Campbell Biology (10th Edition)

Published by Pearson
ISBN 10: 0321775651
ISBN 13: 978-0-32177-565-8

Chapter 41 - Test Your Understanding - Level 3 - Synthesis/Evaluation - Page 914: 8


Vertebrate evolution is tied to the development of the notochord. This mouth structure is a holdover from our common ancestor.

Work Step by Step

The earliest creatures to develop a notochord were aquatic in origin. They had an oral structure that served both as a mouth for eating and for breathing via the passage of water through pharyngeal slits. Other vertebrates still exhibit a similar pharyngeal structure, regardless of respiratory structure.
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