Saurischian dinosaurs




Дата канвертавання25.04.2016
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SAURISCHIAN DINOSAURS







Dinosaurs are divided into two groups based on hip structure, the Order Ornithischia and the Order Saurischia.

The Saurischian dinosaurs (Order Saurischia) were the ancestors of birds. They had a hip structure similar to that of lizards - the pubis bone pointed downwards and forwards. Saurischian skulls also have large, pronounced openings (antorbital fenestrae) between the eye socket and the nares (nostrils), much more so than the ornithischians.

The Saurischians are divided into the sauropodomorpha, four-legged herbivores, and the theropods, two-legged carnivores. The oldest known dinosaurs (Eoraptor and Herrerasaurus) are Saurischians, and date from the mid- to late-Triassic period, about 230 million years ago.





Major divisions of the Saurischian dinosaurs:



SAUROPODOMORPHA

  • Plant eaters

  • Small heads with spatulate or pencil-shaped teeth

  • Usually walked on four legs

  • Largest land animals ever!




THEROPODS
Led to the birds!



  • Fast and agile

  • Carnivorous diet

  • Sharp, slicing teeth or beak, and well-developed jaw muscles

  • Clawed hands (usually with three main digits - exceptions include the Tyrannosaurids, who lost the third digit)

  • Bipedal walk

  • Strong legs with bird-like, clawed feet

  • Large eyes, indicating good eyesight.





ORNITHISCHIAN DINOSAURS


Dinosaurs are divided into two groups based on hip structure, the Order Ornithischia and the Order Saurischia. Harry Seeley, a British scientist, divided the dinosaurs and named the two groups in 1887.

The Ornithischian dinosaurs had a hip structure similar to that of birds, but they were not the ancestors of birds. The pubis bone (part of the structure of the hip) points downwards and toward the tail in Ornithischians, an opisthopubic condition (it points downwards and to the front in the Saurischians) and. The Ornithischian pelvis is wider than the Saurischian pelvis. This may have made Ornithischians more stable while moving.

Ornithischian skulls also had small, reduced openings (antorbital fenestrae) between the eye socket and the nares (nostrils), unlike saurischians.

Ornithischians outnumbered the Saurischians (the lizard-hipped dinosaurs, theropods and sauropods). The Ornithischians were herbivores (plant-eaters).



Major divisions of the Ornithischian dinosaurs:

  • Ornithopods (meaning "Bird feet"): Plant-eaters, Two-legged walk or two-legged and four-legged walk, No body armor, Lived during the early Jurassic to Cretaceous periods

    • Heterodontosaurids - small, early dinosaurs with three kinds of teeth

    • Hypsilophodontids - small, fast-running dinosaurs with self-sharpening teeth and a small beak

    • Dryosaurids - small, fast-running dinosaurs with a long, stiff tail

    • Thescelosaurids - late, fast-running dinosaurs

    • Camptosaurids - beaked dinosaurs with hoof-like claws

    • Iguanodontids - beaked dinosaurs with hoof-like claws and a spike on each thumb

    • Hadrosaurids - large duck-billed dinosaurs with no head crest

    • Lambeosaurids - large duck-billed dinosaurs with a head crest

  • Thyreophorans (meaning "shield bearers"): Plant-eaters, Four-legged walk, Armored plates on the body, Lived during the early Jurassic to Cretaceous periods

    • Ankylosaurids - armored dinosaurs

    • Stegosaurids - plated and spiked dinosaurs

  • Marginocephalians (meaning "fringed heads"): Plant-eaters, Horns or thick skulls, Lived during the Cretaceous period

    • Ceratopsians - horned, beaked dinosaurs

    • Pachycephalosaurs - dome-headed dinosaurs with huge bony skulls



The following is a sampling of Ornithischian dinosaurs:

(Order) Ornithischia (Bird-hipped herbivores)


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Hadrosaurs, the Duck-billed dinosaurs



ANATOTITAN




CORYTHOSAURUS




EDMONTOSAURUS




LAMBEOSAURUS




MAIASAURA




PARASAUROLOPHUS


Hypsilophodontids



DRYOSAURUS




HYPSILOPHODON





Iguanodontids



IGUANODON




OURANOSAURUS





Camptosaurids



CAMPTOSAURUS








Thescelosaurids



THESCELOSAURUS








Fabrosauria = Lesothosauria
(primitive Ornithopoda)



HETERODONTOSAURUS





LESOTHOSAURUS





XIAOSAURUS









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Ceratopsia (Horned dinosaurs)
More about Ceratopsia







PROTOCERATOPS




STYRACOSAURUS




NOTOCERATOPS







TRICERATOPS




MONTANOCERATOPS




MONOCLONIUS





Pachycephalosauria (Thick-skulled dinosaurs)



PACHYCEPHALOSAURUS




STEGOCERAS



WANNANOSAURUS







Thyreophora
=
Enoplosauria

(Armored
dinosaurs)

Ankylosauridae



ACANTHOPHOLIS




ANKYLOSAURUS




EUOPLOCEPHALUS




HYLAEOSAURUS




MINMI




SAUROPELTA


Stegosauridae



STEGOSAURUS




KENTROSAURUS








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