distills the necessary information from vertebrate anatomy, physiology, ecology, and behavioral studies and then helps students see important connections across levels of biological scale. As a result, students come to understand how organisms function effectively in their environments and how lineages of organisms change through evolutionary time. Processing complex detailed information about expansive phylogenies and diverse anatomies can be difficult for even the most motivated students, and addresses this challenge by combining appropriately detailed, clearly written text with outstanding phylogenies and figures, making it a thorough and engaging reference for students and instructors alike. The text's impressive illustration program helps students visualize complex concepts, allowing them to parse difficult anatomical information. The eleventh edition features an upgraded illustration program with several new and revised figures, including layered figures presented in the new enhanced e-Book.