Biology 2010 Student Edition

Published by Prentice Hall
ISBN 10: 9780133669510
ISBN 13: 978-0-13366-951-0

Chapter 25, Introduction to Animals - Assessment - 25.2 Animal Body Plans and Evolution - Understand Key Concepts/Think Critically - Page 747: 29


Multicellularity, tissues, protostome development, deuterostome development

Work Step by Step

Multicellularity evolved first because this characteristic is indicative of an organism being an animal. Tissues arose not too long after multicellularity. Protostome development arose before deuterostome development; therefore, protostomes are more "primitive" than deuterostomes.
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