SAUROPSIDA
CLASSIFICATION
Animalia: Vertebrata: Tetrapoda
CLADOGRAM:
—Sauropsida “lizard faces”
`–Reptilia Linnaeus sensu Gauthier, 1984 “creepers”
|–Romeriida “Romer’s taxon” =Eureptilia
| |?-Batropetidae *
| |?-Bolosauridae *
| |–Captorhinidae *
| `–+–Protorothyrididae *
| `–Diapsida “two apses” (two temporal fenestrae, at least primitively)
| | INCERTAE SEDIS:
| | Longisquama *
| |?-Endennasauridae *
| |?-Mesenosauridae *
| |–Araeoscelida *
| | |–Araeoscelidae *
| | `–Petrolacosauridae *
| `–Neodiapsida “new diapsids”
| | INCERTAE SEDIS:
| | +–Lazarussaurus *
| | `–Choristodera =Champsosauria *
| | |–Cteniogenys *
| | `–Neochoristodera *
| | |–Champsosauridae *
| | `–Simedosauridae *
| |–Coelurosauravidae *
| |?-Thalattosauria *
| | |–Askeptosauridae *
| | |–Claraziidae *
| | `–Thalattosauridae *
| `–Sauria “lizards”
| |?—>Ichthyopterygia
| |?—>Sauropterygia
| |—->Lepidosauromorpha
| `—->Archosauromorpha
`—->Anapsida
ESSAY
| Sauropsida is one of the two great lineages of amniote (the other being Synapsida, which includes Mammalia). All known sauropsids belong to the clade Reptilia. H ISTORY OF CLASSIFICATION:Reptilia was once a “grab-bag” taxon for every amniote that was neither a bird nor a mammal. It was divided into four sections based on the number and alignment of certain holes in the back of the skull (temporal fenestrae): Anapsida (no holes), Synapsida (a low hole), Euryapsida (a high hole), and Diapsida (two holes — includes dinosaurs). Reptilia has since been re-defined as a clade: all the descendants of the most recent common ancestor of the four living groups considered reptiles: Chelonia (turtles), Sphenodon (tuatara), Squamata (lizards and snakes), and Crocodylia (crocodiles and kin). This definition excludes some creatures once considered reptiles (Synapsida — formerly called “mammal-like reptiles”), and includes some creatures previously not considered reptilian Aves — birds). The groups Anapsida and Diapsida are still used as clades within Reptilia, slightly modified from their traditional meanings (Anapsida now excludes the most primitive sauropsids; Diapsida now includes birds). “Euryapsida”, which included marine reptiles such as ichthyosaurs and plesiosaurs, is now recognized as an unnatural grouping of various aberrant diapsid lineages which lost their lower temporal fenestrae. DOMINATION:The Mesozoic is often called “The Age of Reptiles” because of the reptilian dominance during most of that era. Dinosaurs ruled the land, pterosaurs ruled the skies, and a great variety of marine reptiles mosasaurs, plesiosaurs, ichthyosaurs, etc.) ruled the oceans. Most of these creatures died out in the K-T extinction (ichthyosaurs died out earlier; champsosaurs, a freshwater lineage, later). |
