'Diapsids' ("two arches") are a group of
tetrapod animals that developed two holes (
temporal fenestra) in each side of their
skulls, about 300
million years ago during the late
Carboniferous period. Living diapsids are extremely diverse, and include all
birds,
crocodiles,
lizards,
snakes,
tuatara, and possibly even
turtles. While some lost either one hole (lizards), or both holes (snakes), or even have a much more restructured skull (modern birds), they are still
classified as diapsids based on their ancestry. There are 14,600
species of diapsid existing in environments around the world today, including most
flying and
venomous
vertebrates.
The ancestral openings are above and below the eye. This arrangement allows for the attachment of larger, stronger, jaw muscles and enables the jaw to open more widely. A more obscure ancestral characteristic is a relatively long lower arm bone (
radius), compared to the upper arm bone (
humerus). Extinct groups include the
dinosaurs,
pterosaurs,
plesiosaurs,
mosasaurs, and many more obscure lineages. The classification of most of the early groups is fluid and subject to change.
Taxonomy
Classification
★ 'Subclass DIAPSIDA'
★
★ Order
Araeoscelidia
★
★ Order
Avicephala
★
★ Order
Younginiformes
★
★ Superorder
Ichthyopterygia (
ichthyosaurs)
★
★ 'Infraclass
Lepidosauromorpha'
★
★
★ Order
Eolacertilia
★
★
★ Superorder
Lepidosauria (
tuatara,
lizards,
amphisbaenians and
snakes)
★
★
★ Superorder
Sauropterygia (
plesiosaurs)
★
★ 'Infraclass
Archosauromorpha'
★
★
★ Order
Aetosauria
★
★
★ Order
Choristodera
★
★
★ Order
Phytosauria
★
★
★ Order
Prolacertiformes
★
★
★ Order
Pterosauria (pterosaurs)
★
★
★ Order
Rauisuchia
★
★
★ Order
Rhynchosauria
★
★
★ Order
Trilophosauria
★
★
★ Superorder
Crocodylomorpha (
crocodiles and extinct relatives)
★
★
★ Superorder
Dinosauria (
dinosaurs)
Phylogeny
'Diapsida'
|--
Araeoscelida
|-?''
Sphodrosaurus''
|-?''
Palacrodon''
|-?''
Omphalosaurus''
`--+--
Avicephala
`--
Neodiapsida
|--''
Apsisaurus''
`--
Eosuchia
|-?
Younginiformes
`--+-?''
Claudiosaurus''
|-?
Ichthyopterygia
`--
Sauria
|-?
Thalattosauriformes
|--
Lepidosauromorpha
`--
Archosauromorpha
See also
★
Vertebrate paleontology
★
Synapsida
★
Anapsida
External links
★
Diapsida. Michel Laurin and Jacques A. Gauthier. ''Tree of Life Web Project''. June 22, 2000.
★
Diapsida Cladogram at
Mikko's Phylogeny Archive