|
Ceratopsidae
Ceratopsidae (sometimes spelled Ceratopidae) is a family of ceratopsian dinosaurs including ''Triceratops'', ''Centrosaurus'', and ''Styracosaurus''. All known species were quadrupedal herbivores from the Upper Cretaceous. All but one species are known from western North America, which formed the island continent of Laramidia during most of the Late Cretaceous. Ceratopsids are characterized by beaks, rows of shearing teeth in the back of the jaw, elaborate nasal horns, and a thin parietal-squamosal shelf that extends back and up into a frill. The group is divided into two subfamilies— Chasmosaurinae and Centrosaurinae. The chasmosaurines are generally characterized by long, triangular frills and well-developed brow horns. The centrosaurines had well-developed nasal horns or nasal bosses, shorter and more rectangular frills, and elaborate spines on the back of the frill. These horns and frills show remarkable variation and are the principal means by which the various species have ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ceratopsian
Ceratopsia or Ceratopia ( or ; Greek: "horned faces") is a group of herbivorous, beaked dinosaurs that thrived in what are now North America, Europe, and Asia, during the Cretaceous Period, although ancestral forms lived earlier, in the Jurassic. The earliest known ceratopsian, '' Yinlong downsi'', lived between 161.2 and 155.7 million years ago.Holtz, Thomas R. Jr. (2011) ''Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages,'Winter 2010 Appendix./ref> The last ceratopsian species, '' Triceratops prorsus'', became extinct during the Cretaceous–Paleogene extinction event, . ''Triceratops'' is by far the best-known ceratopsian to the general public. It is traditional for ceratopsian genus names to end in "''-ceratops''", although this is not always the case. One of the first named genera was ''Ceratops'' itself, which lent its name to the group, although it is considered a ''nomen dubium'' today as its fossil remains have no distinguishing char ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dinosaur
Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is the subject of active research. They became the dominant terrestrial vertebrates after the Triassic–Jurassic extinction event 201.3 mya; their dominance continued throughout the Jurassic and Cretaceous periods. The fossil record shows that birds are feathered dinosaurs, having evolved from earlier theropods during the Late Jurassic epoch, and are the only dinosaur lineage known to have survived the Cretaceous–Paleogene extinction event approximately 66 mya. Dinosaurs can therefore be divided into avian dinosaurs—birds—and the extinct non-avian dinosaurs, which are all dinosaurs other than birds. Dinosaurs are varied from taxonomic, morphological and ecological standpoints. Birds, at over 10,700 living species ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the Latin word for the white limestone known as chalk. The chalk of northern France and the white cliffs of south-eastern England date from the Cretaceous Period. Climate During the Late Cretaceous, the climate was warmer than present, although throughout the period a cooling trend is evident. The tropics became restricted to equatorial regions and northern latitudes experienced markedly more seasonal climatic conditions. Geography Due to plate tectonics, the Americas were gradually moving westward, causing the Atlantic Ocean to expand. The Western Interior Seaway divided North America into eastern and western halves; Appalachia and Laramidia. India maintained a northward course towards Asia. In the Southern Hemisphere, Australia a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
North America
North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Caribbean Sea, and to the west and south by the Pacific Ocean. Because it is on the North American Plate, North American Tectonic Plate, Greenland is included as a part of North America geographically. North America covers an area of about , about 16.5% of Earth's land area and about 4.8% of its total surface. North America is the third-largest continent by area, following Asia and Africa, and the list of continents and continental subregions by population, fourth by population after Asia, Africa, and Europe. In 2013, its population was estimated at nearly 579 million people in List of sovereign states and dependent territories in North America, 23 independent states, or about 7.5% of the world's population. In Americas (terminology)#Human ge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tyrannosaurids
Tyrannosauridae (or tyrannosaurids, meaning " tyrant lizards") is a family of coelurosaurian theropod dinosaurs that comprises two subfamilies containing up to thirteen genera, including the eponymous '' Tyrannosaurus''. The exact number of genera is controversial, with some experts recognizing as few as three. All of these animals lived near the end of the Cretaceous Period and their fossils have been found only in North America and Asia. Although descended from smaller ancestors, tyrannosaurids were almost always the largest predators in their respective ecosystems, putting them at the apex of the food chain. The largest species was ''Tyrannosaurus rex'', one of the largest and most massive known land predators, which measured over in length and according to most modern estimates to in weight. Tyrannosaurids were bipedal carnivores with massive skulls filled with large teeth. Despite their large size, their legs were long and proportioned for fast movement. I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adolescence
Adolescence () is a transitional stage of physical and psychological development that generally occurs during the period from puberty to adulthood (typically corresponding to the age of majority). Adolescence is usually associated with the teenage years, but its physical, psychological or cultural expressions may begin earlier and end later. Puberty now typically begins during preadolescence, particularly in females. Physical growth (particularly in males) and cognitive development can extend past the teens. Age provides only a rough marker of adolescence, and scholars have not agreed upon a precise definition. Some definitions start as early as 10 and end as late as 25 or 26. The World Health Organization definition officially designates an adolescent as someone between the ages of 10 and 19. Biological development Puberty in general Puberty is a period of several years in which rapid physical growth and psychological changes occur, culminating in sexual maturity. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Centrosaurine
Centrosaurinae (from the Greek, meaning "pointed lizards") is a subfamily of ceratopsid dinosaurs, a group of large quadrupedal ornithischians. Centrosaurine fossil remains are known primarily from the northern region of Laramidia (modern day Alberta, Montana, and Alaska) but isolated taxa have been found in China and Utah as well. Defining features of centrosaurines include a large nasal horn, short supratemporal horns, and an ornamented frill projecting from the back of the skull. With the exception of '' Centrosaurus apertus'', all adult centrosaurines have spike-like ornaments midway up the skull. Morphometric analysis shows that centrosaurines differ from other ceratopsian groups in skull, snout, and frill shapes. There is evidence to suggest that male centrosaurines had an extended period of adolescence, and sexual ornamentation did not appear until adulthood. Centrosaurinae was named by paleontologist Lawrence Lambe in 1915, with '' Centrosaurus'' as the type genus. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Herds
A herd is a social group of certain animals of the same species, either wild or domestic. The form of collective animal behavior associated with this is called ''herding''. These animals are known as gregarious animals. The term ''herd'' is generally applied to mammals, and most particularly to the grazing ungulates that classically display this behaviour. Different terms are used for similar groupings in other species; in the case of birds, for example, the word is '' flocking'', but ''flock'' may also be used for mammals, particularly sheep or goats. Large groups of carnivores are usually called '' packs'', and in nature a herd is classically subject to predation from pack hunters. Special collective nouns may be used for particular taxa (for example a flock of geese, if not in flight, is sometimes called a ''gaggle'') but for theoretical discussions of behavioural ecology, the generic term ''herd'' can be used for all such kinds of assemblage. The word ''herd'', as a noun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Musk Oxen
Musk ( Persian: مشک, ''Mushk'') is a class of aromatic substances commonly used as base notes in perfumery. They include glandular secretions from animals such as the musk deer, numerous plants emitting similar fragrances, and artificial substances with similar odors. ''Musk'' was a name originally given to a substance with a strong odor obtained from a gland of the musk deer. The substance has been used as a popular perfume fixative since ancient times and is one of the most expensive animal products in the world. The name originates from the Late Greek μόσχος 'moskhos', from Persian 'mushk', similar to Sanskrit मुष्क muṣka ("testicle"), derived from Proto-Indo-European noun ''múh₂s'' meaning "mouse". The deer gland was thought to resemble a scrotum. It is applied to various plants and animals of similar smell (e.g. muskox) and has come to encompass a wide variety of aromatic substances with similar odors, despite their often differing chemical structure ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Achelousaurus
''Achelousaurus'' () is a genus of centrosaurine ceratopsid dinosaur that lived during the Late Cretaceous Period of what is now North America, about 74.2 million years ago. The first fossils of ''Achelousaurus'' were collected in Montana in 1987, by a team led by Jack Horner, with more finds made in 1989. In 1994, ''Achelousaurus horneri'' was described and named by Scott D. Sampson; the generic name means "Achelous lizard", in reference to the Greek deity Achelous, and the specific name refers to Horner. The genus is known from a few specimens consisting mainly of skull material from individuals, ranging from juveniles to adults. A large centrosaurine, ''Achelousaurus'' supposedly was about long, with a weight of about . As a ceratopsian, it walked on all fours, had a short tail and a large head with a hooked beak. It had a bony neck-frill at the rear of the skull, which sported a pair of long spikes, which curved towards the outside. Adult ''Achelousaurus'' had ro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pachyrhinosaurus
''Pachyrhinosaurus'' (meaning in Greek "thick-nosed lizard", from ' (), thick; ' (), nose; and (), lizard) is an extinct genus of centrosaurine ceratopsid dinosaur from the Late Cretaceous period of North America. The first examples were discovered by Charles M. Sternberg in Alberta, Canada, in 1946, and named in 1950. Over a dozen partial skulls and a large assortment of other fossils from various species have been found in Alberta and Alaska. A great number were not available for study until the 1980s, resulting in a relatively recent increase of interest in ''Pachyrhinosaurus''. Three species have been identified. ''P. lakustai'', from the Wapiti Formation, the bonebed horizon of which is roughly equivalent age to the upper Bearpaw and lower Horseshoe Canyon Formations, is known to have existed from about 73.5–72.5 million years ago. ''P. canadensis'' is younger, known from the lower Horseshoe Canyon Formation, about 71.5–71 Ma ago and the St. Mary River Formatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intraspecific Combat
Intraspecific competition is an interaction in population ecology, whereby members of the same species compete for limited resources. This leads to a reduction in fitness for both individuals, but the more fit individual survives and is able to reproduce. By contrast, interspecific competition occurs when members of different species compete for a shared resource. Members of the same species have rather similar requirements for resources, whereas different species have a smaller contested resource overlap, resulting in intraspecific competition generally being a stronger force than interspecific competition. Individuals can compete for food, water, space, light, mates, or any other resource which is required for survival or reproduction. The resource must be limited for competition to occur; if every member of the species can obtain a sufficient amount of every resource then individuals do not compete and the population grows exponentially. Prolonged exponential growth is rare i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.jpg "Click for more on -> North America")
.jpg "Click for more on -> Musk Oxen")
