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Pakicetus Fossil
''Pakicetus'' (meaning 'whale from Pakistan') is an extinct genus of amphibious cetacean of the family Pakicetidae, which was endemic to the Indian Subcontinent during the Ypresian (early Eocene) period, about 50 million years ago. It was a wolf-like mammal, about long, and lived in and around water where it ate fish and other animals. The name Pakicetus comes from the fact that the first fossils of this extinct amphibious whale were discovered in Pakistan. The vast majority of paleontologists regard it as the most basal whale, representing a transitional stage between land mammals and whales. It belongs to the even-toed ungulates with the closest living non-cetacean relative being the hippopotamus. Description Based on the sizes of specimens, and to a lesser extent on composite skeletons, species of ''Pakicetus'' are thought to have been to in length. ''Pakicetus'' looked very different from modern cetaceans, and its body shape more resembled those of land-dwelling hoofe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eocene
The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes from the Ancient Greek (''Ēṓs'', 'Eos, Dawn') and (''kainós'', "new") and refers to the "dawn" of modern ('new') fauna that appeared during the epoch.See: *Letter from William Whewell to Charles Lyell dated 31 January 1831 in: * From p. 55: "The period next antecedent we shall call Eocene, from ήως, aurora, and χαινος, recens, because the extremely small proportion of living species contained in these strata, indicates what may be considered the first commencement, or ''dawn'', of the existing state of the animate creation." The Eocene spans the time from the end of the Paleocene Epoch to the beginning of the Oligocene Epoch. The start of the Eocene is marked by a brief period in which the concentration of the carbon isoto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indohyus
''Indohyus'' (Meaning "India's pig" from the Greek words ''Indos'', "from India" and ''hûs'', "pig") is an extinct genus of artiodactyl known from Eocene fossils in Asia. This small chevrotain-like animal found in the Himalayas is among the closest known non-cetacean relatives of whales. Discovery The fossils were discovered among rocks that had been collected in 1971 in Kashmir by the Indian geologist A. Ranga Rao who found a few teeth and parts of a jawbone; when he died, however, many rocks had yet to be broken open. Ranga Rao's widow gave the rocks to Hans Thewissen, who was working on them. When his technician accidentally broke one of the skulls they had found, Thewissen recognised the ear structure of the auditory bulla, formed from the ectotympanic bone in a shape which is highly distinctive, found only in the skulls of cetaceans both living and extinct, including '' Pakicetus''. Paleobiology About the size of a fox, this omnivorous pig-like creature shared some ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ectotympanic
The ectotympanic, or tympanicum, is a bony structure found in all mammals, located on the tympanic part of the temporal bone, which holds the tympanic membrane (eardrum) in place. In catarrhine primates (including humans), it takes a tube-shape. Its position and attachment to the skull vary between primates, and can be either inside or outside the auditory bulla. It is homologous with the angular bone of non-mammalian tetrapods A tetrapod (; from Ancient Greek τετρα- ''(tetra-)'' 'four' and πούς ''(poús)'' 'foot') is any four- limbed vertebrate animal of the clade Tetrapoda (). Tetrapods include all extant and extinct amphibians and amniotes, with the lat .... When the latter is present, it contacts the entotympanic. References External links webref: Anthropology * * Skull bones Mammal anatomy {{Vertebrate anatomy-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inner Ear
The inner ear (internal ear, auris interna) is the innermost part of the vertebrate ear. In vertebrates, the inner ear is mainly responsible for sound detection and balance. In mammals, it consists of the bony labyrinth, a hollow cavity in the temporal bone of the skull with a system of passages comprising two main functional parts: * The cochlea, dedicated to hearing; converting sound pressure patterns from the outer ear into electrochemical impulses which are passed on to the brain via the auditory nerve. * The vestibular system, dedicated to balance (ability), balance. The inner ear is found in all vertebrates, with substantial variations in form and function. The inner ear is innervated by the eighth cranial nerve in all vertebrates. Structure The labyrinth can be divided by layer or by region. Bony and membranous labyrinths The bony labyrinth, or osseous labyrinth, is the network of passages with bony walls lined with periosteum. The three major parts of the bony labyrin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eurasia
Eurasia ( , ) is a continental area on Earth, comprising all of Europe and Asia. According to some geographers, Physical geography, physiographically, Eurasia is a single supercontinent. The concept of Europe and Asia as distinct continents dates back to classical antiquity, antiquity, but their borders have historically been subject to change. For example, the ancient Greeks originally included Africa in Asia but classified Europe as separate land. Eurasia is connected to Africa at the Suez Canal, and the two are sometimes combined to describe the largest contiguous landmass on Earth, Afro-Eurasia. History Eurasia has been the host of many ancient civilizations, including those based in Mesopotamia, Egypt, the Indus Valley and China. In the Axial Age (mid-first millennium BCE), a continuous belt of civilizations stretched through the Eurasian Subtropics, subtropical zone from the Atlantic to the Pacific. This belt became the mainstream of world history for two millennia. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tethys Ocean
The Tethys Ocean ( ; ), also called the Tethys Sea or the Neo-Tethys, was a prehistoric ocean during much of the Mesozoic Era and early-mid Cenozoic Era. It was the predecessor to the modern Indian Ocean, the Mediterranean Sea, and the Eurasian inland marine basins (primarily represented today by the Black Sea and Caspian Sea). During the early Mesozoic, as Pangaea broke up, the Tethys Ocean was defined as the ocean located between the ancient continents of Gondwana and Laurasia. After the opening of the Indian and Atlantic oceans during the Cretaceous Period and the breakup of these continents over the same period, it came to be defined as the ocean bordered by the continents of Africa, Eurasia, India, and Australasia. During the early-mid Cenozoic, the Indian, African, Australian and Arabian plates moved north and collided with the Eurasian plate, which created new borders to the ocean, a land barrier to the flow of currents between the Indian and Mediterranean basins, and t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Terrigenous Sediment
In oceanography, terrigenous sediments are those derived from the erosion of rocks on land; that is, they are derived from ''terrestrial'' (as opposed to marine) environments. Consisting of sand, mud, and silt carried to sea by rivers, their composition is usually related to their source rocks; deposition of these sediments is largely limited to the continental shelf. Sources of terrigenous sediments include volcanoes, weathering of rocks, wind-blown dust, grinding by glaciers, and sediment carried by rivers or icebergs. Terrigenous sediments are responsible for a significant amount of the salt in today's oceans. Over time rivers continue to carry minerals to the ocean but when water evaporates, it leaves the minerals behind. Since chlorine and sodium are not consumed by biological processes, these two elements constitute the greatest portion of dissolved minerals. Quantity Some 1.35 billion tons, or 8% of global river-borne sediment (16.5-17 billion tons globally), is tra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Whale
Whales are a widely distributed and diverse group of fully Aquatic animal, aquatic placental mammal, placental marine mammals. As an informal and Colloquialism, colloquial grouping, they correspond to large members of the infraorder Cetacea, i.e. all cetaceans apart from dolphins and porpoises. Dolphins and porpoises may be considered whales from a formal, Cladistics, cladistic perspective. Whales, dolphins and porpoises belong to the order Cetartiodactyla, which consists of even-toed ungulates. Their closest non-cetacean living relatives are the hippopotamuses, from which they and other cetaceans diverged about 54 million years ago. The two parvorders of whales, baleen whales (Mysticeti) and toothed whales (Odontoceti), are thought to have had their Most recent common ancestor, last common ancestor around 34 million years ago. Mysticetes include four Neontology, extant (living) Family (biology), families: Balaenopteridae (the rorquals), Balaenidae (right whales), Cetotheriid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lutetian
The Lutetian is, in the geologic timescale, a stage (stratigraphy), stage or age (geology), age in the Eocene. It spans the time between . The Lutetian is preceded by the Ypresian and is followed by the Bartonian. Together with the Bartonian it is sometimes referred to as the Middle Eocene Subepoch. Stratigraphic definition The Lutetian was named after Lutetia, the Latin language, Latin name for the city of Paris. The Lutetian Stage was introduced in scientific literature by French geologist Albert de Lapparent in 1883 and revised by A. Blondeau in 1981. The base of the Lutetian Stage is at the first appearance of the nanofossil ''Blackites inflatus'', according to an official reference profile (GSSP) established in 2011. Of two candidates located in Spain, the Gorrondatxe section was chosen.See thwebsite of Eustoquio Molinafor these candidates. The top of the Lutetian (the base of the Bartonian) is at the first appearance of calcareous nannofossils, calcareous nanoplankton s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kala Chitta Range
Kala Chitta Range (in Punjabi and ''Kālā Chiṭṭā'') is a mountain range in the Attock District of Punjab, Pakistan. "Kala" and "Chitta" are Punjabi words, meaning "black" and "white", respectively. The range thrusts eastward across the Potohar plateau towards Rawalpindi. Pakistan's Kuldana Formation is best known for its fossil Eocene mammals, including primitive cetaceans such as '' Pakicetus'', '' Ambulocetus'' and '' Attockicetus''. Kuldana mammals have been considered in different studies as coming from the early Lutetian (early Middle Eocene), late Ypresian (late early Eocene) or, more recently, encompassing much of Ypresian up to early Lutetian time (early part of the early Eocene to early Eocene medium). Kuldana Formation The Kuldana Formation is located in the Kala Chita hills and is a thin, 20-120 m thick tongue of low-lying continental red beds that lie within a much thicker sequence of foraminifera-rich marine formations. Shallow planktonic and benthic foram ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, hair, petrified wood and DNA remnants. The totality of fossils is known as the ''fossil record''. Though the fossil record is incomplete, numerous studies have demonstrated that there is enough information available to give a good understanding of the pattern of diversification of life on Earth. In addition, the record can predict and fill gaps such as the discovery of '' Tiktaalik'' in the arctic of Canada. Paleontology includes the study of fossils: their age, method of formation, and evolutionary significance. Specimens are sometimes considered to be fossils if they are over 10,000 years old. The oldest fossils are around 3.48 billion years to 4.1 billion years old. Early edition, published online before prin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
External Auditory Meatus
The ear canal (external acoustic meatus, external auditory meatus, EAM) is a pathway running from the outer ear to the middle ear. The adult human ear canal extends from the auricle to the eardrum and is about in length and in diameter. Structure The human ear canal is divided into two parts. The elastic cartilage part forms the outer third of the canal; its anterior and lower wall are cartilaginous, whereas its superior and back wall are fibrous. The cartilage is the continuation of the cartilage framework of auricle. The cartilaginous portion of the ear canal contains small hairs and specialized sweat glands, called apocrine glands, which produce cerumen ( ear wax). The bony part forms the inner two thirds. The bony part is much shorter in children and is only a ring (''annulus tympanicus'') in the newborn. The layer of epithelium encompassing the bony portion of the ear canal is much thinner and therefore, more sensitive in comparison to the cartilaginous portion. Size a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
