What is Extinction: Definition and 78 Discussions

Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point. 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 is estimated that there are currently around 8.7 million species of eukaryote globally, and possibly many times more if microorganisms, like bacteria, are included. Notable extinct animal species include non-avian dinosaurs, saber-toothed cats, dodos, mammoths, ground sloths, thylacines, trilobites and golden toads.
Through evolution, species arise through 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 are quite common. 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 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 June 2019, one million species of plants and animals were at risk of extinction. At least 571 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 the name of a species or other taxon normally indicates its status as extinct.

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  1. pinball1970

    Mass Extinction Event 259-263 Mya via volcanic activity.

    In a study published in the journal Earth and Planetary Science Letters, researchers say their analysis provides evidence that the oxygen-deprived oceans precipitated two mass extinctions around 259 million and 262 million years ago during the Middle Permian Period. "We are studying the...
  2. S

    Do viruses eventually cause species extinction?

    I am wondering if some complex species have an in-built probable extinction span. The logic goes : Species X originates, individuals have a long lifetime and require a long development before adulthood and so a slow generation rate. Viruses that are much simpler cross to species X, and mutate...
  3. Isopod

    Dinosaur killed in asteroid strike found

    Scientists have presented a stunningly preserved leg of a dinosaur. The limb, complete with skin, is just one of a series of remarkable finds emerging from the Tanis fossil site in the US State of North Dakota. But it's not just their exquisite condition that's turning heads - it's what these...
  4. jim mcnamara

    Are humans on the verge of extinction? Opinion piece

    https://www.scientificamerican.com/article/humans-are-doomed-to-go-extinct/ <note: edited a grammar faux pas and other atrocities...> This piece is opinion, part Biology, and part sociology, so the best fit is in Discussion. It is a short piece, do consider reading it. It is a projection, not...
  5. jim mcnamara

    Ordovician mass extinction second wave - deep sea anoxia

    https://www.nature.com/articles/s41561-021-00843-9 Popular science version: https://scitechdaily.com/uncovering-the-surprising-secrets-behind-Earth's-first-major-mass-extinction/ Nature paper discusses causes of the second "wave" of mass extinction at the end of the Ordovician (~445mya) Really...
  6. Tech_Rizzle

    I Amount of Noise extinction in Acrylic glass per thickness in mm

    Hey guys, I need your help with the following topic on which I couldn't find sufficient information on the internet to solve. In the need to further insulate my velux roof swing window against against airborne motor and tire sound from the nearby street, I came across the idea to install an...
  7. C

    Extinction law -- How big is the extinction in the H-band?

    Hey, I'm totally blank on this problem, and I'm not even sure what to solve for. I'm told that the H band, which is in 1.63 μm, has an extinction law A_H = 0.591 * E(B - V) and I'm supposed to answer how big the extinction is in the H band. And I'm confused because it involves the difference...
  8. Mikkel

    Measure the distance to a star using magnitude and extinction

    Hello, I'm struggling with this question A star is observed close to the center of the Milky Way and from its spectrum we find that it is a type A3 star. Its observed magnitude is m_v = 25. There is only a diffusive gas between us and the star, so we can assume an extinction, of 1 magnitude per...
  9. L

    Extinction correction (photometry)

    For example suppose the uncorrected extinction instrumental magnitude is ##v^A_V = 9.00##, will the corrected extinction instrumental magnitude always be greater than ##9##?
  10. jim mcnamara

    Carnian Pluvial Episode newly identified mass extinction event

    https://phys.org/news/2020-09-discovery-mass-extinction.html This article discusses a newly identified extinction event that occurred in middle Triassic. Mammals appeared at the end of the event, dinosaurs which were rare, became the dominant animal group. The cause was massive eruptions in...
  11. jim mcnamara

    Possible extinction event: nearby supernova

    A popular science article on the end of the Devonian era examines the likelihood of an extinction event mediated by a nearby supernova. https://www.sciencedaily.com/releases/2020/08/200818142104.htm Per the article - A convincing argument can be made by finding Samarium 146 and/or Plutonium 244...
  12. S

    Would VR cause human extinction?

    If we have full dive VR would there still be people living in real life apart from poeple who maintain the VR equipment ? I am referring to VR brain implants/BCIs not VR headsets, googles, etc? I am asking hypothetically since i know that full dive VR is still a while away If you were to give a...
  13. Mlesnita Daniel

    B Previous thoughts on destroying asteroids were wrong: Nuking them is a bad idea

    This study from Johns Hopkins University shows that even if we manage to nuke an asteroid and "destroy" it, it will have a core back, in almost 2 hours. Nuking them was a bad idea before, but now seems worse. More details here...
  14. AidenFlamel

    Writing: Input Wanted World destroying solar storm/binary orbit

    Soooo, hi PF, it's been a long time since I needed your help, but here I am again. I've been doing some worldbulding lately and I came up with this idea of a world in which civilisation and life are much, much older than in ours. Yet it isn't as developed due to some kind of natural disaster...
  15. Mlesnita Daniel

    B Ideas to protect the Earth from possible asteroid impacts

    Do you have any own idea, on a way to protect the Earth from a possible asteroid impact? (You can not use technologies that are not invented yet, or imaginary. Those that can be invented in the next, let's say, 10 years, are allowed)
  16. alantheastronomer

    What Caused the K/T Extinction 66 Million Years Ago?

    Both an asteroid impact in the Gulf of Mexico and an extensive volcanic event resulting in the formation of the Deccan Traps on the Indian subcontinent are thought to have caused the K/T extinction some 66 million years ago. The timing of both events are extremely close. It has also been...
  17. jim mcnamara

    Mass extinctions past and future

    http://advances.sciencemag.org/content/3/9/e1700906 Abstract: Discussion article from phys.org: https://phys.org/news/2017-09-mathematics-sixth-mass-extinction.html An irreversible change in the carbon cycle will start to occur sometime at or after the year 2100. The changes will not play...
  18. Thinkaholic

    I'm Terrified of Human Extinction

    Hi, all. I'm nearly 14, and self-teaching physics and mathematics. One quote of Newton's really inspires me. It is the 'Shoulders of giants' quote, and even though it was just Newton taking a stab at Robert Hooke's short stature, it has meaning to me, and probably you guys, too. I want people to...
  19. N

    Difference between absorption spectroscopy and extinction

    Hello everyone I want to know what is the difference between Absorption and Extinction spectra. and in term of experiment how can get extinction spectrum. Thank you
  20. Stephanus

    Early hominid spreading and extinction

    Dear PF Forum, I've been wondering about this one thing in the extinction of early hominid. Homo erectus Homo habilis Australopithecus. They were all extinct. Why? Who killed them? What killed them? I read that the spreading of homo erectus (2 million years ago?) reached China and Java. Did homo...
  21. L

    Extinction Coefficient from Time series data

    I have some time series data of the absorbance of Br2 formation using UV Vis spectroscopy and I need to figure out the extinction coefficient/ absorptivity. The overall reaction is BrO3-+5Br- +6H+-->3Br2+3H2O which is expcted to go to completion I know that the equation relating absorbance to...
  22. C

    I Extinction Index K: Expression & Calculations

    We have a monochromatic plane wave with a frequency ω=10^15 (1/s). It is spread in a medium whose resonance frecuency is also ω=10^15 (1/s). The wave is attenuated in the spreading direction. In 1 cm, the electric field of the wave is 10 times smaller. Give an expression for the extinction index...
  23. henrco

    Interaction of dust and starlight - extinction

    Hi, I haven't posted an Astronomy question before. I did see some Astronomy questions in this section so I posted it here. But if it's in the wrong place, for future reference, please let me know where it should be posted. 1) The first problem I need guidance on is the value I have obtained...
  24. D

    Mechanism for extinction by scattering?

    Let's say you have a monochromatic laser beam directed towards a light sensor. As you move the sensor away from the laser, the intensity read by the sensor will decrease because of scattering on air molecules (extinction). Since intensity is proportional to the square of the E-field amplitude of...
  25. wolram

    Extinction curve variations

    All though i do not understand all this i wonder what others think, thees extinction seem significantarXiv:1510.01321 [pdf, ps, other] Interstellar Extinction Curve Variations Toward the Inner Milky Way: A Challenge to Observational Cosmology David M. Nataf, Oscar A. Gonzalez, Luca Casagrande...
  26. K

    What would a virus do if it caused total extinction?

    Ok so I am thinking that it is not in the best interest of a virus to cause total extinction because after that you do not have anything else to infect and sustain your virus cycle. So isn't a virus's best interest to just infest a host and make it want to reproduce like crazy so it could have...
  27. jim mcnamara

    Are We Really Entering the Sixth Mass Extinction?

    http://advances.sciencemag.org/content/1/5/e1400253 Accelerated modern human–induced species losses: Entering the sixth mass extinction Gerardo Ceballos, Paul R. Ehrlich, Anthony D. Barnosky, Andrés García, Robert M. Pringle and Todd M. Palmer Science Advances 19 Jun 2015: Vol. 1, no. 5...
  28. A

    What is an Extinction Spectrum? Plasmonic Gold Nanoparticles

    Would someone please tell me what an extinction spectrum refers to? e.g. for plasmonic gold nanoparticles. Is it the same thing as reflection, absorption, or transmission spectrum? Something else?
  29. J

    Limit involving extinction probability of branching process

    Let x(a) be the extinction probability of a branching process whose offspring is Poisson distributed with parameter a. I need to find the limit as a approaches infinity x(a)e^a. I tried computing x(a) directly using generating functions, and I found that it's the solution to e^(a(s-1))=s, but...
  30. Gotaskor

    Atmospheric Extinction: Calculating Visible & Radio Wave Opacity

    I'm wondering if anyone can help me with something. I've been asked to calculate, assuming no curvature for the Earth, how far through the atmosphere one could see when stood at sea-level - as in, at what distance would the atmosphere become opaque, both to visible light and to radio waves. I...
  31. P

    MMX and the extinction theorem

    It's well understood that extinction effects must be considered when conducting experiments to measure the velocity of light from moving sources. Fox showed that all such experiments prior to the early 60s were flawed on that basis. I'd like to understand why early M-M type experiments...
  32. T

    Could a Rotating Supernova Cause Another O-S Extinction?

    Folks, I'm struggling to write a monograph that details the potential of a rotating supernova directing a gamma ray burst directly at the solar system such that it would strip the Earth of most of its OZone and rain high-energy gamma radiation upon all terrestrial life, similar to as...
  33. Y

    Calculating Air Extinction Coefficient at 275 nm Wavelength

    I'm trying to calculate the extinction coefficient of air at 275 nm wavelength. Can someone help me do this? I can't seem to find enough variables in any equation I've been using to figure it out. Thank you
  34. chasrob

    Atmospheric Extinction: How Deep Can 20/15 Vision See?

    Let's say that you are aboard the ISS looking out a port hole. Far above the atmosphere, how deep should someone of say, 20/15 vision be able to see with the naked eye? 12th or 13th mag.? I read where, in 1944 during the war blackout, amateur astronomers were able to pick out 8th mag. stars...
  35. L

    Molar extinction coefficient calculation.

    Homework Statement I need to calculate molar extinction coefficient for Albumin at 280nm. Homework Equations A=ε*c*L ε=A/(c*L) But since L=constant, I can just say ε=A/c The Attempt at a Solution The given molecular mass of albumin is 66,5kDa, which equals 66500g/mol. I do...
  36. jim mcnamara

    Gamma ray bursts (GRB's) and the Ordovician Mass Extinction

    99% of all marine fossil generating species on Earth that ever existed have gone extinct. There are periods in the fossil record that show massive extinction rates. For example, the K-T (now the K-Pg) boundary marks the extinction of dinosaurs in the fossil record along with marine animals, at...
  37. A

    Determine extinction coefficients in glass for Fe2+/Fe3+

    Hello everybody, I want to determine the extinction coefficients of Fe2+ and Fe3+ in glass. There are literature data (e.g. Weyl's book "coloured glass"), so I know what kind of curves I should expect. As I am studying a slightly different soda-lime-silicate system, I want to recalculate the...
  38. Greg Bernhardt

    Stephen Hawking warning that our extinction is on the horizon

  39. T

    What is the threshold for total extinction of light in a given medium?

    Homework Statement I am given a distance at which a particular object is just discernible and am asked to find the opacity of the air.Homework Equations The Attempt at a SolutionI know that: I(x)=I0e-kρx but I don't know at what point you have total extinction. Obviously you would only have...
  40. J

    What is the Extinction Ratio?

    I am a little bit confused on what an extinction ratio is. I am looking at optical specs and it keeps on coming up. Would someone be kind enough to explain it to me and perhaps provide a mathematical background thank you!
  41. S

    Why do certain characteristics make a species more susceptible to extinction?

    It was given in my school textbook that large body size, small population size, low reproductive rate, feeding at high trophic levels, fixed migratory roots and habitats and localised and narrow range of distribution are the characteristics susceptible to extinction. I don't understand how...
  42. B

    Did K-T extinction event meteor puncture a hole in crust at Chicxulub?

    Did the meteor or comet that struck Earth at the end of the Cretaceous punch a whole in the crust down to the mantle? If so, why isn't that part of the crust weak and showing signs of volcanism? Even if the crust wasn't punctured down to the mantle, wouldn't it still be a weak spot and show...
  43. D

    MHB Why does the population go to extinction if the solution is real?

    The population of a certain species subjected to a specific kind of predation is modeled by the difference equation $$ u_{t+1}=\frac{au_t^2}{b^2+u_t^2}, \quad a>0. $$ Determine the equilibria and show that if $a^2 > 4b^2$ it is possible for the populationto be driven to extinction if it...
  44. Andre

    Extinction rates, hands off the islands

    This is more environment than biology, so I thought this was the best place to post this. http://www.ncasi.org/publications/Detail.aspx?id=3463 compare extinction rates of continents and islands. They find that Trivially, isolated species on islands are often highly specialized and not...
  45. V

    Molar extinction coefficent calculation

    Homework Statement I am to calculate the molar extinction coefficient for Bovine serum albumin Homework Equations ε = (nW×5500) + (nY×1490) + (nC×125) for coefficients around 280nm The Attempt at a Solution I know how to solve this by adding up the tryptophan, tyrosine, and cytosine for...
  46. B

    What Caused the End Permian Mass Extinction?

    A new hypothesis has emerged in the search for the cause of Earth's greatest ever mass extinction: The Permian-Triassic Mass extinction event (~250 million years ago). http://www.nature.com/news/2011/110121/full/news.2011.38.html
  47. atomqwerty

    Extinction and polarization

    Homework Statement A half-wave plate is put between an horizontal polarizer and a vertical analyzer, so we have extinction. If the anylizer is rotated clockwise an angle Theta, Which angle do we have to ratate the polarizer to keep the extinction of the light? Homework Equations The...
  48. M

    Atmospheric Extinction of Light

    If I have a 2,000 candelas red light source under normal rural atmospheric conditions at what distance would I expect the source to no longer be visible to the eye?
  49. P

    Extinction events and an astrolabe

    I'm guessing this requires some difficult and monotonous math so I figure if it has been done, it required expensive computing equipment. But, does anyone know of any info or have participated in a computer astrolabe program that has ran the numbers backwards as to the position of planets and...
  50. D

    Benzoic acid Molar Extinction Coefficient

    Hi guys! First time post here. I was wondering where on the internet you could find such a value? I have tried searching for sites that may have a list of molar extinction coefficient values for various compounds but have found them to be quite hard to access. Would any of you with perhaps...