Get Full Essay Get access to this section to get all help you need with your essay and educational issues. The theory of biological evolution suggests that all living things are related and that the evolution of living things is powered by natural processes.
Download this Term Paper in word format. The function point-of-view fails to account for the presence of a femur in addition to processes from the pelvic bone.
Altogether, these hind legs in this whale present for contemplation a most interesting instance of those significant parts in an animal -- rudimentary structures. Today it is just a double or single blowhole, and the ears are closed and internal, detecting only vibrations from the lower jaw.
They "speak" through a "melon organ" or pad of fat. Milinkovitch used results from molecular studies to determine that sperm whales were more closely related to the baleen whales mysticeti than to The evolution of dolphins essay whales Odontoceti Milinkovitch.
But his conclusion was not well accepted, The evolution of dolphins essay sperm whales have substantial teeth and a single, rather than double nostrilled blowhole. More recently, scientists came back to the traditional arrangement, that the sperm whale is an odontocete.
The evidence and recent molecular analyses strongly indicate the mystecetes and all other extant cetaceans is the oldest division in the ancestral tree. The pygmy sperm whale Kogia beviceps and dwarf sperm whale Kogia simusare much smaller. The kogiids seem to have separated from the lineage that led to the sperm whale at least 9 millions years ago, making the sperm whale the myse phylogenetically distinct of all the seventy-five-odd species of living odontocetes.
There are photographs of hind limb buds on a five-week-old Pantropical Spotted Dolphin embryo, and 1. Thewissen which are available on the Web Thewissen. Sirenians and elephants are evolved from a common ancestor.
Like whales, sirenians returned to the water. Though hind limbs on whales may be hard to find, many sirenians Manatees still retain vestigial toenails like their elephant cousins, and share other traits in common with modern elephants.
There seems to be a controversy over the origins of modern whales which retain vestigial hind limb rudiments.
Creationists call this vestige bone disease and say these remnants were designed for copulation only which they are used forbut science says this is how evolution works --finding new purpose for old structures. In an out of date publication by Creationists they claim that there is no bone in the whale descended from the thigh leg bones, but new fossil finds of early whales contain complete leg bones from basilosaurus, and a reconstruction of the creature's likely appearance shows it has rudimentary legs.
On questions on the dating of varied early whales one might suggest further reading on whale evolution, the evolution of eco-location, the nursing of the young suggesting common ancestry with land mammalsand the brain of humans vs. The transitional inner ear of whales evolved from land to sea mammals.
Professor Hans Thewissen explained the differences of earbone fossils, the incus and tympanic, in his web publication, The Thewissen Lab Thewissen, But scientists have many e xamples of hind limb rudiments, such as one found incaught in the Bering Sea, where an x-ray revealing bone structures and a photograph taken of the protrusions on the whale's body, showed the whale had small legs.
Even better, ina historical record and photos of a female humpback with protruded hind limbs including femur, tibia and tarsus was made. Inthere was a study of protruded limbs on whale and dolphin embryos. A female sperm whale was caught in Upon examining the interior of the limb, partially cartilaginous bones were found, corresponding to the pelvis, femur, and possibly to the tibia.
As there are numerous examples of this feature, a list of catches between and of whales caught and discovery of hind limb protrusions, including the approximate percentage of whales with this feature may be found on the web.
These include the appearance of the first elephants with trunks, early horses, and the appearance of many grass plants that would eventually produce vast tracts of grasslands in Mongolia and North America for these animals to eat in the following epoch, the Miocene.
Two modern lineages of cetaceans had evolved during this epoch from archaeocete ancestors. Interestingly, in the late Oligocene, the whale Aetiocetus, from Oregon, developed skull and jaw features typical of baleen whales, so it is considered to be the earliest mysticete.
Yet it also had a full set of teeth. By the Miocene period, whales of both lineages were relatively common and are found as fossils in many marine deposits.
As a result of the cooling trend prevalent throughout the Oligocene period, the lives and habitats of many organisms were directly affected. In the oceans, marine biotic provinces became more fragmented as sea dwellers capable of withstanding cooler temperatures congregated to places further from the warmer equator, where other species could better survive.
The cooling trend was also responsible for the reduced diversity in marine plankton, the foundation of the food chain. On land, mammals such as horses, deer, camel, elephants, cats, dogs, and primates began to dominate, except in Australia.
The continuation of land mammal faunal migration between Asia and North America was responsible for the dispersion of several lineages onto new continents.
The "bulk feeding" in the open grasslands and savannas that occurred in this period resulted in the increase of general herbivores' size.
As an example, ungulates continued to get larger throughout the Oligocene period. These include the baleen whale families Balaenopteridae including the blue whale and Balaenidae right whalesand the toothed whale families Delphinidae dolphins and killer whalesPhyseteridae sperm whalesMonodontidae belugas and narwhalsPhocaenidae porpoisesand Ziphiidae beaked whales.
During this last century, whales became very important evolutionary study specimens and whaling came under strict scrutiny and criticism, considering the discovery of great intelligence and sociability of the whale. The Minke whale, a rare whale, is known for its uncanny ability to recover from blows to the head and other means of anesthetizing it to prepare it for the kill.
Recently, a Norwegian whaling boat in northern waters was reeling in a harpooned minke whale, when the animal revived. It rammed the ship, causing the mast to break and sent two crew members in the crow's nest toppling into the sea, breaking the ribs of one.Read this essay on The Evolution of the Dolphin.
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Only at tranceformingnlp.com". Below is an essay on "Evolution of Dolphins" from Anti Essays, your source for research papers, essays, and term paper examples. Approximately 95 million years ago, the ancestor of today’s dolphin, the Mesonix, roamed the earth.
Dolphins vary based on their ecosystem and what is required for them to survive in their niche. In the Gulf of Alaska there are few dolphin species, one of which is the pacific white-sided dolphin. This dolphin has a short, rounded beak with about 30 curved teeth in each side of the jaw.
Dolphins normal bosom rate is BMP. but development stepped in and created the plexus mirabila which is a heavy mass of blood vass found under the ribcage that acts as a sponge leting the mahimahi to plunge to deep deepnesss without go throughing out.
The trainers explain that all these dolphins have been bread in captivity, and to not try this in the wild, because these dolphins have been properly tamed to work along side humans. This essay will explain some features of how dolphins evolved physiologically to become better suited to their environment.
Essay Dolphins Dolphins are mammals closely related to whales and porpoises. Dolphins have a powerful and streamlined body. Essay/Term paper: Dolphins Essay, term paper, research paper: Science Reports.
Evolution From A Molecular Perspective Introduction: Why globular evolution? Evolution has been a heavily debated issue .