|
Ambulocetus
''Ambulocetus'' (Latin ''ambulare'' "to walk" + ''cetus'' "whale") is a genus of early amphibious cetacean from the Kuldana Formation in Pakistan, roughly 48 or 47 million years ago during the Early Eocene (Lutetian). It contains one species, ''Ambulocetus natans'' (Latin ''natans'' "swimming"), known solely from a single, near-complete fossil. ''Ambulocetus'' is among the best-studied of Eocene cetaceans, and serves as an instrumental find in the study of cetacean evolution and their transition from land to sea, as it was the first cetacean discovered to preserve a suite of adaptations consistent with an amphibious lifestyle. ''Ambulocetus'' is classified in the group Archaeoceti—the ancient forerunners of modern cetaceans whose members span the transition from land to sea—and in the family Ambulocetidae, which includes '' Himalayacetus'' and '' Gandakasia'' (also from the Eocene of the Indian subcontinent). ''Ambulocetus'' had a narrow, streamlined body, and a long, broa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hans Thewissen
Hans Thewissen is a Dutch-American paleontologist. His field work has discovered fossils for the steps in the transition from land to water in whales: ''Ambulocetus'', ''Pakicetus'', '' Indohyus'' and ''Kutchicetus''. He now studies modern bowhead and beluga whales in Alaska to learn about their biology and their implications for management and conservation. Early life Thewissen has always been interested in paleontology and natural history. His mother said that when Thewissen was a small boy, she had to sort through his pockets before laundry time to take out the rocks and worms he collected. His father used to take him to the town of Maastricht, and they collected fossils from the Maastrichtian period. 12th birthday present was a rock hammer, which has accompanied him on all collecting trips since. He grew up just 2 miles from Liessel, a fossil locale that yielded the first whales he ever collected. Educational background After finishing Gymnasium secondary education in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ambulocetidae
Ambulocetidae is a family of early cetaceans from Pakistan. The genus '' Ambulocetus'', after which the family is named, is by far the most complete and well-known ambulocetid genus due to the excavation of an 80% complete specimen of ''Ambulocetus natans''. The other two genera in the family, '' Gandakasia'' and '' Himalayacetus'', are known only from teeth and mandibular fragments. Retaining large hindlimbs, it was once thought that they could walk on land—indeed, their name means "walking whales"—, but recent research suggests they may have been fully aquatic like modern cetaceans. Description The most basal of marine cetaceans, ambulocetids lived in shallow near-shore environments such as estuaries and bays, but were still dependent on fresh water during some stage of their life. Some of the characteristics related to sound transmission found in the lower jaws of modern whales that were absent in pakicetids are present in ambulocetids. They probably swam by paddling thei ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Archaeoceti
Archaeoceti ("ancient whales"), or Zeuglodontes in older literature, is a paraphyletic group of primitive cetaceans that lived from the Early Eocene to the late Oligocene (). Representing the earliest cetacean radiation, they include the initial amphibious stages in cetacean evolution, thus are the ancestors of both modern cetacean suborders, Mysticeti and Odontoceti. This initial diversification occurred in the shallow waters that separated India and Asia , resulting in some 30 species adapted to a fully oceanic life. Echolocation and filter-feeding evolved during a second radiation . All archaeocetes from the Ypresian (56–47.8 mya) and most from the Lutetian (47.8–41.3 mya) are known exclusively from Indo-Pakistan, but Bartonian (41.3–38.0 mya) and Priabonian (38.0–33.9 mya) genera are known from across Earth, including North America, Egypt, New Zealand, and Europe. Although no consensus exists regarding the mode of locomotion of which cetaceans were capable during ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cetacean
Cetacea (; , ) is an infraorder of aquatic mammals that includes whales, dolphins, and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively carnivorous diet. They propel themselves through the water with powerful up-and-down movement of their tail which ends in a paddle-like fluke, using their flipper-shaped forelimbs to maneuver. While the majority of cetaceans live in marine environments, a small number exclusively reside in brackish water or fresh water. Having a cosmopolitan distribution, they can be found in some rivers and all of Earth's oceans, and many species inhabit vast ranges where they migrate with the changing of the seasons. Cetaceans are famous for their high intelligence and complex social behaviour as well as for the enormous size of some of the group's members, such as the blue whale which reaches a maximum confirmed length of 29.9 meters (98 feet) and a weight of 173 tonnes (190 short tons ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Evolution Of Cetaceans
The evolution of cetaceans is thought to have begun in the Indian subcontinent from even-toed ungulates 50 million years ago (mya) and to have proceeded over a period of at least 15 million years. Cetaceans are fully aquatic marine mammals belonging to the order Artiodactyla and branched off from other artiodactyls around 50 mya. Cetaceans are thought to have evolved during the Eocene (56-34 mya), the second epoch of the present-extending Cenozoic Era. Molecular and morphological analyses suggest Cetacea share a relatively recent closest common ancestor with hippopotami and that they are sister groups. Being mammals, they surface to breathe air; they have 5 finger bones (even-toed) in their fins; they nurse their young; and, despite their fully aquatic life style, they retain many skeletal features from their terrestrial ancestors.Thewissen, J. G. M., L. N. Cooper, J. C. George, and S. Bajpai. 2009. From land to water: the origin of whales, dolphins, and porpoises. Evol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Natural History Museum Of The University Of Pisa
The Natural History Museum of the University of Pisa is a natural history museum in the city of Pisa in Tuscany, Italy. It houses one of the largest collection of cetaceans skeletons in Europe. The museum's oldest collections are seashells collected by the Italian invertebrate scientist, Niccolò Gualtieri. There is also an assembly of five thousand zoological specimens collected by the Italian geologist and ornithologist, Paolo Savi. Grand Duke Ferdinand I of Tuscany established the museum in 1596 by moving specimens from the Florentine palaces of the Medici. In 1981, the museum was moved to the Pisa Charterhouse. Organization The museum is organized into two sectors. One sector includes the * Aquarium * Temporary Exhibitions * Prehistory of Monte Pisano The other sector includes the permanent exhibitions of * Historical Gallery * Garden * Amphibians and Reptiles gallery * Mammals gallery * Hall of Archaeocetes * Cetacean gallery * Hall of the evolution of man * Mineral g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sea Lion
Sea lions are pinnipeds characterized by external ear flaps, long foreflippers, the ability to walk on all fours, short and thick hair, and a big chest and belly. Together with the fur seals, they make up the family Otariidae, eared seals. The sea lions have six extant and one extinct species (the Japanese sea lion) in five genera. Their range extends from the subarctic to tropical waters of the global ocean in both the Northern and Southern Hemispheres, with the notable exception of the northern Atlantic Ocean. They have an average lifespan of 20–30 years. A male California sea lion weighs on average about and is about long, while the female sea lion weighs and is long. The largest sea lions are Steller's sea lions, which can weigh and grow to a length of . Sea lions consume large quantities of food at a time and are known to eat about 5–8% of their body weight (about ) at a single feeding. Sea lions can move around in water and at their fastest they can r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Otter
Otters are carnivorous mammals in the subfamily Lutrinae. The 13 extant otter species are all semiaquatic, aquatic, or marine, with diets based on fish and invertebrates. Lutrinae is a branch of the Mustelidae family, which also includes weasels, badgers, mink, and wolverines, among other animals. Etymology The word ''otter'' derives from the Old English word or . This, and cognate words in other Indo-European languages, ultimately stem from the Proto-Indo-European language root , which also gave rise to the English word "water". Terminology An otter's den is called a holt or couch. Male otters are called dogs or boars, females are called bitches or sows, and their offspring are called pups or cubs. The collective nouns for otters are bevy, family, lodge, romp (being descriptive of their often playful nature) or, when in water, raft. The feces of otters are typically identified by their distinctive aroma, the smell of which has been described as ranging from fres ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Webbed Feet
The webbed foot is a specialized limb with interdigital membranes (webbings) that aids in aquatic locomotion, present in a variety of tetrapod vertebrates. This adaptation is primarily found in semiaquatic species, and has convergently evolved many times across vertebrate taxa. It likely arose from mutations in developmental genes that normally cause tissue between the digits to apoptose. These mutations were beneficial to many semiaquatic animals because the increased surface area from the webbing allowed for more swimming propulsion and swimming efficiency, especially in surface swimmers. The webbed foot also has enabled other novel behaviors like escape responses and mating behaviors. A webbed foot may also be called a paddle to contrast it from a more hydrofoil-like flipper. Morphology A webbed foot has connecting tissue between the toes of the foot. Several distinct conditions can give rise to webbed feet, including interdigital webbing and syndactyly. The webbing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tail Fluke
A fin is a thin component or appendage attached to a larger body or structure. Fins typically function as foils that produce lift or thrust, or provide the ability to steer or stabilize motion while traveling in water, air, or other fluids. Fins are also used to increase surface areas for heat transfer purposes, or simply as ornamentation. Fins first evolved on fish as a means of locomotion. Fish fins are used to generate thrust and control the subsequent motion. Fish, and other aquatic animals such as cetaceans, actively propel and steer themselves with pectoral and tail fins. As they swim, they use other fins, such as dorsal and anal fins, to achieve stability and refine their maneuvering.Helfman G, Collette BB, Facey DE and Bowen BW (2009"Functional morphology of locomotion and feeding" Chapter 8, pp. 101–116. In:''The Diversity of Fishes: Biology'', John Wiley & Sons. . The fins on the tails of cetaceans, ichthyosaurs, metriorhynchids, mosasaurs, and plesiosaurs are ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mangrove
A mangrove is a shrub or tree that grows in coastal saline or brackish water. The term is also used for tropical coastal vegetation consisting of such species. Mangroves are taxonomically diverse, as a result of convergent evolution in several plant families. They occur worldwide in the tropics and subtropics and even some temperate coastal areas, mainly between latitudes 30° N and 30° S, with the greatest mangrove area within 5° of the equator. Mangrove plant families first appeared during the Late Cretaceous to Paleocene epochs, and became widely distributed in part due to the movement of tectonic plates. The oldest known fossils of mangrove palm date to 75 million years ago. Mangroves are salt-tolerant trees, also called halophytes, and are adapted to live in harsh coastal conditions. They contain a complex salt filtration system and a complex root system to cope with saltwater immersion and wave action. They are adapted to the low-oxygen conditions of w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tropical Rainforest
Tropical rainforests are rainforests that occur in areas of tropical rainforest climate in which there is no dry season – all months have an average precipitation of at least 60 mm – and may also be referred to as ''lowland equatorial evergreen rainforest''. True rainforests are typically found between 10 degrees north and south of the equator (see map); they are a sub-set of the tropical forest biome that occurs roughly within the 28-degree latitudes (in the equatorial zone between the Tropic of Cancer and Tropic of Capricorn). Within the World Wildlife Fund's biome classification, tropical rainforests are a type of tropical moist broadleaf forest (or tropical wet forest) that also includes the more extensive seasonal tropical forests. Overview Tropical rainforests are characterized by two words: hot and wet. Mean monthly temperatures exceed during all months of the year. Average annual rainfall is no less than and can exceed although it typically lies betwee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.JPG "Click for more on -> Mangrove")
.jpg "Click for more on -> Tropical Rainforest")