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42-691: Australaves is a clade of birds , defined in 2012, consisting of the Eufalconimorphae ( passerines , parrots and falcons ) as well as the Cariamiformes (including seriemas and the extinct " terror birds "). They appear to be the sister group of Afroaves . This clade was defined in the PhyloCode by George Sangster and colleagues in 2022 as "the least inclusive crown clade containing Cariama cristata and Passer domesticus ". The clade's name, meaning 'southern birds', reflects

84-479: A "ladder", with supposedly more "advanced" organisms at the top. Taxonomists have increasingly worked to make the taxonomic system reflect evolution. When it comes to naming , this principle is not always compatible with the traditional rank-based nomenclature (in which only taxa associated with a rank can be named) because not enough ranks exist to name a long series of nested clades. For these and other reasons, phylogenetic nomenclature has been developed; it

126-623: A clade can be described based on two different reference points, crown age and stem age. The crown age of a clade refers to the age of the most recent common ancestor of all of the species in the clade. The stem age of a clade refers to the time that the ancestral lineage of the clade diverged from its sister clade. A clade's stem age is either the same as or older than its crown age. Ages of clades cannot be directly observed. They are inferred, either from stratigraphy of fossils , or from molecular clock estimates. Viruses , and particularly RNA viruses form clades. These are useful in tracking

168-629: A common ancestor and synchronic variation . Dialectologists are concerned with grammatical features that correspond to regional areas. Thus, they are usually dealing with populations living in specific locales for generations without moving, but also with immigrant groups bringing their languages to new settlements. Immigrant groups often bring their linguistic practices to new settlements, leading to distinct linguistic varieties within those communities. Dialectologists analyze these immigrant dialects to understand how languages develop and diversify in response to migration and cultural interactions. Phonology

210-452: A historical language form is also possible. It may be distinguished from diachronic, which regards a phenomenon in terms of developments through time. Diachronic analysis is the main concern of historical linguistics. However, most other branches of linguistics are concerned with some form of synchronic analysis. The study of language change offers a valuable insight into the state of linguistic representation, and because all synchronic forms are

252-413: A hybrid known as phono-semantic matching . In languages with a long and detailed history, etymology makes use of philology , the study of how words change from culture to culture over time. Etymologists also apply the methods of comparative linguistics to reconstruct information about languages that are too old for any direct information (such as writing) to be known. By analysis of related languages by

294-422: A revised taxonomy based on a concept strongly resembling clades, although the term clade itself would not be coined until 1957 by his grandson, Julian Huxley . German biologist Emil Hans Willi Hennig (1913–1976) is considered to be the founder of cladistics . He proposed a classification system that represented repeated branchings of the family tree, as opposed to the previous systems, which put organisms on

336-429: A suffix added should be e.g. "dracohortian". A clade is by definition monophyletic , meaning that it contains one ancestor which can be an organism, a population, or a species and all its descendants. The ancestor can be known or unknown; any and all members of a clade can be extant or extinct. The science that tries to reconstruct phylogenetic trees and thus discover clades is called phylogenetics or cladistics ,

378-428: Is aspirated , but the p in spin is not. In English these two sounds are used in complementary distribution and are not used to differentiate words so they are considered allophones of the same phoneme . In some other languages like Thai and Quechua , the same difference of aspiration or non-aspiration differentiates words and so the two sounds, or phones , are considered to be distinct phonemes. In addition to

420-438: Is a stub . You can help Misplaced Pages by expanding it . Clade In biological phylogenetics , a clade (from Ancient Greek κλάδος (kládos)  'branch'), also known as a monophyletic group or natural group , is a grouping of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree . In the taxonomical literature, sometimes

462-437: Is a branch of historical linguistics that is concerned with comparing languages in order to establish their historical relatedness. Languages may be related by convergence through borrowing or by genetic descent, thus languages can change and are also able to cross-relate. Genetic relatedness implies a common origin among languages. Comparative linguists construct language families , reconstruct proto-languages , and analyze

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504-401: Is a sub-field of linguistics which studies the sound system of a specific language or set of languages. Whereas phonetics is about the physical production and perception of the sounds of speech, phonology describes the way sounds function within a given language or across languages. Phonology studies when sounds are or are not treated as distinct within a language. For example, the p in pin

546-499: Is also used with a similar meaning in other fields besides biology, such as historical linguistics ; see Cladistics § In disciplines other than biology . The term "clade" was coined in 1957 by the biologist Julian Huxley to refer to the result of cladogenesis , the evolutionary splitting of a parent species into two distinct species, a concept Huxley borrowed from Bernhard Rensch . Many commonly named groups – rodents and insects , for example – are clades because, in each case,

588-512: Is available, such as Uralic and Austronesian . Dialectology is the scientific study of linguistic dialect , the varieties of a language that are characteristic of particular groups, based primarily on geographic distribution and their associated features. This is in contrast to variations based on social factors, which are studied in sociolinguistics , or variations based on time, which are studied in historical linguistics. Dialectology treats such topics as divergence of two local dialects from

630-476: Is in turn included in the mammal, vertebrate and animal clades. The idea of a clade did not exist in pre- Darwinian Linnaean taxonomy , which was based by necessity only on internal or external morphological similarities between organisms. Many of the better known animal groups in Linnaeus's original Systema Naturae (mostly vertebrate groups) do represent clades. The phenomenon of convergent evolution

672-422: Is limited due to chance word resemblances and variations between language groups, but a limit of around 10,000 years is often assumed. Several methods are used to date proto-languages, but the process is generally difficult and its results are inherently approximate. In linguistics, a synchronic analysis is one that views linguistic phenomena only at a given time, usually the present, but a synchronic analysis of

714-441: Is linguistic change in progress. Synchronic and diachronic approaches can reach quite different conclusions. For example, a Germanic strong verb (e.g. English sing ↔ sang ↔ sung ) is irregular when it is viewed synchronically: the native speaker's brain processes them as learned forms, but the derived forms of regular verbs are processed quite differently, by the application of productive rules (for example, adding -ed to

756-515: Is responsible for many cases of misleading similarities in the morphology of groups that evolved from different lineages. With the increasing realization in the first half of the 19th century that species had changed and split through the ages, classification increasingly came to be seen as branches on the evolutionary tree of life . The publication of Darwin's theory of evolution in 1859 gave this view increasing weight. In 1876 Thomas Henry Huxley , an early advocate of evolutionary theory, proposed

798-489: Is still controversial. As an example, see the full current classification of Anas platyrhynchos (the mallard duck) with 40 clades from Eukaryota down by following this Wikispecies link and clicking on "Expand". The name of a clade is conventionally a plural, where the singular refers to each member individually. A unique exception is the reptile clade Dracohors , which was made by haplology from Latin "draco" and "cohors", i.e. "the dragon cohort "; its form with

840-496: Is the study of patterns of word-formation within a language. It attempts to formulate rules that model the knowledge of speakers. In the context of historical linguistics, formal means of expression change over time. Words as units in the lexicon are the subject matter of lexicology . Along with clitics , words are generally accepted to be the smallest units of syntax ; however, it is clear in most languages that words may be related to one another by rules. These rules are understood by

882-650: The Latin form cladus (plural cladi ) is used rather than the English form. Clades are the fundamental unit of cladistics , a modern approach to taxonomy adopted by most biological fields. The common ancestor may be an individual, a population , or a species ( extinct or extant ). Clades are nested, one in another, as each branch in turn splits into smaller branches. These splits reflect evolutionary history as populations diverged and evolved independently. Clades are termed monophyletic (Greek: "one clan") groups. Over

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924-558: The Uralic languages , another Eurasian language-family for which less early written material exists. Since then, there has been significant comparative linguistic work expanding outside of European languages as well, such as on the Austronesian languages and on various families of Native American languages , among many others. Comparative linguistics became only a part of a more broadly-conceived discipline of historical linguistics. For

966-400: The comparative method and the method of internal reconstruction . Less-standard techniques, such as mass lexical comparison , are used by some linguists to overcome the limitations of the comparative method, but most linguists regard them as unreliable. The findings of historical linguistics are often used as a basis for hypotheses about the groupings and movements of peoples, particularly in

1008-482: The comparative method , linguists can make inferences about their shared parent language and its vocabulary. In that way, word roots that can be traced all the way back to the origin of, for instance, the Indo-European language family have been found. Although originating in the philological tradition, much current etymological research is done in language families for which little or no early documentation

1050-475: The origin of language ) studies Lamarckian acquired characteristics of languages. This perspective explores how languages adapt and change over time in response to cultural, societal, and environmental factors. Language evolution within the framework of historical linguistics is akin to Lamarckism in the sense that linguistic traits acquired during an individual's lifetime can potentially influence subsequent generations of speakers. Historical linguists often use

1092-490: The Indo-European languages, comparative study is now a highly specialized field. Some scholars have undertaken studies attempting to establish super-families, linking, for example, Indo-European, Uralic, and other families into Nostratic . These attempts have not met with wide acceptance. The information necessary to establish relatedness becomes less available as the time increases. The time-depth of linguistic methods

1134-484: The basic form of a verb as in walk → walked ). That is an insight of psycholinguistics , which is relevant also for language didactics , both of which are synchronic disciplines. However, a diachronic analysis shows that the strong verb is the remnant of a fully regular system of internal vowel changes, in this case the Indo-European ablaut ; historical linguistics seldom uses the category " irregular verb ". The principal tools of research in diachronic linguistics are

1176-412: The cornerstone of comparative linguistics , primarily as a tool for linguistic reconstruction . Scholars were concerned chiefly with establishing language families and reconstructing unrecorded proto-languages , using the comparative method and internal reconstruction . The focus was initially on the well-known Indo-European languages , many of which had long written histories; scholars also studied

1218-441: The development of the modern title page . Often, dating must rely on contextual historical evidence such as inscriptions, or modern technology, such as carbon dating , can be used to ascertain dates of varying accuracy. Also, the work of sociolinguists on linguistic variation has shown synchronic states are not uniform: the speech habits of older and younger speakers differ in ways that point to language change. Synchronic variation

1260-482: The discipline. Primacy is accorded to synchronic linguistics, and diachronic linguistics is defined as the study of successive synchronic stages. Saussure's clear demarcation, however, has had both defenders and critics. In practice, a purely-synchronic linguistics is not possible for any period before the invention of the gramophone , as written records always lag behind speech in reflecting linguistic developments. Written records are difficult to date accurately before

1302-546: The group consists of a common ancestor with all its descendant branches. Rodents, for example, are a branch of mammals that split off after the end of the period when the clade Dinosauria stopped being the dominant terrestrial vertebrates 66 million years ago. The original population and all its descendants are a clade. The rodent clade corresponds to the order Rodentia, and insects to the class Insecta. These clades include smaller clades, such as chipmunk or ant , each of which consists of even smaller clades. The clade "rodent"

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1344-587: The group's evolutionary origins in the Southern Hemisphere : passerines and parrots in Australia , and falcons and seriemas in South America . As in the case of Afroaves, the most basal clades have predatory extant members, suggesting this was the ancestral lifestyle; however, some researchers like Darren Naish are skeptical of this assessment, since some extinct representatives such as

1386-459: The herbivorous Strigogyps led other lifestyles. Basal parrots and falcons are at any rate vaguely crow -like and probably omnivorous. Cariamiformes (seriemas) [REDACTED] Falconiformes (falcons) [REDACTED] Psittaciformes (parrots) [REDACTED] Passeriformes (songbirds) [REDACTED] Cladogram of Telluraves relationships based on Kuhl et al . (2020) and Braun & Kimball (2021) This bird-related article

1428-409: The historical changes that have resulted in the documented languages' divergences. Etymology studies the history of words : when they entered a language, from what source, and how their form and meaning have changed over time. Words may enter a language in several ways, including being borrowed as loanwords from another language, being derived by combining pre-existing elements in the language, by

1470-590: The last few decades, the cladistic approach has revolutionized biological classification and revealed surprising evolutionary relationships among organisms. Increasingly, taxonomists try to avoid naming taxa that are not clades; that is, taxa that are not monophyletic . Some of the relationships between organisms that the molecular biology arm of cladistics has revealed include that fungi are closer relatives to animals than they are to plants, archaea are now considered different from bacteria , and multicellular organisms may have evolved from archaea. The term "clade"

1512-518: The latter term coined by Ernst Mayr (1965), derived from "clade". The results of phylogenetic/cladistic analyses are tree-shaped diagrams called cladograms ; they, and all their branches, are phylogenetic hypotheses. Three methods of defining clades are featured in phylogenetic nomenclature : node-, stem-, and apomorphy-based (see Phylogenetic nomenclature§Phylogenetic definitions of clade names for detailed definitions). The relationship between clades can be described in several ways: The age of

1554-522: The minimal meaningful sounds (the phonemes), phonology studies how sounds alternate, such as the /p/ in English, and topics such as syllable structure, stress , accent , and intonation . Principles of phonology have also been applied to the analysis of sign languages , but the phonological units do not consist of sounds. The principles of phonological analysis can be applied independently of modality because they are designed to serve as general analytical tools, not language-specific ones. Morphology

1596-495: The past, unless there is clear evidence to suggest otherwise. Historical linguists aim to describe and explain changes in individual languages, explore the history of speech communities, and study the origins and meanings of words ( etymology ). Modern historical linguistics dates to the late 18th century, having originally grown out of the earlier discipline of philology , the study of ancient texts and documents dating back to antiquity. Initially, historical linguistics served as

1638-472: The prehistoric period. In practice, however, it is often unclear how to integrate the linguistic evidence with the archaeological or genetic evidence. For example, there are numerous theories concerning the homeland and early movements of the Proto-Indo-Europeans , each with its own interpretation of the archaeological record. Comparative linguistics , originally comparative philology ,

1680-425: The result of historically evolving diachronic changes, the ability to explain linguistic constructions necessitates a focus on diachronic processes. Initially, all of modern linguistics was historical in orientation. Even the study of modern dialects involved looking at their origins. Ferdinand de Saussure 's distinction between synchronic and diachronic linguistics is fundamental to the present day organization of

1722-739: The speaker, and reflect specific patterns in how word formation interacts with speech. In the context of historical linguistics, the means of expression change over time. Syntax is the study of the principles and rules for constructing sentences in natural languages . Syntax directly concerns the rules and principles that govern sentence structure in individual languages. Researchers attempt to describe languages in terms of these rules. Many historical linguistics attempt to compare changes in sentence between related languages, or find universal grammar rules that natural languages follow regardless of when and where they are spoken. In terms of evolutionary theory, historical linguistics (as opposed to research into

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1764-619: The spread of viral infections . HIV , for example, has clades called subtypes, which vary in geographical prevalence. HIV subtype (clade) B, for example is predominant in Europe, the Americas and Japan, whereas subtype A is more common in east Africa. Historical linguistics This field is grounded in the Uniformitarian Principle , which posits that the processes of language change observed today were also at work in

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