   #copyright

Theropoda

2007 Schools Wikipedia Selection. Related subjects: Dinosaurs

        iTheropods

               Fossil range: Triassic - Cretaceous (non-avian)

   T. rex foot Picture taken at Field Museum of Natural History, Chicago
   T. rex foot
   Picture taken at Field Museum of Natural History, Chicago

                             Conservation status

   Extinct (fossil)
                         Scientific classification

   Kingdom:    Animalia
   Phylum:     Chordata
   Class:      Sauropsida
   Superorder: Dinosauria
   Order:      Saurischia
   Suborder:   Theropoda
               Marsh, 1881

                         Infraorders & Superfamilies

     * Coelophysoidea
     * Ceratosauria
          + Abelisauroidea
     * Megalosauroidea
     * Carnosauria
     * Coelurosauria
          + Tyrannosauroidea
          + Ornithomimosauria
          + Oviraptorosauria
          + Therizinosauria
          + Deinonychosauria

   Theropods ('beast foot') are a group of bipedal saurischian dinosaurs.
   Although they were primarily carnivorous, a number of theropod families
   evolved herbivory, during the Cretaceous Period. Theropods first appear
   during the Carnian age of the Late Triassic about 220 million years ago
   ( mya) and were the sole large terrestrial carnivores from the Early
   Jurassic until the close of the Cretaceous, about 65 million years ago.
   Today, they are represented by the 9,300 living species of birds, which
   evolved in the Late Jurassic from small specialized coelurosaurian
   dinosaurs.

   Among the features linking theropods to birds are the three-toed foot,
   a furcula (wishbone), air-filled bones and (in some cases) feathers and
   brooding of the eggs.

Evolutionary history

   During the late Triassic, a number of primitive proto-theropod and
   theropod dinosaurs existed and evolved alongside each other.

   The earliest and most primitive of the carnivorous dinosaurs were
   Eoraptor of Argentina and the herrerasaurs. The herrerasaurs existed
   from the early late Triassic (Late Carnian to Early Norian). They were
   found in North America and South America and possibly also India and
   Southern Africa. The herrerasaurs were characterised by a mosaic of
   primitive and advanced features. Some paleontologists have in the past
   considered the herrerasaurians to be members of Theropoda, though they
   are now thought to be basal saurischians, and may even have evolved
   prior to the saurischian-ornithischian split.

   The earliest and most primitive unambiguous theropods (or
   alternatively, Eutheropods - 'True Theropods') are the Coelophysidae.
   The Coelophysidae ( Coelophysis, Megapnosaurus) were a group of widely
   distributed, lightly built and apparently gregarious animals. They
   included small hunters like Coelophysis and larger (6 meters) predators
   like Dilophosaurus. These successful animals continued from the Late
   Carnian (early Late Triassic) through to the Toarcian (late Early
   Jurassic). Although in the early cladistic classifications they were
   included under the Ceratosauria and considered a side-branch of more
   advanced theropods (e.g. Rowe & Gauthier 1990), they may have been
   ancestral to all other theropods (which would make them a paraphyletic
   assemblage (e.g. Mortimor 2001, Carrano et al 2002).

   The somewhat more advanced true Ceratosauria (including Ceratosaurus
   and Carnotaurus) appeared during the Early Jurassic and continued
   through to the Late Jurassic in Laurasia. They competed quite well
   alongside their more advanced tetanuran relatives and - in the form of
   the abelisaur lineage - lasted to the end of the Cretaceous in
   Gondwana.

   The Tetanurae are more specialised again than the Ceratosaurs. They are
   subdivided into Megalosauroidea (alternately Spinosauroidea or
   Torvosauroidea) and the Avetheropoda. They were most common during the
   Middle Jurassic but continued to the Middle Cretaceous. The latter
   clade - as their name indicates - were more closely related to birds
   and are again divided into the Carnosauria (including Allosaurus) and
   the Coelurosauria, a very large and diverse dinosaur group that was
   especially common during the Cretaceous.

   Thus, during the late Jurassic, there were no fewer than four distinct
   lineages of theropods - ceratosaurs, megalosaurs, carnosaurs, and
   coelurosaurs - preying on the abundance of small and large herbivorous
   dinosaurs. All four groups survived into the Cretaceous, although only
   two - the abelisaurs and the coelurosaurs - seem to have made it to end
   of the period, where they were geographically separate, the abelisaurs
   in Gondwana, and the coelurosaurs in Asiamerica.

   Of all the theropod groups, the coelurosaurs were by far the most
   diverse. Some coelurosaur clades that flourished during the Cretaceous
   are: tyrannosaurs, including the famous Tyrannosaurus rex, the
   dromaeosaurs, including Velociraptor and Deinonychus, which are
   remarkably similar in form to the Archaeopteryx (Ostrom 1969, Paul
   1988, Dingus & Rowe 1998), the dromaeosaur-like Troodontidae, the
   omnivorous oviraptorosaurs, the herbivorous ornithomimids ("ostrich
   dinosaurs") and Therizinosauridae (giant-clawed herbivores) and the
   birds (the only dinosaur lineage to survive the end Cretaceous
   mass-extinction). While the roots of these various groups must have
   been in the Late or possibly even the Middle Jurassic, they only became
   abundant during the early Cretaceous. A few paleontologists, such as
   Gregory S. Paul, have suggested (Paul 1988, 2002) that some or all of
   these advanced theropods were actually descended from flying dinosaurs
   or proto-birds like Archaeopteryx that lost the ability to fly and
   returned to a terrestrial habitat. While this hypothesis can explain
   why coelurosaurs are so rare during the Jurassic, more fossil evidence
   is needed before the exact relationships of advanced theropods can be
   accurately tested.

Classification

     * Order Saurischia
          + SUBORDER THEROPODA
               o Guaibasaurus
               o (unranked) Neotheropoda
                    # Superfamily Coelophysoidea
                    # Infraorder Ceratosauria
                         @ Family Ceratosauridae
                         @ Family Noasauridae
                         @ Family Abelisauridae
                    # (unranked) Tetanurae
                         @ ? Cryolophosaurus
                         @ Superfamily Megalosauroidea
                              - Family Megalosauridae
                              - Family Spinosauridae
                         @ (unranked) Avetheropoda
                              - Infraorder Carnosauria
                                   = Family Sinraptoridae
                                   = Family Allosauridae
                                   = Family Carcharodontosauridae
                              - Infraorder Coelurosauria
                                   = Family Coeluridae
                                   = Superfamily Tyrannosauroidea
                                   = Ornithomimosauria
                                   = (unranked) Maniraptora
                                   * Oviraptorosauria
                                   * Therizinosauria
                                   * Deinonychosauria

The largest theropods

   Tyrannosaurus was known as the largest and most popular theropod known
   to the general public for many decades. Since its discovery, however, a
   number of other giant carnivorous dinosaurs have been described,
   including Spinosaurus, Carcharodontosaurus, Giganotosaurus,
   Tyrannotitan and Mapusaurus. In the film Jurassic Park 3, Spinosaurus
   is depicted as being larger than Tyrannosaurus and the original
   Spinosaurus specimens (as well as new fossils described in 2006)
   support this, showing that Spinosaurus was about 4 meters longer and 4
   tons heavier than Tyrannosaurus (a size comparison of the largest
   theropods can be found in the article Dinosaur size). There is still no
   clear scientific explanation for exactly why these animals grew so much
   larger than the predators that came before and after them.
   Retrieved from " http://en.wikipedia.org/wiki/Theropoda"
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   with only minor checks and changes (see www.wikipedia.org for details
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