Unit 4 Lesson 5 – Flashcards
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Explain what fossil evidence indicates about the timing of the evolution of the first animals
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My book says, "Such fossil evidence indicates that the first animals began evolving long before the Cambrien explosion."
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Interpret the cladogram of invertebrates
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The cladogram of nonchordate invertebrates present current hypotheses about evolutionary relationships among major groups of modern invertebrates. It also indicates the sequence in which important features evolved.
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appendage
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a structure, such as a leg or an antennae, that protrudes from the body
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exoskeleton
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hard outer coating that is made of chitin and makes up the animals skeleton
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larvae
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immature life stage of some animals
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trochophore
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a free-swimming larval stage that most mollusks have
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1. Few fossils of the earliest animals exist because they
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were soft-bodied and tiny, therefore, unlikely to fossilize.
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2. Some of the fossils that have been found from before the Cambrien Explosion are embryos. This suggests that the organisms these fossils belonged to
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reproduced sexually.
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3. Most of the body features found in invertebrates evolved during which of the following periods?
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Cambrian
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4. A biologist exploring the deep sea trenches locates a new species of soft-bodied creature with an unfamiliar shape. He is able to determine that the creature is a mollusk because it has
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an internal shell
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5. According to Figure 26-1, the development of three germ layers occurred before the development of
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protostome development
