''Lycoptera'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of fish that lived from the late

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 ...

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 ...

periods in present-day China,

North Korea North Korea, officially the Democratic People's Republic of Korea (DPRK), is a country in East Asia. It constitutes the northern half of the Korean Peninsula and shares borders with China and Russia to the north, at the Yalu (Amnok) and T ...

Mongolia Mongolia; Mongolian script: , , ; lit. "Mongol Nation" or "State of Mongolia" () is a landlocked country in East Asia, bordered by Russia to the north and China to the south. It covers an area of , with a population of just 3.3 million, ...

and

Siberia Siberia ( ; rus, Сибирь, r=Sibir', p=sʲɪˈbʲirʲ, a=Ru-Сибирь.ogg) is an extensive region, geographical region, constituting all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has been a ...

. It is known from abundant fossils representing sixteen species, which serve as important

index fossil Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock strata by using the fossil assemblages contained within them.Hine, Robert. “Biostratigraphy.” ''Oxford Reference: Dictionary of Bio ...

used to date

geologic formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...

s in China. Along with the genus ''

Peipiaosteus ''Peipiaosteus'' is an extinct genus of prehistoric chondrostean ray-finned fish. Its fossils are found in the Early Cretaceous Jiufotang Formation, Pani Lake, Liaoning Province, China.Liu, H. T. and Zhou, J . J. 1965A new sturgeon from the ...

'', ''Lycoptera'' has been considered a defining member of the

Jehol Biota The Jehol Biota includes all the living organisms – the ecosystem – of northeastern China between 133 and 120 million years ago. This is the Lower Cretaceous ecosystem which left fossils in the Yixian Formation and Jiufotang Formation. These ...

, a prehistoric ecosystem famous for its

feathered dinosaurs A feathered dinosaur is any species of dinosaur possessing feathers. While this includes all species of birds, there is a hypothesis that many, if not all non-avian dinosaur species also possessed feathers in some shape or form. It has been su ...

, which flourished for 20 million years during the Early Cretaceous, where it occurs abundantly in often monospecific beds, where they are thought to have died in seasonal mass death events.Jin, F., Zhang, F.C., Li, Z.H., Zhang, J.Y., Li, C. and Zhou, Z.H. (2008). "On the horizon of ''Protopteryx'' and the early vertebrate fossil assemblages of the Jehol Biota." ''Chinese Science Bulletin'', 53(18): 2820-2827. ''Lycoptera'' is a crown group

teleost Teleostei (; Greek ''teleios'' "complete" + ''osteon'' "bone"), members of which are known as teleosts ), is, by far, the largest infraclass in the class Actinopterygii, the ray-finned fishes, containing 96% of all extant species of fish. Tele ...

belonging to an early diverging lineage of the

Osteoglossomorpha Osteoglossomorpha is a group of bony fish in the Teleostei. Notable members A notable member is the arapaima (''Arapaima gigas''), the largest freshwater fish in South America and one of the largest bony fishes alive. Other notable members in ...

, which contains living

mooneye Hiodontidae, commonly called mooneyes, is a family of ray-finned fish with a single included genus ''Hiodon''. The genus comprise two living species native to North America and three to five extinct species recorded from Paleocene to Eocene age ...

arapaima The arapaima, pirarucu, or paiche is any large species of bonytongue in the genus ''Arapaima'' native to the Amazon and Essequibo basins of South America. ''Arapaima'' is the type genus of the subfamily Arapaiminae within the family Osteoglossi ...

arowana Arowanas are freshwater bony fish of the subfamily Osteoglossinae, also known as bony tongues (the latter name is now often reserved for Arapaiminae). In this family of fish, the head is bony and the elongated body is covered by large, heavy sc ...

, elephantfish and knifefish/featherbacks.

Description

''Lycoptera'' species were small freshwater fish. Most species fed on

plankton Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucia ...

, and had numerous tiny teeth. A few species like ''L. gansuensis'', ''L. muroii'', and ''L. sinensis'' had larger teeth and probably fed on small

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three ...

s and their larvae. Many specimens preserve minute details and impressions of soft tissues. ''Lycoptera'' was covered in tiny oval scales about 1.2 millimeters across, and, in life, would have had a superficial resemblance to the

Common minnow The Eurasian minnow, minnow, or common minnow (''Phoxinus phoxinus'') is a small species of freshwater fish in the carp family Cyprinidae. It is the type species of genus ''Phoxinus''. It is ubiquitous throughout much of Eurasia, from Britain and ...

. ''Lycoptera'' fossils are commonly found in large groups, buried together quickly in fine lake sediments likely due to mass death events from seasonal

upwelling Upwelling is an oceanographic phenomenon that involves wind-driven motion of dense, cooler, and usually nutrient-rich water from deep water towards the ocean surface. It replaces the warmer and usually nutrient-depleted surface water. The nut ...

anoxic waters Anoxic waters are areas of sea water, fresh water, or groundwater that are depleted of dissolved oxygen. The US Geological Survey defines anoxic groundwater as those with dissolved oxygen concentration of less than 0.5 milligrams per litre. Anoxic ...

during late autumn and winter. This had led to suggestions that they were gregarious in life, congregating in

shoals In oceanography, geomorphology, and geoscience, a shoal is a natural submerged ridge, bank, or bar that consists of, or is covered by, sand or other unconsolidated material and rises from the bed of a body of water to near the surface. I ...

Classification and species

Lycoptera davidi fossil fish, Liaoning Province, China

Sixteen species of ''Lycoptera'' have been described, nine from the Jehol Group. The table below is based primarily on the valid species listed by Zhang and Jin in the 2008 book ''The Jehol Fossils''.

References

{{Taxonbar, from=Q142019 Early Cretaceous fish of Asia Jurassic bony fish Cretaceous bony fish Late Jurassic first appearances Early Cretaceous extinctions Fossil taxa described in 1847 Osteoglossomorpha Prehistoric ray-finned fish genera