''Ptychoceratodus'' is an extinct genus of

lungfish Lungfish are freshwater vertebrates belonging to the order Dipnoi. Lungfish are best known for retaining ancestral characteristics within the Osteichthyes, including the ability to breathe air, and ancestral structures within Sarcopterygii, i ...

living from

Early Triassic The Early Triassic is the first of three epochs of the Triassic Period of the geologic timescale. It spans the time between Ma and Ma (million years ago). Rocks from this epoch are collectively known as the Lower Triassic Series, which is ...

Middle Jurassic The Middle Jurassic is the second Epoch (geology), epoch of the Jurassic Period (geology), Period. It lasted from about 174.1 to 163.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relatively ...

. It was established by

Otto Jaekel Otto Max Johannes Jaekel (21 February 1863 – 6 March 1929) was a German paleontologist and geologist. Biography Jaekel was born in Neusalz (Nowa Sól), Prussian Silesia, the son of a builder and the youngest of seven children. He studied at t ...

for one species (''P. runcinatus''), transferred from ''

Ceratodus ''Ceratodus'' (from el, κέρας , 'horn' and el, ὀδούς 'tooth') was a wide-ranging genus of extinct lungfish. Fossil evidence dates back to the Early Triassic. A wide range of fossil species from different time periods have been found ...

'' genus. Type species is ''P. serratus'' from the

Middle Triassic In the geologic timescale, the Middle Triassic is the second of three epochs of the Triassic period or the middle of three series in which the Triassic system is divided in chronostratigraphy. The Middle Triassic spans the time between Ma an ...

Switzerland ). Swiss law does not designate a ''capital'' as such, but the federal parliament and government are installed in Bern, while other federal institutions, such as the federal courts, are in other cities (Bellinzona, Lausanne, Luzern, Neuchâtel ...

and

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwee ...

. ''Ptychoceratodus'' had two pairs of massive dental plates, bearing 4-6 acute ridges. Its

skull roof The skull roof, or the roofing bones of the skull, are a set of bones covering the brain, eyes and nostrils in bony fishes and all land-living vertebrates. The bones are derived from dermal bone and are part of the dermatocranium. In compar ...

was composed from massive, plate-like bones. In the central part of skull roof was localized an unossified

fenestra A fenestra (fenestration; plural fenestrae or fenestrations) is any small opening or pore, commonly used as a term in the biological sciences. It is the Latin word for "window", and is used in various fields to describe a pore in an anatomical st ...

. Most of the ''Ptychoceratodus'' findings are isolated dental plates, some associated with jaws. Other parts of skull or postcranial skeleton are relatively rarely found as fossils. The anatomy of skull is the best recognized in ''P. serratus'', whereas less complete cranial material is available also for ''P. concinuus, P. phillipsi,'' and ''P. rectangulus''. Although ''Ptychoceratodus'' is known exclusively from the

Triassic The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest per ...

and

Jurassic The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of ...

, there were also

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

specimens referred to this genus. However, they are more often regarded as representants of ''

Metaceratodus ''Metaceratodus'' is an extinct genus of prehistoric lungfish in the family Ceratodontidae, with an indeterminate specimen known from the Late Triassic (Norian)-aged Lissauer Breccia of Poland and more complete specimens known from the Lat ...

''. ''Ptychoceratodus'' is the only member of the family Ptychoceratodontidae. The first named species is ''P. phillipsi'' by

Louis Agassiz Jean Louis Rodolphe Agassiz ( ; ) FRS (For) FRSE (May 28, 1807 – December 14, 1873) was a Swiss-born American biologist and geologist who is recognized as a scholar of Earth's natural history. Spending his early life in Switzerland, he rec ...

in 1837 as a species of ''Ceratodus'' and later moved to ''Ptychoceratodus'' genus. Occurrences of ''Ptychoceratodus'' come mainly from

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

. However, occurrences from other continents suggest it was dispersed globally during the Triassic. After 2010, the new fossil material behind the Europe was reported from

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sou ...

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area, the List of countries and dependencies by population, second-most populous ...

, and

Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland ...

Fossil distribution

Fossils of ''Ptychoceratodus'' have been found in: ''Ptychoceratodus''at

Fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database, a large relational database assembled by hundreds of paleontologists from around the world. History Fossilworks was crea ...

.org ;Triassic *

Burgersdorp Formation The ''Cynognathus'' Assemblage Zone is a tetrapod biozone utilized in the Karoo Basin of South Africa. It is equivalent to the Burgersdorp Formation, the youngest lithostratigraphic formation in the Beaufort Group, which is part of the fossilif ...

, ( ''Cynognathus'' Assemblage Zone), Early Triassic (

Olenekian In the geologic timescale, the Olenekian is an age in the Early Triassic epoch; in chronostratigraphy, it is a stage in the Lower Triassic series. It spans the time between Ma and Ma (million years ago). The Olenekian is sometimes divided i ...

), South Africa (''?Ptychoceratodus'' sp.) * Lipovskaya Formation, Early Triassic (Olenekian), Russia (''P. donensis'') *

Erfurt Formation The Erfurt Formation, also known as the Lower Keuper (German: ''Untere Keuper'', ''Lettenkeuper'', ''Lettenkohle'' or ''Lettenkohlenkeuper''), is a stratigraphic formation of the Keuper group and the Germanic Trias supergroup. It was deposited du ...

, Middle Triassic (

Ladinian The Ladinian is a stage and age in the Middle Triassic series or epoch. It spans the time between Ma and ~237 Ma (million years ago). The Ladinian was preceded by the Anisian and succeeded by the Carnian (part of the Upper or Late Triassic) ...

), Germany (''P. serratus'') *

Weser Formation The Weser () is a river of Lower Saxony in north-west Germany. It begins at Hannoversch Münden through the confluence of the Werra and Fulda. It passes through the Hanseatic city of Bremen. Its mouth is further north against the ports of Br ...

Carnian The Carnian (less commonly, Karnian) is the lowermost stage (stratigraphy), stage of the Upper Triassic series (stratigraphy), Series (or earliest age (geology), age of the Late Triassic Epoch (reference date), Epoch). It lasted from 237 to 227 m ...

, Germany (''P. concinnus'') * Tiki Formation, Carnian, India (''P. oldhami'') * Marnes de Châlins Formation,

Norian The Norian is a division of the Triassic Period. It has the rank of an age ( geochronology) or stage (chronostratigraphy). It lasted from ~227 to million years ago. It was preceded by the Carnian and succeeded by the Rhaetian. Stratigraphic ...

France (''P. rectangulus'') * Löwenstein Formation, Alaunian (Norian), Germany (''P. rectangulus'') * Grès à Avicula contorta Formation,

Rhaetian The Rhaetian is the latest age of the Triassic Period (in geochronology) or the uppermost stage of the Triassic System (in chronostratigraphy). It was preceded by the Norian and succeeded by the Hettangian (the lowermost stage or earliest a ...

, France (''P. phillipsi'') *

Fleming Fjord Formation The Fleming Fjord Formation, alternatively called the Fleming Fjord Group is an Upper Triassic geological formation in the northeastern coast of Jameson Land, Greenland. It consists of terrestrial sediments and is known for its fossil content. ...

, Norian, Greenland (''P. rectangulus'') * Grabowa Formation, Carnian, Poland (''P. roemeri'') ;Jurassic *

Inferior Oolite Group The Inferior Oolite is a sequence of Jurassic age sedimentary rocks in Europe. It was deposited during the Middle Jurassic.Weishampel, David B; et al. (2004). "Dinosaur distribution (Middle Jurassic, Europe)." In: Weishampel, David B.; Dodson, Pet ...

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe ...

(''P. phillipsi'')

References

Prehistoric lobe-finned fish genera Early Triassic first appearances Olenekian genera Ladinian genera Carnian genera Norian genera Rhaetian genera Tithonian genera Maastrichtian genera Late Cretaceous genus extinctions Triassic animals of Africa Prehistoric fish of Africa Triassic fish of Europe Jurassic fish of Asia Late Cretaceous fish of South America Fossils of Argentina Cañadón Asfalto Basin Fossils of China Fossils of France Fossils of Germany Fossils of India Fossils of Russia Fossils of South Africa Fossils of Thailand Fossil taxa described in 1926 {{paleo-lobefinned-fish-stub

Fossil distribution

See also

References