Portal:Prehistory of Oceania

Topics Culture Geography Health History Mathematics Nature People Philosophy Religion Society Technology The Prehistory of Oceania Portal Specifiers for Dinosauria. Dinosaurs are a diverse group of animals that first appeared during the Triassic period, 231.4 million years ago, and were the dominant terrestrial vertebrates for 135 million years, from the beginning of the Jurassic until the end of the Cretaceous (66 million years ago), when the Cretaceous–Paleogene extinction event led to the extinction of most dinosaur groups. The fossil record indicates that birds evolved from theropod dinosaurs and, consequently, they are considered a subgroup of dinosaurs by many paleontologists. Some birds survived the extinction event and their descendants continue the dinosaur lineage to the present day. Using fossil evidence, paleontologists have identified over 500 distinct genera of non-avian dinosaurs. Dinosaurs are represented on every continent. Some are herbivorous, others carnivorous. While dinosaurs were ancestrally bipedal, many extinct groups included quadrupedal species. Elaborate display structures such as horns or crests are common to all dinosaur groups, and some extinct groups developed skeletal modifications such as bony armor and spines. Evidence suggests that egg laying and nest building are additional traits shared by all dinosaurs. While modern birds are generally small due to the constraints of flight, many prehistoric dinosaurs were large-bodied—the largest sauropod dinosaurs may have achieved lengths of 58 meters (190 feet). Many dinosaurs were quite small: Xixianykus, for example, was only about 50 cm (20 in) long. (see more...) The history of paleontology traces the history of the effort to understand the history of life on Earth by studying the fossil record left behind by living organisms. Since it is concerned with understanding living organisms of the past paleontology can be considered to be a field of biology, but its historical development has been closely tied to geology and the effort to understand the history of the Earth itself. In ancient times Xenophanes (570-480 BC), Herodotus (484-425 BC), Eratosthenes (276-194 BC), and Strabo (64 BC-24 AD), wrote about fossils of marine organisms indicating that land was once under water. During the Middle Ages, fossils were discussed by the Persian naturalist, Ibn Sina (known as Avicenna in Europe), in The Book of Healing (1027), which proposed a theory of petrifying fluids that Albert of Saxony would elaborate on in the 14th century. The Chinese naturalist Shen Kuo (1031–1095) would propose a theory of climate change based on evidence from petrified bamboo. In early modern Europe, the systematic study of fossils emerged as an integral part of the changes in natural philosophy that occurred during the Age of Reason. The nature of fossils and their relationship to life in the past became better understood during the 17th and 18th centuries, and at the end of the 18th century the work of Georges Cuvier ended a long running debate about the reality of extinction and led to the emergence of paleontology, in association with comparative anatomy, as a scientific discipline. The expanding knowledge of the fossil record also played an increasing role in the development of geology, particularly stratigraphy. In 1822 the word "paleontology" was invented by the editor of a French scientific journal to refer to the study of ancient living organisms through fossils, and the first half of the 19th century saw geological and paleontological activity become increasingly well organized with the growth of geologic societies and museums and an increasing number of professional geologists and fossil specialists. This contributed to a rapid increase in knowledge about the history of life on Earth, and progress towards definition of the geologic time scale largely based on fossil evidence. As knowledge of life's history continued to improve, it became increasingly obvious that there had been some kind of successive order to the development of life. This would encourage early evolutionary theories on the transmutation of species. After Charles Darwin published Origin of Species in 1859, much of the focus of paleontology shifted to understanding evolutionary paths, including human evolution, and evolutionary theory. The last half of the 19th century saw a tremendous expansion in paleontological activity, especially in North America. The trend continued in the 20th century with additional regions of the Earth being opened to systematic fossil collection, as demonstrated by a series of important discoveries in China near the end of the 20th century. Many transitional fossils have been discovered, and there is now considered to be abundant evidence of how all classes of vertebrates are related, much of it in the form of transitional fossils. The last few decades of the 20th century saw a renewed interest in mass extinctions and their role in the evolution of life on Earth. There was also a renewed interest in the Cambrian explosion that saw the development of the body plans of most animal phyla. The discovery of fossils of the Ediacaran biota and developments in paleobiology extended knowledge about the history of life back far before the Cambrian. (see more...) A stromatolite collected from the 3,600 to 3,200 million year old Paleoarchean Strelley Pool Chert of Western Australia, Australia. Stromatolites are formed over the years by mats (1-10 mm in thickness) of microorganisms (cyanobacteria among others) found in shallow, mainly marine waters. The microorganisms precipitate mineral particles, which makes the mat to thicken, but only the upper part survives. Most stromatolites display characteristically layered structures. Only the layers are visible to the naked eye. Photo credit: Didier Descouens File:Fulica chathamensis 1 1896.jpg ... that the New Zealand and the Chatham Coot were likely hunted to extinction by the Māori people? ... that highlights from 19th century ichnology include the discovery of protomammal tracks in England, dinosaur footprints in Massachusetts, and the mysterious hand-shaped Chirotherium tracks (pictured)? ... that Aquila bullockensis, an extinct species of bird, is the oldest known true eagle from Australia ... that multiple Leptocleidus skeletons have been found preserved as gemstone quality opal over the course of the history of plesiosaur research? ...that the extinct species of Edaphodon, a type of rabbitfish related to the shark, grazed along the bottom of the ocean like land-dwelling herbivores do now? ► Prehistory of Oceania no subcategories Prehistory of Africa Prehistory of North America Prehistory of South America Prehistory of Antarctica Prehistory of Asia Prehistory of Europe Oceania Archaeology Earth sciences Paleontology Extinct and Endangered Species Paleozoic Mesozoic Cenozoic Dinosaurs What are portals? 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