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106-466: Nyaphulia is an extinct genus of dicynodont therapsid from the middle Permian of South Africa , containing only the type species N. oelofseni . The generic name is in honour of John Nyaphuli of the National Museum of Bloemfontein , who contributed extensively to South African palaeontology and discovered the holotype specimen of Nyaphulia in 1982. Nyaphulia was initially named as

212-438: A food chain who lose their prey. "Species coextinction is a manifestation of one of the interconnectednesses of organisms in complex ecosystems ... While coextinction may not be the most important cause of species extinctions, it is certainly an insidious one." Coextinction is especially common when a keystone species goes extinct. Models suggest that coextinction is the most common form of biodiversity loss . There may be

318-657: A nautilus to the Royal Society that was more than two feet in diameter, and morphologically distinct from any known living species. Hooke theorized that this was simply because the species lived in the deep ocean and no one had discovered them yet. While he contended that it was possible a species could be "lost", he thought this highly unlikely. Similarly, in 1695, Sir Thomas Molyneux published an account of enormous antlers found in Ireland that did not belong to any extant taxa in that area. Molyneux reasoned that they came from

424-415: A species or a population is the variety of genetic information in its living members. A large gene pool (extensive genetic diversity ) is associated with robust populations that can survive bouts of intense selection . Meanwhile, low genetic diversity (see inbreeding and population bottlenecks ) reduces the range of adaptions possible. Replacing native with alien genes narrows genetic diversity within

530-436: A viable population for species preservation and possible future reintroduction to the wild, through use of carefully planned breeding programs . The extinction of one species' wild population can have knock-on effects, causing further extinctions. These are also called "chains of extinction". This is especially common with extinction of keystone species . A 2018 study indicated that the sixth mass extinction started in

636-474: A Lazarus species when extant individuals were described in 2019. Attenborough's long-beaked echidna ( Zaglossus attenboroughi ) is an example of a Lazarus species from Papua New Guinea that had last been sighted in 1962 and believed to be possibly extinct, until it was recorded again in November 2023. Some species currently thought to be extinct have had continued speculation that they may still exist, and in

742-495: A cascade of coextinction across the trophic levels . Such effects are most severe in mutualistic and parasitic relationships. An example of coextinction is the Haast's eagle and the moa : the Haast's eagle was a predator that became extinct because its food source became extinct. The moa were several species of flightless birds that were a food source for the Haast's eagle. Extinction as

848-429: A common ancestor with modern horses. Pseudoextinction is much easier to demonstrate for larger taxonomic groups. A Lazarus taxon or Lazarus species refers to instances where a species or taxon was thought to be extinct, but was later rediscovered. It can also refer to instances where large gaps in the fossil record of a taxon result in fossils reappearing much later, although the taxon may have ultimately become extinct at

954-463: A distinct genus. "E." oelofseni would be named as the new genus Nyaphulia in 2024, following a thorough redescription of its material after it was CT-scanned and modelled digitally. Nyaphulia has a mix of features of both earlier anomodonts and dicynodonts. Like early anomodonts, it still has no tusks or secondary palate and a laterally exposed septomaxilla bone around the nose, but like other dicynodonts it has no teeth in its premaxilla or at

1060-447: A distinct taxon. This view has been supported by later researchers and upheld by further analyses, but a formal reassignment was avoided until it could be fully redescribed, accomplished by Duhamel and colleagues in 2024. Nyaphulia has been included in numerous phylogenetic analyses of anomodonts as "Eodicynodon" oelofseni (e.g. Kammerer et al. , 2011; Castanhinha et al. 2013). These analyses consistently found "E." oelofseni to be

1166-399: A fact that was accepted by most scientists. The primary debate focused on whether this turnover caused by extinction was gradual or abrupt in nature. Cuvier understood extinction to be the result of cataclysmic events that wipe out huge numbers of species, as opposed to the gradual decline of a species over time. His catastrophic view of the nature of extinction garnered him many opponents in

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1272-708: A higher risk of extinction and die out faster than less sexually dimorphic species, the least sexually dimorphic species surviving for millions of years while the most sexually dimorphic species die out within mere thousands of years. Earlier studies based on counting the number of currently living species in modern taxa have shown a higher number of species in more sexually dimorphic taxa which have been interpreted as higher survival in taxa with more sexual selection, but such studies of modern species only measure indirect effects of extinction and are subject to error sources such as dying and doomed taxa speciating more due to splitting of habitat ranges into more small isolated groups during

1378-405: A large range, a lack of individuals of both sexes (in sexually reproducing species), or other reasons. Pinpointing the extinction (or pseudoextinction ) of a species requires a clear definition of that species . If it is to be declared extinct, the species in question must be uniquely distinguishable from any ancestor or daughter species, and from any other closely related species. Extinction of

1484-592: A later point. The coelacanth , a fish related to lungfish and tetrapods , is an example of a Lazarus taxon that was known only from the fossil record and was considered to have been extinct since the end of the Cretaceous Period . In 1938, however, a living specimen was found off the Chalumna River (now Tyolomnqa) on the east coast of South Africa. Calliostoma bullatum , a species of deepwater sea snail originally described from fossils in 1844 proved to be

1590-436: A level jaw margin like those of earlier anomodonts. However, unlike earlier anomodonts, both the premaxilla and the tip of the dentaries in the upper and lower jaws, respectively, are entirely toothless, suggesting Nyaphulia had a beak like other dicynodonts. The premaxillae supporting the beak are paired, unlike all other dicynodonts where they are fused into a single bone—except for Eodicynodon . The palatal surface of

1696-587: A mathematical model that falls in all positions. By contrast, conservation biology uses the extinction vortex model to classify extinctions by cause. When concerns about human extinction have been raised, for example in Sir Martin Rees ' 2003 book Our Final Hour , those concerns lie with the effects of climate change or technological disaster. Human-driven extinction started as humans migrated out of Africa more than 60,000 years ago. Currently, environmental groups and some governments are concerned with

1802-456: A natural part of the evolutionary process. Only recently have extinctions been recorded and scientists have become alarmed at the current high rate of extinctions . Most species that become extinct are never scientifically documented. Some scientists estimate that up to half of presently existing plant and animal species may become extinct by 2100. A 2018 report indicated that the phylogenetic diversity of 300 mammalian species erased during

1908-441: A new mega-predator or by transporting animals and plants from one part of the world to another. Such introductions have been occurring for thousands of years, sometimes intentionally (e.g. livestock released by sailors on islands as a future source of food) and sometimes accidentally (e.g. rats escaping from boats). In most cases, the introductions are unsuccessful, but when an invasive alien species does become established,

2014-575: A parabasisphenoid that reaches the interpterygoid vacuity—all features it shares with various earlier anomodonts. Nyaphulia therefore represents a transitional stage in the evolution of dicynodont characteristics. Nyaphulia was part of the Eodicynodon Assemblage Zone (AZ), the oldest known faunal assemblage in the Beaufort Group of the Karoo, South Africa. Fossils are relatively rare in

2120-432: A partial skull, lower jaw and unidentifiable bones from the postcranial skeleton. The specimen was preserved in a calcareous nodule surrounding the skull, which prior to discovery had broken into four separate pieces leading to parts from the middle of the skull being weathered away. The specimen was prepared both in acid and mechanically by Nyaphuli, and was later described in 1990 by Professor Bruce Rubidge. Rubidge named

2226-610: A population a higher chance in the short term of surviving an adverse change in conditions. Effects that cause or reward a loss in genetic diversity can increase the chances of extinction of a species. Population bottlenecks can dramatically reduce genetic diversity by severely limiting the number of reproducing individuals and make inbreeding more frequent. Extinction sometimes results for species evolved to specific ecologies that are subjected to genetic pollution —i.e., uncontrolled hybridization , introgression and genetic swamping that lead to homogenization or out-competition from

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2332-407: A race of animals to become extinct. A series of fossils were discovered in the late 17th century that appeared unlike any living species. As a result, the scientific community embarked on a voyage of creative rationalization, seeking to understand what had happened to these species within a framework that did not account for total extinction. In October 1686, Robert Hooke presented an impression of

2438-502: A reduction in agricultural productivity. Furthermore, increased erosion contributes to poorer water quality by elevating the levels of sediment and pollutants in rivers and streams. Habitat degradation through toxicity can kill off a species very rapidly, by killing all living members through contamination or sterilizing them. It can also occur over longer periods at lower toxicity levels by affecting life span, reproductive capacity, or competitiveness. Habitat degradation can also take

2544-486: A result of climate change has been confirmed by fossil studies. Particularly, the extinction of amphibians during the Carboniferous Rainforest Collapse , 305 million years ago. A 2003 review across 14 biodiversity research centers predicted that, because of climate change, 15–37% of land species would be "committed to extinction" by 2050. The ecologically rich areas that would potentially suffer

2650-649: A rise in metabolic rates and an increase in jaw musculature. The earlier amniotes of the Carboniferous did not have temporal fenestrae, but two more advanced lines did: the synapsids (stem-mammals and mammals) and the diapsids (most reptiles and later birds). There are four types of amniote skull, classified by the number and location of their temporal fenestrae. Though historically important for understanding amniote evolution, some of these configurations have little relevance to modern phylogenetic taxonomy . The four types are: This vertebrate anatomy –related article

2756-407: A second species of the basal dicynodont Eodicynodon by Professor Bruce Rubidge in 1990 as E. oelofseni , named after his mentor in palaeontology and geology Dr. Burger Oelofsen. Phylogenetic analyses since then consistently found "E." oelofseni to be more basal than the type species of Eodicynodon , rather than its sister taxon , which researchers suggested indicated it should belong to

2862-479: A species (or replacement by a daughter species) plays a key role in the punctuated equilibrium hypothesis of Stephen Jay Gould and Niles Eldredge . In ecology , extinction is sometimes used informally to refer to local extinction , in which a species ceases to exist in the chosen area of study, despite still existing elsewhere. Local extinctions may be made good by the reintroduction of individuals of that species taken from other locations; wolf reintroduction

2968-439: A species may come suddenly when an otherwise healthy species is wiped out completely, as when toxic pollution renders its entire habitat unliveable; or may occur gradually over thousands or millions of years, such as when a species gradually loses out in competition for food to better adapted competitors. Extinction may occur a long time after the events that set it in motion, a phenomenon known as extinction debt . Assessing

3074-404: A species or group of species. "Just as each species is unique", write Beverly and Stephen C. Stearns , "so is each extinction ... the causes for each are varied—some subtle and complex, others obvious and simple". Most simply, any species that cannot survive and reproduce in its environment and cannot move to a new environment where it can do so, dies out and becomes extinct. Extinction of

3180-518: A subsequent report, IPBES listed unsustainable fishing, hunting and logging as being some of the primary drivers of the global extinction crisis. In June 2019, one million species of plants and animals were at risk of extinction. At least 571 plant species have been lost since 1750, but likely many more. The main cause of the extinctions is the destruction of natural habitats by human activities, such as cutting down forests and converting land into fields for farming. A dagger symbol (†) placed next to

3286-517: Is also evidence to suggest that this event was preceded by another mass extinction, known as Olson's Extinction . The Cretaceous–Paleogene extinction event (K–Pg) occurred 66 million years ago, at the end of the Cretaceous period; it is best known for having wiped out non-avian dinosaurs , among many other species. According to a 1998 survey of 400 biologists conducted by New York 's American Museum of Natural History , nearly 70% believed that

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3392-444: Is an example of this. Species that are not globally extinct are termed extant . Those species that are extant, yet are threatened with extinction, are referred to as threatened or endangered species . Currently, an important aspect of extinction is human attempts to preserve critically endangered species. These are reflected by the creation of the conservation status "extinct in the wild" (EW) . Species listed under this status by

3498-585: Is difficult to demonstrate unless one has a strong chain of evidence linking a living species to members of a pre-existing species. For example, it is sometimes claimed that the extinct Hyracotherium , which was an early horse that shares a common ancestor with the modern horse , is pseudoextinct, rather than extinct, because there are several extant species of Equus , including zebra and donkey ; however, as fossil species typically leave no genetic material behind, one cannot say whether Hyracotherium evolved into more modern horse species or merely evolved from

3604-417: Is estimated as 100 to 1,000 times "background" rates (the average extinction rates in the evolutionary time scale of planet Earth), faster than at any other time in human history, while future rates are likely 10,000 times higher. However, some groups are going extinct much faster. Biologists Paul R. Ehrlich and Stuart Pimm , among others, contend that human population growth and overconsumption are

3710-417: Is estimated that there are currently around 8.7 million species of eukaryotes globally, and possibly many times more if microorganisms , such as bacteria , are included. Notable extinct animal species include non-avian dinosaurs , saber-toothed cats , dodos , mammoths , ground sloths , thylacines , trilobites , golden toads , and passenger pigeons . Through evolution , species arise through

3816-592: Is the destruction of ocean floors by bottom trawling . Diminished resources or introduction of new competitor species also often accompany habitat degradation. Global warming has allowed some species to expand their range, bringing competition to other species that previously occupied that area. Sometimes these new competitors are predators and directly affect prey species, while at other times they may merely outcompete vulnerable species for limited resources. Vital resources including water and food can also be limited during habitat degradation, leading to extinction. In

3922-525: Is the most important determinant of genus extinction at background rates but becomes increasingly irrelevant as mass extinction arises. Limited geographic range is a cause both of small population size and of greater vulnerability to local environmental catastrophes. Extinction rates can be affected not just by population size, but by any factor that affects evolvability , including balancing selection , cryptic genetic variation , phenotypic plasticity , and robustness . A diverse or deep gene pool gives

4028-479: The Eodicynodon AZ and the fauna of the assemblage is poorly known compared to later zones, but includes a relatively diverse range of tetrapods nonetheless. Nyaphulia coexisted with two other small herbivorous anomodonts, the more basal Patranomodon and the tusked dicynodont Eodicynodon . Other therapsids included the much larger herbivorous tapinocephalian Tapinocaninus as well as several large predators:

4134-474: The International Union for Conservation of Nature (IUCN) are not known to have any living specimens in the wild and are maintained only in zoos or other artificial environments. Some of these species are functionally extinct, as they are no longer part of their natural habitat and it is unlikely the species will ever be restored to the wild. When possible, modern zoological institutions try to maintain

4240-477: The Late Pleistocene could take up to 5 to 7 million years to restore mammal diversity to what it was before the human era. Extinction of a parent species where daughter species or subspecies are still extant is called pseudoextinction or phyletic extinction. Effectively, the old taxon vanishes, transformed ( anagenesis ) into a successor, or split into more than one ( cladogenesis ). Pseudoextinction

4346-451: The anteosaur Australosyodon , the scylacosaurid therocephalian Eutheriodon , and a gorgonopsian of indeterminable affinity. Additionally, there are fossils of indeterminate temnospondyl amphibians and preserved scales of the fish Namaichthys , as well as freshwater bivalves comparable to Palaeanodonta . The depositional environment of the Eodicynodon AZ was a subaerial deltaic plain and floodplain relatively close to

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4452-456: The cynodonts , the orbit fused with the fenestral opening after the latter had started expanding within the therapsids . Most mammals have this merged configuration. Later, primates re-evolved an orbit separated from the temporal fossa . This separation was achieved by the evolution of a postorbital bar , with haplorhines (dry-nosed primates) later evolving a postorbital septum . Physiological speculation associates temporal fenestrae with

4558-505: The pineal foramen , which in Nyaphulia is rimmed entirely by the parietals . The orbital region of Nyaphulia is poorly preserved, missing most of the jugal bone , but what is preserved indicates that the orbits are not as rounded as those Eodicynodon and are more similar to those of Patranomodon . The postorbital bar is thin compared to Eodicynodon . The palate of Nypahulia is characteristic of dicynodonts. The transverse flange of

4664-442: The pterygoid bone is directed anteriorly as in later dicynodonts, rather than laterally to the side as in earlier anomodonts and other therapsids. The transverse flange also has a very prominent and bulbous palatal keel, developed more strongly than in other dicynodonts apart from Eodicynodon . By contrast, the shape of the parabasisphenoid flooring the braincase is more like that of Patranomodon and earlier anomodonts. Unlike

4770-410: The slender-billed curlew ( Numenius tenuirostris ), not seen since 2007. As long as species have been evolving, species have been going extinct. It is estimated that over 99.9% of all species that ever lived are extinct. The average lifespan of a species is 1–10 million years, although this varies widely between taxa. A variety of causes can contribute directly or indirectly to the extinction of

4876-484: The strata of the Paris basin. They saw alternating saltwater and freshwater deposits, as well as patterns of the appearance and disappearance of fossils throughout the record. From these patterns, Cuvier inferred historic cycles of catastrophic flooding, extinction, and repopulation of the earth with new species. Cuvier's fossil evidence showed that very different life forms existed in the past than those that exist today,

4982-619: The 20 biodiversity goals laid out by the Aichi Biodiversity Targets in 2010, only 6 were "partially achieved" by the deadline of 2020. The report warned that biodiversity will continue to decline if the status quo is not changed, in particular the "currently unsustainable patterns of production and consumption, population growth and technological developments". In a 2021 report published in the journal Frontiers in Conservation Science , some top scientists asserted that even if

5088-451: The Aichi Biodiversity Targets set for 2020 had been achieved, it would not have resulted in a significant mitigation of biodiversity loss. They added that failure of the global community to reach these targets is hardly surprising given that biodiversity loss is "nowhere close to the top of any country's priorities, trailing far behind other concerns such as employment, healthcare, economic growth, or currency stability." For much of history,

5194-485: The Beaufort Group). While animal fossils are scarce in the assemblage zone, plant remains are relatively abundant, namely of the woody seed plant Glossopteris and equisetales (horsetails), such as the large Schizoneura that grew in and around the rivers and lakes. Extinct Extinction is the termination of a taxon by the death of its last member . A taxon may become functionally extinct before

5300-605: The Earth is currently in the early stages of a human-caused mass extinction, known as the Holocene extinction . In that survey, the same proportion of respondents agreed with the prediction that up to 20% of all living populations could become extinct within 30 years (by 2028). A 2014 special edition of Science declared there is widespread consensus on the issue of human-driven mass species extinctions. A 2020 study published in PNAS stated that

5406-570: The North American moose and that the animal had once been common on the British Isles . Rather than suggest that this indicated the possibility of species going extinct, he argued that although organisms could become locally extinct, they could never be entirely lost and would continue to exist in some unknown region of the globe. The antlers were later confirmed to be from the extinct deer Megaloceros . Hooke and Molyneux's line of thinking

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5512-518: The Paris basin, could be formed by a slow rise and fall of sea levels . The concept of extinction was integral to Charles Darwin 's On the Origin of Species , with less fit lineages disappearing over time. For Darwin, extinction was a constant side effect of competition . Because of the wide reach of On the Origin of Species , it was widely accepted that extinction occurred gradually and evenly (a concept now referred to as background extinction ). It

5618-509: The United States government, to force the removal of Native Americans , many of whom relied on the bison for food. Temporal fenestra The supratemporal fenestra , also called the upper temporal fenestra , is positioned above the other fenestra and is exposed primarily in dorsal (top) view. In some reptiles, particularly dinosaurs, the parts of the skull roof lying between the supratemporal fenestrae are thinned out by excavations from

5724-419: The absence of premaxillary teeth, forward-projecting transverse processes of the pterygoid with pterygoid keels, a lateral dentary shelf, and the absence of vertical lamina on the surangular of the lower jaw. At the same time, it differs from Eodicynodon and all other dicynodonts by the combination of lacking a tusk and caniniform process, absence of a secondary palate, lateral exposure of the septomaxilla, and

5830-429: The accumulation of slightly deleterious mutations , then a population will go extinct. Smaller populations have fewer beneficial mutations entering the population each generation, slowing adaptation. It is also easier for slightly deleterious mutations to fix in small populations; the resulting positive feedback loop between small population size and low fitness can cause mutational meltdown . Limited geographic range

5936-402: The adjacent fenestrae. These extended margins of thinned bone are called supratemporal fossae . Synapsids , including mammals , have one temporal fenestra, which is ventrally bordered by a zygomatic arch composed of the jugal and squamosal bones. This single temporal fenestra is homologous to the infratemporal fenestra, as displayed most clearly by early synapsids. In later synapsids,

6042-481: The analysis, unlike most other analyses using the same dataset. They also removed many derived dicynodonts from the analysis too, except for those with known endocranial anatomy. They performed various types of phylogenetic analyses, including cladistic and Bayesian analyses, some of the first performed on therapsid relationships. As before, all of their analyses consistently found Nyaphulia to be more basal than Eodicynodon but closer to other dicynodonts than any of

6148-424: The basal-most dicynodont (as the group is defined) and not the sister-taxon to E. oosthuizeni , as would be expected of congeneric species. Nyaphulia was re-coded by Duhamel and colleagues in 2024 based on the updated information on its cranial and endocranial anatomy. Because they were focused on these characteristics, they modified the phylogenetic dataset they used and removed all postcranial characteristics for

6254-600: The consequences can be catastrophic. Invasive alien species can affect native species directly by eating them, competing with them, and introducing pathogens or parasites that sicken or kill them; or indirectly by destroying or degrading their habitat. Human populations may themselves act as invasive predators. According to the "overkill hypothesis", the swift extinction of the megafauna in areas such as Australia (40,000 years before present), North and South America (12,000 years before present), Madagascar , Hawaii (AD 300–1000), and New Zealand (AD 1300–1500), resulted from

6360-418: The contemporary extinction crisis "may be the most serious environmental threat to the persistence of civilization, because it is irreversible." Biologist E. O. Wilson estimated in 2002 that if current rates of human destruction of the biosphere continue, one-half of all plant and animal species of life on earth will be extinct in 100 years. More significantly, the current rate of global species extinctions

6466-541: The death of its last member if it loses the capacity to reproduce and recover. Because a species' potential range may be very large, determining this moment is difficult, and is usually done retrospectively. This difficulty leads to phenomena such as Lazarus taxa , where a species presumed extinct abruptly "reappears" (typically in the fossil record ) after a period of apparent absence. More than 99% of all species that ever lived on Earth , amounting to over five billion species, are estimated to have died out. It

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6572-471: The deliberate destruction of some species, such as dangerous viruses , and the total destruction of other problematic species has been suggested. Other species were deliberately driven to extinction, or nearly so, due to poaching or because they were "undesirable", or to push for other human agendas. One example was the near extinction of the American bison , which was nearly wiped out by mass hunts sanctioned by

6678-539: The dentaries at least eight teeth each. The maxillary teeth are placed entirely behind the openings for the nostrils (equivalent to the position of the tusks in Eodicynodon ), and the dentary teeth are similarly far back from the dentary tips, leaving the jaw tips toothless. Rubidge (1990) reported nutrient foramina at the dentary tip, associated with a keratinous covering, though Duhamel et al. (2024) did not identify them. Rubidge (1990) originally referred Nyaphulia to

6784-403: The endangered wild water buffalo is most threatened with extinction by genetic pollution from the abundant domestic water buffalo ). Such extinctions are not always apparent from morphological (non-genetic) observations. Some degree of gene flow is a normal evolutionary process; nevertheless, hybridization (with or without introgression) threatens rare species' existence. The gene pool of

6890-575: The event of rediscovery would be considered Lazarus species. Examples include the thylacine , or Tasmanian tiger ( Thylacinus cynocephalus ), the last known example of which died in Hobart Zoo in Tasmania in 1936; the Japanese wolf ( Canis lupus hodophilax ), last sighted over 100 years ago; the American ivory-billed woodpecker ( Campephilus principalis ), with the last universally accepted sighting in 1944; and

6996-443: The extinction crisis. According to the International Union for Conservation of Nature (IUCN), 784 extinctions have been recorded since the year 1500, the arbitrary date selected to define "recent" extinctions, up to the year 2004; with many more likely to have gone unnoticed. Several species have also been listed as extinct since 2004. If adaptation increasing population fitness is slower than environmental degradation plus

7102-475: The extinction of species caused by humanity, and they try to prevent further extinctions through a variety of conservation programs. Humans can cause extinction of a species through overharvesting , pollution , habitat destruction , introduction of invasive species (such as new predators and food competitors ), overhunting, and other influences. Explosive, unsustainable human population growth and increasing per capita consumption are essential drivers of

7208-533: The field of zoology , and biology in general, and has also become an area of concern outside the scientific community. A number of organizations, such as the Worldwide Fund for Nature , have been created with the goal of preserving species from extinction. Governments have attempted, through enacting laws, to avoid habitat destruction, agricultural over-harvesting, and pollution . While many human-caused extinctions have been accidental, humans have also engaged in

7314-435: The form of a physical destruction of niche habitats. The widespread destruction of tropical rainforests and replacement with open pastureland is widely cited as an example of this; elimination of the dense forest eliminated the infrastructure needed by many species to survive. For example, a fern that depends on dense shade for protection from direct sunlight can no longer survive without forest to shelter it. Another example

7420-418: The genus Eodicynodon on the basis of shared plesiomorphic (ancestrally present) characteristics that are also absent in any later dicynodonts. These are namely the unfused premaxillae and vomers and the large, bulbous palatal keels of the transverse pterygoid flanges. Rubidge (1990) nonetheless recognised it at least as a distinct species ("E." oelofseni ), primarily on the basis of the number and position of

7526-580: The habitat retreat of taxa approaching extinction. Possible causes of the higher extinction risk in species with more sexual selection shown by the comprehensive fossil studies that rule out such error sources include expensive sexually selected ornaments having negative effects on the ability to survive natural selection , as well as sexual selection removing a diversity of genes that under current ecological conditions are neutral for natural selection but some of which may be important for surviving climate change. There have been at least five mass extinctions in

7632-660: The heaviest losses include the Cape Floristic Region and the Caribbean Basin . These areas might see a doubling of present carbon dioxide levels and rising temperatures that could eliminate 56,000 plant and 3,700 animal species. Climate change has also been found to be a factor in habitat loss and desertification . Studies of fossils following species from the time they evolved to their extinction show that species with high sexual dimorphism , especially characteristics in males that are used to compete for mating, are at

7738-447: The history of life on earth, and four in the last 350 million years in which many species have disappeared in a relatively short period of geological time. A massive eruptive event that released large quantities of tephra particles into the atmosphere is considered to be one likely cause of the " Permian–Triassic extinction event " about 250 million years ago, which is estimated to have killed 90% of species then existing. There

7844-475: The human era since the Late Pleistocene would require 5 to 7 million years to recover. According to the 2019 Global Assessment Report on Biodiversity and Ecosystem Services by IPBES , the biomass of wild mammals has fallen by 82%, natural ecosystems have lost about half their area and a million species are at risk of extinction—all largely as a result of human actions. Twenty-five percent of plant and animal species are threatened with extinction. In

7950-472: The internal surface of the skull), and comparisons to the anatomy of Eodicynodon oosthuizeni confirmed that NMQR 2913 is not referable to Eodicynodon . Consequently, they erected the new genus Nyaphulia for "E." oelofseni , named in honour of John Nyaphuli for his extensive work on South African palaeontology in the Karoo , including the discovery of NMQR 2913 itself. Like other dicynodonts and early anomodonts,

8056-431: The introduced ( or hybrid ) species. Endemic populations can face such extinctions when new populations are imported or selectively bred by people, or when habitat modification brings previously isolated species into contact. Extinction is likeliest for rare species coming into contact with more abundant ones; interbreeding can swamp the rarer gene pool and create hybrids, depleting the purebred gene pool (for example,

8162-602: The lower jaw backwards to chew. Like some other dicynodonts, the dentary tip is curved upwards and so appears hooked from the side. Unlike Eodicynodon but like other dicynodonts, it lacks a coronoid eminence on the rear of the lower jaw. The teeth of Nyaphulia are homodont and consist entirely of small, peg-like teeth slanted forwards in the jaw. This is unlike most other therapsids but similar to other early anomodonts such as Patranomodon and Galeops . As preserved, each maxilla has at least three teeth, potentially up to six (although some of these may be replacement teeth), and

8268-485: The main drivers of the modern extinction crisis. In January 2020, the UN's Convention on Biological Diversity drafted a plan to mitigate the contemporary extinction crisis by establishing a deadline of 2030 to protect 30% of the Earth's land and oceans and reduce pollution by 50%, with the goal of allowing for the restoration of ecosystems by 2050. The 2020 United Nations ' Global Biodiversity Outlook report stated that of

8374-442: The maxillary teeth and the lack of canine tusks. Other researchers, such as Gillian King, accepted Rubidge's referral of "E." oelofseni to Eodicynodon . However, early phylogenetic analyses of dicynodont relationships notably did not actually include "E." oelofseni , and only E. oosthuizeni was used to analyse the genus (e.g. Modesto et al. , 1999; Modesto & Rubidge, 2000). The referral of "E." oelofseni to Eodicynodon

8480-421: The modern understanding of extinction as the end of a species was incompatible with the prevailing worldview. Prior to the 19th century, much of Western society adhered to the belief that the world was created by God and as such was complete and perfect. This concept reached its heyday in the 1700s with the peak popularity of a theological concept called the great chain of being , in which all life on earth, from

8586-490: The name of a species or other taxon normally indicates its status as extinct. Examples of species and subspecies that are extinct include: A species is extinct when the last existing member dies. Extinction therefore becomes a certainty when there are no surviving individuals that can reproduce and create a new generation. A species may become functionally extinct when only a handful of individuals survive, which cannot reproduce due to poor health, age, sparse distribution over

8692-469: The natural course of events, species become extinct for a number of reasons, including but not limited to: extinction of a necessary host, prey or pollinator, interspecific competition , inability to deal with evolving diseases and changing environmental conditions (particularly sudden changes) which can act to introduce novel predators, or to remove prey. Recently in geological time, humans have become an additional cause of extinction of some species, either as

8798-410: The newly emerging school of uniformitarianism . Jean-Baptiste Lamarck , a gradualist and colleague of Cuvier, saw the fossils of different life forms as evidence of the mutable character of species. While Lamarck did not deny the possibility of extinction, he believed that it was exceptional and rare and that most of the change in species over time was due to gradual change. Unlike Cuvier, Lamarck

8904-419: The nose unique to synapsids in the fossil record—is also exposed on the lateral surface of the snout, unlike most later dicynodonts where it is restricted to within the nostril opening. The exposure is thin and tapers back to meet the lacrimal , running between the nasals above and the maxilla below. The squamosal is incomplete and missing the entire zygomatic arch , however the preserved portion encompassing

9010-399: The original population, thereby increasing the chance of extinction. Habitat degradation is currently the main anthropogenic cause of species extinctions. The main cause of habitat degradation worldwide is agriculture, with urban sprawl , logging, mining, and some fishing practices close behind. The degradation of a species' habitat may alter the fitness landscape to such an extent that

9116-571: The other early anomodonts, whose relationships varied considerably between analyses. The following phylogeny is modified from one of the Bayesian phylogenetic analysis Duhamel et al. (2024): Biseridens Anomocephalus Tiarajudens Otsheria Suminia Ulemica Patranomodon Galechirus Galeops Galepus Nyaphulia Eodicynodon Colobodectes Lanthanostegus Pylaecephalidae More derived dicynodonts Nyaphulia shares with other dicynodonts

9222-400: The paired premaxillae, the dentary tips of the lower jaw are fused into a single element at their symphysis . Like later dicynodonts, the dentary tip is toothless with flat dentary tables on either side and a prominent lateral dentary shelf above the mandibular fenestra . This shelf would have served as an attachment point for the forward slip of jaw musculature that allowed dicynodonts to pull

9328-517: The premaxillae extends back somewhat, however, it is short and the bony internal nostrils ( choanae ) still open near the front of the mouth at the level of the maxillary teeth. As such, Nyaphulia does not have the bony secondary palate found in later dicynodonts (wherein the choanae open further back than the tusks). The nasal processes of the premaxilla that wedge between the nasal bones are relatively long in Nyaphulia compared to Eodicynodon and Patranomodon . The septomaxilla —a bone found in

9434-702: The process of speciation —where new varieties of organisms arise and thrive when they are able to find and exploit an ecological niche —and species become extinct when they are no longer able to survive in changing conditions or against superior competition . The relationship between animals and their ecological niches has been firmly established. A typical species becomes extinct within 10 million years of its first appearance, although some species, called living fossils , survive with little to no morphological change for hundreds of millions of years. Mass extinctions are relatively rare events; however, isolated extinctions of species and clades are quite common, and are

9540-456: The rear of the temporal fenestra is curved forward and down and the ventral process beneath the zygomatic arch is slender and fairly straight. This resembles the condition in Patranomodon and other early anomodonts, rather than being thicker and folded back as in later dicynodonts. Like other anomodonts, Nyaphulia has a preparietal bone. However, it unusually does not form part of the border of

9646-410: The relative importance of genetic factors compared to environmental ones as the causes of extinction has been compared to the debate on nature and nurture . The question of whether more extinctions in the fossil record have been caused by evolution or by competition or by predation or by disease or by catastrophe is a subject of discussion; Mark Newman, the author of Modeling Extinction , argues for

9752-470: The shoreline of the Ecca sea, with low sinuosity rivers draining from mountains to the south northwards into the sea. Over time, the plain built up and the shoreline progradated further to the north and northwest. Interchannel deposits indicate the presence of perennial lakes on the floodplains as well, which occasionally dried out but not for prolonged periods (unlike the playa lakes from later assemblage zones in

9858-461: The skull of Nyaphulia has a short snout and large temporal fenestra . The overall shape of its skull is more like those of earlier anomodonts, such as Patranomodon than later dicynodonts, with a slender construction and a rounded—rather than sloping—snout profile. Nyaphulia is notable among dicynodonts for lacking tusks and the associated caniniform processes entirely (the latter still being present even in almost all tuskless dicynodonts), with

9964-407: The snout, crushing the palate, and displacing the entire occiput up and to the side. NMQR 2913 was digitally re-examined and then redescribed in a 2024 paper by Alienor Duhamel and colleagues after the specimen was previously CT-scanned. These techniques allowed Duhamel and colleagues to describe anatomical features that were previously inaccessible through traditional examination (such as sutures and

10070-460: The species is no longer able to survive and becomes extinct. This may occur by direct effects, such as the environment becoming toxic , or indirectly, by limiting a species' ability to compete effectively for diminished resources or against new competitor species. Habitat destruction, particularly the removal of vegetation that stabilizes soil, enhances erosion and diminishes nutrient availability in terrestrial ecosystems. This degradation can lead to

10176-528: The specimen the type of a new species of Eodicynodon that he coined Eodicynodon olefseni , after his mentor in South African palaeontology and geology, Dr. Burger Oelefsen. Since its initial description, the delicate skull has been broken several times and consequently some parts of the skull included in its original description have been lost. The skull has also been taphonomically distorted and damaged by compression during fossilisation, deforming portions of

10282-430: The sudden introduction of human beings to environments full of animals that had never seen them before and were therefore completely unadapted to their predation techniques. Coextinction refers to the loss of a species due to the extinction of another; for example, the extinction of parasitic insects following the loss of their hosts. Coextinction can also occur when a species loses its pollinator , or to predators in

10388-412: The tiniest microorganism to God, is linked in a continuous chain. The extinction of a species was impossible under this model, as it would create gaps or missing links in the chain and destroy the natural order. Thomas Jefferson was a firm supporter of the great chain of being and an opponent of extinction, famously denying the extinction of the woolly mammoth on the grounds that nature never allows

10494-577: The tip of the dentary, a lateral dentary shelf, and reduced transverse wings of the pterygoid. Nyaphulia then represents a transitional stage in dicynodont evolution, demonstrating the order in which dicynodont traits such as beaks and tusks evolved. The holotype specimen of Nyaphulia , NMQR 2913, was discovered in October 1982 by John Nyaphuli from the National Museum in Bloemfontein , South Africa. It

10600-555: The total extinction of the dodo and the extirpation of indigenous horses to the British Isles. He similarly argued against mass extinctions , believing that any extinction must be a gradual process. Lyell also showed that Cuvier's original interpretation of the Parisian strata was incorrect. Instead of the catastrophic floods inferred by Cuvier, Lyell demonstrated that patterns of saltwater and freshwater deposits , like those seen in

10706-577: The wider scientific community of his theory. Cuvier was a well-regarded geologist, lauded for his ability to reconstruct the anatomy of an unknown species from a few fragments of bone. His primary evidence for extinction came from mammoth skulls found in the Paris basin . Cuvier recognized them as distinct from any known living species of elephant, and argued that it was highly unlikely such an enormous animal would go undiscovered. In 1812, Cuvier, along with Alexandre Brongniart and Geoffroy Saint-Hilaire , mapped

10812-483: Was difficult to disprove. When parts of the world had not been thoroughly examined and charted, scientists could not rule out that animals found only in the fossil record were not simply "hiding" in unexplored regions of the Earth. Georges Cuvier is credited with establishing the modern conception of extinction in a 1796 lecture to the French Institute , though he would spend most of his career trying to convince

10918-601: Was discovered on Botterkraal Farm in the Prince Albert District of Western Cape , South Africa in rocks from the lower Abrahamskraal Formation . This locality belongs to the Eodicynodon Assemblage Zone biozone, which has not been firmly dated but is roughly constrained to between 266.9 and 264.7 million years old during the Wordian stage of the middle Permian period ( Guadalupian ). NMQR 2913 consists of

11024-403: Was first questioned in 2003 by Modesto and colleagues after testing its own phylogenetic relationships for the first time together with E. oosthuizeni . From their results, they argued that there was no compelling reason to believe they were each other's closest relatives and that E. oosthuizeni has much more in common with later dicynodonts, and therefore that "E." oelofseni likely represented

11130-430: Was not until 1982, when David Raup and Jack Sepkoski published their seminal paper on mass extinctions, that Cuvier was vindicated and catastrophic extinction was accepted as an important mechanism . The current understanding of extinction is a synthesis of the cataclysmic extinction events proposed by Cuvier, and the background extinction events proposed by Lyell and Darwin. Extinction is an important research topic in

11236-571: Was skeptical that catastrophic events of a scale large enough to cause total extinction were possible. In his geological history of the earth titled Hydrogeologie, Lamarck instead argued that the surface of the earth was shaped by gradual erosion and deposition by water, and that species changed over time in response to the changing environment. Charles Lyell , a noted geologist and founder of uniformitarianism , believed that past processes should be understood using present day processes. Like Lamarck, Lyell acknowledged that extinction could occur, noting

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