The early Devonian period is largely considered to be a world of a diverse array of lobe-finned fish, including lungfish, coelacanths, and bony fish. Over the course of time, vertebrates made evolutionary strides with provided them with the ability to travel on land. Coelacanths developed a single boned shoulder girdle, lungfish developed paired fins, and sauripterus developed the major structures on the arm (humerus, radius, and ulna). As these developments progressed and environmental pressures were amounting in aquatic environments, vertebrates began to venture onto land. Sometimes it was for short excursions, sometimes a bit longer. A major step in vertebrate evolution was the advancement of the tetrapod, a vertebrate animal with four appendages or legs. Buettneria, an early tetrapod was primarily an aquatic animal with very short legs that were used to make brief adventures onto land. Over time tetrapods made longer land excursions and developed more substantial lives on land. As a result, they developed different types of limbs which evolved for a variety of uses. Some limbs were more suited to grasping, others to swimming, flying or walking.
During the late Devonian Period the older aquatic clades split from the tetrapods. The tetrapods continued to evolve over time. There are four classes of tetrapods: amphibians, reptiles, birds, and mammals. They evolved in this order as well. Within the four classes, the limbs of different groups changed and adapted in order to suit their surrounding environment. This led to many different tetrapod morphologies resulting in some tetrapods evolving for terrestrial lifestyles, some for aquatic surroundings and others for aerial existences.
Amphibians, semi-aquatic animals, a...
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...as a strong enough force to move vertebrates onto land. In order to do so, four limbs that allow for movement and radiation in the terrestrial world were developed. Both the fossil records and extant animals provide a cladistics map of how fish became tetrapods and how tetrapods split into amphibians, reptiles, birds, and mammals.
Works Cited
Blount, Kitty, and Maggie Crowley, eds. Encyclopedia of Dinosaurs and Prehistoric Life. New
York: Dk Publishing, Inc., 2008. Accessed November 29, 2011, http://books.google.com/books?id=a8bQxpPqmQgC&dq=Encyclopedia+of+Dinosaurs+and+Prehistoric+Life++By+Dorling+Kindersley&source=gbs_navlinks_s.
Feduccia, Alan. The origin and evolution of birds. New Haven: Yale University Press, 1999.
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1) Carroll, R. L. 1988. Vertebrate Paleontology and Evolution. W. H. Freeman and Company, New York.
One hundred and fifty million years ago, large aquatic species of reptile such as the Plesiosaur dominated the ocean, and were pre-eminent predators of the sea. The branch of now extinct Plesiosaurs, or ‘near lizards’, evolved into variant closely related species specialised to take different niches in the food chain. Such species of Plesiosaur include the phenotypically similar Plesiosauroid and Pliosauroid. The physiological adaptations of the long necked variant, the Plesiosauroid, as it relates to deep sea diving, will be addressed in depth.
In the book, Your Inner Fish, by Neil Shubin he presents the notion of evolution and how we can trace parts that make up the human body back to jellyfish, worms, and even fish. The book not only discusses how we arose to be what we are today, but also the implications our ancestors had on our current body plan. In this essay, I will demonstrate that I have digested the entirety of Shubin’s book by convincing you (dear reader) that everything in our bodies is based on simple changes to already existing systems. To make this case, I will use the evidence of limb development in a vast array of organisms, the four arches found in the embryological stage of development, the structures inside our noses, and how our ears have come about all due to modifications.
Study done from the available fossils show that the body of Liopleurodon was very streamlined and adapted to swimming. Its body had four limbs which were paddle-like in shape. These paddle shaped limbs acted like propellers which made it
Paul, Gregory S. (2002). "Looking for the True Bird Ancestor". Dinosaurs of the Air: The Evolution and Loss of Flight in Dinosaurs and Birds. Baltimore: Johns Hopkins University Press. pp. 171–224. ISBN 0-8018-6763-0.
If you were to live during the tertiary period, this would be one of the things you would often see. All of the mammals that existed during that time period were terrestrial. They all were land dwelling mammals. Before J. G. M. Thewissen and colleagues’ discovery in Pakistan, many scientists believed, since the constant new discoveries twenty years ago, in what the numerous fossils from North America, Pakistan, and Egypt have revealed, “…these early cetaceans had mobile elbows and external hind limbs with articulated knees. However, they were fully aquatic, except for Ambulocetus, which was amphibious-much like sea lions” (Walking with Whales).
ohn Steinbeck's “Cannery Row” offers many interpretations, especially when viewed through the lens of the Holy Bible. From the Christ like figure of Doc to his apostles, Mack and the boys, Cannery Row is ripe with religious tropes. However, Doc is also considered to be quick to anger at times, and carries with him many themes found throughout the Old Testament texts and some legends that are even more aged. However, if we consider Doc to be the messianic figure he is then it wasn't the party that Doc had a problem with, nor that it was held without his knowing on his property. The issue arises with the process by which Mack and the boys use to fund the party. The green frogs harvested ultimately causes Mack and the boys to succumb to greed in an effort to praise Doc. The collection of frogs used as a currency is what sends Doc into a rage.
At the turn of the century, American readers were interested only in stories with happy endings, where goodness was praised and evil was punished. They did not particularly care if that was a false interpretation of the way life really was. When men such as Frank Norris, the author of The Octopus, wrote angrily of the injustices and poverty to be found in America, readers turned away. The Octopus made them change their minds. The course of the novel and the reality of its characters held the readers’ attention. It is so powerful a book that people had to care about the wheat growers, almost against their wishes.
Geologic development contributed to the Cambrian explosion. There was a supercontinent called Rodina that broke up to make continents. There was an ice age but the Earth continued to warm creating new life forms. There things called invertebrates that had no backbone. Life forms also had a hard outer shell to protect them. The trilobite is an arthropod that had a hard outer shell. In only 15 million years many different types of organisms evolved. Cambrian reefs made up of sponges flourished.
...s from the Paleozoic, Mesozoic, and Cenozoic periods show proof of how animals have gone through evolution and why certain fossils look very similar. The Law of Original Horizontality and the Law of Superposition both express true when looking at modern rock layers today. The Law of Original Horizontality happens when sediments are constantly deposited over old layers of rock forming new layers over millions of years, while the Law of Superposition is the law that older rock layers lie beneath the newer layers. Also, Pangea and Panthalassa are now the seven continents and four oceans of the world today as a result of Continental Drift. All things considered, Rock layers are therefore evidence of Evolution for, rock layers holds proof of evolving animals seen through fossils, the plates in the earth separated Pangea, and the relation of evolution and rock layers.
The origin of modern day whales, a mystery that has puzzled paleontologists for years, may have just been solved with the discovery of an ankle bone. This discovery might sound simple and unimportant, but the bones of these ancient animals hold many unanswered questions and provide solid proof of origin and behavior. The relationship between whales and other animals has proven to be difficult because whales are warm-blooded, like humans, yet they live in the sea. The fact that they are warm-blooded suggests that they are related to some type of land animal. However, the questions of exactly which animal, and how whales evolved from land to water, have remained unanswered until now.
The debate of whether dinosaurs were cold blooded or warm blooded has been ongoing since the beginning of the century. At the turn of the century scientists believed that dinosaurs had long limbs and were fairly slim, supporting the idea of a cold blooded reptile. Recently, however, the bone structure, number or predators to prey, and limb position have suggested a warm blooded species. In addition, the recent discovery of a fossilized dinosaur heart has supported the idea that dinosaurs were a warm blooded species. In this essay, I am going to give supporting evidence of dinosaurs being both warm and cold blooded. I will provide background information on the dinosaur that was discovered and what information it provides scientists.
Acanthostega had a fish-like tail and gills for breathing under water, this being the aquatic part of it. But at the ends of the arms were “peddle-shaped” appendages, thought to be the first “hands” on Earth. Clack’s discovery proved that some fish had arms and legs in the water. It showed that arms and legs were already evolved before organisms started actually living on land, they were used more for survival than walking. In a sense, the “blueprints” of an arm were already in place.
When these alterations are helpful, they grow to be fixed in a population and can result in the evolution of new phyla. Evo-devo seeks to figure out how new groups happen by understanding how the method of development has evolved in different lineages. In other word, evo-devo explains the interaction between phenotype and genotype (Hall, 2007). Explanation of morphological novelty of evolutionary origins is one of the middle challenges in current evolutionary biology, and is intertwined with energetic discussion regarding how to connect developmental biology to standard perspectives from the theory of evolution (Laubichler, 2010). A large amount of theoretical and experiential effort is being devoted to novelties that have challenged biologists for more than one hundred years, for instance, the basis of fins in fish, the fin-to-limb change and the evolution of feathers.
The world we live in today is full of an exceptional variety of animals. The time it took to conclude to the various sorts of species seen today has been throughout a period of millions of years. The vast majority of these animals are accredited to evolutionary advancements. When the environment changes, organisms have become accustomed to changing to fit their environment, to ensure their species does not die off. These physical changes have resulted in different phyla, ranging from basic structures, like sponges to advance systems, like that of an octopus.