   #copyright

Pachycephalosaurus

2007 Schools Wikipedia Selection. Related subjects: Dinosaurs

            iPachycephalosaurus

                        Fossil range: Late Cretaceous

   Skull of Pachycephalosaurus from Oxford University Museum of Natural
   History
   Skull of Pachycephalosaurus from Oxford University Museum of Natural
   History

                             Conservation status

   Extinct (fossil)
                        Scientific classification

   Kingdom:    Animalia
   Phylum:     Chordata
   Class:      Sauropsida
   Superorder: Dinosauria
   Order:      Ornithischia
   Suborder:   Pachycephalosauria
   Family:     Pachycephalosauridae
   Genus:      Pachycephalosaurus
               Brown & Schlaikjer, 1943

                                Binomial name

   Pachycephalosaurus wyomingensis
   (Gilmore, 1931)

   Pachycephalosaurus (the 'thick headed lizard', from the Greek
   pachy-/παχυ- meaning 'thick', cephale/κεφαλη meaning 'head' and
   saurus/σαυρος meaning 'lizard') was a dinosaur of the family
   Pachycephalosauridae, from the Late Cretaceous Period of what is now
   North America. It was an herbivorous creature, which is only known from
   a single skull and a few extremely thick skull roofs.

Anatomy

   Pachycephalosaurus was probably bipedal and was the largest of the
   bone-headed dinosaurs. It is famous for having a large, bony dome atop
   its skull, up to 25cm (10 inches) thick, which safely cushioned its
   brain. The dome's rear aspect was edged with bony knobs and short bony
   spikes were projected upwards from the snout. These features suggest
   that, despite their bipedal stance, they were more likely to have been
   relatives of the ceratopsians, rather than ornithopods.

   Using data from other Pachycephalosauridae, it has been estimated that
   Pachycephalosaurus was approximately the length of a large car, maybe
   around 4.6m long (15 feet) and had a fairly short, thick neck, short
   fore limbs, a bulky body, long hind legs and a heavy tail, which was
   likely to have been held rigid by ossified tendons. Large eye-sockets
   that faced forward suggest that the animal had good vision and was
   capable of binocular vision.

Lifestyle

   Scientists once suspected that Pachycephalosaurus and its dome-headed
   relatives were the bipedal equivalents of the big-horned sheep of
   today. It was thought that, in the mating season, big males would run
   at one another, clashing heads to decide which would dominate and mate
   with a herd of females. It was also thought that they might have used
   their domed heads for defence against predators. However, it is now
   believed that the Pachycephalosaurs would not have used their domes in
   this way. The adult head bones could not adequately have withstood
   pressure and impact and the skulls lacked proper shock absorption.
   Also, there is no evidence of scars or other damage on fossilized
   Pachycephalosaurus skulls..

Diet

   Scientists do not yet know what these dinosaurs ate. Having very small,
   ridged teeth they could not have chewed tough, fibrous plants as
   effectively as other dinosaurs of the same period. It is assumed that
   pachycephalosaurs lived on a mixed diet of leaves, seeds, fruit and
   insects. The sharp, serrated teeth would have been very effective for
   shredding angiosperm plants.

In popular culture

     * Pachycephalosaurus appeared in the 1997 film The Lost World:
       Jurassic Park stampeding with the other dinosaurs.
     * A herd of pachycephalosaurus would attack Cera in The Land Before
       Time.
     * Pachycephalosaurus was featured in the Vivendi Universal video game
       Jurassic Park: Operation Genesis.
     * Pachycephalosaurus is the title of a song on a 2006 album by the
       band Showbread, entitled Age of Reptiles.
     * The Transformers characters of Hardhead and Dinotron turned into
       Pachycephalosaurus'.

   Retrieved from " http://en.wikipedia.org/wiki/Pachycephalosaurus"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
   of authors and sources) and is available under the GNU Free
   Documentation License. See also our Disclaimer.
