A phylogenetic overview of the extant groups, note that the tree only indicates relationships not evolutionary branching times. |
All modern snakes are grouped within the
suborder Serpentes in
Linnean taxonomy, part of the
order Squamata, though their precise placement within
squamates is controversial.
There are two
infraorders of
Serpentes:
Alethinophidia and
Scolecophidia.
This separation is based on
morphological characteristics and
mitochondrial DNA sequence similarity. Alethinophidia is sometimes split into
Henophidia and
Caenophidia, with the latter consisting of "Colubroid" snakes (colubrids, vipers, elapids, hydrophiids, and attractaspids) and acrochordids, while the other alethinophidian families comprise Henophidia
. While not extant today, the
Madtsoiidae, a family of giant, primitive, python-like snakes, was around until 50,000 years ago in
Australia, represented by genera such as
Wonambi.
There are numerous debates in the systematics within the group. For instance, many sources classify
Boidae and
Pythonidae as one family, while some keep the
Elapidae and
Hydrophiidae, separate for practical reasons despite their extremely close relation.
Recent molecular studies support the monophyly of the clades of modern snakes, scolecophidians, typhlopids + anomalepidids, alethinophidians, core alethinophidians, uropeltids (
Cylindrophis,
Anomochilus, uropeltines), macrostomatans, booids, boids, pythonids and caenophidians.
No comments:
Post a Comment