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Sperm Whale Family
Physeteroidea is a superfamily that includes three extant species of whales: the sperm whale, in the genus ''Physeter'', and the pygmy sperm whale and dwarf sperm whale, in the genus ''Kogia''. In the past, these genera have sometimes been united in a single family, the Physeteridae, with the two ''Kogia'' species in the subfamily Kogiinae; however, recent practice is to allocate the genus ''Kogia'' to its own family, the Kogiidae, leaving the Physeteridae as a monotypic (single extant species) family, although additional fossil representatives of both families are known. Characteristics The sperm whale (''Physeter macrocephalus'') is the largest species of toothed whale, with adult bulls (males) growing to be about long, and weighing about . The two kogiid species are much smaller, around in length, and weighing . The bodies of physeteroids are robustly proportioned, with paddle-shaped flippers. The lower jaw is always relatively small and thin relative to the upper jaw. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oligocene
The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the exact dates of the start and end of the epoch are slightly uncertain. The name Oligocene was coined in 1854 by the German paleontologist Heinrich Ernst Beyrich from his studies of marine beds in Belgium and Germany. The name comes from the Ancient Greek (''olígos'', "few") and (''kainós'', "new"), and refers to the sparsity of extant forms of molluscs. The Oligocene is preceded by the Eocene Epoch and is followed by the Miocene Epoch. The Oligocene is the third and final epoch of the Paleogene Period. The Oligocene is often considered an important time of transition, a link between the archaic world of the tropical Eocene and the more modern ecosystems of the Miocene. Major changes during the Oligocene included a global expansion o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Visual Perception
Visual perception is the ability to interpret the surrounding environment through photopic vision (daytime vision), color vision, scotopic vision (night vision), and mesopic vision (twilight vision), using light in the visible spectrum reflected by objects in the environment. This is different from visual acuity, which refers to how clearly a person sees (for example "20/20 vision"). A person can have problems with visual perceptual processing even if they have 20/20 vision. The resulting perception is also known as vision, sight, or eyesight (adjectives ''visual'', ''optical'', and ''ocular'', respectively). The various physiological components involved in vision are referred to collectively as the visual system, and are the focus of much research in linguistics, psychology, cognitive science, neuroscience, and molecular biology, collectively referred to as vision science. Visual system In humans and a number of other mammals, light enters the eye through the cornea and is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
