Campbell Biology In Focus, Loose-leaf Edition (3rd Edition)
3rd Edition
ISBN: 9780134895727
Author: Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky
Publisher: PEARSON
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Chapter 27.3, Problem 2CC
WHAT IF? Would it be accurate to describe the Cambrian explosion as consisting of three “explosions,” not one? Explain your reasoning and summarize the major steps in animal evolution shown in Figure 27.10.
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WRITE ABOUT A THEME: Organization You have seenmany examples of how form fits function at all levels of thebiological hierarchy. However, we can imagine forms thatwould function better than some forms actually found innature. For example, if the wings of a bird were not formedfrom its forelimbs, such a hypothetical bird could fly yet alsohold objects with its forelimbs. In a short essay (100–150words), use the concept of “evolution as tinkering” to explainwhy there are limits to the functionality of forms in nature.
You have now studied three different types of anatomical structures.
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1. Give an example of a homologous structure from this activity:
Analogous structures have very different anatomies but similar functions. These are seen in
organismsthat are not necessarily closely related but live in similar environments and have
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2. Give an example of an analogous structure from this activity:
Vestigial structures are anatomical remnants that were important in the organism's ancestors
but are nolonger used in the same way.
3. Give an example of a vestigial structure from this activity:
\. Read some papers (find them using any of several literature-search engines that your instructor can suggest) that make different estimates of the timing of either the origin of bilaterian animal phyla or the orders of mammals. How different are the estimates based on molecular clock evidence versus paleontological evidence? What might account for these differences, and how might they be resolved?
Chapter 27 Solutions
Campbell Biology In Focus, Loose-leaf Edition (3rd Edition)
Ch. 27.1 - Prob. 1CCCh. 27.1 - Prob. 2CCCh. 27.1 - Prob. 3CCCh. 27.2 - What is the Cambrian explosion? Why is it...Ch. 27.2 - Prob. 2CCCh. 27.3 - Prob. 1CCCh. 27.3 - WHAT IF? Would it be accurate to describe the...Ch. 27.4 - Prob. 1CCCh. 27.4 - Describe two key adaptations of aquatic...Ch. 27.4 - MAKE CONNECTIONS The radiation of bilaterians in...
Ch. 27.5 - Describe two adaptations that have enabled insects...Ch. 27.5 - MAKE CONNECTIONS Compare and contrast how the...Ch. 27.6 - Describe three key amniote adaptations for life on...Ch. 27.6 - Prob. 2CCCh. 27.6 - WHAT IF? Which came first, the chicken or the egg?...Ch. 27.7 - Describe how ocean communities changed in the...Ch. 27.7 - Prob. 2CCCh. 27.7 - Prob. 3CCCh. 27 - Prob. 1TYUCh. 27 - Fossil steroid and molecular clock evidence...Ch. 27 - Which of the following was probably the least...Ch. 27 - Prob. 4TYUCh. 27 - Prob. 5TYUCh. 27 - Prob. 6TYUCh. 27 - Prob. 7TYUCh. 27 - FOCUS ON EVOLUTION In Figure 27.29, circle the...Ch. 27 - FOCUS ON ORGANIZATION Early tetrapods had a...Ch. 27 - SYNTHESIZE YOUR KNOWLEDGE Collectively, do these...
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- INTERPRET DATA Imagine that you discover a new animal in a rain forest. It has an elongated, segmented body with bristles, and it has no obvious head. Where would youplace this animal in the accompanying cladogram? Support your decision. Look at the more detailed cladogram inFigure 30-6a (in Chapter 30). What additional characteristicswould help you place your animal in this cladogram? Explainyour decision-making process.arrow_forwardⒸ Macmillan Learning There are many examples of species that were ancestral to or closely related to the ancestors of modern humans, Homo sapiens sapiens. The figure shows when several key human ancestors were alive. Label the figure with the names of the human ancestral species. Millions of years ago 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 Australopithecus africanus Ardipithecus ramidus Australopithecus boisei Australopithecus afarensis Homo erectus Answer Bank Homo habilis Homo sapiens sapiens Australopithecus robustus Homo neanderthalensisarrow_forwardSpecies Embryo (A-F) Describe the Anatomical Changes from Early to Late Stages Human Chicken Rabbit Tortoise Salamander В Fish A Guide Questions: 1. Look again at the six embryos in their earliest stages. Describe the patterns you see. What physical similarities exist between each of the embryos? 2. Does this suggest an evolutionary relationship? Explain how these embryos can be used as evidence of a common ancestor between each of these six organisms.arrow_forward
- Carbon-14 dating works for fossils up to about 75,000 years old;fossils older than that contain too little 14C to be detected. Mostdinosaurs went extinct 65.5 million years ago. (a) Can 14C be usedto date dinosaur bones? Explain. (b) Radioactive uranium-235 hasa half-life of 704 million years. If it was incorporated into dinosaurbones, could it be used to date the dinosaur fossils? Explainarrow_forwardTest Your Understanding 8.VISUALIZE Draw a simple cladogram illustrating the evolutionary relationships among extant mammals (marsupials, eutherians, and monotremes). Include the following characters in your cladogram: well-developed placenta, vivipary, endothermy, marsupium, hair.arrow_forwardANIMAL TREE - use for several questions that specify "Animal Tree" in the test. Bahama Oriole Chicken W Sauropod Dinosaurs Crocodiles Snakes X HUMANS Sea Urchin Yarrow_forward
- The forelimbs of the organisms in Figure 1 are examples of what type of structures? What do these structures indicate about the evolution of the three organisms? What would be an example of a structure analogous to the last structure? How does the anatomy of the forelimbs show an evolutionary pattern?arrow_forwardPlease do fast How old are the first recognizable mammals relative to the K/T boundary layer (i.e., extinction of the dinosaurs), and from what reptilian lineage did they evolve? Is this lineage the same reptilian lineage that gave rise to birds? How are these lineages distinguished? Hold old are the first fossil birds? What other plant/animal lineages first became widespread in the Tertiary that were less common in the Cretaceous?..arrow_forwardWhich of the following was probably the least important factorin bringing about the Cambrian explosion?(A) the emergence of predator-prey relationships(B) an increase in the concentration of atmospheric oxygen(C) the movement of animals onto land(D) the origin of Hox genesarrow_forward
- Test Your Understanding Know and Comprehend 4. The presence of homologous structures in two different groups of organisms suggests that (a) the organisms evolved from a common ancestor (b) convergent evolution has occurred (c) they belong to a polyphyletic group (d) homoplasy has occurred (e) independently acquired characters may evolve when organisms inhabit similar environmentsarrow_forwardTest Your Understanding Know and Comprehend 3. Each branching point in a cladogram (a) is called a root (b) represents a clade (c) represents the divergence of two or more groups from a common ancestor (d) represents horizontal gene transfer (e) marks the divergence of two kingdomsarrow_forwardTest Your Understanding 7.Which of the following is true of mammals? (a) they evolved from saurischian dinosaurs (b) they are exotherms (c) they have hair and three middle ear bones (d) mammalian embryos do not have an amnion (e) they all bear their young alive (do not lay eggs).arrow_forward
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