   #copyright

Saurischia

2007 Schools Wikipedia Selection. Related subjects: Dinosaurs

   iSaurischian dinosaurs

               Fossil range: Triassic - Cretaceous (non-avian)

   Saurischian pelvic structure (left side)
   Saurischian pelvic structure (left side)
                   Scientific classification

   Kingdom:    Animalia
   Phylum:     Chordata
   Class:      Sauropsida
   Superorder: Dinosauria
   Order:      Saurischia
               Seeley, 1887

                                  Suborders

     * Theropoda
     * Sauropodomorpha

   Tyrannosaurus rex saurischian pelvis and hind limbs (left side), taken
   at the Oxford University Museum of Natural History.
   Enlarge
   Tyrannosaurus rex saurischian pelvis and hind limbs (left side), taken
   at the Oxford University Museum of Natural History.

   Saurischians (from the Greek sauros (σαυρος) meaning 'lizard' and
   ischion (ισχιον) meaning 'hip joint') are one of the two
   orders/branches of dinosaurs. In 1888, Harry Seeley classified
   dinosaurs into two great orders, based on their hip structure.
   Saurischians ('lizard-hipped') are distinguished from the
   Ornithischians ('bird-hipped') by retaining the ancestral configuration
   of bones in the hip. All carnivorous dinosaurs (the theropods) are
   saurischians, as are one of the two great lineages of herbivorous
   dinosaurs, the sauropodomorphs. At the end of the Cretaceous Period,
   all non- avian Saurischians became extinct. This is referred to as the
   Cretaceous-Tertiary extinction event.

   The Saurischians were differentiated from the Ornithischians in the
   Late Triassic Period. They had a three-pronged pelvic structure. The
   Ornithischians evolved a new hip structure, with the pubis rotating
   caudally, to become parallel with the ischium, often also with a
   forward-pointing process, giving a four-pronged structure. This hip
   structure is similar to that of birds, and so Ornithischians are termed
   'bird-hipped' dinosaurs, while the Saurischians are 'lizard-hipped'.
   Ironically, the true bird-hip possessed by modern birds evolved from
   the lizard-hipped theropods in the Jurassic Period, an example of
   convergent evolution.

   While Seeley's classification has stood the test of time, there is a
   minority theory, first popularized by Robert Bakker in The Dinosaur
   Heresies that separates the theropods into their own group and places
   the two great groups of herbivorous dinosaurs (the sauropodomorphs and
   ornithischians) together in a separate group named as the
   Phytodinosauria ('plant dinosaurs') (Bakker), or Ornithischiformes
   (Cooper).

Taxonomy

     * Superorder Dinosauria
          + ORDER SAURISCHIA
               o  ? Eoraptor
               o  ? Herrerasauria
               o Guaibasaurus
               o Suborder Sauropodomorpha
                    # Saturnalia (dinosaur)
                    # Thecodontosaurus
                    # Infraorder Prosauropoda
                    # Infraorder Sauropoda
               o Suborder Theropoda
                    # Superfamily Coelophysoidea
                    # Infraorder Ceratosauria
                    # Tetanurae
                         @ Superfamily Megalosauroidea
                         @ Infraorder Carnosauria
                         @ Infraorder Coelurosauria

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