The Caenophidia are a derived
clade
In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...
of
alethinophidian snakes
Snakes are elongated Limbless vertebrate, limbless reptiles of the suborder Serpentes (). Cladistically Squamata, squamates, snakes are ectothermic, amniote vertebrates covered in overlapping Scale (zoology), scales much like other members of ...
, which contains over 80% of all the extant species of snakes.
The largest family is
Colubridae
Colubridae (, commonly known as colubrids , from , 'snake') is a family of snakes. With 249 genera, it is the largest snake family. The earliest fossil species of the family date back to the Late Eocene epoch, with earlier origins suspected. C ...
, but it also includes at least seven other families,
at least four of which were once classified as "Colubridae" before molecular phylogenetics helped us understand their relationships. It has been found to be
monophyletic
In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria:
# the grouping contains its own most recent co ...
.
Although the Caenophidia previously was held to exclude
Acrochordidae
The Acrochordidae, commonly known as wart snakes, Java wart snakes, file snakes, elephant trunk snakes, or dogface snakes are a monogeneric Family (biology), family created for the genus ''Acrochordus''. This is a group of basal aquatic snakes fo ...
, researchers have recognized that acrochordids share several traits with the other caenophidians.
Hence Caenophidia is usually considered to comprise Acrochordidae plus the more derived snakes classified as Colubroidea. Recent molecular studies have also found the families
Xenophidiidae
''Xenophidion'' is a genus of snakes first described in 1995, and the only genus of the monotypic family Xenophidiidae.. Commonly referred to as spinejaw snakes, this genus is found in Borneo and peninsular Malaysia.
Morphology and classificat ...
and
Bolyeriidae to be closely related to caenophidians, forming the sister group to Caenophidia rather than being part of
Henophidia.
Below is a phylogeny of the Caenophidia based on analyses from several studies:
References
Alethinophidia
Extant Santonian first appearances
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