   #copyright

Sauropsid

2007 Schools Wikipedia Selection. Related subjects: Insects, Reptiles and
Fish

   iSauropsid

                  Fossil range: Late Carboniferous - Recent

   Eastern Water dragon, Physignathus lesueurii
   Eastern Water dragon, Physignathus lesueurii
                  Scientific classification

   Kingdom:    Animalia
   Phylum:     Chordata
   Subphylum:  Vertebrata
   Superclass: Tetrapoda
   (unranked)  Amniota
   Class:      Sauropsida/ Reptilia

               Goodrich,  1916

                                   Clades

   see text

   Sauropsids are a diverse group of mostly egg-laying vertebrate animals.
   The Sauropsida includes all modern and most extinct " reptiles", but
   excludes synapsids. Living sauropsids include lizards, snakes, turtles,
   crocodiles, and birds. Extinct sauropsids include non- avian dinosaurs,
   pterosaurs, plesiosaurs, ichthyosaurs, and many others.

History of the Term "Sauropsida"

   The terms "Sauropsida" ("Lizard Faces") and " Theropsida" ("Beast
   Faces") were coined in 1916 by E.S. Goodrich to distinguish between
   lizards, birds, and their relatives on one hand (Sauropsida) and
   mammals and their extinct relatives (Theropsida) on the other. This
   division is supported by the nature of the hearts and blood vessels in
   each group, and other features such as the structure of the forebrain.
   According to Goodrich both lineages evolved from an earlier stem group,
   the Protosauria ("First Lizards") which included some Paleozoic
   amphibians as well as early reptiles.

   In 1956 D.M.S. Watson observed that the first two groups diverged very
   early in reptilian history, and so he divided Goodrich's Protosauria
   among them. He also reinterpreted the Sauropsida and Theropsida to
   exclude birds and mammals respectively. Thus his Sauropsida included
   Procolophonia, Eosuchia, Millerosauria, Chelonia (turtles), Squamata
   (lizards and snakes), Rhynchocephalia, Crocodilia, " thecodonts" (
   paraphyletic basal Archosauria), non- avian dinosaurs, pterosaurs,
   ichthyosaurs, and sauropyterygians.

   This classification supplemented, but was never as popular as, the
   classification of the reptiles (according to Romer's classic Vertebrate
   Paleontology) into four subclasses according to the positioning of
   temporal fenestrae, openings in the sides of the skull behind the eyes.
   Those divisions were:
     * Anapsida - no fenestrae
     * Synapsida - one low fenestra (beneath the postorbital and squamosal
       bones)
     * Euryapsida - one high fenestra (above the postorbital and
       squamosal)
     * Diapsida - two fenestrae

   All of the above but Synapsida fall under Sauropsida.

Sauropsida versus Reptilia

   In the current cladistic system, the Linnean classification of the
   Class Reptilia into four subclasses has been replaced. Euryapsida is
   variously considered a subgroup of Diapsida or rejected altogether.
   Reptilia is often considered a clade including the most recent common
   ancestor of Crocodylia, Squamata, Rhynchocephalia, and Chelonia, plus
   all descendants of that ancestor. (Controversially, this includes birds
   and excludes all synapsids.) Clade Sauropsida includes all amniotes
   sharing more recent ancestry with Clade Reptilia than with Mammalia.
   The term "Theropsida" is usually replaced by Synapsida, which now
   refers to both the old subclass Synapsida plus the mammals.

   Anapsids are generally thought to reflect the ancestral amniote
   condition. If so, they might not form a natural group, but might simply
   be a paraphyletic assemblage of primitive amniotes. It is also possible
   that some anapsids (notoriously turtles) are actually diapsids that
   lost their temporal fenestrae secondarily, which would make the group
   polyphyletic.

   In the 2004 edition of his textbook, Michael J. Benton uses the term
   "Class Sauropsida" to refer to all non-synapsid, non- avian amniotes,
   although most systematists would include Aves ( birds), as in the
   original sense of the taxon.

Taxonomy

   Amniote systematics is still being researched, with many issues still
   disputed (notably the origins of turtles and of snakes, respectively).
   This scheme should be seen as provisional.

   Amniota
     * CLASS SAUROPSIDA
          + Subclass Anapsida (= Parareptilia)
               o Family Mesosauridae (Extinct)
               o Family Millerettidae (Extinct)
               o Family Bolosauridae (Extinct)
               o Order Procolophonomorpha
                    # Suborder Procolophonia
                         @ Family Procolophonidae (Extinct)
                         @ Family Pareiasauridae (Extinct)
               o Order Testudines ( Chelonia) (turtles)
          + unranked Eureptilia
               o Family Captorhinidae (Extinct)
               o Family Protorothyrididae (Extinct)
               o Subclass Diapsida
                    # Order Araeoscelidia (Extinct)
                    # Order Avicephala ("monkey lizards" and relatives)
                      (Extinct)
                    # Family Weigeltisauridae (Extinct)
                    # Order Younginiformes (Extinct)
                    # Superorder Ichthyopterygia ("fish lizards")
                      (Extinct)
                    # Infraclass Lepidosauromorpha
                         @ Superorder Sauropterygia (Extinct)
                              - Order Placodontia (Extinct)
                              - Order Nothosauroidea (Extinct)
                              - Order Plesiosauria (Extinct)
                         @ Superorder Lepidosauria
                              - Order Sphenodontida (tuatara)
                              - Order Squamata (lizards and snakes)
                    # Infraclass Archosauromorpha
                         @ Order Choristodera (Extinct)
                         @ Family Trilophosauridae (Extinct)
                         @ Family Rhynchosauridae ("beaked lizards")
                           (Extinct)
                         @ Order Prolacertiformes (Extinct)
                         @ unranked Archosauriformes (includes "
                           Thecodontia")
                              - Family Proterosuchidae (Extinct)
                              - Family Erythrosuchidae (Extinct)
                              - Family Euparkeriidae (Extinct)
                              - Division Archosauria
                                   = unranked Crurotarsi
                                   * Family Phytosauridae (Extinct)
                                   * Family Ornithosuchidae (Extinct)
                                   * Family Prestosuchidae (" Rauisuchia"
                                     in part) (Extinct)
                                   * Family Stagonolepididae (Extinct)
                                   * Family Rauisuchidae ("Rauisuchia" in
                                     part) (Extinct)
                                   * Family Poposauridae ("Rauisuchia" in
                                     part) (Extinct)
                                   * Superorder Crocodylomorpha
                                   + Family Saltoposuchidae (Extinct)
                                   + Family Sphenosuchidae (Extinct)
                                   + Order Crocodylia (crocodiles and
                                     relatives)
                                   = unranked Ornithodira
                                   * Scleromochlus (Extinct)
                                   * Order Pterosauria (flying reptiles)
                                     (Extinct)
                                   + Suborder Rhamphorhynchoidea
                                   + Suborder Pterodactyloidea
                                   * Dinosauriformes
                                   + Lagerpeton (Extinct)
                                   + Marasuchus (Extinct)
                                   + Superorder Dinosauria
                                   o Order Saurischia
                                   # Family Herrerasauridae (Extinct)
                                   # Suborder Theropoda
                                   @ Class AVES (birds)
                                   # Suborder Sauropodomorpha (Extinct)
                                   o Order Ornithischia (Extinct)

   Retrieved from " http://en.wikipedia.org/wiki/Sauropsid"
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   with only minor checks and changes (see www.wikipedia.org for details
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