Alethinophidia

Alethinophidia; Temporal range: 94–0 Ma PreꞒ Ꞓ O S D C P T J K Pg N Cenomanian to Present
	Grass snake, Natrix natrix
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Squamata
Suborder:	Serpentes
Infraorder:	Alethinophidia; Nopcsa, 1923
Subclades
	Afrophidia; Amerophidia;

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, especially that of their teeth. More modern phylogenetic hypotheses using genetic data^[2]^[3]^[4]^[5]^[6]^[7]^[8]^[9]^[10]^[11]^{[excessive citations]} support the recognition of 19 extant families (see below), although the taxonomy of alethinophidian snakes has long been debated, and ultimately the decision whether to assign a particular clade to a particular Linnaean rank (such as a superfamily, family, or subfamily) is arbitrary.

Etymology

The infraorder name Alethinophidia derives from the two Ancient Greek words ἀληθινός (alēthinós), meaning "truthful, genuine", and ὄφις (óphis), meaning "snake".^[12]^[13]

Fossil record

Fossils of alethinophidians were found in Cenomanian (Middle Cretaceous) sites of Wadi Milk Formation in Wadi Abu Hashim, Sudan.^[1] Coniophis presents the vertebral morphology similar to modern-day Aniliidae. Two extinct families from the same location, the Anomalophiidae and Russellophiidae, also belong to the Alethinophidia. Krebsophis is the earliest russellophiid. The family Nigerophiidae includes both aquatic^[1] Nubianophis from Wadi Abu Hashim and Nigerophis from the Palaeocene of Niger. The genus Eoanilius (belongs to Aniliidae) appeared in the Eocene. It is also existed in Oligocene and early Miocene.^[1] The extinct marine Simoliophidae are known from the Cenomanian of North Africa, the Middle East, and Eastern Europe, indicating a Tethyan distribution; they are notable for preserving evidence of vestigial hindlimbs.^[14]

Systematics

Extant taxa

Superfamily Amerophidia
- Family: Aniliidae Stejneger, 1907—red pipesnake
- Family: Tropidophiidae Brongersma, 1951—Caribbean dwarf "boas" or thunder snakes
Superfamily Booidea
- Family: Boidae Gray, 1825—boas (see article for comments on former families or subfamilies Calabariidae/inae, Sanziniidae/inae, Charinidae/inae, Erycidae/inae, Candoiidae/inae)
Superfamily Pythonoidea
- Family: Pythonidae Fitzinger, 1826—pythons
- Family: Loxocemidae Cope, 1861—Mexican burrowing pythons
- Family: Xenopeltidae Bonaparte, 1845—sunbeam snakes
Superfamily Uropeltoidea
- Family: Uropeltidae Müller, 1832—shield-tailed snakes
- Family: Cylindrophiidae Fitzinger, 1843—Asian pipe snakes
- Family: Anomochilidae Cundall, Wallach and Rossman, 1993—dwarf pipe snakes
Family: Bolyeriidae Hoffstetter, 1946—Splitjaw snakes
Family: Xenophidiidae Wallach & Günther, 1998—Spine-jawed snakes
Family: Acrochordidae Bonaparte, 1831—wart or file snakes
Family: Xenodermidae Oppel, 1811—odd-scaled snakes
Family: Pareidae Oppel, 1811—snail-eating snakes
Family: Viperidae Oppel, 1811—vipers (including pit vipers)
- Subfamily: Azemiopinae Liem, Marx and Rabb, 1971—Fea's viper
- Subfamily: Crotalinae Oppel, 1811—pitvipers (including rattlesnakes)
- Subfamily: Viperinae Oppel, 1811—true vipers
Family: Homalopsidae Günther, 1864—Asian mudsnakes
Superfamily: Elapoidea F. Boie, 1827 (merged with Colubroidea by the Reptile Database)^[15]
- Family: Cyclocoridae Weinell & Brown, 2017—Philippine snakes
- Family: Micrelapidae Das et al., 2023—two-headed snakes
- Family: Elapidae F. Boie, 1827—Cobras, coral snakes, mambas, taipans, sea snakes, and others
- Family: Pseudaspididae Cope, 1893—mole snake, western keeled snake, and mock vipers
- Family: Prosymnidae Gray, 1849—shovel-snouted snakes
- Family: Psammophiidae Dowling, 1967—sand snakes and allies
- Family: Atractaspididae Günther, 1858—African burrowing asps, stiletto snakes, harlequin snakes
- Family: Pseudoxyrhophiidae Dowling, 1975—Malagasy hognose snakes, brook snakes, and allies
- Family: Lamprophiidae Fitzinger, 1843—lamprophiids
Superfamily: Colubroidea Oppel, 1811
- Family: Colubridae Oppel, 1811—colubrids, typical snakes (subfamilies sometimes considered distinct families)
  - Subfamily: Sibynophiinae Dunn, 1928—hinged-teeth snakes
  - Subfamily: Natricinae Bonaparte, 1838—keelbacks
  - Subfamily: Pseudoxenodontinae McDowell, 1987
  - Subfamily: Dipsadinae Bonaparte, 1838