Palaeoniscoid

Palaeoniscidae is an extinct family of ray-finned fishes (Actinopterygii) ascribed to the order Palaeonisciformes. The family includes the genus '' Palaeoniscum'' and potentially other Palaeozoic and Mesozoic early actinopterygian genera. The name is derived from the Ancient Greek words παλαιός (''palaiós'', ancient) and ὀνίσκος (''oniskos'', 'cod-fish' or woodlouse).

Historic background

The family was first named "Palaeoniscini" by Charles Lucien Bonaparte in 1846, and "Palaeonisciden" by Carl Vogt in 1851. Later, the family name was standardized to Palaeoniscidae. The authorship of the family Palaeoniscidae is variably attributed to either Bonaparte or Vogt in the literature. Vogt ascribed the following genera to Palaeoniscidae: ''Palaeoniscum'', ''Platysomus'' (misspelled as ''Platysemius''), ''Amblypterus'', '' Eurynotus'', '' Pygopterus'', and ''Acrolepis''. With the exception of ''Palaeoniscum'', these genera were later placed in separate families ( Platysomidae, Amblypteridae) or are considered ''incertae sedis''.

Over the years, many other genera of Palaeozoic and Mesozoic early actinopterygians have been referred to Palaeoniscidae due to superficial similarities with the type genus ''Palaeoniscum'' from the Guadalupian-Lopingian (middle-late Permian) of Europe. Similarities were noted in their general morphology, such as the bullet shaped head and forward position of the relatively large eyes, the large gape and oblique jaw support, the body being covered with small, rhombic scales that often show peg-and-socket articulation, and the arrangement and structure of the fins, including the heterocercal caudal fin. However, these features are plesiomorphic for actinopterygians. Many taxa ascribed to Palaeoniscidae lack apomorphies that would securely affiliate them with ''Palaeoniscum''. As a result, Palaeoniscidae ''sensu lato'' has become a wastebasket taxon (probably paraphyletic).

In the strict sense, the Palaeoniscidae should only encompass the genus ''Palaeoniscum'' and only those genera that are closely related to it. However, due to insufficient knowledge of ''Palaeoniscum'' and many other early actinopterygians, and because most of these taxa have never been included in cladistic analyses, it is still uncertain which genera other than ''Palaeoniscum'' should be placed in Palaeoniscidae ''sensu stricto'' to make this a monophyletic group.

Classification

The following list includes species and genera that have been referred to Palaeoniscidae in the past, usually because of broad resemblance with ''Palaeoniscum freieslebeni''. Many of these taxa are poorly known and have never been analyzed in cladistic studies. Their inclusion in Palaeoniscidae is in most cases doubtful and requires confirmation by cladistic analyses. The listed taxa would imply that the temporal range of the family Palaeoniscidae stretched from the early Permian to the Cretaceous. If only species of ''Palaeoniscum'' are included, the temporal range of the family would be restricted to the middle-late Permian.

* Family †Palaeoniscidae Vogt, 1852
** Genus ?†'' Agecephalichthys'' Wade, 1935
*** Species †''Agecephalichthys granulatus'' Wade, 1935
** Genus ?†'' Atherstonia'' Woodward, 1889 'Broometta''_Chabakov,_1927.html" ;"title="Broometta.html" ;"title="'Broometta">'Broometta'' Chabakov, 1927">Broometta.html" ;"title="'Broometta">'Broometta'' Chabakov, 1927*** Species †''Atherstonia scutata'' Woodward, 1889 [''Atherstonia cairncrossi'' Broom, 1913; ''Amblypterus capensis'' Broom, 1913; ''Broometta cairncrossi'' Chabakov, 1927]
*** Species †''Atherstonia minor'' Woodward, 1893
** Genus ?†''Cryphaeiolepis'' Traquair, 1881
*** Species †''Cryphaeiolepis scutata'' Traquair, 1881
** Genus ?†'' Cteniolepidotrichia'' Poplin & Su, 1992
*** Species †''Cteniolepidotrichia turfanensis'' Poplin & Su, 1992
** Genus †'' Dicellopyge'' Brough, 1931
*** Species †''Dicellopyge macrodentata'' Brough, 1931
*** Species †''Dicellopyge lissocephalus'' Brough, 1931
** Genus ?†'' Duwaichthys'' Liu ''et al.'', 1990
*** Species †''Duwaichthys mirabilis'' Liu ''et al.'', 1990
** Genus ?†'' Ferganiscus'' Sytchevskaya & Yakolev, 1999
*** Species †''Ferganiscus osteolepis'' Sytchevskaya & Yakolev, 1999
** Genus †''Gyrolepis'' Agassiz, 1833 non Kade, 1858
*** Species †''G. albertii'' Agassiz, 1833
*** Species †''G. gigantea'' Agassiz, 1833
*** Species †''G. maxima'' Agassiz, 1833
*** Species †''G. quenstedti'' Dames, 1888
*** Species †''G. tenuistriata'' Agassiz, 1833
** Genus †'' Gyrolepidoides'' Cabrera, 1944
*** Species †''G. creyanus'' Schaeffer, 1955
*** Species †''G. cuyanus'' Cabrera, 1944
*** Species †''G. multistriatus'' Rusconi, 1948
** Genus ?†'' Palaeoniscinotus'' Rohon, 1890
*** Species †''P. czekanowskii'' Rohon, 1890
** Genus †'' Palaeoniscum'' de Blainville, 1818 'Palaeoniscus''_Agassiz,_1833_non_Von_Meyer,_1858;_''Palaeoniscas.html" ;"title="Palaeoniscus.html" ;"title="'Palaeoniscus">'Palaeoniscus'' Agassiz, 1833 non Von Meyer, 1858; ''Palaeoniscas">Palaeoniscus.html" ;"title="'Palaeoniscus">'Palaeoniscus'' Agassiz, 1833 non Von Meyer, 1858; ''Palaeoniscas'' Rzchak, 1881; ''Eupalaeoniscus'' Rzchak, 1881; ''Palaeomyzon'' Weigelt, 1930; ''Geomichthys'' Sauvage, 1888]
*** Species †''P. angustum'' (Rzehak, 1881) [''Palaeoniscas angustus'' Rzehak, 1881]
*** Species †''P. antipodeum'' (Egerton, 1864) 'Palaeoniscus antipodeus'' Egerton, 1864*** Species †''P. antiquum'' Williams, 1886
*** Species †''P. arenaceum'' Berger, 1832
*** Species †''P. capense'' (Bloom, 1913) 'Palaeoniscus capensis'' Bloom, 1913*** Species †''P. comtum'' (Agassiz, 1833) 'Palaeoniscus comtus'' Agassiz, 1833*** Species †''P. daedalium'' Yankevich & Minich, 1998
*** Species †''P. devonicum'' Clarke, 1885
*** Species †''P. elegans'' (Sedgwick, 1829) 'Palaeoniscus elegans'' Sedgwick, 1829*** Species †''P. freieslebeni'' de Blainville, 1818 'Eupalaeoniscus freieslebeni'' (de Brainville, 1818); ''Palaeoniscus freieslebeni'' (de Brainville, 1818)*** Species †''P. hassiae'' (Jaekel, 1898) 'Galeocerdo contortus hassiae'' Jaekel, 1898; ''Palaeomyzon hassiae'' (Jaekel, 1898)*** Species †''P. kasanense'' Geinitz & Vetter, 1880
*** Species †''P. katholitzkianum'' (Rzehak, 1881) 'Palaeoniscas katholitzkianus'' Rzehak, 1881*** Species †''P. landrioti'' (le Sauvage, 1890) 'Palaeoniscus landrioti'' le Sauvage, 1890*** Species †''P. longissimum'' (Agassiz, 1833) 'Palaeoniscus longissimus'' Agassiz, 1833*** Species †''P. macrophthalmum'' (McCoy, 1855) 'Palaeoniscus macrophthalmus'' McCoy, 1855*** Species †''P. magnum'' (Woodward, 1937) 'Palaeoniscus magnus'' Woodward, 1937*** Species †''P. moravicum'' (Rzehak, 1881) 'Palaeoniscas moravicus'' Rzehak, 1881*** Species †''P. promtu'' (Rzehak, 1881) 'Palaeoniscas promtus'' Rzehak, 1881*** Species †''P. reticulatum'' Williams, 1886
*** Species †''P. scutigerum'' Newberry, 1868
*** Species †''P. vratislavensis'' (Agassiz, 1833) 'Palaeoniscus vratislavensis'' Agassiz, 1833** Genus †''Palaeothrissum'' de Blainville, 1818
*** Species †''P. elegans'' Sedgwick, 1829
*** Species †''P. macrocephalum'' de Blainville, 1818
*** Species †''P. magnum'' de Blainville, 1818
** Genus ?†'' Shuniscus'' Su, 1983
*** Species †''Shuniscus longianalis'' Su, 1983
** Genus ?†'' Suchonichthys'' Minich, 2001
*** Species †''Suchonichthys molini'' Minich, 2001
** Genus ?†'' Trachelacanthus'' Fischer De Waldheim, 1850
*** Species †''Trachelacanthus stschurovskii'' Fischer De Waldheim, 1850
** Genus ?†'' Triassodus'' Su, 1984
*** Species †''Triassodus yanchangensis'' Su, 1984
** Genus ?†'' Turfania'' Liu & Martínez, 1973
*** Species †''T. taoshuyuanensis'' Liu & Martínez, 1973
*** Species †''T. varta'' Wang, 1979
** Genus ?†'' Turgoniscus'' Jakovlev, 1968
*** Species †''Turgoniscus reissi'' Jakovlev, 1968
** Genus ?†'' Weixiniscus'' Su & Dezao, 1994
*** Species †''Weixiniscus microlepis'' Su & Dezao, 1994
** Genus ?†'' Xingshikous'' Liu, 1988
*** Species †''Xingshikous xishanensis'' Liu, 1988
** Genus ?†'' Yaomoshania'' Poplin ''et al.'', 1991
*** Species †''Yaomoshania minutosquama'' Poplin ''et al.'', 1991

References

Palaeonisciformes
Prehistoric ray-finned fish families
Silurian first appearances
Cretaceous extinctions

{{Palaeonisciformes-stub