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Fairlight (company)

Fairlight is a digital audio company based in Sydney. In 1979, it released its Series I Fairlight CMI, one of the earliest digital audio workstations (DAWs) with a digital audio sampler. Their subsequent Series II and III CMIs featured a graphic sequencer known as Page R, during a time when most computerised music sequencers required coding skills.

These computer-instruments were used by artists such as Peter Gabriel, Kate Bush and Jean-Michel Jarre. They became such a prominent part of 1980s pop music that Phil Collins included the text "there is no Fairlight on this record" in the liner notes of No Jacket Required.

Fairlight has since become a manufacturer of media tools such as digital audio recording and mixing consoles.

History
In 1975, Fairlight Instruments Pty Ltd was established by Peter Vogel and Kim Ryrie. The company produced microprocessor-based music workstations with samplers, which were revolutionary for their time.

New sounds could be created by drawing a 'sound wave' on the screen, which the computer would produce as sound. Theoretically, any sound was possible. Apart from opening up a world of new sounds, the Fairlight gave composers and performers instant playback. By changing the wave patterns presented on a screen they could tweak a sound into shape without singing or performing it all over again.

The versatility of the early Fairlight was not lost on recording artists. The first record made entirely on a computer in the United States was done by EBN-OZN (Ned Liben, who represented Fairlight in New York, and Robert Ozn) – "AEIOU Sometimes Y" made in 1981, released in 1983.

A hybrid analogue/digital Computer Video Instrument, invented by Kia Silverbrook, debuted in 1984. The fact that the CVI was also a "computer" was transparent to its use: it did not use a conventional ASCII keyboard (though in later models one could be attached), but rather a set of sliders and a small graphics pad about the size of the palm of a hand. Menu selections were made with a stylus rather than a mouse. The CVI allowed users to paint directly over the top of video footage as well as "with" video footage via an extensive series of effects.

In April 1989, Fairlight ESP (Electric Sound and Picture) was established by Kim Ryrie, with the financial backing of Australian distributor Amber.

In September 2016, Fairlight was acquired by Blackmagic Design.

Products

 * Fairlight CMI music sampler (mid 1970s)
 * MFX digital audio workstation with dedicated audio control surface (at least 3 versions) (MFX3 released 1997)
 * Dream Constellation digital audio workstation with integrated audio control surface and mixing console (2004)
 * Crystal Core processing engine – a sound processing device capable of sampling frequencies up to 384 kHz. Crystal core does not use DSP-based architecture, but a Field Programmable Gate Array. (CC-1 see Dream software below, CC-2 released 2014)
 * Dream II software (ran with Crystal Core engine) (released 2008)
 * Xynergi – a tactile control unit that makes use of self-labeling LCD keys. (2008)
 * Quantum digital audio workstation, audio control surface and mixing console (2012)
 * Quantum Live sound mixing console (2014)

Peter Vogel Instruments
In August 2009, a new company called Fairlight Instruments was launched by Peter Vogel, to produce a new range of computer musical instruments (CMI) based on Fairlight.au's "Crystal Core" media engine.

In July 2012, the company Fairlight Instruments changed its name to ' Peter Vogel Instruments. Peter Vogel announced the company was developing a completely new keyboard synthesizer which would be launched at Winter NAMM 2013. The name change was the result of a disagreement between the owners of the Fairlight Instruments trademark and himself that resulted in Fairlight revoking his license to use the name. According to them, the use of the Fairlight name only extended to the new version of the CMI, called the CMI-30A in reference to the instrument's 30th anniversary. Additionally, it extended to several other CMI hardware products planned, including a PC-based "Series IV." They claimed that because Vogel had also used the Fairlight name for the iOS CMI app as well, he had violated the terms of the agreement, and they were within their rights to terminate the agreement. Vogel said that he believed that the licensing agreement also extended to the app as well, but the Federal Court held the agreement had been validly terminated.

Vogel appealed to a full court of the Federal Court however the appeal was only partially successful, and Fairlight was required to pay 50% of Vogel's costs for the appeal.

The iOS app was temporarily withdrawn from the App Store but subsequently returned. The CMI-30A, however, has remained out of production, and visitors to the Vogel Instruments website are greeted with a notification that sales of the CMI-30A have been suspended pending the resolution of litigation with Fairlight.

title: Fairlight (company)


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Talk:Nanzhao

Untitled
I have never edited a page here before but I could not leave this page as it stands. Firstly, Nanchao in modern Chinese 'pinyin' spelling shoudl be written Nanzhao. Secondly, it was NOT a Thai kingdom. That is a myth that was perpetrated by some Western writers in the early twentieth century I believe. I have written a website about Bai culture and have copied my history page here. The link is http://alcor.eastasiagroup.net/bai/en/history.html

I am sorry I do not know how to do links and stuff. The last part should probably be under Dali kingdom, and I coudl probably add some more info there but not sure I have the time for that.

Bryan Allen

 * I'm sure you understand the topic better than I do; my version of the article was merely a weak attempt to cover a subject on which we were sorely lacking an article. East Asian history certainly isn't my strong point. However, I was working off some rather recent material that said it was a Thai kingdom...oh well, I guess myths can be perpetuated long after the truth is known. I'll work on this a little and try to give it more of a Wikipedia style.

 * Also, I did include the spelling "Nanzhao" as an alternate spelling; however, Nanchao seems to be the most common spelling, so I think we should stick with that for the title. I'll make "Nanzhao" a redirect page to this article. Everyking 18:28, 9 Mar 2004 (UTC)

 * Actually, I changed my mind and went ahead and made the main spelling Nanzhao. "Nanchao" is now a redirect to this page. Everyking

 * This is now a very good article, by the way; I hope you will find the time to contribute more to it in the future, or to create an article on the Kingdom of Dali. Everyking 19:07, 9 Mar 2004 (UTC)

Thanks for the encouragement. I'll try and add more stuff about the Dali Kingdom and the Bai in general when I get more time. Thanks for the editing too. Bryan

The Thai myth and other stuff...
Sirs, The Thai myth is a persistent one, and has thrown a wrench into SE Asian studies for a long time. My writer friend in Chiang Mai says that it originated with a writer trying to curry favor with the Thai Royal publishers by writing a book saying that the Thai originated in the Chinese plains, invented rice cultivation and gave birth to Asian civilization. This myth has spread so far that I've read articles about the Shan, a Thai people in Burma claiming that they are the old Nanzhao royalty! Some other points that may be worth adding if you can varify them are that the Nanzhao supposedly fell to Genghis Khan on his way to Persia, and that the kingdom derived much of its power from control of the Ancient Tea Route, something I think I may write an article on in the future. Regards, Jeff Crosby (in Kunming)

 * I was born in Thailand, and as a child I heard about Genghis Khan driving the Thai people south, etc. and the Thai people originating in SW China. That being said, I moved to the USA while in elementary school and I can no longer speak or read Thai and that was over 40 years ago.  Perhaps there are some Asian sources with better information on this subject.  --Thomas Chongruk  |  Talk 1:13, 27 December 2012 (UTC)

Expansion of the article?
http://www.chinaknowledge.de/History/Altera/nanzhao.html has information that goes into more depth that what is in the current article, ie. the origins of the kingdom and lists its rulers. Abstrakt 05:55, 21 April 2006 (UTC)

Zhao
Is Zhao equal to Saopha?--刻意(Kèyì) 17:56, 28 December 2009 (UTC)

Maharajah Title
http://books.google.com/books?id=BsyFU9FwCIkC&pg=PA160&dq=Yunnan+Maharaja&hl=en&sa=X&ei=yYLtU4CgIoblsATYrYHQBQ&ved=0CCEQ6AEwAA#v=onepage&q=Yunnan%20Maharaja&f=false

Page 480

http://books.google.com/books?id=bsyfAAAAMAAJ&q=Yunnan+Maharaja&dq=Yunnan+Maharaja&hl=en&sa=X&ei=I4PtU6nAJoe_sQSr_oDwAw&ved=0CCYQ6wEwATgK

http://books.google.com/books?id=7xeqhnYtrKcC&pg=PA330&dq=Yunnan+Maharaja&hl=en&sa=X&ei=I4PtU6nAJoe_sQSr_oDwAw&ved=0CCAQ6AEwADgK#v=onepage&q=Yunnan%20Maharaja&f=false

Rajmaan (talk) 03:50, 15 August 2014 (UTC)

A Commons file used on this page or its Wikidata item has been nominated for deletion
The following Wikimedia Commons file used on this page or its Wikidata item has been nominated for deletion: Participate in the deletion discussion at the nomination page. —Community Tech bot (talk) 00:01, 23 January 2021 (UTC)
 * Dali Shield.jpg

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Talk:Nanzhao


text:
Talk:Sipuncula

untitled
Added photo, removed tag.--Abbott75 08:14, 1 April 2007 (UTC) hola bola de putos —Preceding unsigned comment added by 198.60.171.17 (talk) 15:37, 20 March 2008 (UTC)

Phylum status
According to the Annelid article, Sipuncula are a subdivision of that phylum. Is there any reason why we treat them as an independent one in this article? Complainer (talk) —Preceding undated comment added 09:42, 20 July 2011 (UTC).
 * I don't know. Perhaps I should be bold and change the taxonomy template. Hanif Al Husaini (talk) 15:48, 3 May 2018 (UTC)

"Good article"
It may not be up to this particular article to explain the earlier uses of the same name by Lhuyd and others, but it should at least explain why it lists the first use as 1767 while providing a source dated to 1766. — Llywelyn II   01:56, 16 December 2023 (UTC)

title: Talk:Sipuncula


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Wausau Woodchucks

The Wausau Woodchucks are an American baseball team that plays in the Northwoods League, a collegiate summer baseball league. They play their home games at Athletic Park in Wausau, Wisconsin.

History
The team was known as the Wausau Woodchucks from 1994 to 1998, but the team name was changed to Wisconsin Woodchucks for the 1999 season, as they were the only remaining team in Wisconsin in the league at that time.

The team filled the void left by the Wausau Timbers of the Class A Midwest League, who relocated after the 1990 season to Geneva, Illinois, to become the Kane County Cougars.

In 1998 Clark Eckhoff purchased The Wisconsin Woodchucks, and Eckhoff truly made an impact on the team as well as the community as a whole. Not only did attendance dramatically increase with Eckhoff as owner, but the Woodchucks would go on to win two league championships in 2001 and 2003.

The Woodchucks' manager for the 2007–2009 seasons was Jim Gantner, a former Milwaukee Brewer who attended college at the University of Wisconsin–Oshkosh. Gantner had never managed a team previously, and the Woodchucks appealed to him as he had spent time in the area at a second home. Gantner became the team's president of baseball operations in 2009.

On February 2, 2022, the Woodchucks announced their return as the Wausau Woodchucks, with a new logo and color scheme.

Players
A number of major leaguers and other notables have played for the Wausau Woodchucks, including:

 * J. D. Davis, 2012 (third baseman for teams including the New York Mets and the San Francisco Giants)
 * Steve Foster (baseball), 2003 (pitcher for the Cincinnati Reds)
 * Dave Gassner, 1998 (pitcher for the Minnesota Twins)
 * Casey Janssen, 2001 (pitcher for the Toronto Blue Jays)
 * Mark Lowe, 2002–03 (pitcher for teams including the Seattle Mariners and the Texas Rangers)
 * Pat Neshek, 2000 (2-time MLB All Star and relief pitcher for teams including the Minnesota Twins and St. Louis Cardinals)
 * Wes Obermueller, 1995 (relief pitcher for teams including the Milwaukee Brewers)
 * Kevin Pillar, 2010 (outfielder for teams including the Toronto Blue Jays and the New York Mets)
 * Darin Ruf, 2007 (outfielder for teams including the Philadelphia Phillies and San Francisco Giants)
 * Pat Venditte, 2008 (switch pitcher for teams including the Oakland Athletics)
 * Ben Zobrist, 2003–04 (3-time MLB All Star and World Series MVP with the Chicago Cubs)

title: Wausau Woodchucks


text:
User talk:Chrisdolan

Please sign all additions by inserting four '~' characters

List of observatories
Hi, Chris. I just checked and List of observatories is still black. I'm using IE 6.0. Thanks for the good words on the California state parks. I'm SLOWLY adding them. RickK | Talk 02:41, 18 Mar 2004 (UTC)

Hi. Please don't create articles with no useful content other than an external link. If it's worth starting an article on, please have at least a complete sentence or two of text. Cheers, -- Infrogmation 15:16, 18 Mar 2004 (UTC)

Hi Chris. Edits from 209.249.163.62 have now been reattributed to you. Regards  — Kate Turner | Talk 07:53, 2004 Sep 5 (UTC)

Wisconsin State Parks
Hi Chris...just so you're aware, see Wikipedia talk:WikiProject Wisconsin. Cheers, Tom e rtalk 15:40, 29 January 2006 (UTC)

Redirect of Tuits
Hello, this is a message from an automated bot. A tag has been placed on Tuits, by another Wikipedia user, requesting that it be speedily deleted from Wikipedia. The tag claims that it should be speedily deleted because Tuits is a redirect to a non-existent page (CSD R1). To contest the tagging and request that administrators wait before possibly deleting Tuits, please affix the template to the page, and put a note on its talk page. If the article has already been deleted, see the advice and instructions at WP:WMD. Feel free to contact the bot operator if you have any questions about this or any problems with this bot, bearing in mind that this bot is only informing you of the nomination for speedy deletion; it does not perform any nominations or deletions itself. CSDWarnBot 12:34, 28 August 2007 (UTC)

Proposed deletion of Horribly Hilly Hundreds
A proposed deletion template has been added to the article Horribly Hilly Hundreds, suggesting that it be deleted according to the proposed deletion process. All contributions are appreciated, but this article may not satisfy Wikipedia's criteria for inclusion, and the deletion notice should explain why (see also "What Wikipedia is not" and Wikipedia's deletion policy). You may prevent the proposed deletion by removing the  notice, but please explain why you disagree with the proposed deletion in your edit summary or on its talk page.

Please consider improving the article to address the issues raised because even though removing the deletion notice will prevent deletion through the proposed deletion process, the article may still be deleted if it matches any of the speedy deletion criteria or it can be sent to Articles for Deletion, where it may be deleted if consensus to delete is reached. Guy (Help!) 08:32, 31 August 2008 (UTC)

title: User talk:Chrisdolan


text:
User talk:Arvindn/Chess

Disadvantages over wikitex:
 * much, much more verbose, even a single chess board takes up 96 lines of text as opposed to only 2 for wikitex. Trying to show games with more than a few moves would create very large source.
 * This is being discussed on wikitech-l. I wrote a small script to convert a description like

rnbqkbnr pppppppp ........ ........ ........ ........ PPPPPPPP RNBQKBNR

to a table, and I've requested the developers to incorporate it into mediawiki. -- Arvindn 16:11, 9 Mar 2004 (UTC)~

Comments from the village pump
With Arvindn's new system, it is now possible to have a running chess game! Click on the "d" in my signature! Comments? - Woodrow 05:30, 4 Apr 2004 (UTC)

 * The WikiTeX stuff at Wikisophia looks neat too and seems to be easier to use, but it enforces long algebraic notation which isn't so standard... Dysprosia 06:29, 4 Apr 2004 (UTC)

 * Personally, I find Arvindn's idea easier to understand. Also, think of the space that'd be saved with the deletion of dozens of old chess diagrams! - Woodrow 06:35, 4 Apr 2004 (UTC)

 * Neat idea. I'm sorry to tell you, that you aren't the first one to do wiki-chess!  :-) — Sverdrup 10:42, 4 Apr 2004 (UTC)

 * First in English! - Woodrow 17:56, 4 Apr 2004 (UTC)

Yes, it's a nice idea, but at the moment it's too verbose to be completely wonderful. If people want to make new diagrams in this way, I've no problem with that, but please don't delete old ones until the syntax is tightened up somehow (judging from User talk:Arvindn/Chess, this may be about to happen). And, I hate to be a spoilsport, but the Wikipedia really isn't the place to play chess. There are lots and lots of other websites for that. --Camembert

 * I certainly don't consider playing any more games here. The main purpose (for me) was to actually just play around with the commands and such and see how user-friendly it seemed, if I got used to it easily, etc. While I would use one of my own pages as a sandbox to test out boards before posting, this is not really the place to play. Of course, having started this particular game, I'll play it out. It was really just a little experiment (for me, at least) to prove a point that it might be doable. Revolver 01:18, 10 Apr 2004 (UTC)

 * Grr! I was going to use that argument for chess diagrams once I finished a game! It was going to be my surprise twist! However, I still see no problem with using one's user space for chess games. Why do people always steal my surprise twists? Perhaps I should issue an imperial decree about it. - Woodrow, Emperor of the United States 01:28, 10 Apr 2004 (UTC)
 * Well, the point is, if you already have positions or PGN games known and want to use these, you can enter these in by the ways Arvindn has suggested. If you want to play games to generate interesting examples, you can play them somewhere else and then import them here. I don't think this is really damaging at the moment at all, but I do worry that in the future people may get the idea this is Yahoo/games. Admittedly, the line isn't totally clear between messing around, or playing around with positions, ideas, discussing stuff using boards, etc., and actual play. I would hate to see all of these things get banned or something ridiculous like that just because they are perceived as appearing to be playing a game. All those things are actual legitimate talk-related things to the encyclopedia; playing an actual game is akin to "original research", as we say at the math articles. Revolver 01:52, 10 Apr 2004 (UTC)
 * EXAMPLE: If, in the course of discussing a chess concept, you want to give a particular board position as an example, to illustrate something, ask a question, make an observation, or any other way use the board position as a linguistic aid, much the same way TeX is used at the math articles, this is perfectly fine and IMO absolutely essential to the success of the chess articles (it greatly facilitates communication). But this isn't the same thing as playing. Revolver 01:54, 10 Apr 2004 (UTC)

 * I don't have a reply to that, I'm just inserting this to keep it from looking like I'm saying that it's the same thing as playing. - Woodrow, Emperor of the United States 01:58, 10 Apr 2004 (UTC)

 * It most certainly is! - Woodrow 20:13, 4 Apr 2004 (UTC)

 * I think it's close to the line at least. All Wikipedia pages are there to support the goal of building an encyclopedia. Any other use is abuse. Now, I don't want to be a spoilsport either, and there are things such as BJAODN that support this effort by building our community. Maybe chess is like that too. Or, maybe it's helping us learn how to use the software, that's valid too. But, I think the participants should bear in mind that they are pushing the envelope IMO (and it seems I'm not alone in this). Andrewa 10:11, 5 Apr 2004 (UTC)

Excuses:

 * 1) Wikipediholism consumes me. As I find myself spending every spare minute on Wikipedia, this adds a little more meaning to my life.
 * 2) It's helpful in learning to use the code.
 * 3) It helps us relieve stress after hours of watching Recent Changes like hawks.
 * 4) It will expand our minds and thus, our encyclopedia-building powers.
 * 5) It creates a better overall feeling of WikiLove.
 * 6) It's being done on user pages.

Wow, once again I've managed to convince myself that an idea of mine is good! It is close to the line, but I feel we should be allowed to do with our user pages as we please, within reason. Of course, it's ultimately up to Jimbo Wales whether we may keep up this hobby here... - Woodrow 20:08, 5 Apr 2004 (UTC)

 * This is definitely not appropriate for the English Wikipedia. You might have more of a chance of getting away with it on meta, but really, you should find a separate wiki to play chess on. Angela. 18:53, Apr 6, 2004 (UTC)

 * Or on wikibooks, where old chess games could be used as example games in a chess strategy guide. Gentgeen 19:09, 6 Apr 2004 (UTC)

 * I'll get right on it. - Woodrow 01:05, 7 Apr 2004 (UTC)

 * (Sigh) and now we have Wikisex. Andrewa 19:57, 8 Apr 2004 (UTC)

 * Sorry, Calmypal, I can't agree. Once the code is learned and refined and stylised to easy use, this (English wikipedia, at least) isn't the place for games. If you want to play games, you can get a free account on ICC or Yahoo or any number of places that are already easier to do this. I admit, it was a bit thrilling at first, but the novelty will wear off. And if too many people start using it for this, it may cut into the bandwidth. Revolver 01:24, 10 Apr 2004 (UTC)

 * Then I shall raise and donate $1000. - Woodrow, Emperor of the United States 01:28, 10 Apr 2004 (UTC)

Unicode characters for chess pieces: U+2654 to U+2659 : K Q R B N p (White) U+265A to U+265F : K Q R B N p (Black)

You might find http://www.freechess.org/ useful.

Rajasekaran Deepak 17:28, 2004 May 12 (UTC)

title: User talk:Arvindn/Chess


text:
Zinc oxide

Zinc oxide is an inorganic compound with the formula. It is a white powder which is insoluble in water. ZnO is used as an additive in numerous materials and products including cosmetics, food supplements, rubbers, plastics, ceramics, glass, cement, lubricants, paints, sunscreens, ointments, adhesives, sealants, pigments, foods, batteries, ferrites, fire retardants, semi conductors, and first-aid tapes. Although it occurs naturally as the mineral zincite, most zinc oxide is produced synthetically.

History
Early humans probably used zinc compounds in processed and unprocessed forms, as paint or medicinal ointment, but their composition is uncertain. The use of pushpanjan, probably zinc oxide, as a salve for eyes and open wounds is mentioned in the Indian medical text the Charaka Samhita, thought to date from 500 BC or before. Zinc oxide ointment is also mentioned by the Greek physician Dioscorides (1st century AD). Galen suggested treating ulcerating cancers with zinc oxide, as did Avicenna in his The Canon of Medicine. It is used as an ingredient in products such as baby powder and creams against diaper rashes, calamine cream, anti-dandruff shampoos, and antiseptic ointments.

The Romans produced considerable quantities of brass (an alloy of zinc and copper) as early as 200 BC by a cementation process where copper was reacted with zinc oxide. The zinc oxide is thought to have been produced by heating zinc ore in a shaft furnace. This liberated metallic zinc as a vapor, which then ascended the flue and condensed as the oxide. This process was described by Dioscorides in the 1st century AD. Zinc oxide has also been recovered from zinc mines at Zawar in India, dating from the second half of the first millennium BC.

From the 12th to the 16th century zinc and zinc oxide were recognized and produced in India using a primitive form of the direct synthesis process. From India, zinc manufacturing moved to China in the 17th century. In 1743, the first European zinc smelter was established in Bristol, United Kingdom. Around 1782 Louis-Bernard Guyton de Morveau proposed replacing lead white pigment with zinc oxide.

The main usage of zinc oxide (zinc white) was in paints and as an additive to ointments. Zinc white was accepted as a pigment in oil paintings by 1834 but it did not mix well with oil. This problem was solved by optimizing the synthesis of ZnO. In 1845, Edme-Jean Leclaire in Paris was producing the oil paint on a large scale, and by 1850, zinc white was being manufactured throughout Europe. The success of zinc white paint was due to its advantages over the traditional white lead: zinc white is essentially permanent in sunlight, it is not blackened by sulfur-bearing air, it is non-toxic and more economical. Because zinc white is so "clean" it is valuable for making tints with other colors, but it makes a rather brittle dry film when unmixed with other colors. For example, during the late 1890s and early 1900s, some artists used zinc white as a ground for their oil paintings. All those paintings developed cracks over the years.

In recent times, most zinc oxide has been used in the rubber industry to resist corrosion. In the 1970s, the second largest application of ZnO was photocopying. High-quality ZnO produced by the "French process" was added to photocopying paper as a filler. This application was soon displaced by titanium.

Chemical properties
Pure ZnO is a white powder, but in nature it occurs as the rare mineral zincite, which usually contains manganese and other impurities that confer a yellow to red color.

Crystalline zinc oxide is thermochromic, changing from white to yellow when heated in air and reverting to white on cooling. This color change is caused by a small loss of oxygen to the environment at high temperatures to form the non-stoichiometric Zn1+xO, where at 800 °C, x = 0.00007.

Zinc oxide is an amphoteric oxide. It is nearly insoluble in water, but it will dissolve in most acids, such as hydrochloric acid:
 * ZnO +  2 HCl   →   ZnCl2  +  H2O

Solid zinc oxide will also dissolve in alkalis to give soluble zincates:
 * ZnO +  2 NaOH  +  H2O   →   Na2[Zn(OH)4]

ZnO reacts slowly with fatty acids in oils to produce the corresponding carboxylates, such as oleate or stearate. When mixed with a strong aqueous solution of zinc chloride, ZnO forms cement-like products best described as zinc hydroxy chlorides. This cement was used in dentistry.

ZnO also forms cement-like material when treated with phosphoric acid; related materials are used in dentistry. A major component of zinc phosphate cement produced by this reaction is hopeite, Zn3(PO4)2·4H2O.

ZnO decomposes into zinc vapor and oxygen at around 1975 °C with a standard oxygen pressure. In a carbothermic reaction, heating with carbon converts the oxide into zinc vapor at a much lower temperature (around 950 °C).
 * ZnO +  C   →   Zn(Vapor)  +  CO

Structure
Zinc oxide crystallizes in two main forms, hexagonal wurtzite and cubic zincblende. The wurtzite structure is most stable at ambient conditions and thus most common. The zincblende form can be stabilized by growing ZnO on substrates with cubic lattice structure. In both cases, the zinc and oxide centers are tetrahedral, the most characteristic geometry for Zn(II). ZnO converts to the rocksalt motif at relatively high pressures about 10 GPa.

Hexagonal and zincblende polymorphs have no inversion symmetry (reflection of a crystal relative to any given point does not transform it into itself). This and other lattice symmetry properties result in piezoelectricity of the hexagonal and zincblende ZnO, and pyroelectricity of hexagonal ZnO.

The hexagonal structure has a point group 6 mm (Hermann–Mauguin notation) or C6v (Schoenflies notation), and the space group is P63mc or C6v4. The lattice constants are a = 3.25 Å and c = 5.2 Å; their ratio c/a ~ 1.60 is close to the ideal value for hexagonal cell c/a = 1.633. As in most group II-VI materials, the bonding in ZnO is largely ionic (Zn2+O2−) with the corresponding radii of 0.074 nm for Zn2+ and 0.140 nm for O2−. This property accounts for the preferential formation of wurtzite rather than zinc blende structure, as well as the strong piezoelectricity of ZnO. Because of the polar Zn−O bonds, zinc and oxygen planes are electrically charged. To maintain electrical neutrality, those planes reconstruct at atomic level in most relative materials, but not in ZnO – its surfaces are atomically flat, stable and exhibit no reconstruction. However, studies using wurtzoid structures explained the origin of surface flatness and the absence of reconstruction at ZnO wurtzite surfaces in addition to the origin of charges on ZnO planes.

Mechanical properties
ZnO is a wide-band gap semiconductor of the II-VI semiconductor group. The native doping of the semiconductor due to oxygen vacancies or zinc interstitials is n-type.

ZnO is a relatively soft material with approximate hardness of 4.5 on the Mohs scale. Its elastic constants are smaller than those of relevant III-V semiconductors, such as GaN. The high heat capacity and heat conductivity, low thermal expansion and high melting temperature of ZnO are beneficial for ceramics. The E2 optical phonon in ZnO exhibits an unusually long lifetime of 133 ps at 10 K.

Among the tetrahedrally bonded semiconductors, it has been stated that ZnO has the highest piezoelectric tensor, or at least one comparable to that of GaN and AlN. This property makes it a technologically important material for many piezoelectrical applications, which require a large electromechanical coupling. Therefore, ZnO in the form of thin film has been one of the most studied resonator materials for thin-film bulk acoustic resonators.

Electrical and optical properties
Favourable properties of zinc oxide include good transparency, high electron mobility, wide band gap, and strong room-temperature luminescence. Those properties make ZnO valuable for a variety of emerging applications: transparent electrodes in liquid crystal displays, energy-saving or heat-protecting windows, and electronics as thin-film transistors and light-emitting diodes.

ZnO has a relatively wide direct band gap of ~3.3 eV at room temperature. Advantages associated with a wide band gap include higher breakdown voltages, ability to sustain large electric fields, lower electronic noise, and high-temperature and high-power operation. The band gap of ZnO can further be tuned to ~3–4 eV by its alloying with magnesium oxide or cadmium oxide. Due to this large band gap, there have been efforts to create visibly transparent solar cells utilising ZnO as a light absorbing layer. However, these solar cells have so far proven highly inefficient.

Most ZnO has n-type character, even in the absence of intentional doping. Nonstoichiometry is typically the origin of n-type character, but the subject remains controversial. An alternative explanation has been proposed, based on theoretical calculations, that unintentional substitutional hydrogen impurities are responsible. Controllable n-type doping is easily achieved by substituting Zn with group-III elements such as Al, Ga, In or by substituting oxygen with group-VII elements chlorine or iodine.

Reliable p-type doping of ZnO remains difficult. This problem originates from low solubility of p-type dopants and their compensation by abundant n-type impurities. This problem is observed with GaN and ZnSe. Measurement of p-type in "intrinsically" n-type material is complicated by the inhomogeneity of samples.

Current limitations to p-doping limit electronic and optoelectronic applications of ZnO, which usually require junctions of n-type and p-type material. Known p-type dopants include group-I elements Li, Na, K; group-V elements N, P and As; as well as copper and silver. However, many of these form deep acceptors and do not produce significant p-type conduction at room temperature.

Electron mobility of ZnO strongly varies with temperature and has a maximum of ~2000 cm2/(V·s) at 80 K. Data on hole mobility are scarce with values in the range 5–30 cm2/(V·s).

ZnO discs, acting as a varistor, are the active material in most surge arresters.

Zinc oxide is noted for its strongly nonlinear optical properties, especially in bulk. The nonlinearity of ZnO nanoparticles can be fine-tuned according to their size.

Production
For industrial use, ZnO is produced at levels of 105 tons per year by three main processes:

Indirect process
In the indirect or French process, metallic zinc is melted in a graphite crucible and vaporized at temperatures above 907 °C (typically around 1000 °C). Zinc vapor reacts with the oxygen in the air to give ZnO, accompanied by a drop in its temperature and bright luminescence. Zinc oxide particles are transported into a cooling duct and collected in a bag house. This indirect method was popularized by Edme Jean LeClaire of Paris in 1844 and therefore is commonly known as the French process. Its product normally consists of agglomerated zinc oxide particles with an average size of 0.1 to a few micrometers. By weight, most of the world's zinc oxide is manufactured via French process.

Direct process
The direct or American process starts with diverse contaminated zinc composites, such as zinc ores or smelter by-products. The zinc precursors are reduced (carbothermal reduction) by heating with a source of carbon such as anthracite to produce zinc vapor, which is then oxidized as in the indirect process. Because of the lower purity of the source material, the final product is also of lower quality in the direct process as compared to the indirect one.

Wet chemical process
A small amount of industrial production involves wet chemical processes, which start with aqueous solutions of zinc salts, from which zinc carbonate or zinc hydroxide is precipitated. The solid precipitate is then calcined at temperatures around 800 °C.

Laboratory synthesis
Numerous specialised methods exist for producing ZnO for scientific studies and niche applications. These methods can be classified by the resulting ZnO form (bulk, thin film, nanowire), temperature ("low", that is close to room temperature or "high", that is T ~ 1000 °C), process type (vapor deposition or growth from solution) and other parameters.

Large single crystals (many cubic centimeters) can be grown by the gas transport (vapor-phase deposition), hydrothermal synthesis, or melt growth. However, because of the high vapor pressure of ZnO, growth from the melt is problematic. Growth by gas transport is difficult to control, leaving the hydrothermal method as a preference. Thin films can be produced by chemical vapor deposition, metalorganic vapour phase epitaxy, electrodeposition, pulsed laser deposition, sputtering, sol–gel synthesis, atomic layer deposition, spray pyrolysis, etc.

Ordinary white powdered zinc oxide can be produced in the laboratory by electrolyzing a solution of sodium bicarbonate with a zinc anode. Zinc hydroxide and hydrogen gas are produced. The zinc hydroxide upon heating decomposes to zinc oxide:

 * Zn + 2 H2O → Zn(OH)2 + H2

 * Zn(OH)2 → ZnO + H2O

ZnO nanostructures
Nanostructures of ZnO can be synthesized into a variety of morphologies, including nanowires, nanorods, tetrapods, nanobelts, nanoflowers, nanoparticles, etc. Nanostructures can be obtained with most above-mentioned techniques, at certain conditions, and also with the vapor–liquid–solid method. The synthesis is typically carried out at temperatures of about 90 °C, in an equimolar aqueous solution of zinc nitrate and hexamine, the latter providing the basic environment. Certain additives, such as polyethylene glycol or polyethylenimine, can improve the aspect ratio of the ZnO nanowires. Doping of the ZnO nanowires has been achieved by adding other metal nitrates to the growth solution. The morphology of the resulting nanostructures can be tuned by changing the parameters relating to the precursor composition (such as the zinc concentration and pH) or to the thermal treatment (such as the temperature and heating rate).

Aligned ZnO nanowires on pre-seeded silicon, glass, and gallium nitride substrates have been grown using aqueous zinc salts such as zinc nitrate and zinc acetate in basic environments. Pre-seeding substrates with ZnO creates sites for homogeneous nucleation of ZnO crystal during the synthesis. Common pre-seeding methods include in-situ thermal decomposition of zinc acetate crystallites, spin coating of ZnO nanoparticles, and the use of physical vapor deposition methods to deposit ZnO thin films. Pre-seeding can be performed in conjunction with top down patterning methods such as electron beam lithography and nanosphere lithography to designate nucleation sites prior to growth. Aligned ZnO nanowires can be used in dye-sensitized solar cells and field emission devices.

Applications
The applications of zinc oxide powder are numerous, and the principal ones are summarized below. Most applications exploit the reactivity of the oxide as a precursor to other zinc compounds. For material science applications, zinc oxide has high refractive index, high thermal conductivity, binding, antibacterial and UV-protection properties. Consequently, it is added into materials and products including plastics, ceramics, glass, cement, rubber, lubricants, paints, ointments, adhesive, sealants, concrete manufacturing, pigments, foods, batteries, ferrites, fire retardants, etc.

Rubber industry
Between 50% and 60% of ZnO use is in the rubber industry. Zinc oxide along with stearic acid is used in the sulfur vulcanization of rubber. ZnO additives also protect rubber from fungi (see medical applications) and UV light.

Ceramic industry
Ceramic industry consumes a significant amount of zinc oxide, in particular in ceramic glaze and frit compositions. The relatively high heat capacity, thermal conductivity and high temperature stability of ZnO coupled with a comparatively low coefficient of expansion are desirable properties in the production of ceramics. ZnO affects the melting point and optical properties of the glazes, enamels, and ceramic formulations. Zinc oxide as a low expansion, secondary flux improves the elasticity of glazes by reducing the change in viscosity as a function of temperature and helps prevent crazing and shivering. By substituting ZnO for BaO and PbO, the heat capacity is decreased and the thermal conductivity is increased. Zinc in small amounts improves the development of glossy and brilliant surfaces. However, in moderate to high amounts, it produces matte and crystalline surfaces. With regard to color, zinc has a complicated influence.

Skin treatment
Zinc oxide as a mixture with about 0.5% iron(III) oxide (Fe2O3) is called calamine and is used in calamine lotion. Historically the mineral calamine is a mixture of the oxides zincite and hemimorphite.

Zinc oxide is widely used to treat a variety of skin conditions, including atopic dermatitis, contact dermatitis, itching due to eczema, diaper rash and acne. It is used in products such as baby powder and barrier creams to treat diaper rashes, calamine cream, anti-dandruff shampoos, and antiseptic ointments. It is often combined with castor oil to form an emollient and astringent, zinc and castor oil cream, commonly used to treat infants.

It is also a component in tape (called "zinc oxide tape") used by athletes as a bandage to prevent soft tissue damage during workouts.

Antibacterial
Zinc oxide is used in mouthwash products and toothpastes as an anti-bacterial agent proposed to prevent plaque and tartar formation, and to control bad breath by reducing the volatile gases and volatile sulfur compounds (VSC) in the mouth. Along with zinc oxide or zinc salts, these products also commonly contain other active ingredients, such as cetylpyridinium chloride, xylitol, hinokitiol, essential oils and plant extracts. Powdered zinc oxide has deodorizing and antibacterial properties.

ZnO is added to cotton fabric, rubber, oral care products, and food packaging. Enhanced antibacterial action of fine particles compared to bulk material is not exclusive to ZnO and is observed for other materials, such as silver. This property results from the increased surface area of the fine particles.

Sunscreen
Zinc oxide is used in sunscreen to absorb ultraviolet light. It is the broadest spectrum UVA and UVB absorber that is approved for use as a sunscreen by the U.S. Food and Drug Administration (FDA), and is completely photostable. When used as an ingredient in sunscreen, zinc oxide blocks both UVA (320–400 nm) and UVB (280–320 nm) rays of ultraviolet light. Zinc oxide and the other most common physical sunscreen, titanium dioxide, are considered to be nonirritating, nonallergenic, and non-comedogenic. Zinc from zinc oxide is, however, slightly absorbed into the skin.

Many sunscreens use nanoparticles of zinc oxide (along with nanoparticles of titanium dioxide) because such small particles do not scatter light and therefore do not appear white. The nanoparticles are not absorbed into the skin more than regular-sized zinc oxide particles are and are only absorbed into the outermost layer of the skin but not into the body.

Dental restoration
When mixed with eugenol, zinc oxide eugenol is formed, which has applications as a restorative and prosthodontic in dentistry.

Food additive
Zinc oxide is added to many food products, including breakfast cereals, as a source of zinc, a necessary nutrient. Zinc sulfate is also used for the same purpose. Some prepackaged foods also include trace amounts of ZnO even if it is not intended as a nutrient.

Pigment
Zinc oxide (zinc white) is used as a pigment in paints and is more opaque than lithopone, but less opaque than titanium dioxide. It is also used in coatings for paper. Chinese white is a special grade of zinc white used in artists' pigments. The use of zinc white as a pigment in oil painting started in the middle of 18th century. It has partly replaced the poisonous lead white and was used by painters such as Böcklin, Van Gogh, Manet, Munch and others. It is also a main ingredient of mineral makeup (CI 77947).

UV absorber
Micronized and nano-scale zinc oxide provides strong protection against UVA and UVB ultraviolet radiation, and are consequently used in sunscreens, and also in UV-blocking sunglasses for use in space and for protection when welding, following research by scientists at Jet Propulsion Laboratory (JPL).

Coatings
Paints containing zinc oxide powder have long been utilized as anticorrosive coatings for metals. They are especially effective for galvanized iron. Iron is difficult to protect because its reactivity with organic coatings leads to brittleness and lack of adhesion. Zinc oxide paints retain their flexibility and adherence on such surfaces for many years.

ZnO highly n-type doped with aluminium, gallium, or indium is transparent and conductive (transparency ~90%, lowest resistivity ~10−4 Ω·cm ). ZnO:Al coatings are used for energy-saving or heat-protecting windows. The coating lets the visible part of the spectrum in but either reflects the infrared (IR) radiation back into the room (energy saving) or does not let the IR radiation into the room (heat protection), depending on which side of the window has the coating.

Plastics, such as polyethylene naphthalate (PEN), can be protected by applying zinc oxide coating. The coating reduces the diffusion of oxygen through PEN. Zinc oxide layers can also be used on polycarbonate in outdoor applications. The coating protects polycarbonate from solar radiation, and decreases its oxidation rate and photo-yellowing.

Corrosion prevention in nuclear reactors
Zinc oxide depleted in 64Zn (the zinc isotope with atomic mass 64) is used in corrosion prevention in nuclear pressurized water reactors. The depletion is necessary, because 64Zn is transformed into radioactive 65Zn under irradiation by the reactor neutrons.

Methane reforming
Zinc oxide (ZnO) is used as a pretreatment step to remove hydrogen sulfide (H2S) from natural gas following hydrogenation of any sulfur compounds prior to a methane reformer, which can poison the catalyst. At temperatures between about 230 - 430 C, H2S is converted to water by the following reaction:
 * H2S + ZnO → H2O + ZnS

Electronics

ZnO has wide direct band gap (3.37 eV or 375 nm at room temperature). Therefore, its most common potential applications are in laser diodes and light emitting diodes (LEDs). Moreover, ultrafast nonlinearities and photoconductive functions have been reported in ZnO. Some optoelectronic applications of ZnO overlap with that of GaN, which has a similar band gap (~3.4 eV at room temperature). Compared to GaN, ZnO has a larger exciton binding energy (~60 meV, 2.4 times of the room-temperature thermal energy), which results in bright room-temperature emission from ZnO. ZnO can be combined with GaN for LED-applications. For instance, a transparent conducting oxide layer and ZnO nanostructures provide better light outcoupling. Other properties of ZnO favorable for electronic applications include its stability to high-energy radiation and its ability to be patterned by wet chemical etching. Radiation resistance makes ZnO a suitable candidate for space applications. ZnO is the most promising candidate in the field of random lasers to produce an electronically pumped UV laser source.

The pointed tips of ZnO nanorods result in a strong enhancement of an electric field. Therefore, they can be used as field emitters.

Aluminium-doped ZnO layers are used as transparent electrodes. The components Zn and Al are much cheaper and less toxic compared to the generally used indium tin oxide (ITO). One application which has begun to be commercially available is the use of ZnO as the front contact for solar cells or of liquid crystal displays.

Transparent thin-film transistors (TTFT) can be produced with ZnO. As field-effect transistors, they do not need a p–n junction, thus avoiding the p-type doping problem of ZnO. Some of the field-effect transistors even use ZnO nanorods as conducting channels.

Gas sensors
Zinc oxide is used in semiconductor gas sensors for detecting airborne compounds such as hydrogen sulfide, nitrogen dioxide, and volatile organic compounds. ZnO is a semiconductor that becomes n-doped by adsorption of reducing compounds, which reduces the detected electrical resistance through the device, in a manner similar to the widely used tin oxide semiconductor gas sensors. It is formed into nanostructures such as thin films, nanoparticles, nanopillars, or nanowires to provide a large surface area for interaction with gasses. The sensors are made selective for specific gasses by doping or surface-attaching materials such as catalytic noble metals.

Piezoelectricity
The piezoelectricity in textile fibers coated in ZnO have been shown capable of fabricating "self-powered nanosystems" with everyday mechanical stress from wind or body movements.

In 2008 the Center for Nanostructure Characterization at the Georgia Institute of Technology reported producing an electricity generating device (called flexible charge pump generator) delivering alternating current by stretching and releasing zinc oxide nanowires. This mini-generator creates an oscillating voltage up to 45 millivolts, converting close to seven percent of the applied mechanical energy into electricity. Researchers used wires with lengths of 0.2–0.3 mm and diameters of three to five micrometers, but the device could be scaled down to smaller size.

In form of a thin film ZnO has been demonstrated in miniaturised high frequency thin film resonators, sensors and filters.

Li-ion battery and supercapacitors
ZnO is a promising anode material for lithium-ion battery because it is cheap, biocompatible, and environmentally friendly. ZnO has a higher theoretical capacity (978 mAh g−1) than many other transition metal oxides such as CoO (715 mAh g−1), NiO (718 mAh g−1) and CuO (674 mAh g−1). ZnO is also used as an electrode in supercapacitors.

Safety
As a food additive, zinc oxide is on the U.S. FDA's list of generally recognized as safe, or GRAS, substances.

Zinc oxide itself is non-toxic; it is hazardous, however, to inhale high concentrations of zinc oxide fumes, such as generated when zinc or zinc alloys are melted and oxidized at high temperature. This problem occurs while melting alloys containing brass because the melting point of brass is close to the boiling point of zinc. Inhalation of zinc oxide, which may occur when welding galvanized (zinc-plated) steel, can result in a malady called metal fume fever.

In sunscreen formulations that combined zinc oxide with small-molecule UV absorbers, UV light caused photodegradation of the small-molecule asorbers and toxicity in embryonic zebrafish assays.

title: Zinc oxide


text:
Sforzando

Sforzando may refer to:

 * Sforzando (musical direction), in musical notation to play a note with sudden, strong emphasis (also known as sforzito)
 * Sforzando (band), a band from Melbourne, Australia
 * "Sforzando!", a 1996 song by Sebadoh from Harmacy
 * "Sforzando", in music production also refers to a free, highly SFZ 2.0 compliant sample player.

title: Sforzando


text:
Dimetrodon

Dimetrodon ( or ; lit. 'two measures of teeth') is an extinct genus of non-mammalian synapsid belonging to the family Sphenacodontidae that lived during the Cisuralian age of the Early Permian period, around 295–272 million years ago. With most species measuring 1.7 - 4.6 m long and weighing 28 - 250 kg, the most prominent feature of Dimetrodon is the large neural spine sail on its back formed by elongated spines extending from the vertebrae. It was an obligate quadruped (it could only walk 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 as a contemporary of dinosaurs in popular culture, but it became extinct some 40 million years before the advent of dinosaurs. Although reptile-like in appearance and physiology, Dimetrodon is much more closely related to mammals than to reptiles, though it is not a direct ancestor of mammals. Dimetrodon is assigned to the "non-mammalian synapsids", a group traditionally – but incorrectly – called "mammal-like reptiles", but now known as stem mammals. This groups Dimetrodon together with mammals in the clade Synapsida, while reptiles are placed in a separate clade, Sauropsida. Single openings in the skull behind each eye, known as temporal fenestrae, and other skull features distinguish Dimetrodon and true mammals from most of the earliest sauropsids.

Dimetrodon was probably one of the apex predators of the Cisuralian ecosystems, feeding on fish and tetrapods, including reptiles and amphibians. Smaller Dimetrodon species may have had different 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. 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.

Description
Dimetrodon was a quadrupedal, sail-backed synapsid that most likely had a semi-sprawling posture between that of a mammal and a lizard and also could walk in a more upright stance with its body and the majority or all of its tail off the ground. Most Dimetrodon species ranged in length from 1.7 to 4.6 m and are estimated to have weighed between 28 and 250 kg. The smallest known species D. teutonis was about 60 cm long and weighed 14 kg. The larger species of Dimetrodon were among the largest predators of the Early Permian, although the closely related Tappenosaurus, known from skeletal fragments in slightly younger rocks, may have been even larger at an estimated 18 ft long. Although some Dimetrodon species could grow very large, many juvenile specimens are known.

Skull
A single large opening on either side of the back of the skull links Dimetrodon to mammals and distinguishes it from most of the earliest sauropsids, which either lack openings or have two openings. Features such as ridges on the inside of the nasal cavity and a ridge at the back of the lower jaw are thought to be part of an evolutionary progression from early four-limbed land-dwelling vertebrates to mammals.

The skull of Dimetrodon is tall and compressed laterally, or side-to-side. The eye sockets are positioned high and far back in the skull. Behind each eye socket is a single hole called an infratemporal fenestra. An additional hole in the skull, the supratemporal fenestra, can be seen when viewed from above. The back of the skull (the occiput) is oriented at a slight upward angle, a feature that it shares with all other early synapsids. The upper margin of the skull slopes downward in a convex arc to the tip of the snout. The tip of the upper jaw, formed by the premaxilla bone, is raised above the part of the jaw formed by the maxilla bone to form a maxillary "step". Within this step is a diastema, a gap in the tooth row. Its skull was more heavily built than a dinosaur's skull.

Teeth
The size of the teeth varies greatly along the length of the jaws, lending Dimetrodon its name, which means "two measures of tooth" in reference to sets of small and large teeth. One or two pairs of caniniforms (large, pointed, canine-like teeth) extend from the maxilla. Large incisor teeth are also present at the tips of the upper and lower jaws, rooted in the premaxillae and dentary bones. Small teeth are present around the maxillary "step" and behind the caniniforms, becoming smaller further back in the jaw.

Many teeth are widest at their midsections and narrow closer to the jaws, giving them the appearance of a teardrop. Teardrop-shaped teeth are unique to Dimetrodon and other closely related sphenacodontids, which helps to distinguish them from other early synapsids. As in many other early synapsids, the teeth of most Dimetrodon species are serrated at their edges. The serrations of Dimetrodon teeth were so fine that they resembled tiny cracks. The dinosaur Albertosaurus had similarly crack-like serrations, but, at the base of each serration was a round void, which would have functioned to distribute force over a larger surface area and prevent the stresses of feeding from causing the crack to spread through the tooth. Unlike Albertosaurus, Dimetrodon teeth lacked adaptations that would stop cracks from forming at their serrations. The teeth of D. teutonis lack serrations, but still have sharp edges.

A 2014 study shows that Dimetrodon was in an arms race against its prey. The smaller species, D. milleri, had no tooth serrations because it ate small prey. As prey grew larger, several Dimetrodon species started developing serrations on their teeth and increasing in size. For instance, D. limbatus had enamel serrations that helped it cut through flesh (which were similar to the serrations that can be found on Secodontosaurus). The second-largest species, D. grandis, has denticle serrations similar to those of sharks and theropod dinosaurs, making its teeth even more specialized for slicing through flesh. As Dimetrodon's prey grew larger, the various species responded by growing to larger sizes and developing ever-sharper teeth. The thickness and mass of the teeth of Dimetrodon may also have been an adaptation for increasing dental longevity.

Nasal cavity
On the inner surface of the nasal section of skull are ridges called nasoturbinals, which may have supported cartilage that increased the area of the olfactory epithelium, the layer of tissue that detects odors. These ridges are much smaller than those of later synapsids from the Late Permian and Triassic, whose large nasoturbinals are taken as evidence for warm-bloodedness because they may have supported mucous membranes that warmed and moistened incoming air. Thus, the nasal cavity of Dimetrodon is transitional between those of early land vertebrates and mammals.

Jaw joint and ear
Another transitional feature of Dimetrodon is a ridge in the back of the jaw called the reflected lamina, which is found on the articular bone, which connects to the quadrate bone of the skull to form the jaw joint. In later mammal ancestors, the articular and quadrate separated from the jaw joint, while the articular developed into the malleus bone of the middle ear. The reflected lamina became part of a ring called the tympanic annulus that supports the ear drum in all living mammals.

Tail
The tail of Dimetrodon makes up a large portion of its total body length and includes around 50 caudal vertebrae. Tails were missing or incomplete in the first described skeletons of Dimetrodon. The only caudal vertebrae known were the 11 closest to the hip. Since these first few caudal vertebrae narrow rapidly as they progress farther from the hip, many paleontologists in the late 19th and early 20th centuries thought that Dimetrodon had a very short tail. A largely complete tail of Dimetrodon was not described until 1927.

Sail
The sail of Dimetrodon is formed by elongated neural spines projecting from the vertebrae. Each spine varies in cross-sectional shape from its base to its tip in what is known as "dimetrodont" differentiation. Near the vertebra body, the spine cross section is laterally compressed into a rectangular shape and, closer to the tip, it takes on a figure-eight shape as a groove runs along either side of the spine. The figure-eight shape is thought to reinforce the spine, preventing bending and fractures. A cross section of the spine of one specimen of Dimetrodon giganhomogenes is rectangular in shape but preserves figure-eight shaped rings close to its center, indicating that the shape of spines may change as individuals age. The microscopic anatomy of each spine varies from base to tip, indicating where it was embedded in the muscles of the back and where it was exposed as part of a sail. The lower or proximal portion of the spine has a rough surface that would have served as an anchoring point for the epaxial muscles of the back and also has a network of connective tissues called Sharpey's fibers that indicate it was embedded within the body. Higher up on the distal (outer) portion of the spine, the bone surface is smoother. The periosteum, a layer of tissue surrounding the bone, is covered in small grooves that presumably supported the blood vessels that vascularized the sail.

The large groove that runs the length of the spine was once thought to be a channel for blood vessels, but since the bone does not contain vascular canals, the sail is not thought to have been as highly vascularized as once thought. Some specimens of Dimetrodon preserve deformed areas of the neural spines that appear to be healed-over fractures. The cortical bone that grew over these breaks is highly vascularized, suggesting that soft tissue must have been present on the sail to supply the site with blood vessels. Layered lamellar bone makes up most of the neural spine's cross-sectional area, and contains lines of arrested growth that can be used to determine the age of each individual at death. In many specimens of D. gigashomogenes, the distal portions of spines bend sharply, indicating that the sail would have had an irregular profile in life. Their crookedness suggests that soft tissue may not have extended all the way to the tips of the spines, meaning that the sail's webbing may not have been as extensive as it is commonly imagined.

Skin
No fossil evidence of Dimetrodon's skin has yet been found. Impressions of the skin of a related animal, Estemmenosuchus, indicate that it would have been smooth and well-provided with glands, but this form of skin may not have applied to Dimetrodon, as its lineage is fairly distant. Dimetrodon also may have had large scutes on the underside of its tail and belly, as other synapsids had these. Evidence from the varanopid Ascendonanus suggests that some early synapsids may have had squamate-like scales. However, some recent studies have put varanopids as taxonomically closer to diapsid reptiles.

Earliest discoveries
The earliest discovery of Dimetrodon fossils were of a maxilla recovered in 1845 by a man named Donald McLeod, living in the British colony of Prince Edward Island. These fossils were purchased by John William Johnson, a Canadian geologist, and then described by Joseph Leidy in 1854 as the mandible of Bathygnathus borealis, a large carnivore related to Thecodontosaurus, although it was later reclassified as a species of Dimetrodon in 2015, as Dimetrodon borealis.

First descriptions by Cope
Fossils now attributed to Dimetrodon were first studied by American paleontologist Edward Drinker Cope in the 1870s. Cope had obtained the fossils along with those of many other Permian tetrapods from several collectors who had been exploring a group of rocks in Texas called the Red Beds. Among these collectors were Swiss naturalist Jacob Boll, Texas geologist W. F. Cummins, and amateur paleontologist Charles Hazelius Sternberg. Most of Cope's specimens went to the American Museum of Natural History or to the University of Chicago's Walker Museum (most of the Walker fossil collection is now housed in the Field Museum of Natural History).

Sternberg sent some of his own specimens to German paleontologist Ferdinand Broili at Munich University, although Broili was not as prolific as Cope in describing specimens. Cope's rival Othniel Charles Marsh also collected some bones of Dimetrodon, which he sent to the Walker Museum. The first use of the name Dimetrodon came in 1878 when Cope named the species Dimetrodon incisivus, Dimetrodon rectiformis, and Dimetrodon gigas in the scientific journal Proceedings of the American Philosophical Society.

The first description of a Dimetrodon fossil came a year earlier, though, when Cope named the species Clepsydrops limbatus from the Texas Red Beds. (The name Clepsydrops was first coined by Cope in 1875 for sphenacodontid remains from Vermilion County, Illinois, and was later employed for many sphenacontid specimens from Texas; many new species of sphenacodontids from Texas were assigned to either Clepsydrops or Dimetrodon in the late 19th and early 20th centuries.) C. limbatus was reclassified as a species of Dimetrodon in 1940, meaning that Cope's 1877 paper was the first record of Dimetrodon.

Cope was the first to describe a sail-backed synapsid with the naming of C. natalis in his 1878 paper, although he called the sail a fin and compared it to the crests of the modern basilisk lizard (Basilicus). Sails were not preserved in the specimens of D. incisivus and D. gigas that Cope described in his 1878 paper, but elongated spines were present in the D. rectiformis specimen he described. Cope commented on the purpose of the sail in 1886, writing, "The utility is difficult to imagine. Unless the animal had aquatic habits, and swam on its back, the crest or fin must have been in the way of active movements... The limbs are not long enough nor the claws acute enough to demonstrate arboreal habits, as in the existing genus Basilicus, where a similar crest exists."

Early 20th century descriptions
In the first few decades of the 20th century, American paleontologist E. C. Case authored many studies on Dimetrodon and described several new species. He received funding from the Carnegie Institution for his study of many Dimetrodon specimens in the collections of the American Museum of Natural History and several other museums. Many of these fossils had been collected by Cope but had not been thoroughly described, as Cope was known for erecting new species on the basis of only a few bone fragments.

Beginning in the late 1920s, paleontologist Alfred Romer restudied many Dimetrodon specimens and named several new species. In 1940, Romer coauthored a large study with Llewellyn Ivor Price called "Review of the Pelycosauria" in which the species of Dimetrodon named by Cope and Case were reassessed. Most of the species names considered valid by Romer and Price are still used today.

New specimens
In the decades following Romer and Price's monograph, many Dimetrodon specimens were described from localities outside Texas and Oklahoma. The first was described from the Four Corners region of Utah in 1966 and another was described from Arizona in 1969. In 1975, Olson reported Dimetrodon material from Ohio. A new species of Dimetrodon called D. occidentalis (meaning "western Dimetrodon") was named in 1977 from New Mexico. The specimens found in Utah and Arizona probably also belong to D. occidentalis.

Before these discoveries, a theory existed that a midcontinental seaway separated what is now Texas and Oklahoma from more western lands during the Early Permian, isolating Dimetrodon to a small region of North America, while a smaller sphenacodontid called Sphenacodon dominated the western area. While this seaway probably did exist, the discovery of fossils outside Texas and Oklahoma show that its extent was limited and that it was not an effective barrier to the distribution of Dimetrodon.

In 2001, a new species of Dimetrodon called D. teutonis was described from the Lower Permian Bromacker locality at the Thuringian Forest of Germany, extending the geographic range of Dimetrodon outside North America for the first time.

Species
Twenty species of Dimetrodon have been named since the genus was first described in 1878. Many have been synonymized with older named species, and some now belong to different genera.

Dimetrodon limbatus
Dimetrodon limbatus was first described by Edward Drinker Cope in 1877 as Clepsydrops limbatus. (The name Clepsydrops was first coined by Cope in 1875 for sphenacodontid remains from Vermilion County, Illinois, and was later employed for many sphenacontid specimens from Texas; many new species of sphenacodontids from Texas were assigned to either Clepsydrops or Dimetrodon in the late nineteenth and early twentieth centuries.) Based on a specimen from the Red Beds of Texas, it was the first known sail-backed synapsid. In 1940, paleontologists Alfred Romer and Llewellyn Ivor Price reassigned C. limbatus to the genus Dimetrodon, making D. limbatus the type species of Dimetrodon.

Dimetrodon incisivus
The first use of the name Dimetrodon came in 1878 when Cope named the species Dimetrodon incisivus along with Dimetrodon rectiformis and Dimetrodon gigas.

Dimetrodon rectiformis
Dimetrodon rectiformis was named alongside Dimetrodon incisivus in Cope's 1878 paper, and was the only one of the three named species to preserve elongated neural spines. In 1907, paleontologist E. C. Case moved D. rectiformis into the species D. incisivus. D. incisivus was later synonymous with the type species Dimetrodon limbatus, making D. rectiformis a synonym of D. limbatus.

Dimetrodon semiradicatus
Described in 1881 on the basis of upper jaw bones, Dimetrodon semiradicatus was the last species named by Cope. In 1907, E. C. Case synonymized D. semiradicatus with D. incisivus based on similarities in the shape of the teeth and skull bones. D. incisivus' and D. semiradicatus are now considered synonyms of D. limbatus.

Dimetrodon dollovianus
Dimetrodon dollovianus was first described by Edward Drinker Cope in 1888 as Embolophorus dollovianus. In 1903, E. C. Case published a lengthy description of E. dollovianus, which he later referred to Dimetrodon.

Dimetrodon grandis
Paleontologist E. C. Case named a new species of sail-backed synapsid, Theropleura grandis, in 1907. In 1940, Alfred Romer and Llewellyn Ivor Price reassigned Theropleura grandis to Dimetrodon, erecting the species D. grandis.

Dimetrodon gigas
In his 1878 paper on fossils from Texas, Cope named Clepsydrops gigas along with the first named species of Dimetrodon, D. limbatus, D. incisivus, and D. rectiformis. Case reclassified C. gigas as a new species of Dimetrodon in 1907. Case also described a very well preserved skull of Dimetrodon in 1904, attributing it to the species Dimetrodon gigas. In 1919, Charles W. Gilmore attributed a nearly complete specimen of Dimetrodon to D. gigas. Dimetrodon gigas is now recognized as a synonym of D. grandis.

Dimetrodon giganhomogenes
Dimetrodon giganhomogenes was named by E. C. Case in 1907 and is still considered a valid species of Dimetrodon.

Dimetrodon macrospondylus
Dimetrodon macrospondylus was first described by Cope in 1884 as Clepsydrops macrospondylus. In 1907, Case reclassified it as Dimetrodon macrospondylus.

Dimetrodon platycentrus
Dimetrodon platycentrus was first described by Case in his 1907 monograph. It is now considered a synonym of Dimetrodon macrospondylus.

Dimetrodon natalis
Paleontologist Alfred Romer erected the species Dimetrodon natalis in 1936, previously described as Clepsydrops natalis. D. natalis was the smallest known species of Dimetrodon at that time, and was found alongside remains of the larger-bodied D. limbatus.

Dimetrodon booneorum
Dimetrodon booneorum was first described by Alfred Romer in 1937 on the basis of remains from Texas.

"Dimetrodon" kempae
Dimetrodon kempae was named by Romer in 1937, in the same paper as D. booneorum, D. loomisi, and D. milleri. Dimetrodon kempae was named on the basis of a single humerus and a few vertebrae, and may therefore be a nomen dubium that cannot be distinguished as a unique species of Dimetrodon. In 1940, Romer and Price raised the possibility that D. kempae may not fall within the genus Dimetrodon, preferring to classify it as Sphenacodontidae incertae sedis.

Dimetrodon loomisi
Dimetrodon loomisi was first described by Alfred Romer in 1937 along with D. booneorum, D. kempae, and D. milleri. Remains have been found in Texas and Oklahoma.

Dimetrodon milleri
Dimetrodon milleri was described by Romer in 1937. It is one of the smallest species of Dimetrodon in North America and may be closely related to D. occidentalis, another small-bodied species. D. milleri is known from two skeletons, one nearly complete (MCZ 1365) and another less complete but larger (MCZ 1367). D. milleri is the oldest known species of Dimetrodon.

Besides its small size, D. milleri differs from other species of Dimetrodon in that its neural spines are circular rather than figure-eight shaped in cross-section. Its vertebrae are also shorter in height relative to the rest of the skeleton than those of other Dimetrodon species. The skull is tall and the snout is short relative to the temporal region. A short vertebrae and tall skull are also seen in the species D. booneorum, D. limbatus and D. grandis, suggesting that D. milleri may be the first of an evolutionary progression between these species.

Dimetrodon angelensis
Dimetrodon angelensis was named by paleontologist Everett C. Olson in 1962. Specimens of the species were reported from the San Angelo Formation of Texas. It is also the largest species of Dimetrodon.

Dimetrodon occidentalis
Dimetrodon occidentalis was named in 1977 from New Mexico. Its name means "western Dimetrodon" because it is the only North American species of Dimetrodon known west of Texas and Oklahoma. It was named on the basis of a single skeleton belonging to a relatively small individual. The small size of D. occidentalis is similar to that of D. milleri, suggesting a close relationship. Dimetrodon specimens found in Utah and Arizona probably also belong to D. occidentalis.

Dimetrodon teutonis
Dimetrodon teutonis was named in 2001 from the Thuringian Forest of Germany and was the first species of Dimetrodon to be described outside North America. It is also the smallest species of Dimetrodon.

Dimetrodon cruciger
In 1878, Cope published a paper called "The Theromorphous Reptilia" in which he described Dimetrodon cruciger. D. cruciger was distinguished by the small projections that extended from either side of each neural spine like the branches of a tree. In 1886, Cope moved D. cruciger to the genus Naosaurus because he considered its spines so different from those of other Dimetrodon species that the species deserved its own genus. Naosaurus would later be synonymized with Edaphosaurus, a genus which Cope named in 1882 on the basis of skulls that evidently belonged to herbivorous animals given their blunt crushing teeth.

Dimetrodon longiramus
E. C. Case named the species Dimetrodon longiramus in 1907 on the basis of a scapula and elongated mandible from the Belle Plains Formation of Texas. In 1940, Romer and Price recognized that the D. longiramus material belonged to the same taxon as another specimen described by paleontologist Samuel Wendell Williston in 1916, which included a similarly elongated mandible and a long maxilla. Williston did not consider his specimen to belong to Dimetrodon but instead classified it as an ophiacodontid. Romer and Price assigned Case and Williston's specimens to a newly erected genus and species, Secodontosaurus longiramus, that was closely related to Dimetrodon.

Phylogenetic classification
Dimetrodon is an early member of a group called synapsids, which include mammals and many of their extinct relatives, though it is not an ancestor of any mammal (which appeared millions of years later ). It is often mistaken for a dinosaur in popular culture, despite having become extinct some 40 million years (Ma) before the first appearance of dinosaurs in the Triassic period. As a synapsid, Dimetrodon is more closely related to mammals than to dinosaurs or any living reptile. By the early 1900s most paleontologists called Dimetrodon a reptile in accordance with Linnean taxonomy, which ranked Reptilia as a class and Dimetrodon as a genus within that class. Mammals were assigned to a separate class, and Dimetrodon was described as a "mammal-like reptile". Paleontologists theorized that mammals evolved from this group in (what they called) a reptile-to-mammal transition.

Phylogenetic taxonomy of Synapsida
Under phylogenetic systematics, the descendants of the last common ancestor of Dimetrodon and all living reptiles would include all mammals because Dimetrodon is more closely related to mammals than to any living reptile. Thus, if it is desired to avoid the clade that contains both mammals and the living reptiles, then Dimetrodon must not be included in that clade—nor any other "mammal-like reptile". Descendants of the last common ancestor of mammals and reptiles (which appeared around 310 Ma in the Late Carboniferous) are therefore split into two clades: Synapsida, which includes Dimetrodon and mammals, and Sauropsida, which includes living reptiles and all extinct reptiles more closely related to them than to mammals.

Within clade Synapsida, Dimetrodon is part of the clade Sphenacodontia, which was first proposed as an early synapsid group in 1940 by paleontologists Alfred Romer and Llewellyn Ivor Price, along with the groups Ophiacodontia and Edaphosauria. All three groups are known from the Late Carboniferous and Early Permian. Romer and Price distinguished them primarily by postcranial features such as the shapes of limbs and vertebrae. Ophiacodontia was considered the most primitive group because its members appeared the most reptilian, and Sphenacodontia was the most advanced because its members appeared the most like a group called Therapsida, which included the closest relatives to mammals. Romer and Price placed another group of early synapsids called varanopids within Sphenacodontia, considering them to be more primitive than other sphenacodonts like Dimetrodon. They thought varanopids and Dimetrodon-like sphenacodonts were closely related because both groups were carnivorous, although varanopids are much smaller and more lizard-like, lacking sails.

The modern view of synapsid relationships was proposed by paleontologist Robert R. Reisz in 1986, whose study included features mostly found in the skull rather than in the postcranial skeleton. Dimetrodon is still considered a sphenacodont under this phylogeny, but varanodontids are now considered more basal synapsids, falling outside clade Sphenacodontia. Within Sphenacodontia is the group Sphenacodontoidea, which in turn contains Sphenacodontidae and Therapsida. Sphenacodontidae is the group containing Dimetrodon and several other sail-backed synapsids like Sphenacodon and Secodontosaurus, while Therapsida includes mammals and their mostly Permian and Triassic relatives.

Below is the cladogram Clade Synapsida, which follows this phylogeny of Synapsida as modified from the analysis of Benson (2012).

The below cladogram shows the relationships of a few Dimetrodon species, from Brink et al., (2015).

Function of neural spines
Paleontologists have proposed many ways in which the sail could have functioned in life. Some of the first to think about its purpose suggested that the sail may have served as camouflage among reeds while Dimetrodon waited for prey, or as an actual boat-like sail to catch the wind while the animal was in the water. Another is that the long neural spines could have stabilized the trunk by restricting up-and-down movement, which would allow for a more efficient side-to-side movement while walking.

Thermoregulation
In 1940, Alfred Romer and Llewellyn Ivor Price proposed that the sail served a thermoregulatory function, allowing individuals to warm their bodies with the Sun. In the following years, many models were created to estimate the effectiveness of thermoregulation in Dimetrodon. For example, in a 1973 article in the journal Nature, paleontologists C. D. Bramwell and P. B. Fellgett estimated that it took a 200 kg individual about one and a half hours for its body temperature to rise from 26 to 32 °C. In 1986, Steven C. Haack concluded that the warming was slower than previously thought and that the process probably took four hours. Using a model based on a variety of environmental factors and hypothesized physiological aspects of Dimetrodon, Haack found that the sail allowed Dimetrodon to warm faster in the morning and reach a slightly higher body temperature during the day, but that it was ineffective in releasing excess heat and did not allow Dimetrodon to retain a higher body temperature at night. In 1999, a group of mechanical engineers created a computer model to analyze the ability of the sail to regulate body temperature during different seasons, and concluded that the sail was beneficial for capturing and releasing heat at all times in the year. Most of these studies give two thermoregulatory roles for the sail of Dimetrodon: one as a means of warming quickly in the morning, and another as a way to cool down when body temperature becomes high. Dimetrodon and all other Early Permian land vertebrates are assumed to have been cold-blooded or poikilothermic, relying on the sun to maintain a high body temperature. Because of its large size, Dimetrodon had high thermal inertia, meaning that changes in body temperature occurred more slowly in it than in smaller-bodied animals. As temperatures rose in the mornings, the small-bodied prey of Dimetrodon could warm their bodies much faster than could something the size of Dimetrodon. Many paleontologists including Haack have proposed that the sail of Dimetrodon may have allowed it to warm quickly in the morning in order to keep pace with its prey. The sail's large surface area also meant heat could dissipate quickly into the surroundings, useful if the animal needed to release excess heat produced by metabolism or absorbed from the sun. Dimetrodon may have angled its sail away from the sun to cool off or restricted blood flow to the sail to maintain heat at night.

In 1986, J. Scott Turner and C. Richard Tracy proposed that the evolution of a sail in Dimetrodon was related to the evolution of warm-bloodedness in mammal ancestors. They thought that the sail of Dimetrodon enabled it to be homeothermic, maintaining a constant, albeit low, body temperature. Mammals are also homeothermic, although they differ from Dimetrodon in being endothermic, controlling their body temperature internally through heightened metabolism. Turner and Tracy noted that early therapsids, a more advanced group of synapsids closely related to mammals, had long limbs which can release heat in a manner similar to that of the sail of Dimetrodon. The homeothermy that developed in animals like Dimetrodon may have carried over to therapsids through a modification of body shape, which would eventually develop into the warm-bloodedness of mammals. Recent studies on the sail of Dimetrodon and other sphenacodontids support Haack's 1986 contention that the sail was poorly adapted to releasing heat and maintaining a stable body temperature. The presence of sails in small-bodied species of Dimetrodon such as D. milleri and D. teutonis does not fit the idea that the sail's purpose was thermoregulation because smaller sails are less able to transfer heat and because small bodies can absorb and release heat easily on their own. Moreover, close relatives of Dimetrodon such as Sphenacodon have very low crests that would have been useless as thermoregulatory devices. The large sail of Dimetrodon is thought to have developed gradually from these smaller crests, meaning that over most of the sail's evolutionary history, thermoregulation could not have served an important function.

Although the function of its sail remains uncertain, Dimetrodon and other Sphenacodontids were likely to have been whole-body endotherms, characterised by a high energy metabolism (tachymetabolism) and probably a capacity for maintaining a high and stable body temperature. This conclusion was part of an amniote-wide study that found tachymetabolic endothermy to have been widespread throughout, and likely plesiomorphic to both synapsids and sauropsids. For Dimetrodon the evidence was the endothermy-indicative size of the foramina through which blood was delivered to their long bones and the high blood pressure that would have been necessary to provide blood to the tops of the well-vascularised spines supporting the sail.

Larger bodied specimens of Dimetrodon have larger sails relative to their size, an example of positive allometry. Positive allometry may benefit thermoregulation because it means that, as individuals get larger, surface area increases faster than mass. Larger-bodied animals generate a great deal of heat through metabolism, and the amount of heat that must be dissipated from the body surface is significantly greater than what must be dissipated by smaller-bodied animals. Effective heat dissipation can be predicted across many different animals with a single relationship between mass and surface area. However, a 2010 study of allometry in Dimetrodon found a different relationship between its sail and body mass: the actual scaling exponent of the sail was much larger than the exponent expected in an animal adapted to heat dissipation. The researchers concluded that the sail of Dimetrodon grew at a much faster rate than was necessary for thermoregulation, and suggested that sexual selection was the primary reason for its evolution.

Sexual selection
The allometric exponent for sail height is similar in magnitude to the scaling of interspecific antler length to shoulder height in cervids. Furthermore, as Bakker (1970) observed in the context of Dimetrodon, many lizard species raise a dorsal ridge of skin during threat and courtship displays, and positively allometric, sexually dimorphic frills and dewlaps are present in extant lizards (Echelle et al. 1978; Christian et al. 1995). There is also evidence of sexual dimorphism both in the robustness of the skeleton and in the relative height of the spines of D. limbatus (Romer and Price 1940).

Sexual dimorphism
Dimetrodon may have been sexually dimorphic, meaning that males and females had slightly different body sizes. Some specimens of Dimetrodon have been hypothesized as males because they have thicker bones, larger sails, longer skulls, and more pronounced maxillary "steps" than others. Based on these differences, the mounted skeletons in the American Museum of Natural History (AMNH 4636) and the Field Museum of Natural History may be males and the skeletons in the Denver Museum of Nature and Science (MCZ 1347) and the University of Michigan Museum of Natural History may be females.

Paleoecology
Fossils of Dimetrodon are known from the United States (Texas, Oklahoma, New Mexico, Arizona, Utah and Ohio) and Germany, areas that were part of the supercontinent Euramerica during the Early Permian. Within the United States, almost all material attributed to Dimetrodon has come from three geological groups in north-central Texas and south-central Oklahoma: the Clear Fork Group, the Wichita Group, and the Pease River Group. Most fossil finds are part of lowland ecosystems which, during the Permian, would have been vast wetlands. In particular, the Red Beds of Texas is an area of great diversity of fossil tetrapods, or four-limbed vertebrates. In addition to Dimetrodon, the most common tetrapods in the Red Beds and throughout Early Permian deposits in the southwestern United States, are the amphibians Archeria, Diplocaulus, Eryops, and Trimerorhachis, the reptiliomorph Seymouria, the reptile Captorhinus, and the synapsids Ophiacodon and Edaphosaurus. These tetrapods made up a group of animals that paleontologist Everett C. Olson called the "Permo-Carboniferous chronofauna", a fauna that dominated the continental Euramerican ecosystem for several million years. Based on the geology of deposits like the Red Beds, the fauna is thought to have inhabited a well-vegetated lowland deltaic ecosystem.

Food web
Olson made many inferences on the paleoecology of the Texas Red beds and the role of Dimetrodon within its ecosystem. He proposed several main types of ecosystems in which the earliest tetrapods lived. Dimetrodon belonged to the most primitive ecosystem, which developed from aquatic food webs. In it, aquatic plants were the primary producers and were largely fed upon by fish and aquatic invertebrates. Most land vertebrates fed on these aquatic primary consumers. Dimetrodon was probably the top predator of the Red Beds ecosystem, feeding on a variety of organisms such as the shark Xenacanthus, the aquatic amphibians Trimerorhachis and Diplocaulus, and the terrestrial tetrapods Seymouria and Trematops. Insects are known from the Early Permian Red Beds and were probably involved to some degree in the same food web as Dimetrodon, feeding small reptiles like Captorhinus. The Red Beds assemblage also included some of the first large land-living herbivores like Edaphosaurus and Diadectes. Feeding primarily on terrestrial plants, these herbivores did not derive their energy from aquatic food webs. According to Olson, the best modern analogue for the ecosystem Dimetrodon inhabited is the Everglades. The exact lifestyle of Dimetrodon (amphibious to terrestrial) has long been controversial, but bone microanatomy supports a terrestrial lifestyle, which implies that it would have fed mostly on land, on the banks, or in very shallow water. Evidence also exists for Dimetrodon preying on aestivating Diplocaulus during times of drought, with three partially eaten juvenile Diplocaulus in a burrow of eight bearing teeth marks from a Dimetrodon that unearthed and killed them.

The only species of Dimetrodon found outside the southwestern United States is D. teutonis from Germany. Its remains were found in the Tambach Formation in a fossil site called the Bromacker locality. The Bromacker's assemblage of Early Permian tetrapods is unusual in that there are few large-bodied synapsids serving the role of top predators. D. teutonis is estimated to have been only 1.7 m in length, too small to prey on the large diadectid herbivores that are abundant in the Bromacker assemblage. It more likely ate small vertebrates and insects. Only three fossils can be attributed to large predators, and they are thought to have been either large varanopids or small sphenacodonts, both of which could potentially prey on D. teutonis. In contrast to the lowland deltaic Red Beds of Texas, the Bromacker deposits are thought to have represented an upland environment with no aquatic species. It is possible that large-bodied carnivores were not part of the Bromacker assemblage because they were dependent on large aquatic amphibians for food.

title: Dimetrodon


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Tongue-in-cheek

Tongue-in-cheek is an idiom that describes a humorous or sarcastic statement expressed in a serious manner.

History
The phrase originally expressed contempt, but by 1842 had acquired its modern meaning. Early users of the phrase include Sir Walter Scott in his 1828 The Fair Maid of Perth.

The physical act of putting one's tongue into one's cheek once signified contempt. For example, in Tobias Smollett's The Adventures of Roderick Random, which was published in 1748, the eponymous hero takes a coach to Bath and on the way apprehends a highwayman. This provokes an altercation with a less brave passenger: "He looked back and pronounced with a faltering voice, 'O! 'tis very well—damn my blood! I shall find a time.' I signified my contempt of him by thrusting my tongue in my cheek, which humbled him so much, that he scarce swore another oath aloud during the whole journey."

The phrase appears in 1828 in The Fair Maid of Perth by Sir Walter Scott: "The fellow who gave this all-hail thrust his tongue in his cheek to some scapegraces like himself."

It is not clear how Scott intended readers to understand the phrase. The more modern ironic sense appeared in the 1842 poem "The Ingoldsby Legends" by the English clergyman Richard Barham, in which a Frenchman inspects a watch and cries: " 'Superbe! Magnifique!' / (with his tongue in his cheek)"

The ironic usage originates with the idea of suppressed mirth—biting one's tongue to prevent an outburst of laughter.

title: Tongue-in-cheek


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Pelycosaur

Pelycosaur is an older term for basal or primitive Late Paleozoic synapsids, excluding the therapsids and their descendants. Previously, the term mammal-like reptile had been used, and pelycosaur was considered an order, but this is now thought to be incorrect, and seen as outdated.

Because it excludes the advanced synapsid group Therapsida, the term is paraphyletic and contrary to modern formal naming practice. Thus the name pelycosaurs, similar to the term mammal-like reptiles, had fallen out of favor among scientists by the 21st century, and is only used informally, if at all, in the modern scientific literature. The terms stem mammals, protomammals, and basal or primitive synapsids are instead used where needed.

Etymology
The modern word was created from Greek pélyx meaning 'basin' and saûros meaning 'lizard'. The term pelycosaur has been fairly well abandoned by paleontologists because it no longer matches the features that distinguish a clade.

Pelycosauria is a paraphyletic taxon because it excludes the therapsids. For that reason, the term is sometimes avoided by proponents of a strict cladistic approach. Eupelycosauria is used to designate the clade that includes most pelycosaurs, along with the Therapsida and Mammalia. In contrast to "pelycosaurs", Eupelycosauria is a proper monophyletic group. Caseasauria is a pelycosaur side-branch, or clade, that did not leave any descendants.

Evolutionary history
The pelycosaurs appear to have been a group of synapsids that have direct ancestral links with the mammals, having differentiated teeth and a developing hard palate. The pelycosaurs appeared during the Late Carboniferous and reached their apex in the early part of the Permian, remaining the dominant land animals for some 40 million years. A few continued into the Capitanian, but they experienced a sharp decline in diversity in the late Kungurian. They were succeeded by the therapsids.

Description
Some species were quite large, growing to a length of 3 m or more, although most species were much smaller. Well-known pelycosaurs include the genera Dimetrodon, Sphenacodon, Edaphosaurus, and Ophiacodon.

Pelycosaur fossils have been found mainly in Europe and North America, although some small, late-surviving forms are known from Russia and South Africa.

Unlike lepidosaurian reptiles, pelycosaurs lacked reptilian epidermal scales. Fossil evidence from some varanopids shows that parts of the skin were covered in rows of osteoderms, presumably overlain by horny scutes. The belly was covered in rectangular scutes, looking like those present in crocodiles. Parts of the skin not covered in scutes might have had naked, glandular skin like that found in some mammals. Dermal scutes are also found in a diverse number of extant mammals with conservative body types, such as in the tails of some rodents, sengis, moonrats, the opossums and other marsupials, and as regular dermal armour with underlying bone in the armadillo.

At least two pelycosaur clades independently evolved a tall sail, consisting of elongated vertebral spines: the edaphosaurids and the sphenacodontids. In life, this would have been covered by skin, and likely functioned as a thermoregulatory device or as a mating display.

Taxonomy
In phylogenetic nomenclature, "Pelycosauria" is not used formally, since it does not constitute a group of all organisms descended from some common ancestor (a clade), because the group specifically excludes the therapsids which are descended from pelycosaurs. Instead, it represents a paraphyletic "grade" of basal synapsids leading up to the clade Therapsida.

In 1940, the group was reviewed in detail, and every species known at the time described, with many illustrated, in an important monograph by Alfred Sherwood Romer and Llewellyn Price.

In traditional classification, the order Pelycosauria is paraphyletic in that the therapsids (the "higher" synapsids) have emerged from them. That means Pelycosauria is a grouping of animals that does not contain all descendants of its common ancestor, as is often required by phylogenetic nomenclature. In evolutionary taxonomy, Therapsida is a separated order from Pelycosauria, and mammals (having evolved from therapsids) are separated from both as their own class. This use has not been recommended by a majority of systematists since the 1990s, but several paleontologists nevertheless continue using this word.

The following classification was presented by Benton in 2004.

 * Order Pelycosauria*
 * Suborder Caseasauria
 * Family Eothyrididae
 * Family Caseidae
 * Suborder Eupelycosauria
 * Family Varanopidae
 * Family Ophiacodontidae
 * Family Edaphosauridae
 * Infraorder Sphenacodontia
 * Family Sphenacodontidae
 * '''Order Therapsida

title: Pelycosaur


text: User talk:62.171.194.43

title: User talk:62.171.194.43


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User:Wilberth

Drie hoeraatjes voor de anarchistische encyclopedie --Dozo 14:46, 2004 Mar 9 (UTC)

title: User:Wilberth