Cambrian Explosion Research Paper Example | Topics and Well Written Essays - 1500 words

Welsh Explosion - Research Paper ExampleParker defines it thus The Welsh salvo is the evolutionary episode in which all creature phyla attained confused external forms. (Parker, 2003, p. 9) The phylum is the eubstance plan of an animal, and in the period sooner 543 million years ago, called the Precambrian era, there were only three unambiguous animal phyla, whereas at 538 million years ago, there were 38, and this phenomenal increase is what gives rise to the term Cambrian explosion. Some aspects of this theory atomic number 18, however, disputed, and there are studies which support a much more gradual instruction of the 38 animal phyla over a much longer time, reaching back long before the so-called explosion period from 543 million years ago. This paper examines the key arguments in favour and against the phenomenon cognize as the Cambrian explosion concludes with round reflection on what the implications of the Cambrian explosion debate are for modern erudition. Most scholars agree that there is a step-change in the fossil record at most 543 million years ago. There are some problems, however, in assuming that this surviving record video display a sudden increase in phyla variation gives us a true and complete limning of what actually happened. As scientists discover and analyse further samples, and as new technologies emerge which allow distinct kinds of analysis, the picture can change dramatically. Above all, it must always be remembered that the preservation of specimens is largely a matter of chance, and there is always the possibility that key pieces of evidence take a leak not survived, or have not yet been discovered While fossils provide the only tangible evidence for the origin of animals, some key early metazoan fossils are rare and many lack informative characters, making the derivation of a rigorous phylogenetic hypothesis based solely on fossil data difficult. (Cartwright and Collins, 2007) Referring to new technologies such( prenominal) as comparative genomics , Cartwright and Collins conclude that currently available genomic data supports the origin of a complex genome predating the Cambrian radiation, with the ancestral genome possessing the molecular toolkit necessary for an explosion of body plans and complex traits. (Cartwright and Collins, 2007) This position modifies the theory of the Cambrian explosion only slightly, since it theorizes a large number of evolutionary changes before 543 million years ago, at the molecular level, which then had the effect of causing a rapid divergence of organisms in the Cambrian explosion period. Factors external to the animals then prompt the adaptations that we see in the physical record. Some of the more popular science books propose single factors as triggers for the Cambrian explosion, such as changes in the way that light bear on the earth which in turn prompte the evolution of sight, which had the effect of increasing pressure on organisms to avoid macroc osm seen and eaten by other organisms (Parker, 2003). The importance of the Burgess shale deposits in British Columbia, Canada is recognized as a critical piece of evidence and has been labelled as the indicator of a Big Bang in animal evolution. (Carroll, 2005, p. 138) The diversity of forms is explained in terms of adaptation to changes in the environment Genes in the tool kit are important actors in this picture, but the tool kit itself represents only possibilities, not destiny. The drama of the Cambrian was control by ecology on a global