Colubridae is a family of snakes. With 249 genera, it is the largest snake family. The earliest species of the family date back to the Oligocene epoch. Colubrid snakes are found on every continent except Antarctica.
Squamata is the largest order of reptiles, comprising lizards, snakes, and amphisbaenians, which are collectively known as squamates or scaled reptiles. With over 11,500 species, it is also the second-largest order of extant (living) vertebrates, after the perciform fish. Members of the order are distinguished by their skins, which bear horny scales or shields, and must periodically engage in molting. They also possess movable quadrate bones, making possible movement of the upper jaw relative to the neurocranium. This is particularly visible in snakes, which are able to open their mouths very wide to accommodate comparatively large prey. Squamates are the most variably sized living reptiles, ranging from the 16 mm (0.63 in) dwarf gecko to the 6.5 m (21 ft) reticulated python. The now-extinct mosasaurs reached lengths over 14 m (46 ft).
Toxicofera is a proposed clade of scaled reptiles (squamates) that includes the Serpentes (snakes), Anguimorpha and Iguania. Toxicofera contains about 4,600 species, of extant Squamata. It encompasses all venomous reptile species, as well as numerous related non-venomous species. There is little morphological evidence to support this grouping; however, it has been recovered by all molecular analyses as of 2012.
Pantherophis is a genus of nonvenomous colubrid snakes endemic to central and eastern regions of North America. It consists of the North American ratsnakes, the foxsnakes, and the cornsnakes. The genus, which contains 10 recognized species, first appeared in the fossil record in the Middle Miocene around 16.3 million years ago. They are a large terrestrial snake genus that lack subocular scales. Originally classified in the genus Elaphe, phylogenetic studies have found this taxon to be closely related to Pituophis. As with all snakes Pantherophis is an obligate faunivore with a diet that consists of small mammals, birds, reptiles and amphibians, and even insects. While many species conservation status is categorized as "least concern", many local populations in some species have declined where some places have them listed as federally protected. The corn snake is a popular pet reptile, due to the availability of captive-bred animals, their low maintenance and calm disposition, and the variety of color morphs. There are other species of Pantherophis that are in the pet trade, though are not as popular as the corn snake.
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 support the recognition of 19 extant families, 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 is arbitrary.
The Polychrotidae family of iguanian lizards contains the living genus Polychrus and the extinct genus Afairiguana. The family Polychrotidae was once thought to encompass all anoles, including those in the genus Anolis. Studies of the evolutionary relationships of anoles based on molecular information has shown that Polychrus is not closely related to Anolis, but instead closer to Hoplocercidae. It is therefore not part of Dactyloidae and instead is treated as the family, Polychrotidae.
The Lamprophiidae are a family of snakes found throughout much of Africa, including the Seychelles. There are 89 species as of July 2022.
Colubroidea is a superfamily of snakes in the clade Colubroides that includes Colubridae, with some studies splitting Colubridae into multiple families that make up Colubroidea. Historically, Colubroidea also included other caenophidian snakes such as cobras and vipers, as these snakes form a clade. However these groups are now divided into several distinct, but related, families. Zaher et al. (2009) proposed to redefine Colubroidea for colubrids and related families, while designating Colubroides as the group containing vipers and cobras as well as colubroids. The ReptileDatabase considers Colubroidea to be composed of Colubridae and the members of its sister group, Elapoidea, and does not recognize the division of Colubridae into multiple families.
Venom in snakes and some lizards is a form of saliva that has been modified into venom over its evolutionary history. In snakes, venom has evolved to kill or subdue prey, as well as to perform other diet-related functions. While snakes occasionally use their venom in self defense, this is not believed to have had a strong effect on venom evolution. The evolution of venom is thought to be responsible for the enormous expansion of snakes across the globe.
Dipsadinae is a large subfamily of colubroid snakes, sometimes referred to as a family (Dipsadidae). They are found in most of the Americas, including the West Indies, and are most diverse in South America. There are more than 700 species.
Pseudoxenodontinae is a small subfamily of colubroid snakes, sometimes referred to as a family (Pseudoxenodontidae). They are found in southern and southeastern Asia, from northeast India to southern China and south into Indonesia as far east as Wallace's Line. There are 10 species in 2 genera. Most are very poorly known, such that Pseudoxenodontinae is one of the most poorly known groups of snakes.
Acrodonta are a subclade of iguanian squamates consisting almost entirely of Old World taxa. Extant representation include the families Chamaeleonidae (chameleons) and Agamidae, with at least over 500 species described. A fossil genus, Gueragama, was found in Brazil, making it the only known American representative of the group.
Lamprophiinae is a subfamily of lamprophiid snakes, a large group of mostly African snakes, most of which were formerly classified as colubrids but which we now know are actually more closely related to elapids.
Lampropeltini is a tribe of colubrid snake endemic to New World. These include the kingsnakes, milk snake, corn snake, gopher snakes, pine snakes, and bullsnakes. At least 51 species have been recognized and the group have been heavily studied for biogeography, morphology, ecology, and phylogenetics. The internal relationships among the genera has been disputed, but generally the most supported placement of the genera are as follows:
Neoanguimorpha is a clade of anguimorphs comprising Monstersauria and Diploglossa. Morphological studies in the past had classified helodermatids with the varanoids in the clade Platynota, while the Chinese crocodile lizard was classified as a xenosaurid. However molecular work found no support in these groupings and instead has found the helodermatids more related to Diploglossa, while the Chinese crocodile lizard and varanoids to form the clade Paleoanguimorpha.
Paleoanguimorpha is a clade of anguimorphs comprising Shinisauria and Goannasauria. Morphological studies in the past also classified helodermatids and pythonomorphs with the varanoids in the clade Platynota, while the Chinese crocodile lizard was classified as a xenosaurid. Current molecular work finds no support in these groupings and instead has found the helodermatids more related to Diploglossa in the sister clade Neoanguimorpha, while the Chinese crocodile lizard is the closet living relative to varanoids. Pythonomorphs represented by snakes today are not closely related to varanoids and are instead a sister lineage to Anguimorpha and Iguania in the clade Toxicofera.
Diploglossa is a clade of neoanguimorphs represented by the families Xenosauridae, Diploglossidae, Anniellidae and Anguidae, the latter three placed in the superfamily Anguioidea. In the past the Chinese crocodile lizard was classified as a xenosaurid; current molecular work has shown evidence the species related to varanoids in the clade Paleoanguimorpha.
The Colubroides are a clade in the suborder Serpentes (snakes). It contains over 85% of all the extant species of snakes. The largest family is Colubridae, but it also includes at least six other families, at least four of which were once classified as "Colubridae" before molecular phylogenetics helped in understanding their relationships. It has been found to be monophyletic.
Afrophidia is a clade of alethinophidian snakes comprising the groups Henophidia and Caenophidia, essentially making up the snakes people commonly associate with. The name refers to the deep split between Afrophidia and their sister taxon, Amerophidia, which originated in South American origin, and the afrophidians was recently hypothesized to represent a vicariant event of the breakup of Gondwanan South America and Africa.
The Elapoidea are a superfamily of snakes in the clade Colubroides, traditionally comprising the families Lamprophiidae and Elapidae. Advanced genomic sequence studies, however, have found lamprophiids to be paraphyletic in respect to elapids, and anywhere between four and nine families are now recognized.
