Editing Dimetrodon (section)

{{Short description|Genus of carnivorous synapsids from the Permian}}
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{{Automatic taxobox
| fossil_range = [[Cisuralian]] to [[Guadalupian]] ([[Asselian]] to [[Roadian]]), {{fossil range|295|270}}
| image = Dimetrodon incisivum 01.jpg
| image_upright = 1.15
| image_caption = Skeleton of ''D. limbatus'', [[Staatliches Museum für Naturkunde Karlsruhe]]
| taxon = Dimetrodon
| authority = [[Edward Drinker Cope|Cope]], [[1878 in paleontology|1878]] ([[conserved name]])
| type_species = {{extinct}}'''''Dimetrodon limbatus'''''
| type_species_authority = Cope, 1877
| subdivision_ranks = Species
| subdivision = See [[List of Dimetrodon species|below]]
| synonyms = {{collapsible list|bullets = true
 |title=<small>Genus synonymy</small>
|''[[Dimetrodon borealis|Bathygnathus]]''<br /><small>Leidy, 1854</small>
|''Embolophorus''<br /><small>Cope, 1878</small>
|''Theropleura''<br /><small>Cope, 1880</small>
|''Bathyglyptus''<br /><small>Case, 1911</small>
|''Eosyodon''<br /><small>Olson, 1962</small>
}}
{{collapsible list|bullets = true
 |title=<small>Species synonymy</small>
|''[[Dimetrodon borealis|Bathygnathus borealis]]''<br /><small>Leidy, 1854</small>
|''[[Clepsydrops]] limbatus''<br /><small>Cope, 1877</small>
|''Clepsydrops gigas''<br /><small>Cope, 1878</small>
|''Clepsydrops natalis''<br /><small>Cope, 1878</small>
|''Dimetrodon gigas''<br /><small>Cope, 1878</small>
|''Dimetrodon incisivus''<br /><small>Cope, 1878</small>
|''Dimetrodon rectiformis''<br /><small>Cope, 1878</small>
|''Embolophorus dollovianus''<br /><small>Cope, 1878</small>
|''Dimetrodon semiradicatus''<br /><small>Cope, 1881</small>
|''Clepsydrops macrospondylus''<br /><small>Cope 1884</small>
|''Dimetrodon platycentrus''<br /><small>Case, 1907</small>
|''Theropleura grandis''<br /><small>Case, 1907</small>
|''Bathyglyptus theodori''<br /><small>Case, 1911</small>
|''Dimetrodon maximus''<br /><small>Romer, 1936</small>
|''Eosyodon hudsoni''<br /><small>Olson, 1962</small>
}}
}}

'''''Dimetrodon''''' ({{IPAc-en|d|aɪ|ˈ|m|iː|t|r|ə|ˌ|d|ɒ|n}}{{refn|{{cite dictionary |url=https://lexico.com/definition/Dimetrodon |archive-url=https://web.archive.org/web/20200322182731/https://www.lexico.com/definition/dimetrodon |url-status=dead |archive-date=2020-03-22 |title=Dimetrodon |dictionary=[[Lexico]] UK English Dictionary |publisher=[[Oxford University Press]]}}}} or {{IPAc-en|d|aɪ|ˈ|m|ɛ|t|r|ə|ˌ|d|ɒ|n|audio=En-us-Dimetrodon.ogg}};<ref>{{cite Dictionary.com |dimetrodon |access-date=2018-02-12}}</ref> {{lit|two measures of teeth}}) is an extinct [[genus]] of [[sphenacodontid]] [[synapsid]] that lived during the [[Cisuralian]] (Early Permian) [[Epoch (geology)|epoch]] of the [[Permian]] period, around 295–272&nbsp;million years ago.<ref name=PaleoDB>{{cite web |url=https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=38904 |title=Dimetrodon |work=Paleobiology Database |access-date=23 August 2012 |archive-date=2 October 2013 |archive-url=https://web.archive.org/web/20131002102758/http://paleodb.org/cgi-bin/bridge.pl?a=checkTaxonInfo&taxon_no=38904 |url-status=live }}</ref><ref name=AKD09>{{cite journal | last1 = Angielczyk | first1 = K. D. | title = Dimetrodon is Not a Dinosaur: Using Tree Thinking to Understand the Ancient Relatives of Mammals and their Evolution | doi = 10.1007/s12052-009-0117-4 | journal = Evolution: Education and Outreach | volume = 2 | issue = 2 | pages = 257–271 | year = 2009 | doi-access = free }}</ref><ref>{{cite book |last1=Huttenlocker |first1=A. K. |first2=E. |last2=Rega |year=2012 |chapter=The Paleobiology and Bone Microstructure of Pelycosauriangrade Synapsids |pages=90–119 |editor-first=A. |editor-last=Chinsamy |title=Forerunners of Mammals: Radiation, Histology, Biology |publisher=Indiana University Press |isbn=978-0-253-35697-0 }}</ref> With most species measuring {{convert|1.7|-|4.6|m|ft|abbr=on}} long and weighing {{convert|28|-|250|kg|lb|abbr=on}}, the most prominent feature of ''Dimetrodon'' is the large [[neural spine sail]] on its back formed by elongated spines extending from the [[vertebra]]e. It was an obligate [[Quadrupedalism|quadruped]] (it could walk only on four legs) and had a tall, curved skull with large teeth of different sizes set along the jaws. Most fossils have been found in the [[Southwestern United States]], the majority of these coming from a geological deposit called the [[Red Beds of Texas and Oklahoma]]. More recently, its fossils have also been found in [[Germany]] and over a dozen species have been named since the [[genus]] was first erected in 1878.

''Dimetrodon'' is often mistaken for a [[dinosaur]] or portrayed as a contemporary of dinosaurs in [[popular culture]], but it became extinct by the middle [[Permian]], some 40 million years before the advent of dinosaurs.<ref name=":0">{{Cite web|date=Feb 17, 2021|title=Famous Prehistoric Animals That Weren't Actually Dinosaurs|url=https://medium.com/prehistoric-tales/famous-prehistoric-animals-that-werent-actually-dinosaurs-730bb941ed50|url-status=live|archive-url=https://web.archive.org/web/20210407023624/https://medium.com/prehistoric-tales/famous-prehistoric-animals-that-werent-actually-dinosaurs-730bb941ed50 |archive-date=2021-04-07 }}</ref><ref>{{Cite web|last1=Black|first1=Riley|title=The Dimetrodon in Your Family Tree|url=https://www.smithsonianmag.com/science-nature/the-dimetrodon-in-your-family-tree-54302176/|access-date=2021-12-05|website=Smithsonian Magazine|language=en}}</ref> Although [[reptile]]-like in appearance and physiology, ''Dimetrodon'' is much more closely related to [[mammal]]s, as it belongs to the closest [[sister taxon|sister]] [[family (biology)|family]] to [[therapsid]]s, the latter of which contains the direct ancestor of mammals.<ref name=AKD09 /> ''Dimetrodon'' is traditionally assigned to the [[paraphyletic]] group "[[pelycosaur]]s", a term now considered obsolete and replaced by terms such as "primitive synapsids" or "basal synapsids"; another name "[[mammal-like reptile]]s" is also used traditionally but incorrectly for non-mammalian synapsids<ref name=AKD09 /> due to some of the features shared with modern mammals such as [[heterodont|tooth specialization]] and [[endothermy]], but that term is now also defunct. ''Dimetrodon'' [[skull]] has a single opening ([[temporal fenestra]]) behind each eye, a feature shared among all synapsids, unlike the skulls of reptiles and birds, both of which belonging to the clade [[Sauropsida]], which diverged from the synapsids at least since the [[Late Carboniferous]].

''Dimetrodon'' was probably one of the [[apex predator]]s of the Cisuralian ecosystems, feeding on fish and [[tetrapod]]s, including reptiles and [[amphibian]]s. Smaller ''Dimetrodon'' species may have had different [[ecological niche|ecological roles]]. The sail of ''Dimetrodon'' may have been used to stabilize its spine or to heat and cool its body as a form of [[thermoregulation]].<ref>{{Cite book|last=Cloudsley-Thompson|first=J. L.|url=https://books.google.com/books?id=7PN7y4YjczYC&q=Dimetrodon+Sail+Heat&pg=PA102|title=Ecology and Behaviour of Mesozoic Reptiles|date=2005-01-19|publisher=Springer Science & Business Media|isbn=978-3-540-22421-1|language=en}}</ref> Some recent studies argue that the sail would have been ineffective at removing heat from the body, due to large species being discovered with small sails and small species being discovered with large sails, essentially ruling out heat regulation as its main purpose. The sail was most likely used in [[courtship display]], including threatening away rivals or showing off to potential mates.<ref>{{Cite book|last1=Fiesta|first1=Enrique|url=https://books.google.com/books?id=9q0gBgAAQBAJ&q=Dimetrodon+Sail+Heat&pg=PA8|title=Dimetrodon - Permian Predator|last2=Davidson|first2=John|date=2015-01-10|publisher=Mendon Cottage Books|isbn=978-1-310-19617-1|language=en}}</ref><ref>{{Cite book|last1=Zachos|first1=Frank|url=https://books.google.com/books?id=dQd2DwAAQBAJ&q=Dimetrodon+Sail+Heat&pg=PA141|title=Mammalian Evolution, Diversity and Systematics|last2=Asher|first2=Robert|date=2018-10-22|publisher=Walter de Gruyter GmbH & Co KG|isbn=978-3-11-034155-3|language=en}}</ref>
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