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GVA THEROPODA - DINOSAURS IN TIME AND SPACE TIME Dinosaurs first appeared 228 million years ago and became extinct 65 million years ago. Their reign on Earth was a considerable 163 million years, by any measure a considerable span of time cut short by a global catastrophe. Dinosaurs reign spanned all three periods of the Mesozoic Era, the last portion of the Triassic (245-208 million years ago), and the entirety of the Jurassic (208-144 million years ago) and Cretaceous (144-66.4 million years ago). SPACE Dinosaurs inhabited all continents, although their record is sparse record in Australia and Antarctica. DIVERSITY More than three hundred species of dinosaurs have been described. In recent years, new discoveries have increased, especially in remote areas of the world. A new genus is being described every six weeks. - THE THEROPODS CHARACTERISTICS OF THE THEROPODS (web) This group of dinosaurs exhibits a wide variety of adaptive features making them efficient predators: sharp, large, serrated, recurved teeth for slicing claws on all fingers and toes largest brain (relative to body size) among dinosaurs bipedal, strong hind limbs long hands with three main fingers (4th and 5th reduced) and three main toes (1st and 5th reduced) elongated zygopophyses (processes of the neural arch of vertebrae) on the vertebrae near the end of the tail hollow bones (important adaptation), as in birds stiffened tail toward end to act as a body balance. GEOLOGIC RANGE AND GEOGRAPHIC DISTRIBUTION
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Late Triassic-Late Cretaceous TYPES OF THEROPODS Ceratosauria (web) The Ceratosauria (named after Ceratosaurus) and the Tetanurae (tetanus - stiff; uro - tail) are the two major descendant groups within the Theropoda. Ceratosaurs are primitive theropods but younger than the rare basal theropods not dealt with herein. The group is not very diverse but is characterized by several important derived features, including: fusion of ilium, pubis, and ischium in adults (web) to form a strong support between the hind limbs and the vertebral column neck vertebrae with two pairs of pleurocoels (side cavities) (web) a flaring of the lower end of the fibula bone fusion in the ankles and feet s-shaped neck inherited from archosaurian ancestors gap between premaxillary and maxillary bones of skull for placement of a large tooth fitted to dentary bone (in Coelophysis and Dilophosaurus but lacking in Ceratosaurus) Ceratosaurs exhibit a great deal of sexual dimorphism. Females often have longer skulls and necks and more robust thicker limbs than in male forms. Crests of thin bone only occur on some adults, presumably functioning in display, probably by males. Ceratosaurs were fast bipedal runners with a narrow gait. Most are restricted to the Late Triassic and Jurassic and are known from North America, Europe, Africa, and possibly South America. Within the Ceratosauria their appear to be two groups the Coelophysoidea and
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