Dinosaurs (from the Greek word deinos (δεινός) meaning "terrible" or "potent," and sauros (σαύρα) meaning "lizard") are a diverse group of animals that were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period (about 230 million years ago) until the end of the Cretaceous (about 65 million years ago), when the Cretaceous–Paleogene extinction event led to the extinction of all non-avian dinosaurs at the close of the Mesozoic era. The fossil record indicates that birds evolved within theropod dinosaurs during the Jurassic period. Some of them survived the Cretaceous–Paleogene extinction event, including the ancestors of all modern birds. Consequently, in modern classification systems, birds are considered a type of dinosaur—the only group which survived to the present day.[1][2]

Dinosaurs are a varied group of animals. Birds, at over 9,000 species, are the most diverse group of vertebrate besides perciform fish.[3] Paleontologists have identified over 500 distinct genera[4] and more than 1,000 different species of non-avian dinosaurs.[5] Dinosaurs are represented on every continent by both extant species and fossil remains.[6] Some are herbivorous, others carnivorous. Many dinosaurs have been bipedal, and many extinct groups were also quadrupedal, and some were able to shift between these body postures. Many species possess elaborate display structures such as horns or crests, and some prehistoric groups even developed skeletal modifications such as bony armor and spines. Avian dinosaurs have been the planet's dominant flying vertebrate since the extinction of the pterosaurs, and evidence suggests that all ancient dinosaurs built nests and laid eggs much as avian species do today. Although generally known for the large sizes of some groups, most Mesozoic dinosaurs were human-sized or smaller.

手机旧照(2011)_14: 游波光粼粼的十七哩(2)

手机旧照(2010)_13: 海钓鲨鱼
手机旧照(2011)_12:参观U吧牧场-加拿大国家历史遗址-

手机旧照(2011)_11:小小摄影师在-卡城牛仔节上-

手机旧照(2011)_10：恐龙-Dinosaurs(下)
手机旧照(2011)_09：恐龙-Dinosaurs(上)
手机旧照(2011)_08：七月登班夫山，看落基雪山云彩

手机旧照(2011)_07：卡城晚霞与乌鸦巢哑口(落基山)云彩

手机旧照(2011)_06：卡尔加里牛仔节游街

手机旧照(2011)_05：艾伯塔省涟湖

手机旧照(2011)_04: Pacific Rim(Tofino)-哥伦比亚冰原-Jasper

手机旧照(2011)_03: 游三颗馒头、太浩湖

手机旧照(2011)_02: 游加州十七哩(17 Mile Drive)

手机旧照(2011)_01: 游加利福尼亚、班夫等地