of boo notes. This display is thought to be part of a courtship ritual . Each pair digs one to six nesting burrows during the breeding season; the extra burrows are known as speculative burrows. Between October and January, and peaking in November, the species normally lays two smooth, white eggs, though sometimes it lays three or four. The incubation period and fledging time of this ground roller
11050-421: The burrow widens into a 20-centimeter (7.9 in) wide chamber with a shallow depression covered in dry leaves and earthy pellets. When digging its nest, the long-tailed ground roller occasionally walks underneath a low branch, tilts its head upwards, and, while remaining motionless, releases a rising crescendo of its tu-tuc calls. At the height of the crescendo the bird breaks off its call and flies upwards onto
11180-566: The cavities and sinuses. In some animals such as ungulates and elephants , the skull also has a function in anti-predator defense and sexual selection by providing the foundation for horns , antlers and tusks . The English word skull is probably derived from Old Norse skulle , while the Latin word cranium comes from the Greek root κρανίον ( kranion ). The human skull fully develops two years after birth. The human skull
11310-446: The chest, neck, and eyes. Although it is generally a silent species, during the breeding season the vocalizations of the long-tailed ground roller include a "hooting" sound, a "popping" tu-tuc , and a soft boo sound. The low-pitched "hooting" is given by males from a perch 2 to 6 meters (6.6 to 19.7 ft) above the ground at dusk or at night. The sound carries for a distance of at least 200 meters (660 ft) and may either attract
11440-433: The concept of a chronospecies can be applied. During anagenesis (evolution, not necessarily involving branching), some palaeontologists seek to identify a sequence of species, each one derived from the phyletically extinct one before through continuous, slow and more or less uniform change. In such a time sequence, some palaeontologists assess how much change is required for a morphologically distinct form to be considered
11570-416: The concept of the chronospecies since fossil reproduction cannot be examined. The most recent rigorous estimate for the total number of species of eukaryotes is between 8 and 8.7 million. About 14% of these had been described by 2011. All species (except viruses ) are given a two-part name , called a "binomial". The first part of a binomial is the genus to which the species belongs. The second part
11700-444: The day and night. During courtship, males have been observed feeding the female . Male and female long-tailed ground rollers use their bills and feet to excavate a burrow in consolidated, flat sand and construct their nest at the end of it. The burrow, always constructed away from grassy vegetation, is downward-sloping and is between 0.8 and 1.2 meters (2.6 and 3.9 ft) long with a diameter of 8 centimeters (3.1 in). The end of
11830-438: The desired sex. These procedures can be an important part of the treatment of transgender people for gender dysphoria . Artificial cranial deformation is a largely historical practice of some cultures. Cords and wooden boards would be used to apply pressure to an infant's skull and alter its shape, sometimes quite significantly. This procedure would begin just after birth and would be carried on for several years. Like
11960-446: The early twentieth century, it was hunted by herdsmen with blowguns . In the 1950s and 1960s, natives trapped this ground roller and dug out its nesting burrows. This bird has been featured on several of Madagascar's stamps. Only one zoo, Germany's Weltvogelpark Walsrode , keeps this species. It is considered by birdwatchers to be one of the world's most elusive birds. [REDACTED] Species A species ( pl. : species)
12090-435: The evidence to support hypotheses about evolutionarily divergent lineages that have maintained their hereditary integrity through time and space. Molecular markers may be used to determine diagnostic genetic differences in the nuclear or mitochondrial DNA of various species. For example, in a study done on fungi , studying the nucleotide characters using cladistic species produced the most accurate results in recognising
12220-531: The face, the skull and teeth can also indicate a person's life history and origin. Forensic scientists and archaeologists use quantitative and qualitative traits to estimate what the bearer of the skull looked like. When a significant amount of bones are found, such as at Spitalfields in the UK and Jōmon shell mounds in Japan, osteologists can use traits, such as the proportions of length, height and width, to know
12350-418: The foramen magnum lies immediately above a single condyle , articulating with the first vertebra . There are, in addition, at various points throughout the cranium, smaller foramina for the cranial nerves. The jaws consist of separate hoops of cartilage, almost always distinct from the cranium proper. In ray-finned fish , there has also been considerable modification from the primitive pattern. The roof of
12480-438: The frontal (top of head), parietal (back of head), premaxillary and nasal (top beak), and the mandible (bottom beak). The skull of a normal bird usually weighs about 1% of the bird's total bodyweight. The eye occupies a considerable amount of the skull and is surrounded by a sclerotic eye-ring, a ring of tiny bones. This characteristic is also seen in reptiles. Living amphibians typically have greatly reduced skulls, with many of
12610-445: The ground, and it is absent from parts of the spiny forest lacking these features. It has no recognized subspecies , and its closest relative is the scaly ground roller . The long-tailed ground roller is the only ground roller to definitively display sexual dimorphism (differences in plumage or size between sexes). It is a medium-sized bird with a plump silhouette and a long tail. The upperparts are dark brown with black streaks while
12740-484: The length of the head. Humans may be: Trepanning , a practice in which a hole is created in the skull, has been described as the oldest surgical procedure for which there is archaeological evidence, found in the forms of cave paintings and human remains. At one burial site in France dated to 6500 BCE, 40 out of 120 prehistoric skulls found had trepanation holes. [REDACTED] This article incorporates text in
12870-418: The lessening of the weight of the skull, the aiding of resonance to the voice and the warming and moistening of the air drawn into the nasal cavity . The foramina are openings in the skull. The largest of these is the foramen magnum , of the occipital bone, that allows the passage of the spinal cord as well as nerves and blood vessels . The many processes of the skull include the mastoid process and
13000-479: The long-tailed ground roller in 1895, giving it the scientific name Uratelornis chimaera ; Rothschild published his description in Novitates Zoologicae , the periodical of his private museum. The adaptations required for the ancestral long-tailed ground roller to inhabit scrubland led Rothschild to create the monotypic genus Uratelornis for the species in his description. The genus name Uratelornis
13130-767: The long-tailed ground roller inhabits a narrow strip of suitable habitat by the coast in the southwestern part of the island. This strip is bordered by the Mangoky River in the north, the Fiherenana River in the south, and lowland hills in the east. It totals about 10,500 square kilometers (4,100 sq mi ) in area; however, the species is extremely uncommon within its range and occurs at densities of about 0.8 to 10 per square kilometer (2.1 to 25 per square mile). This area ranges in elevation from sea level to 100 meters (330 ft). The long-tailed ground roller does not migrate , though it may disperse across
13260-453: The lower jaw is composed of multiple bones, only the most anterior of which (the dentary) is homologous with the mammalian mandible. In living tetrapods, a great many of the original bones have either disappeared or fused into one another in various arrangements. Birds have a diapsid skull, as in reptiles, with a prelacrimal fossa (present in some reptiles). The skull has a single occipital condyle. The skull consists of five major bones:
13390-406: The lower surface and the sides, but always at least partially open at the top as a large fontanelle . The most anterior part of the cranium includes a forward plate of cartilage, the rostrum , and capsules to enclose the olfactory organs. Behind these are the orbits, and then an additional pair of capsules enclosing the structure of the inner ear . Finally, the skull tapers towards the rear, where
13520-441: The mid-nineteenth century, anthropologists found it crucial to distinguish between male and female skulls. An anthropologist of the time, James McGrigor Allan , argued that the female brain was similar to that of an animal. This allowed anthropologists to declare that women were in fact more emotional and less rational than men. McGrigor then concluded that women's brains were more analogous to infants, thus deeming them inferior at
13650-409: The middle two toes turned inwards. The female resembles the male, but is smaller and has a narrower chestband and a shorter tail. Also, the female loses her tail while nesting. These differences make the long-tailed ground roller the only ground roller to definitively display sexual dimorphism . Juveniles of both sexes resemble the adult female, but have duller plumage, particularly in the black bands on
13780-483: The numerous fungi species of all the concepts studied. Versions of the phylogenetic species concept that emphasise monophyly or diagnosability may lead to splitting of existing species, for example in Bovidae , by recognising old subspecies as species, despite the fact that there are no reproductive barriers, and populations may intergrade morphologically. Others have called this approach taxonomic inflation , diluting
13910-401: The openings in the skull are called fenestrae , the most prominent of which is the foramen magnum , where the brainstem goes through to join the spinal cord . In human anatomy , the neurocranium (or braincase), is further divided into the calvarium and the endocranium , together forming a cranial cavity that houses the brain. The interior periosteum forms part of the dura mater ,
14040-442: The overall general consensus of the number of bones in the human skull is the stated twenty-two. Some of these bones—the occipital, parietal, frontal, in the neurocranium, and the nasal, lacrimal, and vomer, in the facial skeleton are flat bones . The skull also contains sinuses , air-filled cavities known as paranasal sinuses , and numerous foramina . The sinuses are lined with respiratory epithelium . Their known functions are
14170-593: The paper is accepted for publication. The type material is usually held in a permanent repository, often the research collection of a major museum or university, that allows independent verification and the means to compare specimens. Describers of new species are asked to choose names that, in the words of the International Code of Zoological Nomenclature , are "appropriate, compact, euphonious, memorable, and do not cause offence". Books and articles sometimes intentionally do not identify species fully, using
14300-493: The parallel direction. Sometimes the resulting growth pattern provides the necessary space for the growing brain, but results in an abnormal head shape and abnormal facial features. In cases in which the compensation does not effectively provide enough space for the growing brain, craniosynostosis results in increased intracranial pressure leading possibly to visual impairment, sleeping impairment, eating difficulties, or an impairment of mental development. A copper beaten skull
14430-674: The person who named the species, while the antonym sensu lato ("in the broad sense") denotes a wider usage, for instance including other subspecies. Other abbreviations such as "auct." ("author"), and qualifiers such as "non" ("not") may be used to further clarify the sense in which the specified authors delineated or described the species. Species are subject to change, whether by evolving into new species, exchanging genes with other species, merging with other species or by becoming extinct. The evolutionary process by which biological populations of sexually-reproducing organisms evolve to become distinct or reproductively isolated as species
14560-399: The relationships of the population of the study with other living or extinct populations. The German physician Franz Joseph Gall in around 1800 formulated the theory of phrenology , which attempted to show that specific features of the skull are associated with certain personality traits or intellectual capabilities of its owner. His theory is now considered to be pseudoscientific . In
14690-487: The result of misclassification leading to questions on whether there really are any ring species. The commonly used names for kinds of organisms are often ambiguous: "cat" could mean the domestic cat, Felis catus , or the cat family, Felidae . Another problem with common names is that they often vary from place to place, so that puma, cougar, catamount, panther, painter and mountain lion all mean Puma concolor in various parts of America, while "panther" may also mean
14820-586: The ring. Ring species thus present a difficulty for any species concept that relies on reproductive isolation. However, ring species are at best rare. Proposed examples include the herring gull – lesser black-backed gull complex around the North pole, the Ensatina eschscholtzii group of 19 populations of salamanders in America, and the greenish warbler in Asia, but many so-called ring species have turned out to be
14950-508: The same species. This concept was narrowed in 2006 to a similarity of 98.7%. The average nucleotide identity (ANI) method quantifies genetic distance between entire genomes , using regions of about 10,000 base pairs . With enough data from genomes of one genus, algorithms can be used to categorize species, as for Pseudomonas avellanae in 2013, and for all sequenced bacteria and archaea since 2020. Observed ANI values among sequences appear to have an "ANI gap" at 85–95%, suggesting that
15080-529: The same species. When two species names are discovered to apply to the same species, the older species name is given priority and usually retained, and the newer name considered as a junior synonym, a process called synonymy . Dividing a taxon into multiple, often new, taxa is called splitting . Taxonomists are often referred to as "lumpers" or "splitters" by their colleagues, depending on their personal approach to recognising differences or commonalities between organisms. The circumscription of taxa, considered
15210-474: The skull is formed from cartilage , and its overall structure is reduced. The skulls of the earliest tetrapods closely resembled those of their ancestors amongst the lobe-finned fishes . The skull roof is formed of a series of plate-like bones, including the maxilla, frontals , parietals , and lacrimals , among others. It is overlaying the endocranium , corresponding to the cartilaginous skull in sharks and rays . The various separate bones that compose
15340-455: The skull is generally well formed, and although the exact relationship of its bones to those of tetrapods is unclear, they are usually given similar names for convenience. Other elements of the skull, however, may be reduced; there is little cheek region behind the enlarged orbits, and little, if any bone in between them. The upper jaw is often formed largely from the premaxilla , with the maxilla itself located further back, and an additional bone,
15470-409: The skull is one of the least deformable structures found in nature, needing the force of about 1 ton to reduce its diameter by 1 cm. In some cases of head injury , however, there can be raised intracranial pressure through mechanisms such as a subdural haematoma . In these cases, the raised intracranial pressure can cause herniation of the brain out of the foramen magnum ("coning") because there
15600-459: The skull through which the immune cells combined with the bone marrow reach the areas of inflammation after an injury to the brain tissues. Surgical alteration of sexually dimorphic skull features may be carried out as a part of facial feminization surgery or facial masculinization surgery , these reconstructive surgical procedures that can alter sexually dimorphic facial features to bring them closer in shape and size to facial features of
15730-456: The species concept and making taxonomy unstable. Yet others defend this approach, considering "taxonomic inflation" pejorative and labelling the opposing view as "taxonomic conservatism"; claiming it is politically expedient to split species and recognise smaller populations at the species level, because this means they can more easily be included as endangered in the IUCN red list and can attract conservation legislation and funding. Unlike
15860-404: The suture known as Wormian bones or sutural bones . Most commonly these are found in the course of the lambdoid suture . The human skull is generally considered to consist of 22 bones—eight cranial bones and fourteen facial skeleton bones. In the neurocranium these are the occipital bone , two temporal bones , two parietal bones , the sphenoid , ethmoid and frontal bones . The bones of
15990-457: The symplectic, linking the jaw to the rest of the cranium. Although the skulls of fossil lobe-finned fish resemble those of the early tetrapods, the same cannot be said of those of the living lungfishes . The skull roof is not fully formed, and consists of multiple, somewhat irregularly shaped bones with no direct relationship to those of tetrapods. The upper jaw is formed from the pterygoids and vomers alone, all of which bear teeth. Much of
16120-413: The temporal bone of humans are also part of the skull roof series. A further plate composed of four pairs of bones forms the roof of the mouth; these include the vomer and palatine bones . The base of the cranium is formed from a ring of bones surrounding the foramen magnum and a median bone lying further forward; these are homologous with the occipital bone and parts of the sphenoid in mammals. Finally,
16250-554: The time. To further these claims of female inferiority and silence the feminists of the time, other anthropologists joined in on the studies of the female skull. These cranial measurements are the basis of what is known as craniology . These cranial measurements were also used to draw a connection between women and black people. Research has shown that while in early life there is little difference between male and female skulls, in adulthood male skulls tend to be larger and more robust than female skulls, which are lighter and smaller, with
16380-648: The underparts are light gray. The white throat is framed by black malar stripes and a black breastband, and a white stripe is present at the base of the bill. Sky-blue feathers are visible at the edge of the wings and the tail. Calls are rarely made outside the breeding season , though multiple courtship calls are made. These ground rollers feed primarily on invertebrates , including ants, beetles, butterflies, and worms, which they find by searching through deep leaf litter or by remaining still and watching attentively. The ground roller primarily runs through its habitat on its strong legs, as its wings are relatively weak. It
16510-540: The wild. It is difficult to define a species in a way that applies to all organisms. The debate about species concepts is called the species problem. The problem was recognised even in 1859, when Darwin wrote in On the Origin of Species : I was much struck how entirely vague and arbitrary is the distinction between species and varieties. He went on to write: No one definition has satisfied all naturalists; yet every naturalist knows vaguely what he means when he speaks of
16640-452: Was degraded between the mid-1970s and 2000. Slash-and-burn agriculture, charcoal production, logging, and cattle grazing have all contributed to the loss of habitat . As of 2012, no reserves protect any portion of its habitat, and as a result its habitat has been described as the area of Madagascar most in need of conservation efforts . It is also threatened by both hunting and egg-collecting . In addition to humans, dogs hunt this species, and
16770-425: Was formerly believed that the long-tailed ground roller preferred an undisturbed forest habitat, while tolerating small amounts of disturbance. Later studies have concluded that it actually prefers degraded habitat. Despite this, shade is necessary, and the species is not found in deforested habitat or on the shadeless dunes prevalent in its range. The long-tailed ground roller is a shy and elusive bird and, if seen by
16900-400: Was sometimes performed. This involved drilling a burr hole in the cranium. Examination of skulls from this period reveals that the patients sometimes survived for many years afterward. It seems likely that trepanning was also performed purely for ritualistic or religious reasons. Nowadays this procedure is still used but is normally called a craniectomy . In March 2013, for the first time in
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