''Pterosphenus'' is an extinct genus of marine

snake Snakes are elongated limbless reptiles of the suborder Serpentes (). Cladistically squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales much like other members of the group. Many species of snakes have s ...

of the

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

period.

Classification

''Pterosphenus'' belong to the

Alethinophidia :''Common names: advanced snakes.'' The Alethinophidia are an infraorder of snakes that includes all snakes other than blind snakes and thread snakes. Snakes have long been grouped into families within Alethinophidia based on their morphology, e ...

snakes, a clade which includes all snakes outside of blind and thread snakes, and more specifically to the extinct

Palaeophiidae Palaeophiidae is an extinct family of marine snake within the infraorder Alethinophidia. Species within this family lived from the Late Cretaceous to the Late Eocene, approximately from 70.6 to 33.9 million years ago.Palaeophis ''Palaeophis'' ('ancient snake') is an extinct genus of marine snake that is the type genus of the extinct snake family Palaeophiidae. Described species within this genus lived in the Eocene epoch, with some unnamed or questionable records from ...

'', of which both belong to the subfamily Palaeophiinae. Five species are known, ''P. schucherti'' from North America, ''P. sheppardi'' from South America, ''P. schweinfurthi'' from northern Africa and ''P. biswasi'', and ''P. kutchensis'' from Asia.

Description

While only known from partial remains, enough has been found of ''Pterosphenus'' to suggest it was a large reptile. Based on the regression model used to estimate the length of

boids Boids is an artificial life program, developed by Craig Reynolds in 1986, which simulates the flocking behaviour of birds, and related group motion. His paper on this topic was published in 1987 in the proceedings of the ACM SIGGRAPH confere ...

, the most reliable length estimate lies between ; the largest vertebra may have belonged to an individual reaching in length. Its body was strongly laterally compressed as an adaptation to pelagic life. Pterosphenus schweinfurthi vertebra

Palaeoenvironment and Palaeoecology

A marine ocean dweller, ''Pterosphenus'' lived in the shallow seas of the future eastern US (fossils are known from

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 ...

Louisiana Louisiana ( ; ; ) is a state in the Deep South and South Central regions of the United States. It borders Texas to the west, Arkansas to the north, and Mississippi to the east. Of the 50 U.S. states, it ranks 31st in area and 25 ...

Mississippi Mississippi ( ) is a U.S. state, state in the Southeastern United States, Southeastern and Deep South regions of the United States. It borders Tennessee to the north, Alabama to the east, the Gulf of Mexico to the south, Louisiana to the s ...

, 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 ...

and up north to

New Jersey New Jersey is a U.S. state, state located in both the Mid-Atlantic States, Mid-Atlantic and Northeastern United States, Northeastern regions of the United States. Located at the geographic hub of the urban area, heavily urbanized Northeas ...

), Africa in the

Tethys Ocean The Tethys Ocean ( ; ), also called the Tethys Sea or the Neo-Tethys, was a prehistoric ocean during much of the Mesozoic Era and early-mid Cenozoic Era. It was the predecessor to the modern Indian Ocean, the Mediterranean Sea, and the Eurasia ...

(fossils are known from

Morocco Morocco, officially the Kingdom of Morocco, is a country in the Maghreb region of North Africa. It has coastlines on the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to Algeria–Morocc ...

Libya Libya, officially the State of Libya, is a country in the Maghreb region of North Africa. It borders the Mediterranean Sea to the north, Egypt to Egypt–Libya border, the east, Sudan to Libya–Sudan border, the southeast, Chad to Chad–L ...

Nigeria Nigeria, officially the Federal Republic of Nigeria, is a country in West Africa. It is situated between the Sahel to the north and the Gulf of Guinea in the Atlantic Ocean to the south. It covers an area of . With Demographics of Nigeria, ...

, and

Egypt Egypt ( , ), officially the Arab Republic of Egypt, is a country spanning the Northeast Africa, northeast corner of Africa and Western Asia, southwest corner of Asia via the Sinai Peninsula. It is bordered by the Mediterranean Sea to northe ...

), South America (fossils are known from

Ecuador Ecuador, officially the Republic of Ecuador, is a country in northwestern South America, bordered by Colombia on the north, Peru on the east and south, and the Pacific Ocean on the west. It also includes the Galápagos Province which contain ...

) and southern Asia (fossils are known from

India India, officially the Republic of India, 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 by population (United Nations), most populous country since ...

). Pterosphenus was a top predator of the ecosystem, likely preying on fish and molluscs found in the same area. It is certain that ''Pterosphenus'' would have encountered basal

cetacea Cetacea (; , ) is an infraorder of aquatic mammals belonging to the order Artiodactyla that includes whales, dolphins and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively c ...

ns of the time like ''

Zygorhiza ''Zygorhiza'' ("Yoke-Root") is an extinct genus of basilosaurid early whale known from the Late Eocene (Priabonian, 38–34 Ma) of Louisiana, Alabama, and Mississippi, United States, and the Bartonian (43–37 Ma on the New Zealand geologic tim ...

'', ''

Dorudon ''Dorudon'' ("spear-tooth") is a genus of extinct basilosaurid ancient whales that lived alongside ''Basilosaurus'' 41.03 to 33.9 million years ago in the Eocene. It was a small whale, with ''D. atrox'' measuring long and weighing . ''Dorudon'' ...

'', and ''

Basilosaurus ''Basilosaurus'' (meaning "king lizard") is a genus of large, predatory, prehistoric archaeocete whale from the late Eocene, approximately 41.3 to 33.9 million years ago (mya). First described in 1834, it was the first archaeocete and prehisto ...

'', though its likely a mixed of

niche partitioning In ecology, a niche is the match of a species to a specific environmental condition. Three variants of ecological niche are described by It describes how an organism or population responds to the distribution of resources and competitors (for e ...

and living in different areas in the case of ''Basilosaurus'' (which lived in estuary ecosystems according to recent finds) would prevent competition between the species.

References

Extinct reptiles Sea snakes Eocene reptiles of Africa Eocene reptiles of North America Eocene reptiles of Asia Eocene reptiles of South America {{paleo-snake-stub