{{Short description|Extinct genus of cartilaginous fishes}} {{Automatic taxobox | fossil_range = {{Fossil range|335|318}} <small>Middle [[Viséan]] - Late [[Serpukhovian]]</small> | image = Falcatus Vienna.jpg | image_caption = Specimen in Vienna | taxon = Falcatus | authority = Lund, 1985 | subdivision_ranks = [[Species]] | subdivision = *''Falcatus falcatus'' }}
'''''Falcatus''''' is an extinct genus of [[Falcatidae|falcatid]] [[chondrichthyan]] which lived during the early [[Carboniferous Period]] in [[Bear Gulch Limestone|Bear Gulch bay]] in what is now [[Montana]].
==Description== [[File:Falcatus.jpg|Life restoration of female (top) and male (bottom)|thumb|left|alt=Illustration - Falcatus falcatus]] [[Image:Falcatus falcatus 01.JPG|thumb|left|''Falcatus falcatus'' male. Lower Carboniferous, Montana, USA]] This fish was quite small, only getting to around 25–30 cm or 10-12 inches long. This is about as big as some of the smallest sharks around today, like the [[Pygmy lanternshark|pygmy lanternshark]].<ref>{{Cite web|title=A Golden Age of Sharks|url=http://www.elasmo-research.org/education/evolution/golden_age.htm|website=elasmo-research.org}}</ref> ''Falcatus'' was a chondrichthyan known as a "[[cladodont]]-toothed stethacanthid [[Holocephali|holocephalan]]".<ref>{{cite web |url=http://www.sju.edu/research/bear_gulch/pages_fish_species/Falcatus_falcatus.php |title=Bear Gulch - Falcatus falcatus |access-date=2008-09-04 |archive-url=https://web.archive.org/web/20080821203413/http://www.sju.edu/research/bear_gulch/pages_fish_species/Falcatus_falcatus.php |archive-date=2008-08-21 }} Fossil Fish of Bear Gulch 2005 by Richard Lund and Eileen Grogan Accessed 2009-01-14</ref> The first material known from the genus were the prominent fin spines that curve anteriorly over the head of the animal. When first described in 1883 from the [[St. Louis Limestone]], these remains were given the name ''Physonemus falcatus''. However, in 1985, fossils of a new type of chondrichthyan from [[Montana]] were described that displayed a high degree of [[sexual dimorphism]]. The same spines that were previously named ''P. falcatus'' were found on one of the morphs, identified as the male due to the presence of [[valva]]e.<ref name=":0">The morphology of ''Falcatus falcatus'' (St. John and Worthen), a Mississippian stethacanthid chondrichthyan from the Bear Gulch Limestone of Montana. ''Journal of Vertebrate Paleontology'' '''5'''(1):1-19.</ref>
==Classification== Despite often being called a shark, ''Falcatus'' and its relatives were part of the order [[Symmoriiformes]], which itself was part of the [[Subclass (biology)|subclass]] Holocephali.<ref name=":0" /> This means that this fish was more closely related to [[Chimaera|Chimaeras]] than to true sharks.<ref name=":1">Coates, M., Gess, R., Finarelli, J., Criswell, K., Tietjen, K. 2016. A symmoriiform chondrichthyan braincase and the origin of chimaeroid fishes. Nature. doi: 10.1038/nature20806</ref> Other members of its family include ''[[Ozarcus]]'' from the Carboniferous of [[Arkansas]],<ref name="ozarcus">{{cite journal|author1=Alan Pradel|author2=John G. Maisey|author3=Paul Tafforeau|author4=Royal H. Mapes|author5=Jon Mallatt|year=2014|title=A Palaeozoic shark with osteichthyan-like branchial arches|journal=Nature|volume=509|issue=7502|pages=608–611|doi=10.1038/nature13195|pmid=24739974|s2cid=3504437}}</ref> and potentially ''[[Cretacladoides]]'' from the [[Cretaceous]] of Austria.<ref>{{Cite journal|author1=Iris Feichtinger|author2=Andrea Engelbrecht|author3=Alexander Lukeneder|author4=Jürgen Kriwet|year=2018|title=New chondrichthyans characterised by cladodont-like tooth morphologies from the Early Cretaceous of Austria, with remarks on the microstructural diversity of enameloid|journal=Historical Biology: An International Journal of Paleobiology|volume=32|issue=6|pages=1–14|doi=10.1080/08912963.2018.1539971|s2cid=92392461}}</ref>
[[File:StethacanthusesDB_2.jpg|thumb|Two ''[[Stethacanthus]]'' species, ''S. altonensis'' and ''S. productus'', lived alongside ''Falcatus'']]
==Paleoecology== {{main|Bear Gulch Limestone}}
The bear gulch limestone is a fossil deposit from the [[Big Snowy Mountains]] of Montana. It is a smaller part of the larger St. louis limestone, which dates to the middle carboniferous. During the time, the area was a series of [[Mudflat|mudflats]] and [[Lagoon|lagoons]] with brackish and freshwater.<ref>{{Cite web|title=Bear Gulch Limestone Fossil Lagerstätte|url=http://www.fossilmuseum.net/Fossil_Sites/beargulch.htm|website=fossilmuseum.net}}</ref> Many theories have been put forth for the preservation. One is that the creatures sank to the bottom and died of [[Asphyxia|asphyxiation]] in the [[oxygen]] poor waters, being preserved without scavenging took place.<ref name=":9">{{Cite journal|last1=Grogan|first1=Eileen D.|last2=Lund|first2=Richard|date=1997|title=Soft tissue pigments of the Upper Mississippian chondrenchelyid, ''Harpagofututor volsellorhinus'' (Chondrichthyes, Holocephali) from the Bear Gulch Limestone, Montana, USA|url=https://www.cambridge.org/core/journals/journal-of-paleontology/article/abs/soft-tissue-pigments-of-the-upper-mississippian-chondrenchelyid-harpagofututor-volsellorhinus-chondrichthyes-holocephali-from-the-bear-gulch-limestone-montana-usa/E8F6AEF8F06E7F34DC79657BA4C0A311|journal=Journal of Paleontology|language=en|volume=71|issue=2|pages=337–342|doi=10.1017/S002233600003924X|issn=0022-3360|url-access=subscription}}</ref> Another theory is that the bottom of the bay created mudslides because of heavy rainfall, which rapidly buried the creatures.<ref name=":12">{{Cite journal|last1=Grogan|first1=Eileen D.|last2=Lund|first2=Richard|date=2002|title=The geological and biological environment of the Bear Gulch Limestone (Mississippian of Montana, USA) and a model for its deposition|url=https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/g2002n2a2.pdf|journal=Geodiversitas|volume=24|issue=2|pages=295–315}}</ref> However, because many of the fish fossils were found with distended gills, this would suggest death by asphyxiation.<ref name=":02">{{Cite book|last=Hagadorn|first=James W.|title=Exceptional fossil preservation; a unique view on the evolution of marine life|publisher=Columbia University Press|year=2002|editor1-last=Bottjer|editor1-first=D.J.|location=New York|pages=167–183|chapter=Bear Gulch: An Exceptional Upper Carboniferous Plattenkalk|editor2-last=Etter|editor2-first=W.|editor3-last=Hagadorn|editor3-first=J.W.|editor4-last=Tang|editor4-first=C.M.|chapter-url=https://www.researchgate.net/publication/242175100}}</ref> Falcatus lived alongside many strange creatures like the chondrichthyans ''[[Agassizodus]],'' ''[[Listracanthus]]<ref name=":23">{{Cite journal|last=Lund|first=Richard|date=1990-01-01|title=Chondrichthyan life history styles as revealed by the 320 million years old Mississippian of Montana|journal=Environmental Biology of Fishes|language=en|volume=27|issue=1|pages=1–19|doi=10.1007/BF00004900|issn=1573-5133|s2cid=13249799}}</ref>'' and ''[[Delphyodontos]].''<ref>{{Cite journal|last=Lund|first=Richard|date=1980-08-08|title=Viviparity and Intrauterine Feeding in a New Holocephalan Fish from the Lower Carboniferous of Montana|url=https://www.researchgate.net/publication/6019589|journal=Science|volume=209|issue=4457|pages=697–699|bibcode=1980Sci...209..697L|doi=10.1126/science.209.4457.697|pmid=17821193|s2cid=36858963}}</ref> It also lived alongside many [[Actinopterygii|ray-finned fish]] like ''[[Discoserra]]<ref name=":19">{{Cite journal|last=Lund|first=Richard|date=2000|title=The new Actinopterygian order Guildayichthyiformes from the Lower Carboniferous of Montana (USA)|url=https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/g2000n2a2.pdf|journal=Geodiversitas|volume=22|issue=2|pages=171–206}}</ref>'' and [[Tarrasiiformes|''Paratarrasius'']].''<ref>{{Cite journal|last1=Lund|first1=Richard|last2=Melton|first2=William G. Jr.|date=1982|title=A new actinopterygian fish from the Mississippian Bear Gulch Limestone of Montana|url=https://www.palass.org/publications/palaeontology-journal/archive/25/3/article_pp485-498|journal=Palaeontology|volume=25|issue=3|pages=485–498}}</ref>'' Other fish included the [[Rhabdodermatidae|rhabdodermatid]] [[Caridosuctor|''Cardiosuctor'']],''<ref name=":14">{{Cite journal|last1=Lund|first1=Richard|last2=Lund|first2=Wendy|date=1984|title=New genera and species of coelacanths from the Bear Gulch Limestone (Lower Carboniferous) of Montana (U.S.A.)|journal=Geobios|volume=17|issue=2|pages=237–244|doi=10.1016/s0016-6995(84)80145-x|issn=0016-6995}}</ref>'' the [[Rhizodontida|rhizodont]] ''[[Strepsodus]],<ref name=":6">{{Cite journal|last1=Lund|first1=Richard|last2=Greenfest-Allen|first2=Emily|last3=Grogan|first3=Eileen D.|date=2015-02-01|title=Ecomorphology of the Mississippian fishes of the Bear Gulch Limestone (Heath formation, Montana, USA)|journal=Environmental Biology of Fishes|language=en|volume=98|issue=2|pages=739–754|doi=10.1007/s10641-014-0308-x|issn=1573-5133|s2cid=14850973}}</ref>'' and ''[[Hardistiella]]'', one of the oldest known [[lamprey]].<ref name=":34">{{Cite journal|last1=Janvier|first1=Philippe|last2=Lund|first2=Richard|date=1983|title=''Hardistiella montanensis'' n. gen. et sp. (Petromyzontida) from the Lower Carboniferous of Montana, with remarks on the affinities of the lampreys|journal=Journal of Vertebrate Paleontology|volume=2|issue=4|pages=407–413|doi=10.1080/02724634.1983.10011943|issn=0272-4634}}</ref> The [[Invertebrate|invertebrates]] of bear gulch were very diverse creatures, like the [[Hoplocarida|hoplocarids]] (relatives of the [[mantis shrimp]]),<ref name="FF85">{{Cite journal|last1=Factor|first1=David F.|last2=Feldmann|first2=Rodney M.|date=11 October 1985|title=Systematics and paleoecology of malacostracan arthropods in the Bear Gulch Limestone (Namurian) of Central Montana|url=https://www.biodiversitylibrary.org/page/52403449#page/343/mode/1up|journal=Annals of Carnegie Museum|volume=54|issue=10|pages=319–356}}</ref> ''[[Anderella]]'', which is the youngest known [[Synziphosurina|synziphosurine]]''<ref name=":33">{{Cite journal|last1=Moore|first1=Rachel A.|last2=McKenzie|first2=Scott C.|last3=Lieberman|first3=Bruce S.|date=2007|title=A Carboniferous synziphosurine (Xiphosura) from the Bear Gulch Limestone, Montana, USA|url=https://mndi.museunacional.ufrj.br/aracnologia/Xiphosura/Moore%20et%20al%202007.pdf|journal=Palaeontology|language=en|volume=50|issue=4|pages=1013–1019|doi=10.1111/j.1475-4983.2007.00685.x|issn=1475-4983}}</ref>'' and more enigmatic creatures like the potential gastropod relative ''[[Typhloesus]],<ref name=":13">{{Cite journal|last=Conway Morris|first=Simon|date=1990-04-12|title=''Typhloesus wellsi'' (Melton and Scott, 1973), a bizarre metazoan from the Carboniferous of Montana, U. S. A|url=https://royalsocietypublishing.org/doi/abs/10.1098/rstb.1990.0102|journal=Philosophical Transactions of the Royal Society of London. B, Biological Sciences|volume=327|issue=1242|pages=595–624|bibcode=1990RSPTB.327..595M|doi=10.1098/rstb.1990.0102|url-access=subscription}}</ref>'' and the "Square objects" which might be [[Salp|sea salps]] or [[Cnidaria|cnidarians]].<ref>{{Cite web|title=Description of the 'square objects' of the Bear Gulch Limestone, Montana, USA|url=https://www.newhaven.edu/_resources/documents/academics/surf/past-projects/2015/stephanie-rosbach-paper.pdf|website=newhaven.edu}}</ref> Other inverts include, mollusks like the [[nautiloid]] ''[[Tylonautilus]],<ref name=":7">{{Cite journal|last=Cox|first=Robt S.|date=1986|title=Preliminary report on the age and palynology of the Bear Gulch Limestone (Mississippian, Montana)|url=https://www.cambridge.org/core/journals/journal-of-paleontology/article/abs/preliminary-report-on-the-age-and-palynology-of-the-bear-gulch-limestone-mississippian-montana/555EDC346DDB615D3CA2741592F93383|journal=Journal of Paleontology|language=en|volume=60|issue=4|pages=952–956|doi=10.1017/S0022336000043092|issn=0022-3360|url-access=subscription}}</ref>'' [[Pteriida|pterioid]] [[Bivalvia|bivalves]] which have been found encrusting ''[[sargassum]]'' like brown algae''<ref name=":31">{{Cite journal|last1=McRoberts|first1=Christopher A.|last2=Stanley|first2=George D.|date=1989|title=A unique bivalve–algae life assemblage from the Bear Gulch Limestone (Upper Mississippian) of central Montana|url=https://www.cambridge.org/core/journals/journal-of-paleontology/article/abs/unique-bivalvealgae-life-assemblage-from-the-bear-gulch-limestone-upper-mississippian-of-central-montana/A3CCEA3C99F10D7E5954426E3332074C|journal=Journal of Paleontology|language=en|volume=63|issue=5|pages=578–581|doi=10.1017/S0022336000041214|issn=0022-3360|url-access=subscription}}</ref>'' as well as [[Productida|productid]] [[Brachiopod|brachiopods]],<ref name="SH785">{{Cite journal|last1=Schram|first1=Frederick R.|last2=Horner|first2=John|date=1978|title=Crustacea of the Mississippian Bear Gulch Limestone of Central Montana|journal=Journal of Paleontology|volume=52|issue=2|pages=394–406|issn=0022-3360|jstor=1303712}}</ref> [[List of xiphosuran genera|''Paleolimulus'']],''<ref name="S79Limulines">{{Cite journal|last=Schrams|first=Frederick R.|date=1979|title=Limulines of the Mississippian Bear Gulch Limestone of Central Montana, USA|url=https://www.biodiversitylibrary.org/page/5784863#page/81/mode/1up|journal=Transactions of the San Diego Society of Natural History|volume=19|issue=6|pages=67–74}}</ref>'' [[Phyllocarida|phyllocarids]]<ref name="SH78">{{Cite journal|last1=Schram|first1=Frederick R.|last2=Horner|first2=John|date=1978|title=Crustacea of the Mississippian Bear Gulch Limestone of Central Montana|journal=Journal of Paleontology|volume=52|issue=2|pages=394–406|issn=0022-3360|jstor=1303712}}</ref> and [[Echinoderm|echinoderms]] like [[Crinoid|Crinoids]], [[Sea urchin|echinoids]], [[Starfish|sea stars]], [[Brittle star|brittle stars]] and a many armed starfish called ''Lepidasterella montanensis.<ref>{{Cite journal|last=Welch|first=James R.|date=1984|title=The Asteroid, ''Lepidasterella montanensis'' n. sp., from the Upper Mississippian Bear Gulch Limestone of Montana|journal=Journal of Paleontology|volume=58|issue=3|pages=843–851|issn=0022-3360|jstor=1304921}}</ref>''
==References== * David Norman. (2001): The Big Book Of Dinosaurs. Pg.84 and Pg.286, Walcome books. <references/>
==External links== * http://www.elasmo-research.org/education/evolution/golden_age.htm * https://web.archive.org/web/20070927011823/http://comenius.susqu.edu/biol/202/Animals/DEUTEROSTOMES/CRANIATA/CHONDRICHTHYES.htm
{{Portal|Paleontology}} {{Chondrichthyan genera|C.}} {{Taxonbar|from=Q144625}}
[[Category:Symmoriiformes]] [[Category:Carboniferous fish of North America]] [[Category:Fossil taxa described in 1985]]