Y gwahaniaeth rhwng diwygiadau o "Defnyddiwr:Llywelyn2000/Pwll Tywod"

Crewyd drwy gyfieithu'r dudalen "Animal"
(Crewyd drwy gyfieithu'r dudalen "Animal")
(Crewyd drwy gyfieithu'r dudalen "Animal")
== Tarddiad esblygiadol ==
[[Delwedd:DickinsoniaCostata.jpg|chwith|bawd| ''Dickinsonia costata'' o'r biota Ediacaran (c. 635–542 miliwn o flynyddoedd [[CP|yn ôl]]) yw un o'r rhywogaethau anifeiliaid hysbys cynharaf.<ref name="Bobrovskiy Hope Ivantsov Nettersheim pp. 1246–1249">{{Cite journal|last=Bobrovskiy|first6=Jochen J.|pages=1246–1249|pmid=30237355|doi=10.1126/science.aat7228|date=20 September 2018|issue=6408|volume=361|journal=Science|title=Ancient steroids establish the Ediacaran fossil Dickinsonia as one of the earliest animals|last6=Brocks|first=Ilya|first5=Christian|last5=Hallmann|first4=Benjamin J.|last4=Nettersheim|first3=Andrey|last3=Ivantsov|first2=Janet M.|last2=Hope|bibcode=2018Sci...361.1246B}}</ref>]]
Mae'r [[Ffosil|ffosilau]] cyntaf a allai gynrychioli anifeiliaid yn ymddangos yng nghreigiau 665-miliwn oed Ffurfiant Trezona yn [[De Awstralia|Ne Awstralia]] . [[Sbwng|Mae'n debyg mai sbyngau]] cynnar yw'r ffosilau hyn. <ref name="roseMaloof">{{Cite journal|title=Possible animal-body fossils in pre-Marinoan limestones from South Australia|last4=Samuels|last9=Simons|first8=Nan|last8=Yao|first7=Gerald R.|last7=Poirier|first6=Douglas H.|last6=Erwin|first5=Claire C.|last5=Calmet|first4=Bradley M.|first3=Robert|journal=Nature Geoscience|last3=Beach|first2=Catherine V.|last2=Rose|first=Adam C.|last=Maloof|bibcode=2010NatGe...3..653M|issue=9|doi=10.1038/ngeo934|date=17 August 2010|pages=653–659|volume=3|first9=Frederik J.}}</ref>
 
Mae anifeiliaid i'w cael mor bell yn ôl â'r biota Ediacaran, tua diwedd y [[Cyn-Gambriaidd]], ac efallai ychydig yn gynharach. Roedd amheuaeth ers tro a oedd y ffurfiau bywyd hyn yn cynnwys anifeiliaid,<ref>{{Cite journal|last=Shen|title=The Avalon Explosion: Evolution of Ediacara Morphospace|pmid=18174439|doi=10.1126/science.1150279|pages=81–84|issue=5859|volume=319|journal=Science|year=2008|first=Bing|first4=Michał|last4=Kowalewski|first3=Shuhai|last3=Xiao|first2=Lin|last2=Dong|bibcode=2008Sci...319...81S}}</ref><ref>{{Cite journal|title=Late Ediacaran trackways produced by bilaterian animals with paired appendages|date=1 June 2018|pmc=5990303|pmid=29881773|doi=10.1126/sciadv.aao6691|pages=eaao6691|issue=6|volume=4|journal=Science Advances|last5=Xiao|first=Zhe|first5=Shuhai|last4=Yuan|first4=Xunlai|last3=Zhou|first3=Chuanming|last2=Chen|first2=Xiang|last=Chen|bibcode=2018SciA....4.6691C}}</ref><ref>{{Cite book|last=Schopf|first=J. William|title=Evolution!: facts and fallacies|year=1999|publisher=Academic Press|isbn=978-0-12-628860-5|page=[https://archive.org/details/evolutionfactsfa0000unse/page/7 7]|url=https://archive.org/details/evolutionfactsfa0000unse/page/7}}</ref> ond mae darganfod [[Cholesterol|colesterol]] lipid anifeiliaid mewn ffosilau ''Dickinsonia'' yn cadarnhau hyn.<ref name="Bobrovskiy Hope Ivantsov Nettersheim pp. 1246–1249">{{Cite journal|last=Bobrovskiy|first6=Jochen J.|pages=1246–1249|pmid=30237355|doi=10.1126/science.aat7228|date=20 September 2018|issue=6408|volume=361|journal=Science|title=Ancient steroids establish the Ediacaran fossil Dickinsonia as one of the earliest animals|last6=Brocks|first=Ilya|first5=Christian|last5=Hallmann|first4=Benjamin J.|last4=Nettersheim|first3=Andrey|last3=Ivantsov|first2=Janet M.|last2=Hope|bibcode=2018Sci...361.1246B}}<cite class="citation journal cs1" data-ve-ignore="true" id="CITEREFBobrovskiyHopeIvantsovNettersheim2018">Bobrovskiy, Ilya; Hope, Janet M.; Ivantsov, Andrey; Nettersheim, Benjamin J.; Hallmann, Christian; Brocks, Jochen J. (20 September 2018). [[doi:10.1126/science.aat7228|"Ancient steroids establish the Ediacaran fossil Dickinsonia as one of the earliest animals"]]. ''Science''. '''361''' (6408): 1246–1249. [[Bibcode (dynodydd)|Bibcode]]:[https://ui.adsabs.harvard.edu/abs/2018Sci...361.1246B 2018Sci...361.1246B]. [[Adnabyddwr gwrthrychau digidol|doi]]:<span class="cs1-lock-free" title="Freely accessible">[[doi:10.1126/science.aat7228|10.1126/science.aat7228]]</span>. [[PubMed|PMID]]&nbsp;[//pubmed.ncbi.nlm.nih.gov/30237355 30237355].</cite></ref> Credir bod anifeiliaid wedi tarddu o dan amodau [[ocsigen]] isel, sy'n awgrymu eu bod yn gallu byw'n gyfan gwbl trwy resbiradaeth anaerobig, ond wrth iddynt arbenigo mewn metaboledd <u>aerobig</u> daethant yn gwbl ddibynnol ar ocsigen yn eu hamgylcheddau.<ref name="Zimorski2019">{{Cite journal|last=Zimorski|first=Verena|last2=Mentel|first2=Marek|last3=Tielens|first3=Aloysius G. M.|last4=Martin|first4=William F.|title=Energy metabolism in anaerobic eukaryotes and Earth's late oxygenation|journal=Free Radical Biology and Medicine|volume=140|pages=279–294|year=2019|doi=10.1016/j.freeradbiomed.2019.03.030|pmid=30935869|pmc=6856725}}</ref>
[[Delwedd:20191203_Anomalocaris_canadensis.png|bawd| Mae ''Anomalocaris canadensis'' yn un o'r llu o rywogaethau o anifeiliaid a esblygodd yn y [[ffrwydrad Cambriaidd]], gan ddechrau tua 542 miliwn o flynyddoedd yn ôl, ac a ddarganfuwyd yng ngwâu ffosil y siâl Burgess.]]
Ymddangosodd llawer o [[Ffylwm|ffyla]] o anifeiliaid am y tro cyntaf yn y cofnodion ffosil yn y [[ffrwydrad Cambriaidd]], gan ddechrau tua 542 miliwn o flynyddoedd yn ôl, mewn gwelyau fel siâl Burgess. Ymhlith y ffyla sy'n bodoli yn y creigiau hyn mae [[Molwsg|molysgiaid]], [[Braciopod|braciopodau]], onychophorans, [[Arafsymudwr]] (y tardigrades), [[Arthropod|arthropodau]], [[Echinoderm|echinodermau]] a'r hemichordatiaid, ynghyd â nifer o ffurfiau a [[Difodiant|ddifodwyd]]<nowiki/>megis y rheibus ''Anomalocaris''. Fodd bynnag, gall sydynrwydd y digwyddiad fod oherwydd fod y cofnod ffosil yn wallus, yn hytrach na bod yr holl anifeiliaid hyn wedi ymddangos ar yr un pryd.<ref>{{Cite journal|last=Maloof|first7=D. A.|doi=10.1130/B30346.1|pages=1731–1774|issue=11–12|volume=122|year=2010|journal=Geological Society of America Bulletin|title=The earliest Cambrian record of animals and ocean geochemical change|first8=M. P.|last8=Eddy|last7=Fike|first=A. C.|first6=J. A.|last6=Higgins|first5=S. A.|last5=Bowring|first4=F. O.|last4=Dudas|first3=J. L.|last3=Moore|first2=S. M.|last2=Porter|bibcode=2010GSAB..122.1731M}}</ref><ref>{{Cite web|title=New Timeline for Appearances of Skeletal Animals in Fossil Record Developed by UCSB Researchers|url=http://www.ia.ucsb.edu/pa/display.aspx?pkey=2364|publisher=The Regents of the University of California|access-date=1 September 2014|date=10 November 2010|archiveurl=https://web.archive.org/web/20140903062054/http://www.ia.ucsb.edu/pa/display.aspx?pkey=2364|archivedate=3 September 2014}}</ref><ref>{{Cite journal|last=Conway-Morris|first=Simon|author-link=Simon Conway Morris|title=The Cambrian "explosion" of metazoans and molecular biology: would Darwin be satisfied?|journal=The International Journal of Developmental Biology|year=2003|volume=47|issue=7–8|pages=505–515|pmid=14756326|url=http://www.ijdb.ehu.es/web/paper.php?doi=14756326|access-date=28 February 2018|archive-url=https://web.archive.org/web/20180716111730/http://www.ijdb.ehu.es/web/paper.php?doi=14756326|archive-date=16 July 2018}}</ref><ref name="Royal Ontario Museum">{{Cite web|title=The Tree of Life|url=http://burgess-shale.rom.on.ca/en/science/origin/01-life-tree.php|website=The Burgess Shale|publisher=[[Royal Ontario Museum]]|access-date=28 February 2018|archiveurl=https://web.archive.org/web/20180216054845/http://burgess-shale.rom.on.ca/en/science/origin/01-life-tree.php|archivedate=16 February 2018|date=10 June 2011}}</ref>
 
== Ffylogeni ==
Mae anifeiliaid yn fonoffyletig, sy'n golygu eu bod yn deillio o hynafiad cyffredin. Mae anifeiliaid yn chwaer i'r Choanoflagellata ac maent yn ffurfio'r Choanozoa.<ref name="Budd2015">{{Cite journal|doi=10.1111/brv.12239|pmid=26588818|title=The origin of the animals and a 'Savannah' hypothesis for early bilaterian evolution|journal=[[Biological Reviews]]|volume=92|issue=1|pages=446–473|year=2017|last=Budd|first=Graham E.|last2=Jensen|first2=Sören}}</ref> Mae gan yr anifeiliaid mwyaf sylfaenol, y [[Sbwng|Porifera]], Ctenophora, [[Cnidariad|Cnidaria]], a Placozoa, gynlluniau corff sydd heb gymesuredd dwyochrog. Mae eu perthynas yn dal i fod yn destun dadl; gallai'r chwaer grŵp i bob anifail arall fod yn Porifera neu'r Ctenophora,<ref name="Kapli_2020">{{Cite journal|last=Kapli|first=Paschalia|last2=Telford|first2=Maximilian J.|title=Topology-dependent asymmetry in systematic errors affects phylogenetic placement of Ctenophora and Xenacoelomorpha|journal=Science Advances|date=11 Dec 2020|volume=6|issue=10|pages=eabc5162|doi=10.1126/sciadv.abc5162|pmid=33310849|pmc=7732190|bibcode=2020SciA....6.5162K}}</ref> sydd â diffyg genynnau hox, sy'n holl bwysig wrth ddatblygu cynllun y corff cyfan.<ref name="Giribet 2016">{{Cite journal|last=Giribet|first=Gonzalo|title=Genomics and the animal tree of life: conflicts and future prospects|journal=[[Zoologica Scripta]]|volume=45|date=27 September 2016|doi=10.1111/zsc.12215|pages=14–21}}</ref>
 
Mae'r goeden ffylogenetig (o'r prif linachau yn unig) yn dynodi tua sawl miliwn o flynyddoedd yn ôl ( mya ) y holltodd y llinachau.<ref>{{Cite journal|last=Peterson|title=The Ediacaran emergence of bilaterians: congruence between the genetic and the geological fossil records|pmid=18192191|doi=10.1098/rstb.2007.2233|pages=1435–1443|issue=1496|volume=363|journal=Philosophical Transactions of the Royal Society of London B: Biological Sciences|date=27 April 2008|first=Kevin J.|first4=Davide|last4=Pisani|first3=James G.|last3=Gehling|first2=James A.|last2=Cotton|pmc=2614224}}</ref><ref>{{Cite journal|last=Parfrey|title=Estimating the timing of early eukaryotic diversification with multigene molecular clocks|bibcode=2011PNAS..10813624P|pmid=21810989|doi=10.1073/pnas.1110633108|pages=13624–13629|issue=33|volume=108|journal=[[Proceedings of the National Academy of Sciences]]|date=16 August 2011|first=Laura Wegener|first4=Laura A.|last4=Katz|author-link4=Laura A. Katz|first3=Andrew H.|last3=Knoll|first2=Daniel J. G.|last2=Lahr|pmc=3158185}}</ref><ref>{{Cite web|title=Raising the Standard in Fossil Calibration|url=http://fossilcalibrations.org/|website=Fossil Calibration Database|access-date=3 March 2018|archiveurl=https://web.archive.org/web/20180307054141/http://fossilcalibrations.org/|archivedate=7 March 2018}}</ref><ref>{{Cite journal|last=Laumer|last7=Giribet|pmid=30373720|doi=10.7554/eLife.36278|pages=e36278|volume=2018;7|journal=eLife|title=Support for a clade of Placozoa and Cnidaria in genes with minimal compositional bias|year=2018|first7=Gonzalo|first6=John C.|first=Christopher E.|last6=Marioni|first5=Ana|last5=Riesgo|first4=Vicki B.|last4=Pearse|first3=Michael G.|last3=Hadfield|first2=Harald|last2=Gruber-Vodicka|pmc=6277202}}</ref><ref>{{Cite journal|last=Adl|last8=Berney|pmid=30257078|doi=10.1111/jeu.12691|pages=4–119|issue=1|volume=66|journal=Journal of Eukaryotic Microbiology|title=Revisions to the Classification, Nomenclature, and Diversity of Eukaryotes|date=2018|first9=Matthew W.|last9=Brown|first8=Cedric|first7=Sabine|first=Sina M.|last7=Agatha|first6=Alexey|last6=Smirnov|first5=Conrad L.|last5=Schoch|first4=Julius|last4=Lukeš|first3=Christopher E.|last3=Lane|first2=David|last2=Bass|pmc=6492006}}</ref>
 
=== Anifeiliaid nad ydynt yn ddwyochrog ===
[[Delwedd:Elephant-ear-sponge.jpg|de|bawd| Mae rhai nad ydynt yn ddwyochrog (o ran cymesuredd) yn cynnwys [[Sbwng|sbyngau]] (canol) a [[Cwrel|chwrelau]] (cefndir).]]
Mae gan nifer o anifeiliaid ddiffyg cymesuredd dwyochrog ac ymhlith y rhain, mae'n debyg bod y sbyngau (Porifera) wedi dargyfeirio gyntaf, gan gynrychioli'r ffylwm anifail hynaf.<ref>{{Cite book|last=Bhamrah|first=H. S.|last2=Juneja|first2=Kavita|title=An Introduction to Porifera|year=2003|publisher=Anmol Publications|isbn=978-81-261-0675-2|page=58}}</ref> Nid ydynt yn [[Organeb byw|organebau]] cymhleth, fel y rhan fwyaf o ffyla eraill;<ref>{{Cite book|last=Sumich|first=James L.|title=Laboratory and Field Investigations in Marine Life|year=2008|publisher=Jones & Bartlett Learning|isbn=978-0-7637-5730-4|page=67}}</ref> ceir amrywiaeth yn y math o gelloedd, ond yn y rhan fwyaf o achosion nid ydynt wedi'u trefnu'n feinweoedd gwahanol.<ref>{{Cite book|last=Jessop|first=Nancy Meyer|title=Biosphere; a study of life|year=1970|publisher=[[Prentice-Hall]]|page=428}}</ref> Maent fel arfer yn bwydo trwy dynnu dŵr trwy fandyllau.<ref>{{Cite book|last=Sharma|first=N. S.|title=Continuity And Evolution Of Animals|year=2005|publisher=Mittal Publications|isbn=978-81-8293-018-6|page=106}}</ref>
 
=== Dwyochredd (Bilateria) ===
Mae'r anifeiliaid sy'n weddill, y mwyafrif helaeth—yn cynnwys rhyw 29 ffyla a thros filiwn o rywogaethau—yn ffurfio cytras (<nowiki><i>clade</i></nowiki>), sef y ''Bilateria''. Mae'r corff yn driploblastig, gyda thair haen o germ sydd wedi'u datblygu'n dda, ac mae eu meinweoedd yn ffurfio organau gwahanol. Mae gan y siambr dreulio ddau agoriad, ceg ac anws, a cheir ceudod corff mewnol, coelom neu ffug-goelom. Mae gan anifeiliaid sydd â'r cynllun dwyochrog cymesur hwn i'w corff y gallu i symud, pen blaen (''anterior''), a phen ôl (''posterior'') yn ogystal â chefn (''dorsal'') a bol (''ventral''); felly y mae ganddynt hefyd ochr dde ac ochr chwith.<ref name="Minelli2009">{{Cite book|last=Minelli|first=Alessandro|title=Perspectives in Animal Phylogeny and Evolution|url=https://books.google.com/books?id=jIASDAAAQBAJ&pg=PA53|year=2009|publisher=[[Oxford University Press]]|isbn=978-0-19-856620-5|page=53}}</ref><ref name="Brusca2016">{{Cite book|url=http://www.sinauer.com/media/wysiwyg/samples/Brusca3e_Chapter_9.pdf|title=Introduction to the Bilateria and the Phylum Xenacoelomorpha {{!}} Triploblasty and Bilateral Symmetry Provide New Avenues for Animal Radiation|last=Brusca|first=Richard C.|date=2016|publisher=[[Sinauer Associates]]|pages=345–372|isbn=978-1-60535-375-3|access-date=4 March 2018}}</ref>
 
Mae astudiaethau genetig wedi newid dealltwriaeth sŵolegwyr yn sylweddol o'r perthnasoedd o fewn y ''Bilateria''. Ymddengys bod y rhan fwyaf yn perthyn i ddwy brif linach, y protostomau a'r deuterostomau.<ref name="Telford 2008 pp. 457–459">{{Cite journal|last=Telford|first=Maximilian J.|title=Resolving Animal Phylogeny: A Sledgehammer for a Tough Nut?|journal=Developmental Cell|volume=14|issue=4|year=2008|doi=10.1016/j.devcel.2008.03.016|pages=457–459|pmid=18410719}}</ref><ref name="Philippe2011">{{Cite journal|last=Philippe|first8=K. J.|issue=7333|bibcode=2011Natur.470..255P|doi=10.1038/nature09676|pmid=21307940|year=2011|pages=255–258|volume=470|journal=[[Nature (journal)|Nature]]|title=Acoelomorph flatworms are deuterostomes related to ''Xenoturbella''|first9=M.J.|last9=Telford|last8=Peterson|first=H.|first7=A.|last7=Wallberg|first6=A.J.|last6=Poustka|first5=H.|last5=Nakano|first4=L. L.|last4=Moroz|first3=R.R.|last3=Copley|first2=H.|last2=Brinkmann|pmc=4025995}}</ref><ref name="Perseke2007">{{Cite journal|last=Perseke|first8=M.|archive-url=https://web.archive.org/web/20190424154927/http://www.bioinf.uni-leipzig.de/Publications/PREPRINTS/07-009.pdf|access-date=4 March 2018|doi=10.1007/s12064-007-0007-7|pmid=18087755|url=http://www.bioinf.uni-leipzig.de/Publications/PREPRINTS/07-009.pdf|pages=35–42|date=August 2007|issue=1|volume=126|journal=Theory Biosci|title=The mitochondrial DNA of Xenoturbella bocki: genomic architecture and phylogenetic analysis|last8=Schlegel|first=M.|first7=D.|last7=Bernhard|first6=O.|last6=Israelsson|first5=P.F.|last5=Stadler|first4=G.|last4=Fritzsch|first3=B.|last3=Weich|first2=T.|last2=Hankeln|archive-date=24 April 2019}}</ref><ref name="Cannon 2016">{{Cite journal|last=Cannon|date=3 February 2016|bibcode=2016Natur.530...89C|pmid=26842059|doi=10.1038/nature16520|pages=89–93|issue=7588|volume=530|journal=[[Nature (journal)|Nature]]|title=Xenacoelomorpha is the sister group to Nephrozoa|first6=Andreas|first=Johanna T.|last6=Hejnol|first5=Ulf|last5=Jondelius|first4=Frederik|last4=Ronquist|first3=Julian.|last3=Smith III|first2=Bruno C.|last2=Vellutini|url=http://urn.kb.se/resolve?urn=urn:nbn:se:nrm:diva-1844}}</ref>
 
 
== Cyfeiriadau ==
 
== Dolenni allanol ==
 
* [http://tolweb.org/ Prosiect Coeden Fywyd]
* [http://animaldiversity.org/ Animal Diversity Web] – cronfa ddata anifeiliaid [[Prifysgol Michigan]]
* [https://archive.today/20160426231847/http://www.arkive.org/ ARKive] – cronfa ddata amlgyfrwng o rywogaethau sydd mewn perygl/a warchodir
<nowiki>
[[Categori:Tacsa wedi'u henwi gan Carolus Linnaeus]]
[[Categori:Teyrnasoedd (bioleg)]]
[[Categori:Anifeiliaid]]</nowiki>
[[Categori:All articles containing potentially dated statements]]</nowiki>