{{Short description|Extinct genus of temnospondyls}} {{Automatic taxobox | fossil_range = [[Late Triassic]], {{Fossil range|Carnian|Norian}} | image = Buettneria.jpg | image_caption = Skeleton of ''Anaschisma'' at the [[AMNH]] | taxon = Anaschisma | authority = [[Edward Branson|Branson]], 1905 | type_species = {{extinct}}'''''Anaschisma browni''''' | subdivision = | type_species_authority = Branson, 1905 | synonyms = {{collapsible list|bullets = true |title=<small>Genus synonymy</small> |''Borborophagus'' Branson & Mehl, 1929 |''Buettneria'' Case 1922 ([[Buettneria (insect)|preoccupied]]) |''Koskinonodon'' Branson & Mehl, 1929 }} {{collapsible list|bullets = false |title=<small>Species synonymy</small> |''Anaschisma brachygnatha'' Branson, 1905 |''Borborophagus wyomingensis'' Branson & Mehl, 1929 |''Buettneria perfecta'' Case, 1922 |''Koskinonodon perfectus'' (Case, 1922) }} }}
'''''Anaschisma''''' ("ripped up") is an extinct genus of large [[temnospondyl]]s. These animals were part of the family called [[Metoposauridae]], which filled the crocodile-like predatory [[Ecological niche|niche]]s in the late Triassic.<ref name=r8>{{cite journal|last1=Brusatte|first1=Stephen L|title=A new species of ''Metoposaurus'' from the Late Triassic of Portugal and comments on the systematics and biogeography of metoposaurid temnospondyls |journal=Journal of Vertebrate Paleontology |date=2015 |volume=35 |issue=3 |article-number=e912988 |doi=10.1080/02724634.2014.912988 |s2cid=84007744}}</ref> It had a large skull about {{convert|62|cm}} long,<ref>{{Cite journal|last1=Hunt|first1=Adrian P.|last2=Lucas|first2=Spencer G.|date=1993|title=Taxonomy and stratigraphic distribution of Late Triassic metoposaurid amphibians from Petrified Forest National Park, Arizona |journal=Journal of the Arizona-Nevada Academy of Science|volume=27|issue=1|pages=89–96|jstor=40023709 }}</ref> and possibly reached {{convert|3|m}} long.<ref name=r2>{{Cite web|url=http://palaeos.com/vertebrates/temnospondyli/metoposauroidea.html|title=Palaeos Vertebrates Temnospondyli: Trematosauria: Metaposaurs|website=palaeos.com}}</ref> It was an ambush hunter, snapping up anything small enough to fit in its huge jaws.<ref name=r2 /> It was very common during the Late [[Triassic]] ([[Carnian]]-[[Norian]] age) in what is now the American Southwest.<ref>{{Cite journal|last1=Gee |first1=B. M. |last2=Jasinski |first2=S. E. |year=2021 |title=Description of the metoposaurid ''Anaschisma browni'' from the New Oxford Formation of Pennsylvania |journal=Journal of Paleontology |volume=95 |issue=5 |pages=1061–1078 |doi=10.1017/jpa.2021.30 |bibcode=2021JPal...95.1061G |s2cid=235546289 }}</ref>
==History of discovery== ''Anaschisma'' was erected by Branson (1905) from two metoposaurid skulls from the [[Popo Agie Formation]] ([[Carnian]]) of Wyoming. The generic name ''Anaschisma'' ("ripped up") was not explained but would derive from [[Ancient Greek]] ἀνασχίζω [anaskhizo] "rip up, rend", likely alluding to the fragmented state of the original fossils noted by Branson: "The skulls were {{as written|incased}} in a hard matrix of arenaceous shale, and had been broken in many pieces." The type species, ''A. browni'', was coined for the skull UC 447, while a second nominal species, ''A. brachygnatha'', was erected for the skull UC 448.<ref name="Branson 1905">{{cite journal |last1=Branson |first1=E. B. |title=Structure and Relationships of American Labyrinthodontidæ |journal=The Journal of Geology |date=1905 |volume=13 |issue=7 |pages=568–610 |doi=10.1086/621258|bibcode=1905JG.....13..568B |doi-access=free |hdl=2027/njp.32101055916710 |hdl-access=free }}</ref> Moodie (1908) considered ''A. brachygnatha'' a junior synonym of ''A. browni'', although Branson and Mehl (1929) retained the two species as distinct.<ref name="Moodie, R. L 1908">{{cite journal |last1=Moodie |first1=Roy L. |title=The lateral line system in extinct amphibia |journal=Journal of Morphology |date=1908 |volume=19 |issue=2 |pages=511–540 |doi=10.1002/jmor.1050190206|s2cid=83822416 |url=https://zenodo.org/record/2174606 }}</ref><ref name="Branson, E. B. 1929">Branson, E. B. & Mehl, M. G. 1929. Triassic amphibians from the Rocky Mountain region. The University of Missouri Studies, 4, 154–253.</ref> Colbert and Imbrie (1956) synonymized ''Anaschisma'' with the Newark Supergroup genus ''[[Eupelor]]'' but retained it as a valid ''Eupelor'' species endemic to the Popo Aggie Formation.<ref>{{Cite journal |last1=Colbert |first1=Edwin |last2=Imbrie |first2=John |date=1956 |title=Triassic metoposaurid amphibians |url=http://digitallibrary.amnh.org/handle/2246/431 |journal=Bulletin of the American Museum of Natural History |volume=110 |pages=399–452|hdl=2246/431 }}</ref> Chowdhury (1965) synonymized ''Anaschisma'' with ''Metoposaurus'' and sunk all North American metoposaurids from the Chinle and Dockum into ''browni''.<ref>{{cite journal |last1=Chowdhury |first1=T. Roy |title=A new metoposaurid amphibian from the upper Triassic Maleri formation of Central India |journal=Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences |date=1965 |volume=250 |issue=761 |pages=1–52 |doi=10.1098/rstb.1965.0019|bibcode=1965RSPTB.250....1C |s2cid=86592771 }}</ref>
Hunt (1989) recovered ''Anaschisma'' as an advanced or highly derived form.<ref name="Hunt 1989">{{cite book |author=Hunt, A.P. |year=1989 |chapter=Comments on the taxonomy of North American metoposaurids and a preliminary phylogenetic analysis of the family Metoposauridae |editor1=Lucas, SG |editor2=Hunt, AP |title=Dawn of the age of dinosaurs in the American Southwest |pages=292–300 |location=Albuquerque |publisher=New Mexico Museum of Natural History |chapter-url=http://www.nmnaturalhistory.org/publications/assets/files/Bulletins/DawnAgeDinos/dawn_16_hunt.pdf}}</ref> Some specimens attributed to ''Anaschisma'' from the Redonda Formation were renamed ''[[Apachesaurus]]'' by Hunt (1993).<ref>{{Cite journal |last=Sulej |first=T. |year=2002 |url=https://www.app.pan.pl/archive/published/app47/app47-535.pdf |title=Species discrimination of the Late Triassic temnospondyl amphibian ''Metoposaurus diagnosticus''|journal=Acta Palaeontologica Polonica |volume=47 |issue=3 |pages=535–546 }}</ref><ref>Hunt, A.P. 1993. Revision of the Metoposauridae (Amphibia: Temnospondyli) and description of a new genus from Western North America. In: M. Morales (eds.), Aspects of Mesozoic Geology and Paleontology of the Colorado Plateau. Museum of Northern Arizona Bulletin 59: 67–97.</ref>
===''Koskinonodon''=== [[File:Buettneria perfecta.JPG|thumb|''Koskinonodon perfectus'' skull, now thought to belong to ''Anaschisma'']] The genus ''Koskinonodon'' was formerly named ''Buettneria'' by Case in 1922, but in 2007, B.D. Mueller realized that the name ''[[Buettneria (insect)|Buettneria]]'' had already been given to a bush cricket from the Republic of Congo by Karsch (1889), so he made the genus ''Koskinonodon'' the earliest available unpreoccupied name for the temnospondyl.<ref name=first>{{cite journal |author=Mueller, B.D. |year=2007 |title=''Koskinonodon'' Branson and Mehl, 1929, a replacement name for the preoccupied temnospondyl ''Buettneria'' Case, 1922 |journal=Journal of Vertebrate Paleontology |volume=27 |issue=1 |page=225 |pmid= |doi=10.1671/0272-4634(2007)27[225:KBAMAR]2.0.CO;2|s2cid=85763026 }}</ref> Lucas ''et al.'' (2007), however, petitioned the ICZN to suppress Karsch's name in favor of Case's name, citing evidence that the amphibian name is much more well known and widely used (the authors cited 75 uses of the name in scientific literature and books over the last 85 years), and that the bush cricket name had been seldom used in technical literature.<ref name=last>{{cite journal |last1=Lucas |first1=SG |last2=Rinehart |first2=LF |last3=Spielmann |first3=JA |title=Comments on the proposed conservation of ''Buettneria'' Case, 1922 (Amphibia) 2 (Case 3420) |journal=Bulletin of Zoological Nomenclature |date=2008 |volume=65 |issue=3 |pages=218–219 |url=http://iczn.org/content/comments-proposed-conservation-buettneria-case-1922-amphibia-2-case-3420-0}}</ref> However, ICZN Opinion 2255 issued in 2010 rejected the petition.<ref>{{Cite web |url=http://iczn.org/content/opinion-2255-case-3420-buettneria-case-1922-amphibia-generic-name-not-conserved |title=OPINION 2255 (Case 3420) Buettneria Case, 1922 (Amphibia): Generic name not conserved | International Commission on Zoological Nomenclature |access-date=2019-06-09 |archive-date=2018-10-04 |archive-url=https://web.archive.org/web/20181004112343/http://iczn.org/content/opinion-2255-case-3420-buettneria-case-1922-amphibia-generic-name-not-conserved }}</ref>
Known ''Koskinonodon'' fossils have been found in the [[United States]], especially the [[Chinle Formation]] of Petrified Forest National Park and the ''Placerias'' Quarry in Arizona, the [[Garita Creek Formation]] of central New Mexico (the quarry at Lamy), the [[Petrified Forest Member]] of northern New Mexico, the [[Bluewater Creek Formation]] of western New Mexico, the [[New Oxford Formation]] of Pennsylvania, the [[Tecovas Formation]] of western Texas, and the [[Popo Agie Formation]] of the Chugwater Group of Wyoming.<ref name="Romer, A. S 1947">{{cite journal |last=Romer |first=A.S. |year=1947 |title=Review of the Labyrinthodontia |journal=Bulletin of the Museum of Comparative Zoology |volume=99 |issue=1 |pages=1–368 |url=https://archive.org/stream/cbarchive_48224_1947reviewofthelabyrinthodonti1863/1947reviewofthelabyrinthodonti1863#page/n1/mode/2up}}</ref><ref name="Branson, E. B. 1929"/>
Synonymy of ''Koskinonodon'' with ''Anaschisma'' started when Romer (1947) proposed that ''Anaschisma'' was a senior synonym of ''Buettneria'', ''Koskinonodon'', and ''Borborophagus''.<ref name="Romer, A. S 1947"/> This was followed by Gee ''et al.'' (2019), where they redescribed the holotypes of the two nominal ''Anaschisma'' species, and then synonymized ''Koskinonodon'', ''Buettneria'' and ''Borborophagus'' with ''Anaschisma''.<ref>{{cite journal |last1=Gee |first1=Bryan M. |last2=Parker |first2=William G. |last3=Marsh |first3=Adam D. |title=Redescription of ''Anaschisma'' (Temnospondyli: Metoposauridae) from the Late Triassic of Wyoming and the phylogeny of the Metoposauridae |journal=Journal of Systematic Palaeontology |date=2020 |volume=18 |issue=3 |pages=233–258 |doi=10.1080/14772019.2019.1602855|s2cid=190896742 |url=https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1200&context=natlpark |url-access=subscription }}</ref> The species ''B. bakeri'' which has long been assigned to the various synonyms of ''Anaschisma'', was moved to its own genus, ''[[Buettnererpeton]]'', in 2022.<ref name="Buettnererpeton">{{cite journal |last1=Gee |first1=Bryan M. |last2=Kufner |first2=Aaron M. |title=Revision of the Late Triassic metoposaurid ''"Metoposaurus" bakeri'' (Amphibia: Temnospondyli) from Texas, USA and a phylogenetic analysis of the Metoposauridae |journal=PeerJ |date=2022 |volume=10 |article-number=e14065 |doi=10.7717/peerj.14065|doi-access=free }}</ref>
==Description==
[[File:Apachesaurus.jpg|thumb|Size of ''Anaschisma'' (large) and ''[[Apachesaurus]]'' (small) compared to a human]] The skull of ''Anaschisma'' differs from the skulls of other closely related organisms in a few key ways. It is wider overall and features eye sockets that are very [[anterior]] and forward oriented, more so than its contemporaries.<ref name="Moodie, R. L 1908"/> Also, the skull has prominent slime canals, which are used for transporting mucus, as well as large external nares.<ref name=r4 /> In addition, the upper jaw is relatively weak and thin, used only for holding teeth.<ref name=r4 /> Their large jaws could have held many teeth at once, maybe even over 100 on each side of the upper and lower jaws, but the actual number varies constantly over the animal's lifetime due to natural causes such as fighting, eating, disease, etc.<ref name=r4 /> The sheer size of the skull is one of the most defining traits for the genus ''Anaschisma''.<ref name=r4 />
Other more minor skull traits characterize ''Anaschisma'' as well: elongation of the [[Lacrimal bone|lacrimal]], shortening of the [[prefrontal bone|prefrontal]], reduction of the [[interclavicle]], and the most characteristic is the center lachrymal entering margin of the [[orbit]].<ref name=r2 /> While the shortened prefrontal is a characteristic of the family Metoposauridae, it is shorted even more in ''Anaschisma''.<ref name=r8 /> The interclavicle is reduced in the way that it has many hexagonal pits as well as grooves and ridges.<ref name=r8 /> The skull of ''Anaschisma'' is also covered in this reticulate ornamentation.<ref name=r11 /> Some researchers believe that ''Anaschisma'' has a shorter posterior process of the interclavicle, which may discriminate it from other closely related species, while others believe that there is not enough information to make that distinction.<ref name=r8 /> ''Anaschisma'' also has ossified opisthotics, the more posterior of the bones surrounding the inner ear.<ref name=r11>{{cite book |last1=Rinehart|first1=Larry F|last2=Lucas|first2=Spencer G |chapter=The functional morphology of dermal bone ornamentation in temnospondyl amphibians |pages=524–532 |editor-last1=Tanner |editor-first1=Lawrence H. |editor2=Justin A. Spielmann |editor3=Spencer G. Lucas|title=The Triassic System: New Developments in Stratigraphy and Paleontology |series=Bulletin of the New Mexico Museum of Natural History and Science |volume=61 |url=https://books.google.com/books?id=BqF-oAEACAAJ |year=2013 }}</ref>
''Anaschisma'' had sharp, pointy teeth for catching and killing prey. They had marginal teeth as well as larger teeth on the palate, specifically [[palatine]] and ectopterygoid teeth.<ref name=r8 /> They had two basic types: large with shallow grooves and small with deeper grooves. These grooves run lengthwise down the teeth and aided the animals in catching prey.<ref name=r5>{{cite book |editor-last1=Tanner |editor-first1=Lawrence H. |editor2=Justin A. Spielmann |editor3=Spencer G. Lucas|title=The Triassic System: New Developments in Stratigraphy and Paleontology |series=Bulletin of the New Mexico Museum of Natural History and Science |volume=61 |url=https://books.google.com/books?id=BqF-oAEACAAJ |year=2013 }}</ref> The teeth are elongated labio-lingually at their base and opposite, mesiodistally, at their tip. In the middle, they are not elongated either way but instead circular.<ref name=r5 /> These dental adaptations enhanced the ability of ''Anaschisma'' to capture prey; the teeth are optimized for piercing prey and not allowing it to escape, resisting the bending force applied by the struggling organism, and propagating cracks in the hard parts of the object, such as bone, allowing for easier eating and digestion.<ref name=r5 />
''Anaschisma'' had a wide, wedge-shaped, powerful tail to assist it with swimming, hunting and likely defense.<ref name=r2/> It was not long like the crocodiles of today, but more likely short and strong to enable it to quickly spring up from hiding and capture prey before it escapes.<ref name=r2/> The legs of ''Anaschisma'' display a sprawling stance and short legs with 4-digits on the front and 5 on the back limbs.<ref name=r2/> ''Anaschisma'' likely spent a lot of time motionless, waiting for prey, which these short legs were likely an adaptation to.<ref name="Branson 1905"/>
==Paleobiology== [[File:Koskinonodon perfectus.jpg|thumb|Life restoration of ''Anaschisma'' chasing a fish]] The hunting style of ''Anaschisma'' involved lying at the bottom of a shallow swamp, waiting for a fish, [[crustacean]], smaller amphibian, or even a young phytosaur to wander by.<ref name=r2 /> When it spotted prey, it used its huge jaws to engulf and consume them.<ref name=r2 /> A few particular adaptations suggest ''Koskinonodon'' had this aquatic lifestyle. First, they had [[lateral line]]s formed by the sensory sulci. These are useful for detecting changes in water pressure made by the swimming motions of nearby organisms. Their sprawling limbs were also adapted for water. They would not move quickly or efficiently on land, although they may have done it to find another water pool with more food or other resource. Mass graves have been found, thought to be a result of a group of these animals gathering together in a withering water pool during a drought and all perishing because the water was never replenished.<ref name=r4 />
==Paleoecology==
[[File:Fossils of Buettneria perfecta.jpg|thumb|left|Multiple fossils, [[National Museum of Natural History]]]] They lived mostly in the late Triassic; by the time the [[Jurassic]] began, most temnospondyls, ''Anaschisma'' included, were gone.<ref>{{cite thesis |last1=McHugh|first1=Julia Beth|title=Temnospondyl ontogeny and phylogeny, a window into terrestrial ecosystems during the Permian-Triassic mass extinction |type=PhD thesis |publisher=Graduate College of the University of Iowa |date=2012}}</ref> It is likely that they went extinct during the [[Triassic-Jurassic extinction event]], along with the majority of other large amphibians, the class of [[Conodonts]] and 34% of all marine genera. It is unknown what caused this [[mass extinction]]; hypotheses include huge volcanic eruptions (the [[Central Atlantic magmatic province]] is a prime example), climate change, [[oceanic acidification]], or an asteroid impact. It is known, however, that over half of the species living on Earth at that time went extinct from this event.<ref>{{cite web|title=End-Triassic extinction|url=https://www.britannica.com/science/end-Triassic-extinction|website=Encyclopedia Britannica}}</ref> It lived alongside many other smaller amphibians, and its fossils are also commonly found with [[phytosaur]] fossils.<ref name=r4>{{cite web |last1=Peredo |first1=Carlos |title=''Koskinonodon perfectus'' |website=Encyclopedia of Life |url=https://eol.org/pages/47451546/articles }}</ref><ref>{{cite journal|last1=Parker|first1=W.G.|last2=Martz|first2=J.W.|title=The Late Triassic (Norian) Adamanian–Revueltian tetrapod faunal transition in the Chinle Formation of Petrified Forest National Park, Arizona|journal=Earth and Environmental Science Transactions of the Royal Society of Edinburgh|date=2010|volume=101|issue=3–4|pages=231–260|doi=10.1017/S1755691011020020|s2cid=140536630}}</ref> It was named in 1931 by Case. The best conditions for [[fossil]]ization occur in river valleys or floodplains where deposition is occurring, and this animal likely lived in similar shallow, swampy habitats. As it follows, ''Anaschisma'' is famous for having extremely well preserved fossils, and they are often found in groups.<ref name=r4 />
==See also== * [[Prehistoric amphibian]] * [[List of prehistoric amphibians]]
==References== {{Reflist}}
{{Trematosauria|M.}} {{Taxonbar|from=Q4751797}}
[[Category:Metoposauridae]] [[Category:Norian genera]] [[Category:Triassic temnospondyls of North America]] [[Category:Fossil taxa described in 1905]] [[Category:Taxa named by Edwin Branson]]