The Biology and Diversity of Extant Reptiles Essay

The Biology and Diversity of Extant Reptiles The word reptile itself does not describe a monophyletic group of vertebrates, like the mammals or birds. It is used to classify a polyphyletic group of animals that are a subset of the larger group of Amniotes. The term is best described through a cladogram: [IMAGE] The reptiles first appeared in the early Carboniferous, having evolved from labyrinthodont amphibians. They had several distinct advantages over the amphibians that allowed them to flourish during the cold, dry Permian period. These lead them to be the most successful group of vertebrates and this period was referred to as the age of reptiles. They exploited all terrestrial niches,†¦show more content†¦Because of this reptiles were able withstand osmotic water loss and re-invade the sea. The Chelonia (turtles) have become the most prolific marine reptile and they also have an interesting skin that is worth mentioning. The have a shell covering their body, made out of a horny layer attached to a denser bony layer. It comes in two pieces, the carapace, for dorsal protection and the plastrom for ventral protection. 2 Excretion. Reptiles have modified their excretory products to conserve water. Because they do not have a complex enough kidney to produce urea they create uric acid, a large molecule that has a very low water content. Although the water content is lower than urea the trade off is that the molecule is expensive to make. Reptiles also reduce the water content of their faeces through active removal of NaCl. This creates an osmotic gradient to draw water out and desiccate the excrement. The excess NaCl is then excreted through the nose. 3 Creation of the cloaca. This is a cavity into which the urinary, alimentary and genital ducts open. It has three sections, the coprodaeum where faeces collect and enter, the urodeum where the ureter empties out and water is removed and finally the proctodaeum, the collection point for uric acid and faeces. This centralisation of all the excretory products allows for greater water retention as well as providing for theShow MoreRelatedEssay about Evidence for Evolution920 Words   |  4 Pages Evolution and Diversity†¨ Evolution and Diversity The foundation for the theory of evolution was laid by Charles Darwin (Rose, n.d.). He developed hypotheses about natural selection which helped scientists develop the theory. Evolution is a theory and not a hypothesis because evolution has been proven by vast amounts of scientific data, research, and testing. The definition of a hypothesis is an educated explanation that needs to be researched and tested but has not yetRead MoreEssay about Placental Ruminants and Herbivorous Marsupials of Australia3561 Words   |  15 Pagesmarsupial animal species that have evolved on the isolated continent of Australia are unique compared to the rest of the animal kingdom in many ways due to the harsh and distinctive environment found on the continent. The major area of marsupial biology that distinguishes them from all other eutherian mammals is their mode of reproduction. However, it can be said that there are many other areas in which unique differences can be seen between marsupials an d eutherian mammals; one such area of adaptationRead MoreStephen P. Robbins Timothy A. Judge (2011) Organizational Behaviour 15th Edition New Jersey: Prentice Hall393164 Words   |  1573 PagesTitle. HD58.7.R62 2012 658.3—dc23 2011038674 10 9 8 7 6 5 4 3 2 1 ISBN 10: 0-13-283487-1 ISBN 13: 978-0-13-283487-2 Brief Contents Preface xxii 1 2 Introduction 1 What Is Organizational Behavior? 3 The Individual 2 3 4 5 6 7 8 Diversity in Organizations 39 Attitudes and Job Satisfaction 69 Emotions and Moods 97 Personality and Values 131 Perception and Individual Decision Making 165 Motivation Concepts 201 Motivation: From Concepts to Applications 239 3 The Group 9 10 11