THE DISSECTION OF VERTEBRATES A Laboratory Manual THIRD EDITION GERARDO DE IULIIS, PhD Department of Ecology and Evolutionary Biology, University of Toronto; Royal Ontario Museum; and George Brown College of Art and Technology DINO PULERÀ, MScBMC, CMI Academic Press is an imprint of Elsevier 125 London Wall, London EC2Y 5AS, United Kingdom 525 B Street, Suite 1650, San Diego, CA 92101, United States 50 Hampshire Street, 5th Floor, Cambridge, MA 02139, United States The Boulevard, Langford Lane, Kidlington, Oxford OX5 1GB, United Kingdom Copyright © 2019 Elsevier Inc. All rights reserved. The authors are the creators of all the illustrations and photographs and retain their copyright unless otherwise stated. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. 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With deep respect, admiration, and gratitude, we dedicate this book to three teachers at the University of Toronto, who early on in our academic paths instilled in us a passion for anatomy, paleontology, and art as well as the intellectual discipline required to make these passions our careers. Their contributions are evident throughout the following pages. Charles S. “Rufus” Churcher Stephen G. Gilbert Thomas S. Parsons To our readers: Despite our best efforts, some errors are bound to have escaped our notice, and we would appreciate being informed of these. We encourage you to contact us directly with your comments, suggestions, and possible ideas for text and illustrations in future editions of this book. We look forward to hearing from you. Sincerely, Dr. Gerry De Iuliis [email protected] Dino Pulerà [email protected] Preface The resurgence of comparative vertebrate anatomy the actual hands-on experience. It is only through a care- and the recognition of its broad value to many aspects of ful, patient, and repeated practical approach that we biological inquiry, including the history of vertebrates, gain the expertise and practice required for understand- have continued since the publication of the second edi- ing the spatial relationships that are essential to learning tion of this manual—Budd and Olsson’s (2007:1) asser- how a vertebrate body is constructed, how its compo- tion that there “has never been a better time to study nent structures are related to each other, and how form morphology” rings truer than ever. Not only does ver- and function interact. tebrate anatomy provide the only direct evidence for the There are those who would suggest that such a course steps, sequence, and timing of the changes that occurred of study is unnecessary and that anatomy can be learned during earlier parts of vertebrate evolution, but its value through texts or software. While such materials (this text in helping elucidate the relationships among more recent among them) may prove invaluable as aids or tools for members of the vertebrate clade is becoming increasingly learning, we ought not to substitute these adjuncts for apparent among researchers, particularly those that the means through which we must come to know the have often been dismissive of morphological data. This vertebrate body. To do so would be akin to preparing for development, which might almost—somewhat face- an acting career by watching films, rather than through tiously—be described as a radical change has, resulted in rehearsing and attending acting workshops. Few of us several recent analyses that employ combined molecular would feel comfortable with mechanics trained solely and morphological data sets in trying to determine ver- through the Internet, trust a surgeon who has learned tebrate relationships. Unfortunately, however, the study the craft strictly through instructional videos, or fly with of anatomy at the introductory and intermediate college a pilot who has only flown missions on a flight simula- levels continues to suffer, and its stature and perceived tor. We would not be suspicious because we believe that importance have yet to regain their luster. The reasons such instructional methods are not useful. Rather, we rec- remain the same as those noted in earlier editions of this ognize that for fields whose subject matter includes com- manual—regrettably, the trend at most major academic ponents arranged in complex spatial relationships, these institutions has followed a path away from whole organ- media are meant to be used as tools that supplement ismal biology, and positions related to vertebrate anat- and guide the trainee through a methodical, firsthand omy seem to be fewer and farther between. Despite the experience with the subject matter itself. And science, intense (and certainly justified) focus on genetics over of course, is an empirical endeavor. When practiced, sci- the last several decades, it remains “clear that morphol- ence is based on observation and experience. If we are ogy still stands at the heart of comparative biology. From to train students to become scientists, it is not sufficient functional morphology to ultrastructure, morphological to merely present them with the products of science; we topics link into ecology and physiology, developmental must engage students in actual scientific practice. genetics and the fossil record; they connect them all” The debate on the value of dissection is particularly (Budd and Olsson, 2007:1). lively for human medical anatomy (see, for example, Increased resistance from some quarters to the use Sugand et al., 2010; Roseth and Saltarelli, 2014; Ross, of animals in various scientific endeavors has also hin- 2015; Van Wyk and Rennie, 2015). Many researchers dered introductory study in vertebrate anatomy. Further, are clearly in favor of dissection but also see the need easily accessible computer software has been developed to incorporate the advanced imaging technologies cur- that allows convenient visual journeys through verte- rently available. Indeed, a combination of the two tech- brate bodies without the effort, expense, and “mess” of niques apparently leads to superior results (see Biasutto actual dissection. et al., 2006). The same logic should apply for any verte- The study of anatomy and morphology has much to brate, but similarly advanced technologies are unlikely offer the student wishing to pursue a career in biological to be applied to a broad range of vertebrates in the fore- or medical fields. Proper training in vertebrate anatomy seeable future. must include a practical component that involves dissec- The central theme of most previous dissection manu- tion, in addition to lectures. No other method, regardless als has been structural changes in vertebrates through of how intricate in presentation and scope, can replace their evolution from fish to mammals, with the ultimate xiii xiv PREFACE goal being to place mammalian anatomy in context. This in the vast majority of cases because illustration is the is certainly a necessary prerequisite for one interested method that affords the most control in communicating principally in mammalian systematics or medicine. the pertinent features of a particular dissection. Photos However, not all students or instructors are