''Pythonichthys'' is a genus of

eels Eels are ray-finned fish belonging to the order (biology), order Anguilliformes (), which consists of eight suborders, 20 Family (biology), families, 164 genus, genera, and about 1000 species. Eels undergo considerable development from the earl ...

of the family

Heterenchelyidae The Heterenchelyidae or mud eels are a small family of eels native to the Atlantic, Mediterranean, and eastern Pacific. Heterenchelyids are bottom-dwelling fish adapted to burrowing into soft mud. They have large mouths and no pectoral fins, and ...

that occur in tropical waters of the eastern

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...

off of

Panama Panama, officially the Republic of Panama, is a country in Latin America at the southern end of Central America, bordering South America. It is bordered by Costa Rica to the west, Colombia to the southeast, the Caribbean Sea to the north, and ...

and in the

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

near the

Caribbean Sea The Caribbean Sea is a sea of the Atlantic Ocean, North Atlantic Ocean in the tropics of the Western Hemisphere, located south of the Gulf of Mexico and southwest of the Sargasso Sea. It is bounded by the Greater Antilles to the north from Cuba ...

and the west coast of

Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

. It contains the following described species: * '' Pythonichthys asodes'' Rosenblatt & Rubinoff, 1972 (Pacific mud eel) * '' Pythonichthys macrurus'' ( Regan, 1912) (Long-tailed short-faced eel) * '' Pythonichthys microphthalmus'' ( Regan, 1912) (Short-tailed short-faced eel) * '' Pythonichthys sanguineus'' Poey, 1868 (no common name) In addition, the fossil species '' Pythonichthys arkansasensis'' Schwarzhans & Stringer, 2020 is known by

otoliths An otolith (, ' ear + , ', a stone), also called otoconium, statolith, or statoconium, is a calcium carbonate structure in the saccule or utricle of the inner ear, specifically in the vestibular system of vertebrates. The saccule and utricle, i ...

from the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...

(

Maastrichtian The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (geology), age (uppermost stage (stratigraphy), stage) of the Late Cretaceous epoch (geology), Epoch or Upper Cretaceous series (s ...

) and

Early Paleocene The Danian is the oldest age (geology), age or lowest stage (stratigraphy), stage of the Paleocene Epoch or series (stratigraphy), Series, of the Paleogene Period or system (stratigraphy), System, and of the Cenozoic Era or Erathem. The beginnin ...

Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...

and

Arkansas Arkansas ( ) is a landlocked state in the West South Central region of the Southern United States. It borders Missouri to the north, Tennessee and Mississippi to the east, Louisiana to the south, Texas to the southwest, and Oklahoma ...

, USA. Its fossils are very common in formations shortly after the Cretaceous-Paleogene extinction event, suggesting that it was a

disaster taxon A disaster is an event that causes serious harm to people, buildings, economies, or the environment, and the affected community cannot handle it alone. ''Natural disasters'' like avalanches, floods, earthquakes, and wildfires are caused by natur ...

that thrived in the wake of the extinction.

References

* Eels Heterenchelyidae {{Anguilliformes-stub Extant Maastrichtian first appearances