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Camarasaurus

2007 Schools Wikipedia Selection. Related subjects: Dinosaurs

   iCamarasaurus

                         Fossil range: Late Jurassic

   Camarasaurus lentus skull
   Camarasaurus lentus skull

                             Conservation status

   Extinct (fossil)
              Scientific classification

   Kingdom:    Animalia
   Phylum:     Chordata
   Class:      Sauropsida
   Superorder: Dinosauria
   Order:      Saurischia
   Suborder:   Sauropodomorpha
   Infraorder: Sauropoda
   Family:     Camarasauridae
   Genus:      Camarasaurus
               Cope, 1877

                                   Species

   C. grandis
   C. lentus
   C. lewisi
   C. supremus ( type species)

   Camarasaurus (KAM-ah-rah-SAWR-us) meaning 'chambered lizard', referring
   to the holes in its vertebrae ( Greek kamara meaning 'vaulted chamber',
   or anything with an arched cover, and sauros meaning 'lizard') was a
   genus of quadrupedal, herbivorous dinosaurs. It was the most common of
   the giant sauropods to be found in North America but only average in
   size: about 18 metres (60 feet) in length as adults, and weighing up to
   18 tonnes (19.8 tons). It lived in the Late Jurassic Period, between
   155 and 145 million years ago.

Anatomy

   Camarasaurus skull and neck - Natural History Museum, London.
   Enlarge
   Camarasaurus skull and neck - Natural History Museum, London.

   The arched skull of Camarasaurus may have contributed to the name
   'chambered lizard'. The skull was remarkably square and the blunt snout
   had many fenestrae, though it was sturdy and is frequently recovered in
   good condition by paleontologists. The huge nostrils, positioned in
   front of the eyes, probably contained a large area of moist membrane to
   cool the brain in the hot climate of the Jurassic.

   The 19 centimetre long (7.5 inch) teeth were shaped like chisels
   (spatulate) and arranged evenly along the jaw. The strength of the
   teeth indicates that Camarasaurus probably ate coarser plant material
   than the slender-toothed diplodocids. Like a chicken, it would probably
   have swallowed stones ( gastroliths) to help grind the food in the
   stomach and then regurgitated or passed them when they became too
   smooth. Consistent with this suggestion, the rock formation, in which
   they are frequently found (the Morrison Formation), includes a large
   number of isolated piles of unusually smooth stones.

   Each giant foot bore five toes, with the inner toe having a large
   sharpened claw for self-defense. Like most sauropods, the front legs
   were shorter than the hind legs, but the high position of the shoulders
   meant there was little slope in the back. In some sauropods, there were
   long upward projections on each vertebra but the absence of such
   structures from the spine of Camarasaurus suggests that it was not able
   to raise itself on its hind legs.

   The vertebrae were nevertheless specialised. Serving the purpose of
   weight-saving, as seen in many later sauropods, some of the vertebrae
   were hollowed out. This feature may have contributed to the name
   "chambered lizard". Like a modern elephant, Camarasaurus appears to
   have had a wedge of spongy tissue at the base of the heel, to support
   the weight of such a large creature. The neck and counter-balancing
   tail were shorter than usual for a sauropod of this size.
   Sketches of Camarasaurus' head
   Enlarge
   Sketches of Camarasaurus' head

   Camarasaurus, again like certain other sauropods, had an enlargement of
   the spinal cord near the hips. Palaeontologists originally believed
   this to be a second brain, perhaps necessary to co-ordinate such a huge
   creature. Modern opinion asserts that, while it would have been an area
   of large nervous possibly reflex (automatic) activity, it was not a
   brain. However, this enlargement was actually larger than the
   remarkably small brain contained in the animals' box-like skull.

   It is suggested by some palaeontologists that Camarasaurus may have
   lived for up to a hundred years.

Behaviour

   There is a fossil record of two adults and a 12.2 metre (40 ft) long
   juvenile that died together in the Late Jurassic Period, approximately
   150 million years ago (in north east Wyoming, USA, excavated by the
   Division of Vertebrate Paleontology of the University of Kansas Natural
   History Museum and Biodiversity Centre, during the 1997 and 1998 'field
   seasons'). It is assumed that their bodies were washed to their final
   resting place, in alluvial mud, by a river in spate. This suggests that
   Camarasaurus travelled in herds or, at least, 'family' groups. Also,
   recovered camarasaur eggs have been found in lines, rather than in
   neatly arranged nests as with some other dinosaurs, which appears to
   suggest that, like most sauropods, Camarasaurus did not tend its young.

Discovery

   1925 illustration of the first full skeleton of Camarasaurus.
   Enlarge
   1925 illustration of the first full skeleton of Camarasaurus.

   The first record of Camarasaurus comes from 1877, when a few scattered
   vertebrae were located in Colorado, by Oramel W. Lucas. The
   paleontologist Edward Drinker Cope paid for the bones, as part of his
   long-running and acrimonious competition with Othniel Charles Marsh
   (known as the Bone Wars) and named them in the same year. Marsh later
   named some of his sauropod findings Morosaurus grandis but most
   paleontologists today consider this to be a species of Camarasaurus .
   Such naming conflicts were common between the two rival dinosaur
   hunters, the most famous being Brontosaurus/Apatosaurus.

   It was not until 1925 that a complete skeleton of Camarasaurus was
   recovered, by Charles W. Gilmore. However, it was the skeleton from a
   young Camarasaurus, which is why so many illustrations of the dinosaur
   from the time show it to be much smaller than it is now known to be.

   The Morrison Formation, along the eastern flank of the Rocky Mountains,
   is home to a rich stretch of Late Jurassic rock. A large number of
   dinosaur species can be found here, including relatives of the
   Camarasaurus such as Diplodocus, Apatosaurus and Brachiosaurus.
   However, camarasaurs are the most abundant of all the dinosaurs in the
   Formation and there have been a number of complete skeletons recovered
   from Colorado, New Mexico, Utah, and Wyoming.

Classification

   The scientific classification of Camarasaurus, using the Linnaean
   system, is given in the box to the upper right but, among
   palaeontologists, this method of taxonomic classification of dinosaurs
   is being supplanted by the cladistics inspired phylogenetic taxonomy. A
   simplified version of one possible branching evolutionary tree, showing
   the relationship between Camarasaurus and the other major groups of
   sauropods, follows:
     * Saurischia ("lizard hipped" dinosaurs)
          + Sauropoda ("lizard feet")
               o Macronaria ("large nostrils")
                    # Camarasauridae
                    # Titanosauriformes
                         @ Brachiosauridae (which includes Brachiosaurus
                           and Sauroposeidon)
                         @ Titanosauria (species such as Argentinosaurus)
               o Diplodocoidea (which includes Apatosaurus and Diplodocus)

   Camarasaurus is considered to be a basal macronarian, more closely
   related to the common ancestor of all macronarians than to more derived
   forms like Brachiosaurus.

   The holotype species of Camarasaurus is Cope's original species, C.
   supremus ("the biggest chambered lizard"), named in 1877. Other species
   since discovered include C. grandis ("grand chambered lizard") in 1877,
   C. lentus in 1889, and C. lewisi (originally Cathetosaurus) in 1988.

In popular culture

   Camarasaurus is featured in When Dinosaurs Roamed America, browsing on
   leaves.

   Camarasaurus is also featured in the Vivendi Universal game Jurassic
   Park: Operation Genesis.
   Retrieved from " http://en.wikipedia.org/wiki/Camarasaurus"
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