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{{Short description|Extinct genus of fishes}}
{{Merge from|Birgeriidae|date=February 2020}}
{{Automatic taxobox
{{Italic title}}
| fossil_range = Early–Late [[Triassic]] ([[Induan|Griesbachian]]–[[Rhaetian]]) {{Fossilrange|251.9|201.6}}
{{Taxobox
| fossil_range= <small>[[Triassic]] ([[Induan|Griesbachian]] - [[Rhaetian]])</small> {{Fossilrange|251.902|201.6}}
| image = Birgeria.JPG
| image = Birgeria.JPG
| image_caption = Fossil of ''Birgeria acuminata'', [[Museo Civico Scienze Naturali Enrico Caffi|Civic Museum of Natural Science]], Bergamo, Italy.<ref>{{cite journal |last1=Stefani |first1=Marco |last2=Arduini |first2=Paolo |last3=Garassino |first3=Alessandro |last4=Pinna |first4=Giovanni |last5=Teruzzi |first5=Giorgio |last6=Trombetta |first6=Gian Luigi |year=1992 |title=Palaeoenvironment of extraordinary fossil biotas from the Upper Triassic of Italy |journal=Atti della Società Italiana di Scienze Naturali e del Museo Civico di Storia Naturale di Milano |volume=132 |issue=24 |pages=309–335 |url=https://www.researchgate.net/publication/289957463}}</ref>
| image_width = 240px
| taxon = Birgeria
| image_caption = Fossil of ''Birgeria acuminata'', [[Museo Civico Scienze Naturali Enrico Caffi|Civic Museum of Natural Science]], Bergamo, Italy.<ref>Stefani et al. (1992): Palaeoenvironment of extraordinary fossil biotas from the Upper Triassic of Italy. Atti della Società Italiana di Scienze Naturali e del Museo Civico di Storia Naturale di Milano 132:309-335. https://www.researchgate.net/publication/289957463_Palaeoenvironment_of_extraordinary_fossil_biotas_from_the_Upper_Triassic_of_Italy</ref>
| grandparent_authority = Heyler, 1969
| regnum = [[Animal]]ia
| parent_authority = Aldinger, 1937
| phylum = [[Chordate|Chordata]]
| authority = [[Erik Stensiö|Stensiö]], 1919
| subphylum = [[Vertebrata]]
| subdivision_ranks = Species<ref name="Romano et al 2017"/>
| infraphylum = [[Gnathostomata]]
| subdivision = See text
| classis = [[Osteichthyes]]
| type_species = {{extinct}}''Saurichthys mougeoti''
| subclassis = [[Actinopterygii]]
| type_species_authority = [[Louis Agassiz|Agassiz]], 1844
| ordo = †[[Birgeriformes]]
| synonyms = *?''Xenestes'' <small>Jordan, 1907</small>
| familia = †[[Birgeriidae]]
| genus = †'''''Birgeria'''''
| genus_authority = [[Erik Stensiö|Stensiö]], 1919
| subdivision_ranks = Other species
| subdivision =
* †''[[Birgeria acuminata]]''
* †''[[Birgeria aldingeri]]''
* †''[[Birgeria americana]]''
* †''[[Birgeria groenlandica]]''
* †''[[Birgeria liui]]''
* †''[[Birgeria nielseni]]''
* †''[[Birgeria stensioei]]''
* †''[[Birgeria? velox]]''
| type species=†''[[Birgeria mougeoti]]''
| type_species_authority = ([[Louis Agassiz|Agassiz]], 1844)
}}
}}


'''''Birgeria''''' is a [[genus]] of [[carnivorous]] marine [[Actinopterygii|ray-finned fish]] from the [[Triassic]] [[Period (geology)|period]].<ref name="Romano&Brinkmann2009">{{Cite journal|author1=Romano, C. |author2=Brinkmann, W. |name-list-style=amp |year=2009|title=Reappraisal of the lower actinopterygian ''Birgeria stensioei'' ALDINGER, 1931 (Osteichthyes; Birgeriidae) from the Middle Triassic of Monte San Giorgio (Switzerland) and Besano (Italy).|journal=Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen |volume=252 |pages=17–31|doi=10.1127/0077-7749/2009/0252-0017}}</ref> ''Birgeria'' had a global distribution, with fossil known from [[Madagascar]], [[Spitsbergen]], [[Germany]], [[Switzerland]], [[Italy]], [[Slovenia]], [[China]], [[Russia]], [[Canada]] and [[Nevada]], [[United States]]. The oldest fossils are from [[Induan|Griesbachian]] aged beds of the [[Wordie Creek Formation]] of East [[Greenland]].<ref>{{cite journal |last=Nielsen |first=Eigil |author-link=Eigil Nielsen (paleontologist) |year=1949 |title=Studies on Triassic fishes from East Greenland 2. ''Australosomus'' and ''Birgeria'' |journal=Palaeozoologica Groenlandica |volume=3 |pages=1–309}}.</ref> ''Birgeria'' existed throughout the entire Triassic period, from the very beginning just after the [[Permian-Triassic mass extinction]], up to the very end with its extinction during the [[Triassic-Jurassic mass extinction]].
[[File:Birgeria.png|thumb|left|Skull fragments of ''[[Birgeria aldingeri]]'' from the [[Olenekian]] ([[Early Triassic]]) of Spitsbergen and restoration. Skull length ~{{convert|35|cm|ft}}: Br = branchiostegal ray, D = dentary, Mc = Meckelian cartilage]]

[[File:BirgeriaDB15.jpg|thumb|left|Restoration]]
The type species was first described as ''Saurichthys mougeoti''. Following a reinvestigation, [[Erik Stensiö]] concluded that this species cannot be ascribed to ''[[Saurichthys]]''. He thus erected a new genus, which he named after his colleague Birger Sjöström, who had joined him on an expedition to the Arctic island of Spitsbergen ([[Svalbard]]) in 1915.<ref>{{cite journal |last=Stensiö |first=Erik |author-link=Erik Stensiö |year=1919 |title=Einige Bemerkungen über die systematische Stellung von ''Saurichthys mougeoti'' Agassiz |journal=Senckenbergiana |volume=1 |pages=177–181}}.</ref>
[[File:Triassic marine vertebrate apex predators.png|thumb|left|[[Early Triassic]] and [[Middle Triassic]] marine predators: 6. ''Birgeria''<ref>Scheyer et al. (2014): Early Triassic Marine Biotic Recovery: The Predators' Perspective. PLoS ONE https://doi.org/10.1371/journal.pone.0088987</ref>]]

[[File:Birgeria jaws.JPG|thumb|left|Jaws and teeth of ''[[Birgeria acuminata]]'']]
==Systematics==
'''''Birgeria''''' is a [[genus]] of [[carnivorous]] marine [[Actinopterygii|ray-finned fish]] from the [[Triassic]] [[Period (geology)|period]].<ref name="Romano&Brinkmann2009">{{Cite journal|author1=Romano, C. |author2=Brinkmann, W. |name-list-style=amp |year=2009|title=Reappraisal of the lower actinopterygian Birgeria stensioei ALDINGER, 1931 (Osteichthyes; Birgeriidae) from the Middle Triassic of Monte San Giorgio (Switzerland) and Besano (Italy).|journal=Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen |volume=252 |pages=17–31|doi=10.1127/0077-7749/2009/0252-0017}}</ref> ''Birgeria'' had a global distribution. Fossils were found in [[Madagascar]], [[Spitsbergen]], [[Germany]], [[Switzerland]], [[Italy]], [[Slovenia]], [[China]], [[Russia]], [[Canada]] and [[Nevada]], [[United States]]. The oldest fossils are from [[Induan|Griesbachian]] aged beds of the [[Wordie Creek Formation]] of East [[Greenland]].
[[File:Birgeria.png|thumb|left|Skull fragments of ''[[Birgeria aldingeri]]'' from the [[Olenekian]] ([[Early Triassic]]) of Spitsbergen and restoration. Skull length ~{{convert|35|cm|ft}}: Br = branchiostegal ray, D = dentary, Mc = Meckelian cartilage]]
[[File:Birgeria americana white background.jpg|thumb|Skull of ''Birgeria americana'']]
''Birgeria'' is the [[monotypic taxon|only genus]] of the [[family (taxonomy)|family]] '''Birgeriidae''' and order '''Birgeriformes'''.<ref name="Romano&Brinkmann2009" /><ref name=":0">{{cite web |title=Birgeria |url=https://paleobiodb.org/classic/basicTaxonInfo?taxon_no=34974 |accessdate= |publisher=Paleobiology Database}}</ref>
The genera ''[[Psilichthys]]'', ''[[Ohmdenia]]'' and ''[[Brazilichthys]]'' have been previously referred to Birgeriidae, but they were shown to be only distantly related to ''Birgeria''.<ref name="Romano&Brinkmann2009" /><ref name="Figueroa2019">{{cite journal |last1=Figueroa |first1=Rodrigo T. |last2=Friedman |first2=Matt |last3=Gallo |first3=Valéria |date=2019 |title=Cranial anatomy of the predatory actinopterygian ''Brazilichthys macrognathus'' from the Permian (Cisuralian) Pedra de Fogo Formation, Parnaíba Basin, Brazil |journal=Journal of Vertebrate Paleontology |volume=39 |issue=3 |pages=e1639722 |bibcode=2019JVPal..39E9722F |doi=10.1080/02724634.2019.1639722 |s2cid=92614261}}</ref><ref name="Friedman 2012">{{Cite journal |author1=Friedman, M. |name-list-style=amp |year=2012 |title=Parallel evolutionary trajectories underlie the origin of the giant suspension-feeding whales and bony fish. |journal=Proceedings of the Royal Society B |volume=279 |issue=1730 |pages=944–951 |doi=10.1098/rspb.2011.1381 |pmc=3259929 |pmid=21849314 |doi-access=free}}</ref> The family was erected by [[Hermann Aldinger]] in 1937. [[Eigil Nielsen (paleontologist)|Eigil Nielsen]] gave the first [[Taxonomy (biology)#Taxonomic descriptions|diagnosis]] of Birgeriidae in his 1949 monograph. Birgeriidae first appears in the [[Early Triassic]] ([[Induan]]) of [[Greenland]] and went extinct in the [[Late Triassic]]. It was most speciose during the [[Early Triassic|Early]] and [[Middle Triassic]].<ref name="Romano et al 2017" />

In most [[cladistics|cladistic analyses]], ''Birgeria'' and the [[Saurichthyiformes]] are recovered as each others' closest relatives.<ref name=":2">{{Cite journal |last1=Argyriou |first1=Thodoris |last2=Giles |first2=Sam |last3=Friedman |first3=Matt |last4=Romano |first4=Carlo |last5=Kogan |first5=Ilja |last6=Sánchez-Villagra |first6=Marcelo R. |date=2018-11-01 |title=Internal cranial anatomy of Early Triassic species of †Saurichthys (Actinopterygii: †Saurichthyiformes): implications for the phylogenetic placement of †saurichthyiforms |journal=BMC Evolutionary Biology |volume=18 |issue=1 |pages=161 |doi=10.1186/s12862-018-1264-4 |doi-access=free |issn=1471-2148 |pmc=6211452 |pmid=30382811|bibcode=2018BMCEE..18..161A }}</ref> Together, they are also often recovered as stem [[Chondrostei|chondrosteans]], closely related to [[sturgeons]] and [[paddlefish]] ([[Acipenseriformes]]), with their exact relationship to each other and to sturgeons/paddlefish varying depending on the study.<ref name="Gardiner et al. 2005">{{Cite journal |author1=Gardiner, B.G. |author2=Schaeffer, B. |author3=Masserie, J.A. |name-list-style=amp |year=2005 |title=A review of the lower actinopterygian phylogeny. |journal=Zoological Journal of the Linnean Society |volume=144 |issue=4 |pages=511–525 |doi=10.1111/j.1096-3642.2005.00181.x |doi-access=free}}</ref><ref>{{Cite journal |last1=Wu |first1=Feixiang |last2=Chang |first2=Mee-mann |last3=Sun |first3=Yuanlin |last4=Xu |first4=Guanghui |date=2013-12-04 |title=A New Saurichthyiform (Actinopterygii) with a Crushing Feeding Mechanism from the Middle Triassic of Guizhou (China) |journal=PLOS ONE |language=en |volume=8 |issue=12 |pages=e81010 |doi=10.1371/journal.pone.0081010 |doi-access=free |issn=1932-6203 |pmc=3852010 |pmid=24324657|bibcode=2013PLoSO...881010W }}</ref>'''<ref name=":1">{{cite journal |last1=Near |first1=Thomas J |last2=Thacker |first2=Christine E |date=18 April 2024 |title=Phylogenetic classification of living and fossil ray-finned fishes (Actinopterygii) |journal=Bulletin of the Peabody Museum of Natural History |volume=65 |doi=10.3374/014.065.0101 |doi-access=free}}</ref>'''<ref>{{Cite journal |last=Tsessarsky |first=A. A. |date=2022-12-01 |title=Origin and Diversification of Acipenseriforms |url=https://doi.org/10.1134/S0032945222060297 |journal=Journal of Ichthyology |language=en |volume=62 |issue=7 |pages=1361–1380 |doi=10.1134/S0032945222060297 |issn=1555-6425}}</ref> However, other studies have suggested that they are not closely related to Acipenseriformes, and instead are part of the stem-group of [[Actinopterygii]], and thus are not closely related to any living group of fish.<ref name=":2" /><ref>{{Cite journal |last1=Giles |first1=Sam |last2=Feilich |first2=Kara |last3=Warnock |first3=Rachel C. M. |last4=Pierce |first4=Stephanie E. |last5=Friedman |first5=Matt |date=2022-11-17 |title=A Late Devonian actinopterygian suggests high lineage survivorship across the end-Devonian mass extinction |url=https://www.nature.com/articles/s41559-022-01919-4 |journal=Nature Ecology & Evolution |language=en |volume=7 |issue=1 |pages=10–19 |doi=10.1038/s41559-022-01919-4 |issn=2397-334X |pmid=36396970 |bibcode=2022NatEE...7...10G |s2cid=253626895}}</ref>

A few species, such as ''Birgeria''? ''costata'' or ''Birgeria''? ''annulata'', are only known from fragmentary material. Their affinity with ''Birgeria'' is uncertain. The type material of ''Birgeria guizhouensis'' appears to be lost.<ref name="Ni et al. 2019" /> A jaw fragment from the [[Late Triassic]] of California, described as ''Xenestes velox'' by [[David Starr Jordan]], was tentatively synonymized with ''Birgeria''. With about eight valid species, ''Birgeria'' was much less speciose than ''Saurichthys''.

The following species are known:<ref name=":0" /><ref name="Romano et al 2017" />


* †''B. acuminata'' <small>(Agassiz, 1843)</small> - Middle Triassic ([[Anisian]]) of India, Late Triassic ([[Carnian]] to [[Rhaetian]]) of Europe (Belgium, France, Germany, the Netherlands, Poland, Slovakia, Switzerland, and the United Kingdom)
The type species was first described as ''Saurichthys mougeoti''. Following a reinvestigation, [[Erik Stensiö]] concluded that this species cannot be ascribed to ''[[Saurichthys]]''. He thus erected a new genus, which he named after his colleague Birger Sjöström, who had joined him on an expedition to the Arctic island of Spitsbergen ([[Svalbard]]) in 1915.<ref>Stensiö, E. 1919, Einige Bemerkungen über die systematische Stellung von Saurichthys mougeoti Agassiz: Senckenbergiana 1:177–181.</ref>
* †''B. aldingeri'' <small>Schwarz, 1970</small> - Early Triassic ([[Olenekian]]) of Norway
* †''B. americana'' <small>Romano et al., 2017</small> - Olenekian of [[Nevada]], US
* †''B.? costata'' <small>([[Georg zu Münster|Münster]], 1839 )</small> - Middle Triassic (Anisian to Ladinian) of Germany
* †''B. groenlandica'' <small>[[Erik Stensiö|Stensiö]], 1932</small> - Earliest Triassic ([[Induan]]) of Greenland
* †''B. guizhouensis''? <small>Liu et al, 2006</small> - Carnian of China
* †''B. liui'' <small>Jin, 2001</small> - Ladinian to Carnian of China
* †''B. mougeoti'' <small>(Agassiz, 1844)</small> - Induan to Olenekian of France and [[Svalbard]]
* †''B. nielseni'' <small>[[Jean-Pierre Lehman|Lehman]], 1948</small> - Induan of [[Madagascar]]
* †''B. stensioei'' <small>Aldinger, 1931</small> - Anisian of Italy
* †''B.? velox'' <small>([[David Starr Jordan|Jordan]], 1907)</small> - Carnian/Norian of California, US
Fossils of indeterminate species are known from Canada ([[British Columbia]]), [[Bolivia]], [[Luxembourg]], and [[Saudi Arabia]].<ref name=":0" />


==Appearance==
==Appearance==
[[File:BirgeriaDB15.jpg|thumb|left|Restoration]]
The scale cover of ''Birgeria'' is reduced. Most of the body is devoid of scales. Scales are only developed on the upper lobe of the [[caudal fin]] and the hind portion of the [[caudal peduncle]]. The scales are small, rhombic and lack a ganoine layer.
The scale cover of ''Birgeria'' is reduced. Most of the body is devoid of scales. Scales are only developed on the upper lobe of the [[caudal fin]] and the hind portion of the [[caudal peduncle]]. The scales are small, rhombic and lack a ganoine layer.


The tail fin is large and deeply forked. The [[fish fin|dorsal and anal fins]] are situated at the same level in the back of the body. The fin rays are segmented.
The [[heterocercal]] tail fin is large and deeply forked. The [[fish fin|dorsal and anal fins]] are situated at the same level in the back of the body. The fin rays are segmented.
[[File:Birgeria stensioei skeleton.jpg|left|thumb|PIMUZ T 5, a complete skeleton of ''Birgeria stensioei'' from the [[Besano Formation]] of [[Monte San Giorgio]].]]
The eyes were located in the front of the skull. The jaws are long and the [[gape]] is large. The "parietals" ([[postparietal]]s) are small and medially separated by the elongate "frontals" ([[parietal bone|parietals]]). The [[postrostral]] is large. The (rostro-)[[premaxilla]] is unpaired. The [[maxilla]] is cleaver-shaped with a large postorbital blade. Two to three rows of conical teeth are present. The teeth normally show cutting edges. The preopercle is boomerang-shaped. The bones of the [[gill cover]] are small, often weakly [[ossified]] or not ossified at all.


The [[axial skeleton]] consists of ossified [[neural arches|neural]] and [[haemal arches]], both of which may show [[neural spines|spines]], and additional supraneurals. Other elements are interpreted as parapophyses. Ossified [[centra (anatomy)|centra]] are missing.<ref name="Ni et al. 2019">{{Cite journal|author1=Ni, P. |author2=Tintori, A. |author3=Sun, Z. |author4=Lombardo, C. |author5=Jiang, D. |name-list-style=amp |year=2019 |title=Postcranial skeleton of ''Birgeria liui'' (Osteichthyes, Actinopterygii) from the Longobardian (Ladinian, Middle Triassic) of Xingyi, Guizhou, South China. |journal=[[Swiss Journal of Geosciences]] |volume=112 |issue=2–3 |pages=307–324 |doi=10.1007/s00015-018-0329-0|s2cid=135305199 }}</ref> The axial skeleton is regionalized, meaning that there are differences in bone [[morphology (biology)|morphology]] between segments of the axial skeleton, although these differences are relatively subtle in ''Birgeria''.<ref name="Maxwell et al. 2021">{{Cite journal|author1=Maxwell, E.E. |author2=Romano, C. |author3=Wu, F.-X. |name-list-style=amp |year=2021 |title=Regional disparity in the axial skeleton of Saurichthyidae and implications for axial regionalization in non-teleostean actinopterygians. |journal=Journal of Zoology |volume= 315|pages= 29–41|doi=10.1111/jzo.12878|doi-access=free}}</ref>
The eyes were located in the front of the skull. The [[gape]] is large. The "parietals" ([[postparietal]]s) are small and medially separated by the elongate "frontals" ([[parietal bone|parietals]]). The [[postrostral]] is large. The (rostro-)[[premaxilla]] is unpaired. The [[maxilla]] is cleaver-shaped with a large postorbital blade. Two to three rows of conical teeth are present. The teeth normally show cutting edges. The preopercle is boomerang-shaped. The bones of the [[gill cover]] are small, often weakly [[ossified]] or not ossified at all.


==Ecology==
==Ecology==
[[File:Triassic marine vertebrate apex predators.png|thumb|left|[[Early Triassic]] and [[Middle Triassic]] marine predators: 6. ''Birgeria''<ref name="Scheyer2014">{{cite journal |last1=Scheyer |first1=Torsten M. |last2=Romano |first2=Carlo |last3=Jenks |first3=Jim |last4=Bucher |first4=Hugo |year=2014 |title=Early Triassic Marine Biotic Recovery: The Predators' Perspective" |journal=PLOS ONE |volume=9 |issue=3 |pages=e88987 |doi=10.1371/journal.pone.0088987 |pmid=24647136 |pmc=3960099 |bibcode=2014PLoSO...988987S |doi-access=free}}</ref>]]''Birgeria'' was an [[apex predator]] among Triassic [[Actinopterygii|ray-finned fish]], together with ''[[Saurichthys]]''.
''Birgeria'' was an [[apex predator]] among Triassic [[Actinopterygii|ray-finned fish]], together with ''[[Saurichthys]]''. Most species of ''Birgeria'' grew over {{convert|1|m|ft}} in length, some even up to {{convert|2|m|ft}} or possibly more. Some of the largest species are ''Birgeria aldingeri'' (Spitsbergen) and ''Birgeria americana'' (USA).<ref>Romano et al. (2017): Marine Early Triassic Actinopterygii from Elko County (Nevada, USA): implications for the Smithian equatorial vertebrate eclipse. Journal of Paleontology 91:1025-1046 https://doi.org/10.1017/jpa.2017.36</ref>


Most species of ''Birgeria'' grew over {{convert|1|m|ft}} in length, some even up to {{convert|2|m|ft}} or possibly more. Some of the largest species are the [[Early Triassic]] ''Birgeria aldingeri'' (Spitsbergen) and ''Birgeria americana'' (Nevada). They were the first large-bodied predators after the [[Permian-Triassic mass extinction]].<ref name="Romano et al 2017">{{cite journal |last1=Romano |first1=Carlo |last2=Jenks |first2=James F. |last3=Jattiot |first3=Romain |last4=Scheyer |first4=Torsten M. |last5=Bylund |first5=Kevin G. |last6=Bucher |first6=Hugo |year=2017 |title=Marine Early Triassic Actinopterygii from Elko County (Nevada, USA): implications for the Smithian equatorial vertebrate eclipse |journal=Journal of Paleontology |volume=91 |issue=5 |pages=1025–1046 |doi=10.1017/jpa.2017.36|bibcode=2017JPal...91.1025R |s2cid=134496299 |doi-access=free }}</ref>
A specimen of ''Birgeria nielseni'' from Madagascar was described as supposedly carrying embryos whose bodies are covered with rhombic scales. However, this interpretation was later dismissed.<ref>Bürgin, T. (1990): Reproduction in Middle Triassic actinopterygians; complex fin structures and evidence of viviparity in fossil fishes. Zoological Journal of the Linnean Society 100:379–391. doi:10.1111/j.1096-3642.1990.tb01866.x</ref> It is more likely that these "embryos" were actually preyed ray-fins, which would indicate that the diet of ''Birgeria'' included small actinopterygians. Unlike ''Saurichthys'', ''Birgeria'' was probably not [[viviparous]]. This view is supported by the fact that fossils with [[sex organ|copulatory organs]] are yet unknown.

A specimen of ''Birgeria nielseni'' from Madagascar was described as supposedly carrying embryos whose bodies are covered with rhombic scales. However, this interpretation was later dismissed.<ref>{{cite journal |last=Bürgin |first=Toni |year=1990 |title=Reproduction in Middle Triassic actinopterygians; complex fin structures and evidence of viviparity in fossil fishes |journal=Zoological Journal of the Linnean Society |volume=100 |issue=4 |pages=379–391 |doi=10.1111/j.1096-3642.1990.tb01866.x}}</ref> It is more likely that these "embryos" were actually preyed ray-fins, which would indicate that the diet of ''Birgeria'' included small actinopterygians. Unlike ''Saurichthys'', ''Birgeria'' was probably not [[viviparous]]. This view is supported by the fact that fossils with [[sex organ|copulatory organs]] are yet unknown.


Based on its anatomical features, ''Birgeria'' is interpreted as a [[pelagic]], swift swimmer. Fossils are sparse, which supports the view that it lived offshore.
Based on its anatomical features, ''Birgeria'' is interpreted as a [[pelagic]], swift swimmer. Fossils are sparse, which supports the view that it lived offshore.


==Systematics==
==See also==
* [[Prehistoric fish]]
''Birgeria'' is the only genus of the [[family (taxonomy)|family]] [[Birgeriidae]] ([[monotypy]]). ''[[Psilichthys]]'', ''[[Ohmdenia]]'' and ''[[Brazilichthys]]'' are not closely related to ''Birgeria'' and therefore excluded from Birgeriidae.<ref>Rodrigo T. Figueroa; Matt Friedman; Valéria Gallo (2019). Cranial anatomy of the predatory actinopterygian Brazilichthys macrognathus from the Permian (Cisuralian) Pedra de Fogo Formation, Parnaíba Basin, Brazil. Journal of Vertebrate Paleontology. 39: e1639722. https://doi.org/10.1080/02724634.2019.1639722</ref><ref>M. Friedmann. 2012. Parallel evolutionary trajectories underlie the origin of the giant suspension-feeding whales and bony fish. Proceedings of the Royal Society B 279: 944-951</ref>
* [[List of prehistoric bony fish]]

A few species, such as ''Birgeria''? ''costata'' or ''Birgeria''? ''annulata'', are only known from fragmentary material. Their affinity with ''Birgeria'' is uncertain. With about eight valid species, ''Birgeria'' was much less speciose than ''Saurichthys''.


{{clear}}
==References==
==References==
{{Reflist}}
{{Reflist}}


==Further reading==
==Further reading==
{{Portal|Paleontology|Fish}}
* Fossils (Smithsonian Handbooks) by [[David Ward (paleontologist)|David Ward]] (Page 211)
* Fossils (Smithsonian Handbooks) by [[David Ward (paleontologist)|David Ward]] (Page 211)


{{Actinopterygian genera|A.}}
{{Taxonbar|from=Q1027507}}
{{Chondrostei}}
{{Taxonbar|from1=Q1027507|from2=Q865178}}


[[Category:Palaeonisciformes]]
[[Category:Prehistoric ray-finned fish genera]]
[[Category:Triassic fish of North America]]
[[Category:Triassic fish of Europe]]
[[Category:Triassic fish of Asia]]
[[Category:Triassic fish of Africa]]
[[Category:Late Triassic vertebrates of South America]]
[[Category:Early Triassic fish]]
[[Category:Middle Triassic fish]]
[[Category:Late Triassic fish]]
[[Category:Triassic bony fish]]
[[Category:Triassic bony fish]]
[[Category:Fossils of Austria]]
[[Category:Fossils of Belgium]]
[[Category:Fossils of Bolivia]]
[[Category:Fossils of British Columbia]]
[[Category:Fossils of California]]
[[Category:Fossils of China]]
[[Category:Fossils of England]]
[[Category:Fossils of Germany]]
[[Category:Fossils of Greenland]]
[[Category:Fossils of Greenland]]
[[Category:Prehistoric ray-finned fish genera]]
[[Category:Fossils of India]]
[[Category:Fossils of Italy]]

[[Category:Fossils of Luxembourg]]

[[Category:Fossils of Madagascar]]
{{Triassic-fish-stub}}
[[Category:Fossils of Nevada]]
{{Palaeonisciformes-stub}}
[[Category:Fossils of Norway]]
[[Category:Fossils of Poland]]
[[Category:Fossils of Saudi Arabia]]
[[Category:Fossils of Slovakia]]
[[Category:Fossils of Svalbard]]
[[Category:Fossils of Switzerland]]
[[Category:Induan genus first appearances]]
[[Category:Olenekian genera]]
[[Category:Anisian genera]]
[[Category:Ladinian genera]]
[[Category:Carnian genera]]
[[Category:Norian genera]]
[[Category:Rhaetian genus extinctions]]
[[Category:Fossil taxa described in 1919]]

Latest revision as of 12:08, 14 October 2024

Birgeria
Temporal range: Early–Late Triassic (Griesbachian–Rhaetian) 251.9–201.6 Ma
Fossil of Birgeria acuminata, Civic Museum of Natural Science, Bergamo, Italy.[2]
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: †Birgeriiformes
Heyler, 1969
Family: †Birgeriidae
Aldinger, 1937
Genus: †Birgeria
Stensiö, 1919
Type species
†Saurichthys mougeoti
Agassiz, 1844
Species[1]

See text

Synonyms
  • ?Xenestes Jordan, 1907

Birgeria is a genus of carnivorous marine ray-finned fish from the Triassic period.[3] Birgeria had a global distribution, with fossil known from Madagascar, Spitsbergen, Germany, Switzerland, Italy, Slovenia, China, Russia, Canada and Nevada, United States. The oldest fossils are from Griesbachian aged beds of the Wordie Creek Formation of East Greenland.[4] Birgeria existed throughout the entire Triassic period, from the very beginning just after the Permian-Triassic mass extinction, up to the very end with its extinction during the Triassic-Jurassic mass extinction.

The type species was first described as Saurichthys mougeoti. Following a reinvestigation, Erik Stensiö concluded that this species cannot be ascribed to Saurichthys. He thus erected a new genus, which he named after his colleague Birger Sjöström, who had joined him on an expedition to the Arctic island of Spitsbergen (Svalbard) in 1915.[5]

Systematics

[edit]
Skull fragments of Birgeria aldingeri from the Olenekian (Early Triassic) of Spitsbergen and restoration. Skull length ~35 centimetres (1.15 ft): Br = branchiostegal ray, D = dentary, Mc = Meckelian cartilage
Skull of Birgeria americana

Birgeria is the only genus of the family Birgeriidae and order Birgeriformes.[3][6] The genera Psilichthys, Ohmdenia and Brazilichthys have been previously referred to Birgeriidae, but they were shown to be only distantly related to Birgeria.[3][7][8] The family was erected by Hermann Aldinger in 1937. Eigil Nielsen gave the first diagnosis of Birgeriidae in his 1949 monograph. Birgeriidae first appears in the Early Triassic (Induan) of Greenland and went extinct in the Late Triassic. It was most speciose during the Early and Middle Triassic.[1]

In most cladistic analyses, Birgeria and the Saurichthyiformes are recovered as each others' closest relatives.[9] Together, they are also often recovered as stem chondrosteans, closely related to sturgeons and paddlefish (Acipenseriformes), with their exact relationship to each other and to sturgeons/paddlefish varying depending on the study.[10][11][12][13] However, other studies have suggested that they are not closely related to Acipenseriformes, and instead are part of the stem-group of Actinopterygii, and thus are not closely related to any living group of fish.[9][14]

A few species, such as Birgeria? costata or Birgeria? annulata, are only known from fragmentary material. Their affinity with Birgeria is uncertain. The type material of Birgeria guizhouensis appears to be lost.[15] A jaw fragment from the Late Triassic of California, described as Xenestes velox by David Starr Jordan, was tentatively synonymized with Birgeria. With about eight valid species, Birgeria was much less speciose than Saurichthys.

The following species are known:[6][1]

  • †B. acuminata (Agassiz, 1843) - Middle Triassic (Anisian) of India, Late Triassic (Carnian to Rhaetian) of Europe (Belgium, France, Germany, the Netherlands, Poland, Slovakia, Switzerland, and the United Kingdom)
  • †B. aldingeri Schwarz, 1970 - Early Triassic (Olenekian) of Norway
  • †B. americana Romano et al., 2017 - Olenekian of Nevada, US
  • †B.? costata (Münster, 1839 ) - Middle Triassic (Anisian to Ladinian) of Germany
  • †B. groenlandica Stensiö, 1932 - Earliest Triassic (Induan) of Greenland
  • †B. guizhouensis? Liu et al, 2006 - Carnian of China
  • †B. liui Jin, 2001 - Ladinian to Carnian of China
  • †B. mougeoti (Agassiz, 1844) - Induan to Olenekian of France and Svalbard
  • †B. nielseni Lehman, 1948 - Induan of Madagascar
  • †B. stensioei Aldinger, 1931 - Anisian of Italy
  • †B.? velox (Jordan, 1907) - Carnian/Norian of California, US

Fossils of indeterminate species are known from Canada (British Columbia), Bolivia, Luxembourg, and Saudi Arabia.[6]

Appearance

[edit]
Restoration

The scale cover of Birgeria is reduced. Most of the body is devoid of scales. Scales are only developed on the upper lobe of the caudal fin and the hind portion of the caudal peduncle. The scales are small, rhombic and lack a ganoine layer.

The heterocercal tail fin is large and deeply forked. The dorsal and anal fins are situated at the same level in the back of the body. The fin rays are segmented.

PIMUZ T 5, a complete skeleton of Birgeria stensioei from the Besano Formation of Monte San Giorgio.

The eyes were located in the front of the skull. The jaws are long and the gape is large. The "parietals" (postparietals) are small and medially separated by the elongate "frontals" (parietals). The postrostral is large. The (rostro-)premaxilla is unpaired. The maxilla is cleaver-shaped with a large postorbital blade. Two to three rows of conical teeth are present. The teeth normally show cutting edges. The preopercle is boomerang-shaped. The bones of the gill cover are small, often weakly ossified or not ossified at all.

The axial skeleton consists of ossified neural and haemal arches, both of which may show spines, and additional supraneurals. Other elements are interpreted as parapophyses. Ossified centra are missing.[15] The axial skeleton is regionalized, meaning that there are differences in bone morphology between segments of the axial skeleton, although these differences are relatively subtle in Birgeria.[16]

Ecology

[edit]
Early Triassic and Middle Triassic marine predators: 6. Birgeria[17]

Birgeria was an apex predator among Triassic ray-finned fish, together with Saurichthys.

Most species of Birgeria grew over 1 metre (3.3 ft) in length, some even up to 2 metres (6.6 ft) or possibly more. Some of the largest species are the Early Triassic Birgeria aldingeri (Spitsbergen) and Birgeria americana (Nevada). They were the first large-bodied predators after the Permian-Triassic mass extinction.[1]

A specimen of Birgeria nielseni from Madagascar was described as supposedly carrying embryos whose bodies are covered with rhombic scales. However, this interpretation was later dismissed.[18] It is more likely that these "embryos" were actually preyed ray-fins, which would indicate that the diet of Birgeria included small actinopterygians. Unlike Saurichthys, Birgeria was probably not viviparous. This view is supported by the fact that fossils with copulatory organs are yet unknown.

Based on its anatomical features, Birgeria is interpreted as a pelagic, swift swimmer. Fossils are sparse, which supports the view that it lived offshore.

See also

[edit]

References

[edit]
  1. ^ a b c d Romano, Carlo; Jenks, James F.; Jattiot, Romain; Scheyer, Torsten M.; Bylund, Kevin G.; Bucher, Hugo (2017). "Marine Early Triassic Actinopterygii from Elko County (Nevada, USA): implications for the Smithian equatorial vertebrate eclipse". Journal of Paleontology. 91 (5): 1025–1046. Bibcode:2017JPal...91.1025R. doi:10.1017/jpa.2017.36. S2CID 134496299.
  2. ^ Stefani, Marco; Arduini, Paolo; Garassino, Alessandro; Pinna, Giovanni; Teruzzi, Giorgio; Trombetta, Gian Luigi (1992). "Palaeoenvironment of extraordinary fossil biotas from the Upper Triassic of Italy". Atti della Società Italiana di Scienze Naturali e del Museo Civico di Storia Naturale di Milano. 132 (24): 309–335.
  3. ^ a b c Romano, C. & Brinkmann, W. (2009). "Reappraisal of the lower actinopterygian Birgeria stensioei ALDINGER, 1931 (Osteichthyes; Birgeriidae) from the Middle Triassic of Monte San Giorgio (Switzerland) and Besano (Italy)". Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen. 252: 17–31. doi:10.1127/0077-7749/2009/0252-0017.
  4. ^ Nielsen, Eigil (1949). "Studies on Triassic fishes from East Greenland 2. Australosomus and Birgeria". Palaeozoologica Groenlandica. 3: 1–309..
  5. ^ Stensiö, Erik (1919). "Einige Bemerkungen über die systematische Stellung von Saurichthys mougeoti Agassiz". Senckenbergiana. 1: 177–181..
  6. ^ a b c "Birgeria". Paleobiology Database.
  7. ^ Figueroa, Rodrigo T.; Friedman, Matt; Gallo, Valéria (2019). "Cranial anatomy of the predatory actinopterygian Brazilichthys macrognathus from the Permian (Cisuralian) Pedra de Fogo Formation, Parnaíba Basin, Brazil". Journal of Vertebrate Paleontology. 39 (3): e1639722. Bibcode:2019JVPal..39E9722F. doi:10.1080/02724634.2019.1639722. S2CID 92614261.
  8. ^ Friedman, M. (2012). "Parallel evolutionary trajectories underlie the origin of the giant suspension-feeding whales and bony fish". Proceedings of the Royal Society B. 279 (1730): 944–951. doi:10.1098/rspb.2011.1381. PMC 3259929. PMID 21849314.
  9. ^ a b Argyriou, Thodoris; Giles, Sam; Friedman, Matt; Romano, Carlo; Kogan, Ilja; Sánchez-Villagra, Marcelo R. (2018-11-01). "Internal cranial anatomy of Early Triassic species of †Saurichthys (Actinopterygii: †Saurichthyiformes): implications for the phylogenetic placement of †saurichthyiforms". BMC Evolutionary Biology. 18 (1): 161. Bibcode:2018BMCEE..18..161A. doi:10.1186/s12862-018-1264-4. ISSN 1471-2148. PMC 6211452. PMID 30382811.
  10. ^ Gardiner, B.G.; Schaeffer, B. & Masserie, J.A. (2005). "A review of the lower actinopterygian phylogeny". Zoological Journal of the Linnean Society. 144 (4): 511–525. doi:10.1111/j.1096-3642.2005.00181.x.
  11. ^ Wu, Feixiang; Chang, Mee-mann; Sun, Yuanlin; Xu, Guanghui (2013-12-04). "A New Saurichthyiform (Actinopterygii) with a Crushing Feeding Mechanism from the Middle Triassic of Guizhou (China)". PLOS ONE. 8 (12): e81010. Bibcode:2013PLoSO...881010W. doi:10.1371/journal.pone.0081010. ISSN 1932-6203. PMC 3852010. PMID 24324657.
  12. ^ Near, Thomas J; Thacker, Christine E (18 April 2024). "Phylogenetic classification of living and fossil ray-finned fishes (Actinopterygii)". Bulletin of the Peabody Museum of Natural History. 65. doi:10.3374/014.065.0101.
  13. ^ Tsessarsky, A. A. (2022-12-01). "Origin and Diversification of Acipenseriforms". Journal of Ichthyology. 62 (7): 1361–1380. doi:10.1134/S0032945222060297. ISSN 1555-6425.
  14. ^ Giles, Sam; Feilich, Kara; Warnock, Rachel C. M.; Pierce, Stephanie E.; Friedman, Matt (2022-11-17). "A Late Devonian actinopterygian suggests high lineage survivorship across the end-Devonian mass extinction". Nature Ecology & Evolution. 7 (1): 10–19. Bibcode:2022NatEE...7...10G. doi:10.1038/s41559-022-01919-4. ISSN 2397-334X. PMID 36396970. S2CID 253626895.
  15. ^ a b Ni, P.; Tintori, A.; Sun, Z.; Lombardo, C. & Jiang, D. (2019). "Postcranial skeleton of Birgeria liui (Osteichthyes, Actinopterygii) from the Longobardian (Ladinian, Middle Triassic) of Xingyi, Guizhou, South China". Swiss Journal of Geosciences. 112 (2–3): 307–324. doi:10.1007/s00015-018-0329-0. S2CID 135305199.
  16. ^ Maxwell, E.E.; Romano, C. & Wu, F.-X. (2021). "Regional disparity in the axial skeleton of Saurichthyidae and implications for axial regionalization in non-teleostean actinopterygians". Journal of Zoology. 315: 29–41. doi:10.1111/jzo.12878.
  17. ^ Scheyer, Torsten M.; Romano, Carlo; Jenks, Jim; Bucher, Hugo (2014). "Early Triassic Marine Biotic Recovery: The Predators' Perspective"". PLOS ONE. 9 (3): e88987. Bibcode:2014PLoSO...988987S. doi:10.1371/journal.pone.0088987. PMC 3960099. PMID 24647136.
  18. ^ Bürgin, Toni (1990). "Reproduction in Middle Triassic actinopterygians; complex fin structures and evidence of viviparity in fossil fishes". Zoological Journal of the Linnean Society. 100 (4): 379–391. doi:10.1111/j.1096-3642.1990.tb01866.x.

Further reading

[edit]
  • Fossils (Smithsonian Handbooks) by David Ward (Page 211)
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