Editing Vertebrate (section)

== Evolutionary history ==

=== Cambrian explosion: first vertebrates ===

{{further|Cambrian explosion}}

[[File:Haikouichthys cropped.jpg|thumb|upright=0.9|The [[Cambrian]] ''[[Haikouichthys]]'', 518 [[myr|mya]]<ref name="Shu 2003"/>]]

Vertebrates originated during the [[Cambrian explosion]] at the start of the Paleozoic, which saw a rise in animal diversity. The earliest known vertebrates belong to the [[Chengjiang biota]]<ref name="Shu1999">{{cite journal |last1=Shu |first1=D-G. |last2=Luo |first2=H-L. |last3=Conway Morris |first3=S. |author3-link=Simon Conway Morris |last4=Zhang |first4=X-L. |last5=Hu |first5=S-X. |last6=Chen |first6=L. |last7=Han |first7=J. |last8=Zhu |first8=M. |last9=Li |first9=Y. |last10=Chen |first10=L-Z. |display-authors=5 |title=Lower Cambrian vertebrates from south China |journal=[[Nature (journal)|Nature]] |volume=402 |issue=6757 |year=1999 |pages=42–46 |doi=10.1038/46965 |bibcode=1999Natur.402...42S |s2cid=4402854 }}</ref> and lived about 518 million years ago.<ref name="Yang2018"/> These include ''[[Haikouichthys]]'', ''[[Myllokunmingia]]'',<ref name="Shu1999"/> ''[[Zhongjianichthys]]'',<ref name="Shu 2003">{{cite journal |last=Shu |first=D. |date=2003 |title=A paleontological perspective of vertebrate origin |journal=[[Chinese Science Bulletin]] |volume=48 |issue=8 |pages=725–735 |doi=10.1360/03wd0026}}</ref> and probably ''[[Yunnanozoon]]''.<ref>{{cite journal |last1=Chen |first1=J.-Y. |last2=Huang |first2=D.-Y. |last3=Li |first3=C.-W. |year=1999 |title=An early Cambrian craniate-like chordate |journal=[[Nature (journal)|Nature]] |volume=402 |issue=6761|pages=518–522 |doi=10.1038/990080 |bibcode=1999Natur.402..518C |s2cid=24895681 }}</ref> Unlike other Cambrian animals, these groups had the basic vertebrate body plan: a notochord, rudimentary vertebrae, and a well-defined head and tail, but lacked jaws.<ref>{{cite web |last=Waggoner |first=B. |title=Vertebrates: Fossil Record |url=http://www.ucmp.berkeley.edu/vertebrates/vertfr.html |publisher=[[University of California Museum of Paleontology]] |access-date=15 July 2011 |archive-url=https://web.archive.org/web/20110629070158/http://www.ucmp.berkeley.edu/vertebrates/vertfr.html |archive-date=29 June 2011 |url-status=dead}}</ref> A vertebrate group of uncertain phylogeny, small eel-like [[conodont]]s, are known from [[microfossil]]s of their paired tooth segments from the late Cambrian to the end of the Triassic.<ref>{{cite journal |doi=10.1111/j.1469-185X.1999.tb00045.x |last1=Donoghue |first1=P. C. J. |last2=Forey |first2=P. L. |last3=Aldridge |first3=R. J. |date=May 2000 |title=Conodont affinity and chordate phylogeny |journal=[[Biological Reviews]] |volume=75 |issue=2 |pages=191–251 |pmid=10881388 |s2cid=22803015 }}</ref> Zoologists have debated whether teeth [[Mineralized tissues|mineralized]] first, given the hard teeth of the soft-bodied conodonts, and then bones, or vice versa, but it seems that the mineralized skeleton came first.<ref name="Murdock Dong 2013">{{cite journal |last=Murdock |first=Duncan J. E. |last2=Dong |first2=Xi-Ping |last3=Repetski |first3=John E. |last4=Marone |first4=Federica |last5=Stampanoni |first5=Marco |last6=Donoghue |first6=Philip C. J. |display-authors=5 |title=The origin of conodonts and of vertebrate mineralized skeletons |journal=Nature |volume=502 |issue=7472 |date=2013 |doi=10.1038/nature12645 |pages=546–549}}</ref>

=== Paleozoic: from fish to amphibians ===

{{see also|Evolution of fish|Evolution of tetrapods}}

[[File:Acanthostega BW.jpg|thumb|upright=0.9|''[[Acanthostega]]'', a [[Devonian]] [[Labyrinthodontia|labyrinthodont]], {{circa}} 365 mya<ref>{{cite book |last=Benton |first=Michael J. |title=Vertebrate Palaeontology |date=2019 |publisher=[[Wiley (publisher)|Wiley]] |section=Acanthostega |page=90 |edition=Kindle}}</ref> ]]

The first [[Gnathostomata|jawed vertebrates]] may have appeared in the late [[Ordovician]] (~445 mya) and became common in the [[Devonian|Devonian period]], often known as the "Age of Fishes".<ref name=britannica1954>{{cite book |title=Encyclopædia Britannica |volume=17 |year=1954 |publisher=Encyclopædia Britannica |page=107}}</ref> The two groups of [[bony fishes]], [[Actinopterygii]] and [[Sarcopterygii]], evolved and became common.<ref>{{cite book |last1=Berg |first1=L. R. |last2=Solomon |first2=E. P. |last3=Martin |first3=D. W. |title=Biology |year=2004 |publisher=Cengage Learning |isbn=978-0-534-49276-2 |page=599}}</ref> By the middle of the Devonian, a lineage of sarcopterygii with both gills and air-breathing lungs adapted to life in swampy pools used their muscular paired fins to propel themselves on land.<ref name="Carroll 1977">{{cite book |title=Patterns of Evolution, as Illustrated by the Fossil Record |last=Carroll |first=Robert L. |editor-last=Hallam |editor-first=Anthony |editor-link=Anthony Hallam |year=1977 |publisher=[[Elsevier]] |isbn=978-0-444-41142-6 |pages=405–420 |url=https://books.google.com/books?id=q7GjDIyyWegC&q=Amphibian+evolution&pg=PA405 |access-date=October 15, 2020 |archive-date=April 14, 2021 |archive-url=https://web.archive.org/web/20210414082736/https://books.google.com/books?id=q7GjDIyyWegC&q=Amphibian+evolution&pg=PA405 |url-status=live }}</ref> The fins, already possessing bones and joints, evolved into two pairs of walking legs.<ref name="NarkiewiczNarkiewicz2015">{{cite journal |last1=Narkiewicz |first1=Katarzyna |last2=Narkiewicz |first2=Marek |title=The age of the oldest tetrapod tracks from Zachełmie, Poland |journal=[[Lethaia]] |volume=48 |issue=1 |date=January 2015 |pages=10–12 |doi=10.1111/let.12083 |bibcode=2015Letha..48...10N }}</ref> These established themselves as [[amphibian]]s, terrestrial [[tetrapod]]s, in the next geological period, the [[Carboniferous]].<ref>{{cite book |url=https://books.google.com/books?id=Z0YWn5F9sWkC&pg=PA209 |title=Fins into Limbs: Evolution, Development, and Transformation |isbn=9780226313405 |access-date=2020-04-25 |archive-date=2020-08-09 |archive-url=https://web.archive.org/web/20200809023449/https://books.google.no/books?id=Z0YWn5F9sWkC&pg=PA209 |url-status=live |last=Hall |first=Brian K. |date=15 September 2008 |publisher=[[University of Chicago Press]] |page=209}}</ref> A group of vertebrates, the [[amniote]]s, with membranes around the [[embryo]] allowing it to survive on dry land, branched from amphibious tetrapods in the Carboniferous.<ref name="benton2014">{{Cite book| edition = 4th| publisher = John Wiley & Sons| isbn = 978-1-118-40764-6| last = Benton| first = Michael| title = Vertebrate Palaeontology| date = 2014 |pages=119, 148}}</ref>

=== Mesozoic: from reptiles to mammals and birds ===

[[File:Hyperodapedon BW2 white background.jpg|thumb|upright=0.9|''[[Hyperodapedon]]'', a [[diapsid]] reptile of the [[Triassic]], {{circa}} 230 mya]]

At the onset of the Mesozoic, all larger vertebrate groups were devastated after the [[Permian-Triassic extinction event|largest mass extinction in earth history]]. The following [[Triassic|recovery phase]] saw the emergence of many new vertebrate groups that are still around today, and this time has been described as the origin of modern ecosystems. On the continents, the ancestors of modern [[lissamphibia]]ns, [[turtle]]s, [[crocodilia]]ns, [[lizard]]s, and mammals appeared, as well as [[dinosaur]]s, which gave rise to birds later in the Mesozoic. In the seas, various groups of marine reptiles evolved, as did new groups of fish.<ref name="benton2014"/> At the end of the Mesozoic, [[Cretaceous–Paleogene extinction event|another extinction event]] extirpated dinosaurs (other than birds) and many other vertebrate groups.<ref name="Fortey 1999">{{cite book |last=Fortey |first=Richard |author-link=Richard Fortey |title=[[Life: A Natural History of the First Four Billion Years of Life on Earth]] |publisher=[[Vintage Books]] |year=1999 |pages=238–260 |isbn=978-0-375-70261-7}}</ref>

=== Cenozoic: Age of Mammals ===

[[File:Fossil bird (Green River Formation, Lower Eocene; Fossil Lake Basin, southwestern Wyoming, USA) (15529177925).jpg|thumb|upright=0.6|''[[Nahmavis]]'', an [[Eocene]] bird, {{circa}} 50 mya]]

The [[Cenozoic]], the current era, is sometimes called the "Age of Mammals", because of the dominance of the terrestrial environment by that group. [[Placental mammals]] have predominantly occupied the Northern Hemisphere, with [[Marsupial|marsupial mammals]] in the Southern Hemisphere.<ref>{{cite journal |last1=Pires |first1=Mathias |last2=Mankin |first2=Brian |last3=Silvestro |first3=Daniele |last4=Quental |first4=Tiago |date=26 September 2018 |title=Diversification dynamics of mammalian clades during the K–Pg mass extinction |journal=[[Biology Letters]] |volume=14 |issue=9 |doi=10.1098/rsbl.2018.0458 |doi-access=free |pmid=30258031 |pmc=6170748 }}</ref><ref>{{cite journal |last1=Lowery |first1=Christopher |last2=Fraass |first2=Andrew |date=8 April 2019 |title=Morphospace expansion paces taxonomic diversification after end Cretaceous mass extinction |url=https://www.nature.com/articles/s41559-019-0835-0 |journal=[[Nature Ecology & Evolution]] |volume=3 |issue=6 |pages=900–904 |doi=10.1038/s41559-019-0835-0 |pmid=30962557 |bibcode=2019NatEE...3..900L |s2cid=102354122 |via=[[Nature Portfolio|Nature]] |hdl=1983/fb08c3c1-c203-4780-bc90-5994ec1030ff |hdl-access=free }}</ref>