BIOLOGY, MEDICINE, AND SURGERY OF ELEPHANTS · 550 Swanston Street, Carlton, Victoria 3053, Australia Tel.: +61 (0)3 8359 1011 Cover design by Hank Hammatt ... “Sarada Vihar”

BIOLOGY, MEDICINE, AND SURGERY OF ELEPHANTS

BIOLOGY, MEDICINE,AND SURGERY OFELEPHANTS

Murray E. Fowler

Susan K. Mikota

Murray E. Fowler is the editor and author of the bestseller Zoo

and Wild Animal Medicine, Fifth Edition (Saunders). He has writtenMedicine and Surgery of South American Camelids; Restraint and

Handling of Wild and Domestic Animals and Biology; and Medicine

and Surgery of South American Wild Animals for Blackwell. He is cur-rently Professor Emeritus of Zoological Medicine, University ofCalifornia-Davis. For the past four years he has been a part-timeemployee of Ringling Brothers, Barnum and Bailey’s Circus.

Susan K. Mikota is a co-founder of Elephant Care Internationaland the Director of Veterinary Programs and Research. She is anauthor of Medical Management of the Elephants and numerous arti-cles and book chapters on elephant healthcare and conservation.

© 2006 Blackwell PublishingAll rights reserved

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First edition, 2006

Library of Congress Cataloging-in-Publication Data

Elephant biology, medicine, and surgery / edited by Murray E.Fowler, Susan K. Mikota.—1st ed.

p. cm.Includes bibliographical references and index.ISBN-13: 978-0-8138-0676-1 (alk. paper)ISBN-10: 0-8138-0676-3 (alk. paper)1. Asiatic elephant—Diseases. 2. African elephant—Diseases.

3. Captive wild animals—Diseases—Southeast Asia 4. Captive wild animals—Diseases—Africa. 5. Veterinary medicine—SoutheastAsia 6. Veterinary medicine—Africa. 7. Veterinary surgery—Southeast Asia 8. Veterinary surgery—Africa. I. Fowler, Murray E. II.Mikota, Susan K.

SF997.5.E4B56 2006636.9�676—dc22

2006002167

The last digit is the print number: 9 8 7 6 5 4 3 2 1

Contributors vii

Acknowledgments xi

Introduction xiii

01. Taxonomy, Classification, History, and 3Evolution of Elephants Jeheskel Shoshani

02. Elephants in Captivity 15Blair Csuti

03. Laws and Legislation 23Denise M. Sofranko

04. Behavior and Social Life 35Bruce A. Schulte

05. Husbandry 45John Lehnhardt

06. Nutrition 57Ellen S. Dierenfeld

07. Preventive Health Care and Physical 67ExaminationSusan K. Mikota

08. Physical Restraint and Handling 75Murray E. Fowler

09. Chemical Restraint and General 91Anesthesia

Section I: Chemical Restraint 91Murray E. Fowler and Susan K. Mikota

Section II: General Anesthesia 110Eugene P. Steffey

10. Surgery and Surgical Conditions 119Murray E. Fowler

11. Infectious Diseases 131Murray E. Fowler

12. Parasitology 159Murray E. Fowler

13. Antemortem Diagnostics 183Section I: General Techniques 183

Susan K. Mikota

Section II: Radiology 192Laurie Gage

14. Postmortem Diagnostics 199Richard J. Montali

15. Therapeutics 211Susan K. Mikota

Color Section

16. Neonatal Care and Hand Rearing 233Karen Emanuelson

17. Multisystem Disorders 243Murray E. Fowler

18. Integument System 253Susan K. Mikota

19. Musculoskeletal System 263Gary West

20. Foot Disorders 271Murray E. Fowler

21. Respiratory System 291Ramiro Isaza

22. Digestive System 299Genevieve A. Dumonceaux

23. Endocrine and Immune Systems 309Linda J. Lowenstine

24. Cardiovascular System 317Susan Bartlett

25. Hemolymphatic System 325Susan K. Mikota

26. Reproductive System 347Dennis Schmitt

v

Contents

27. Reproductive and Diagnostic 357UltrasonographyThomas B. Hildebrandt

28. Reproductive Endocrinology 377Janine L. Brown

29. Urinary System 389R. Eric Miller

30. Nervous System 393Michele Miller

31. Special Senses 399Wm. Kirk Suedmeyer

32. Chemical, Tactile, and Taste Sensory 409SystemsL. E. L. Rasmussen

33. Toxicology 415Murray E. Fowler

34. Zoonoses and Human Injury 431Joel Maslow

35. Veterinary Problems of Geographical 439Concern

Introduction 439Susan K. Mikota and Murray E. Fowler

Section I Africa 439Jacobus G. du Toit

Section II India 444Jacob V. Cheeran and K. Chandrasekharan

Section III Indochina and Bangladesh 447Paolo Martelli

Section IV Indonesia 454Yudha Fahrimal and Retno Sudarwati

Section V Malaysia 457Vellayan Subramanian

Section VI Myanmar 460Khyne U Mar

Section VII Nepal 465Sunder Shrestha and Kamal P. Gairhe

Section VIII Sri Lanka 468Indira Silva and Ashoka Dangolla

36. Conservation 475Simon Hedges

AppendicesAppendix 1. Abbreviations Used in This 491

BookAppendix 2. Measurement Conversion 493

TablesAppendix 3. Sources for Agents Used in 495

Sedating, Tranquilizing, Immobilizing, and Anesthetizing Elephants

Appendix 4. Toxicology Terms, 497Abbreviations, and Equivalents

Appendix 5. Elephant Vital Signs and 499Physiological Parameters

Appendix 6. Glossary of Terms Associated 501with Elephant Feet

Appendix 7. Weight Conversion Chart for 505Asian Elephants

Appendix 8. Conversion Between 507Conventional and SI Units, Hematology

Appendix 9. Conversion Between 509Conventional and SI Units, Blood and Fluid Chemistry

Appendix 10. AZA Standards for Elephant 511Management and Care

Appendix 11. Guidelines for Elephant 519Management and Care (EMA)

Appendix 12. Guidelines for Comprehensive 525Elephant Health Monitoring Program (AZA/SSP)

Appendix 13. Quarantine Guidelines for 535Elephants (AZA/SSP)

Appendix 14. Recommended Elephant 537Preshipment Guidelines (AZA/SSP)

Appendix 15. Transport Guidelines for 543Elephants (AZA/SSP)

Index 545

vi CONTENTS

iarchives

Susan Bartlett9 Evergreen Lane Ithaca, NY [email protected]

Janine L. Brown1500 Remount RoadFront Royal, VA [email protected]

K. Chandrasekharan“Sarada Vihar”Opposite Mathrubhumi officeVeliyannurThrissur-680 021Kerala, India

Jacob V. CheeranDirector of Technical ServicesCheerans Lab (P) Ltd.Animal Health DivisionNew Church StreetTrichur 680 001Kerala, [email protected]

Blair CsutiDepartment of BiologyPortland State UniversityP.O. Box 751Portland, OR 97207-0751

Ashoka DangollaDepartment of Veterinary Clinical SciencesUniversity of PeradeniyaPeradeniya, 20400 Sri [email protected]

Ellen S. DierenfeldSt. Louis Zoological ParkForest Park, One Government DriveSt. Louis, MO 63110 [email protected]

Genevieve A. DumonceauxBusch Gardens Tampa BayP.O. Box 9158Tampa, FL [email protected]

Jacobus G. du ToitP.O. Box 12780Onderstepoort 0110South [email protected]

Karen Emanuelson370 Mt. Sequoia PlaceClayton, CA [email protected]

Yudha FahrimalFaculty of Veterinary ScienceUniversity of Syiah KualaDarussalam, Banda Aceh [email protected]

Murray E. Fowler427 Cabrillo AvenueDavis, CA 95616 [email protected]

Laurie GageUSDA, APHIS, Animal Care2150 Centre Ave., Building BFort Collins, CO [email protected]

Kamal P. GairheVeterinary OfficerRoyal Chitwan National ParkChitwan, [email protected]

vii

Contributors

Simon HedgesAsian Elephant CoordinatorWildlife Conservation SocietyInternational Programsc/o 1 Kearstwick CottagesKearstwick, Kirkby LonsdaleCumbria, LA6 2EB, U.K. [email protected]

Thomas B. HildebrandtHead, Department of Reproduction Management Institute for Zoo Biology and Wildlife ResearchAlfred-Kowalke-Str. 17D-10315 Berlin, [email protected]

Ramiro IsazaDepartment of Small Animal Clinical SciencesCollege of Veterinary MedicineUniversity of FloridaP.O. Box 100126Gainesville, FL [email protected]

John LehnhardtAnimal Operations DirectorDisney Animal KingdomP.O. Box 10,000Lake Buena Vista, FL 32830-1000 [email protected]

Linda J. LowenstineDepartment of Pathology, Microbiology & ImmunologySchool of Veterinary MedicineUniversity of CaliforniaDavis, CA 95616 [email protected]

Khyne U Mar Institute of ZoologyZoological Society of LondonRegents ParkLondon NW1 [email protected] or [email protected]

Paolo MartelliChief VeterinarianOcean Park CorporationAberdeen, Hong [email protected]

Joel Maslow ACOS for Research VA Medical CenterUniversity and Woodland Avenues Philadelphia, PA 19104 [email protected]

Susan K. Mikota Director of Veterinary Programs and ResearchElephant Care International 438 N. Central Ave.Waveland, MS [email protected]

Michele MillerDisney’s Animal KingdomDepartment of Veterinary ServicesP.O. Box 10,000Lake Buena Vista, FL [email protected]

R. Eric MillerSt. Louis Zoos Wildcare InstituteOne Government DriveSt. Louis, MO 63110 [email protected]

Richard J. Montali 6624 East Wakefield DriveApt B-2Alexandria, VA [email protected]

L. E. L. RasmussenProfessor, Department of Environmental & Biomolecular

SystemsOregon Graduate Institute, School of Science & EngineeringOHSU-West Campus20,000 N.W. Walker RoadBeaverton, OR 97006 [email protected]/BMB rasmussen.html

Dennis SchmittProfessor, Dept. of AgricultureMissouri State University901 South National Ave.Springfield, MO [email protected]

Bruce A. SchulteDepartment of BiologyP.O. Box 8042Georgia Southern UniversityStatesboro, GA [email protected]

Jeheskel ShoshaniDepartment of Biology, University of AsmaraP.O. Box 1220Asmara, EritreaElephant Research Foundation106 East Hickory Grove RoadBloomfield Hills, MI 48304 [email protected]@eol.com.er

viii CONTRIBUTORS

Sunder ShresthaAlbert Einstein College of Medicine1300 Morris Park AvenueUllman 1103, lASBronx, NY [email protected]

Indira SilvaDepartment of Veterinary Clinical SciencesUniversity of PeradeniyaPeradeniya, 20400 Sri [email protected]@yahoo.com

Denise M. SofrankoUSDA, APHIS, Animal Care2150 Centre Ave., Building BFort Collins, CO [email protected]

Eugene P. SteffeySurgical & Radiological SciencesSchool of Veterinary MedicineUniversity of CaliforniaDavis, CA 95616 [email protected]

Retno SudarwatiTaman Safari IndonesiaJl. Raya Puncak No. 601Cisarua, Bogor (16750)[email protected]

Wm. Kirk SuedmeyerUniversity of Missouri-ColumbiaCollege of Veterinary MedicineColumbia, MO 65211 Director of Animal HealthThe Kansas City Zoo6800 Zoo DriveKansas City, MO 64132 [email protected]

Vellayan Subramanian Zoo Negara MalaysiaUlu Klang, 68000Ampang, [email protected]@hotmail.com

Gary WestOklahoma City Zoological Park2101 NE 50th StreetOklahoma City, OK 73111-7199Oklahoma State UniversityCollege of Veterinary MedicineDept. of Veterinary Clinical ScienceStillwater, OK [email protected]

CONTRIBUTORS ix

The editors express appreciation to the authors of thisbook for their willingness to spend countless hoursbringing together the state of the art concerning thewellbeing of elephants. Likewise, those who have con-tributed to the world’s literature have added immeasur-ably to this collective presentation.

Special thanks to Hank Hammatt who has patientlyand professionally edited and managed the illustrationsfor the book. Photographs were submitted in numerous

formats and sizes and scanned at various resolutions, re-quiring considerable effort to put them into a publish-able form.

Thanks also to Audrey Fowler for her support andencouragement and to the Alexander Abraham Foun-dation for its support of Elephant Care International,which helped to make this work possible.

Murray E. FowlerSusan K. Mikota

xi

Acknowledgments

Elephants are possibly the most well-known animal inthe animal kingdom. The enormous size, unusualanatomy, and longevity of elephants have fascinatedhumans for millennia. Today, their intelligence, strongfamily bonds, and the irresistible appeal of their youngcontinue to endear them to many.

Elephants have served man as a means of transport,a vehicle for carrying soldiers into war, and laborers inthe timber industry. Despite the long association ofelephants with man they have never been truly domes-ticated.

Elephants evoke strong emotions and opinions.Depending on circumstances, elephants may be viewedas objects of worship, beasts of burden, food for a village,an endangered species worthy of the highest conserva-tion efforts, or as crop-raiding killers.

The highly specialized morphology of the elephant isdepicted by John Godfrey Saxes’ (1817–1887) poem basedon the famous Indian fable (see page xv). We chose topresent this poem because much like the blind men,there is still much we do not know about elephants.

As long as humans have kept elephants in captivity,their health care has been a topic of concern. One of theearliest recorded treatments of an elephant was of“Kadol Etha” belonging to King Dutugemunu (161–137B.C.). Kadol was treated for wounds sustained frommolten metal. The first treatises on elephant health carewere written in Asia over 2000 years ago (theHastiayurveda and Gajasastra). Scientific articles beganto appear in the 19th century. In the 20th century theworks of G. H. Evans (Elephants and Their Diseases, 1910),A. J. W. Milroy (Management of Elephants in Captivity,

1922, republished by S. S. Bist in 2002), Francis Benedict(The Physiology of the Elephant, 1936), G. Pfaff (Reports on

the Investigation of Diseases of Elephants, 1940), A. J.Ferrier (The Care and Management of Elephants in Burma,

1947), Sylvia Sikes (The Natural History of the African

Elephant, 1971), U Toke Gale (The Burmese Timber

Elephant, 1974), and others certainly contributed to ourcollective knowledge of elephant care and husbandry atthe time.

But despite the fact that one-third of all Asian ele-phants remaining in the world are in captivity, no mod-ern comprehensive text on elephant medicine and sur-gery exists. The editors and contributing authors hopethat this volume will begin to fill that void. Thirty-sixscientists and clinical veterinarians have shared their ex-pertise and experiences to compile information on biol-ogy, husbandry, and veterinary medicine and surgery ofthe elephant as we know it today.

Each author presents his or her experiences plusthose of others expressed in the literature. Although notan exhaustive literature review, over 3000 references arecited to provide readers the opportunity to delve moredeeply into specific topics. The opinions expressed arethose of the authors.

Free-ranging elephants face a precarious future.Habitat loss, poaching, and exploitation are decimatingmany populations to near extinction. Elephants andman compete for limited space and resources in Africaand Asia. Reports of human-elephant conflict appear inthe news almost daily, with losses incurred on bothsides.

Captive or “domesticated” elephants in Asia also faceuncertainty because the timber industry in most Asiancountries no longer requires the labor once provided byelephants. Many of these elephants now find them-selves in an urban environment with no chance of for-aging for natural feeds and often no access to proper vet-erinary care.

Anecdotal information has always been and will con-tinue to be important to the care of elephants. It ishoped that this book will open a venue for the greatersharing of such information. At the same time the

xiii

IntroductionMurray E. Fowler and Susan K. Mikota

paucity of information currently available on some top-ics may help to focus attention on areas of needed re-search. Those with special expertise and experience whohave a bearing on the topics involved in the book are in-vited to contact the editors so that a future edition mayreflect expanded information and other viewpoints.

Elephants deserve our care and our concern for theirwelfare.

Murray E. Fowler Susan K. Mikota427 Cabrillo Avenue Elephant Care InternationalDavis, CA 95616 438 N. Central [email protected] Waveland, MS 39576

[email protected]

xiv INTRODUCTION

It was six men of IndostanTo learning much inclined,Who went to see the Elephant(Though all of them were blind),That each by observationMight satisfy his mind.

The First approached the Elephant,And happening to fallAgainst his broad and sturdy side,At once began to bawl:“God bless me! but the ElephantIs very like a wall!”

The Second, feeling of the tuskCried, “Ho! what have we here,So very round and smooth and sharp?To me ‘tis mighty clearThis wonder of an ElephantIs very like a spear!”

The Third approached the animal,And happening to takeThe squirming trunk within his hands,Thus boldly up he spake:“I see,” quoth he, “the ElephantIs very like a snake!”

The Fourth reached out an eager hand,And felt about the knee:“What most this wondrous beast is likeIs mighty plain,” quoth he;“‘Tis clear enough the Elephant Is very like a tree!”

The Fifth, who chanced to touch the ear,Said: “E’en the blindest manCan tell what this resembles most;Deny the fact who can,This marvel of an ElephantIs very like a fan!”

The Sixth no sooner had begunAbout the beast to grope,Then, seizing on the swinging tailThat fell within his scope.“I see,” quoth he, “the ElephantIs very like a rope!”

And so these men of IndostanDisputed loud and long,Each in his own opinionExceeding stiff and strong,Though each was partly in the right,And all were in the wrong!

xv

The Blind Men and the Elephant

BIOLOGY, MEDICINE, AND SURGERY OF ELEPHANTS

3

Taxonomy, Classification,History, and Evolution ofElephantsJeheskel Shoshani

1

INTRODUCTION

Biological classification is categorization and organizationof organisms by their unique characters. A sound classifi-cation with standardized scientific names provides a uni-versal language for laymen and scientists alike in caseswhere common names are not standardized.

During the 18th and 19th century, however, the con-cept of homology was just beginning to emerge, andgrouping of animals was based on external morphologyand habitat. In this system, manatee was grouped withseals (as “Aquatilia” of Scopolli 1777) or with cetaceans(as “Natalia” of Illiger 1811), and elephants weregrouped with rhinoceroces and tapirs as “Pachydermes”(of G. Cuvier 1800). A summary of these earlier ideas ofclassfication is given in Shoshani.35

In modern times, to classify an organism, a re-searcher must follow certain rules and procedures. Tofacilitate classifications, taxonomists developed guide-lines, the Code of Nomenclature (International Com-mission of Zoological Nomenclature 1999)20 (referred tohereafter as “the Code”), which is updated on a regularbasis. The Code guides the naming of the taxa, not theirdiscovery and conception. It emerges that classification,taxonomy, systematics, and phylogeny are all interre-lated. Information from one discipline can be applied toanother; this can easily be understood when comparingtheir definitions (these terms are defined in the section“Definitions” below). The field of phylogeny, however,requires some elaboration. Relationships among taxacan be obtained and tested using cladistic or phyloge-netic methods, employing morphological or molecularcharacters. In ideal situations, results from both ap-proaches corroborate each other. One school of thoughtholds that cladistic or phylogenetic relationshipsshould be reflected in the classification (more on thatlater).16

The main purpose of classifying animals and plantsis to facilitate better communication among scientists.

An example of the applicability of classification and alsoof phylogeny is in the fields of communicable diseases,zoonotic diseases, susceptibility and resistance to dis-eases in general (discussed later), and organ transplant.The more closely related two animals are, the morelikely that incompatibility will be reduced and the bet-ter chances for a successful transplant.42

DEFINITIONS

Clade. A cluster of taxa derived from a single commonancestor.

Cladistic methods. A mode of classification based, inprincipal, on grouping of taxa that possess shared, simi-lar (“derived”) characters that differ from the ancestralcondition.

Cladogram. A tree diagram representing phylogenetic(or cladistic) relationships among taxa based on theirshared-derived characters or synapomorphies.

Classification. The practice of grouping organisms intoa hierarchy of categories ranging from subspecies,species, genera, families, orders, classes, phyla, and king-doms (except for the subspecies, all these are obligatorycategories, see definition below). Taxa included in eachof these categories are entities to themselves encompass-ing unique features. Thus, organisms classified in aspecies are more similar to each other than they are tomembers of other species in the same genus. Similarly,genera in one family share more characters with eachother than with genera in other families, and so on.

Grade. Distantly related or unrelated species (or taxa)that reach the same level due to parallel or convergentevolution.

Homology. Shared similarity due to common descent.

Nomenclature. The practice of giving names to animalsand plants.

Obligatory categories in classification. The majorranks (or categories) that are usually employed in classi-fication of organisms. They include the species, genus,order, family, class, phylum, and kingdom. All other cat-egories, such as those with the prefix sub- or super- (e.g.,subfamily, superfamily, subclass, and superclass) are notobligatory of formal, general classification.

Phylogeny. The evolutionary history of common de-scent or of a lineage (that is, of a species or a group ofspecies) as related to their ancestor-descendant relation-ships. In a restricted sense, the history of descent of agiven set of taxa.

Species. A basic taxonomic category. In the biologicalspecies concept, a species (taxon) includes interbreedingor potentially interbreeding populations possessingunique characters and reproductively isolated fromother such groups (taxa), under natural conditions.

Systematics. The study of diversity of organisms andtheir comparative and evolutionary relationships (= classification and taxonomy).

Taxon (plural taxa). A group of organisms that sharecommon characters, included at any level of the classifi-cations (e.g., species, genus, or family).

Taxonomy. The discipline including the rules and pro-cedures used to classify organisms.

CLASSIFICATION IN HISTORICALPERSPECTIVE

Among the earliest attempts to organize and classify or-ganisms was that attributed to Aristotle, the Greekphilosopher and naturalist (384–322 B.C.). Aristotle, it isbelieved, came to view nature as a continuum of organiza-tion, from lifeless matter through the complex forms ofplants and animals. Carolus Linnaeus (Latinized namefrom Carolus Linné, lived from 1707–1778), a Swedishbotanist, was the first authority to develop a formal classi-fication scheme for organisms, giving them two-partnames (hence the term Binomial Classification); the first isthe genus and the second is the species, and both are de-scriptive names. This system is still used by most taxono-mists. The 10th edition of Linnaeus’s book Systema

Naturae23 (published in 1758) is considered the primarytreatise on classification, and 1758 is taken to be the begin-ning date for which published scientific names are valid.

It is important to keep matters in perspective.Linnaeus was a devout, religious man. This was reflectedin his belief that the number of species created was lim-ited. In this context, the African and the Asian elephants

belonged to one species. Thus, the name Elephas max-

imus given by Linnaeus in 1758 was apparently based ona fetus of an African elephant and a specimen of theAsian elephant. It is believed that Elephas maximus ofLinnaeus combines these two different elephantspecies—Elephas for the Asian elephant, and maximus forthe African elephant, the larger of the two species (de-tails are given in Shoshani and Tassy,40 pp. 354 and 360).

The etymology of the word elephant or Elephas isfrom ele, a Greek derivative meaning an arch, and phant

or phas from the Greek/Latin derivative meaning fantas-

tic or huge. Thus, elephant or Elephas translates into ahuge arch (from the shape of an elephant in side view).A separate scientific name for the African elephant(Loxodonta africana) was coined in 1827, 69 years later.The genus name Loxodonta describes the lozenge pat-tern of the enamel loops on the chewing (occlusal) sur-face of the tooth, and the species name, africana (notelowercase a) refers to the origin and habitat of this ani-mal; it is usually found in savannahs of sub-SaharanAfrica. The other elephant species in Africa is the forestAfrican elephant (Loxodonta cyclotis), found in forestedregions of central and western Africa. The species namecyclotis describes the roundish shape (cycl) of the ear(otis). In the africana species the ear has a trapezoidalshape. Not all authorities subscribe to the two speciesconcept of the African elephant; some still hold thatthere is one species with two subspecies—L. a. africana

and L. a. cyclotis (more on that below).

LINNAEAN CLASSIFICATION AND THE CODE

The Binomial Classification, established by Linnaeus in1758, is the most commonly used system today. TheCode of Nomenclature is an attempt to standardize thework of taxonomists and systematists, including no-menclaturists and classifiers, and to provide some pub-lished guidelines and rules that are regularly updated(see International Commission of Zoological Nomen-clature 1999).20 Binomial Classification and the Codeare closely related, but for practical purposes, I presentthe two subjects separately.

Binomial and Trinomial ClassificationRecall that in this system, each species is given twonames: the genus and the species. Both names must beLatinized, although their origin may be Latin, Greek, oranother language. The first letter of the genus is writtenin uppercase and all subsequent letters of the genus andspecies are in lowercase, even if the species name is aftera locality or a person. For example, the scientific nameof the Asian elephant is Elephas maximus and that of theAmerican mastodon is Mammut americanum (to accen-tuate the names they are italicized, underlined, or writ-ten in different formats from the rest of the text). Whenthere is sufficient anatomical evidence to divide aspecies into two or more subspecies, we use three names

4 ELEPHANT BIOLOGY, MEDICINE, AND SURGERY

(hence the term Trinomial). For example, the scientificname of the Asian elephant from Sri Lanka is Elephas

maximus maximus; other examples are given below.The next step in this process is to place the species in

a higher category. In the Linnaean system of classifica-tion, the primary or obligatory categories, from higherto lower are Kingdom, Phylum, Class, Order, Family,Genus, and Species. It is not an easy matter to decideinto which hierarchy or category to place a newly foundspecies. The criteria that govern this decision have to dowith the differences between genus and family level,and they are related to the size of the gap of charactersbetween different categories. Suffice it to say that in theexample of the Asian elephant given above, scientistsdetermined that, based on anatomical characters, Ele-

phas maximus, the African elephant (Loxodonta afri-

cana), and woolly mammoths (Mammuthus primigenius)are distinctly unique yet they share similar charactersand should be grouped in the subfamily Elephantinae,family Elephantidae. The skeleton of Mammut ameri-

canum possesses very different sets of characters; thus, itwas decided to classify it in another family, the Mam-mutidae. Elephantidae, Mammutidae, and other fami-lies that share similar characters due to common ances-try were then grouped under the umbrella of a highercategory, called Order, the Proboscidea. Related ordersare classified in one Class, classes are grouped under aPhylum, and phyla under a Kingdom. An example of asimplified classification of the Proboscidea withinAnimalia is given in Table 1.1. Note that the suffixes of

CHAPTER 1 TAXONOMY, CLASSIFICATION, HISTORY, AND EVOLUTION OF ELEPHANTS 5

Table 1.1. A Partial, Simplified Classification of Proboscidean Taxa*

Category (= Rank) Taxon

Kingdom AnimaliaPhylum Chordata

Subphylum VertebrataClass Mammalia

Nonranked Uranotheria (= Paenungulata)a

Order HyracoideaNonranked Tethytheria

Order SireniaOrder Proboscidea

Nonranked Mammutidab

Superfamily Mammutoideab

Family Mammutidaeb

Genus Mammutb

Species Mammut americanumb,c

Nonranked ElephantidaSuperfamily Gomphotherioideab

Family Gomphotheriidaeb

Genus & Species Gomphotherium angustidensb

Superfamily ElephantoideaFamily Stegodontidaeb

Genus & Species Stegodon zdanskyib

Family ElephantidaeSubfamily Elephantinae

Tribe LoxodontiniGenus & Species Loxodonta cyclotisd

Loxodonta africanae

Tribe ElephantiniGenus & Species Elephas maximusf

Subspecies Elephas maximus sumatranusg

Elephas maximus indicush

Elephas maximus maximusi

Genus & Species Mammuthus primigeniusb,j

*Refer to Figure 1.1 for depiction of the species on the cladogram; modified after Shoshani 2000, p. 22, and other sources.aAfter McKenna et. al. 1997.b= extinct.cThe American mastodon, now extinct, osteological remains were found in North America.dThe Forest African elephant, living (see text for possible use of the subspecies name Loxodonta africana cyclotis).eThe Bush or Savanna African elephant, living (see text for possible use of the subspecies name Loxodonta africana africana).fThe Asian elephant, living.gThe Sumatran Asian elephant subspecies, living (found on the island of Sumatra).hThe Indian, or mainland Asian elephant subspecies, living (found in India and Indochina).iThe Sri Lankan Asian elephant subspecies, living (found on the island of Sri Lanka, formerly Ceylon).jThe woolly mammoth, extinct; remains and intact carcasses were found frozen in the Arctic. The Colombian mammoth (Mammuthus

columbi), extinct; remains were found in North America.

family names in any classification of animals are alwaysidae and those of subfamilies are inae. These two con-ventional suffixes help identify quickly these categoriesor ranks.

In this classification (Table 1.1), it is noted that en-tries are indented such that the taxon listed below isnested within the taxon listed above it. This system em-bodies the idea that one or more species are grouped ina genus, one or more genera are grouped in a family, andso on. Some aspects of the process of giving names ofranks to certain taxa are discussed below.

Table 1.1 also reflects the relationships amongHyracoidea (hyraxes), Sirenia (manatees and dugongs),and Proboscidea.26 Shared, derived, characters amongHyracoidea, Sirenia, and Proboscidea include serial ver-sus alternate carpal bones, and affinity between Sireniaand Proboscidea include bifid heart39 (see also figure onp. 16 of Shoshani).37

The CodeBeing a reference of standard terminologies, recommen-dations, and rules, the Code is the authority for a taxon-omist. An important rule in nomenclature and classifi-cation is the Principle of Priority (published in theCode, see International Commission of ZoologicalNomenclature 1999).20 This principle states that if twodifferent names have been given to the same animal orplant by two different researchers, the one that was pub-lished first is valid. For example, in 1817 the famousFrench anatomist Georges Cuvier coined the nameMastodonte for an animal that was found in Big BoneLick site, not far from the Ohio River, Kentucky, USA. Itappears that G. Cuvier and C. S. Rafinesque (who in 1814coined the name Mastodon for the same animal) werenot aware of the publication of Johan F. Blumenbach, aGerman naturalist, who, in 1799, named the same ani-mal Mammut. Following the Principle of Priority, theolder name has prevailed (details in Shoshani andTassy,40 p. 351).

If only the genus name is employed, the author ofthe name and the year it was published follows it—e.g.,Mammut Blumenbach, 1799. If, however, the speciesname is also to be included, it also is followed by the au-thor and year of publication—Mammut americanum

(Kerr, 1792). Note that the author and year are writteninside the parentheses ( ). This is because the originalType Species name coined by Kerr for the same animalwas Elephas americanus; thus, the credit still goes to theoriginal author who first named the species, eventhough it is no longer a valid original genus name (inthis case, Mammut is the valid generic name, see above).

Another important rule in the Code is the Latini-zation of scientific names. In 1825, F. Cuvier coined thename Loxodonte for the African elephant. This name isnot valid because it is not Latinized (Article 11[b] of theCode). In 1827 the Latinized version of this name(Loxodonta) was used in the journal where the review of

F. Cuvier’s work appeared. It was not clear from the textwho was the writer who Latinized the name; for this rea-son, the scientific name of the African elephant appearsas Loxodonta Anonymous, 182740 (details in Shoshaniand Tassy 1996, p. 361).

NUMBERS OF PROBOSCIDEAN SPECIESAND SUBSPECIES

Living and Extinct TaxaIn 1942 Henry Fairfield Osborn recognized 352 speciesand subspecies of Proboscidea, living and extinct. Themost recent revision was that of Shoshani and Tassy,40

where they recognized 177 species and subspecies classi-fied in 43 genera and at least 10 families. Since thenSanders34 named one new genus and five new species,bringing the total to 182 species and subspecies and 44genera. Of these, today there are two extant genera, withthree species. Living elephants are listed by CITES(Convention on International Trade in EndangeredSpecies of Wild Fauna and Flora) either in Appendix I orin Appendix II. Appendix I includes taxa that are threat-ened with extinction and are or may be affected bytrade. Appendix II species need not be threatened, buteither require regulation so that they do not become soor must be listed to help control trade in other species,the so-called “look-alike species.”30 The vast majority ofliving elephant populations are continuously decreas-ing due to shrinking range or habitat fragmentation.

Living TaxaGeneralized Features and Medicine. Today we recog-nize three living species of elephants, classified in twogenera—Loxodonta and Elephas (Tables 1.2 and 1.3 in-clude differences between these genera). Based on theavailable morphological evidence, Loxodonta, repre-sented by the living African elephant, appears to bemore primitive than Elephas, represented by the livingAsian elephants. Both Loxodonta and Elephas originatedin East Africa, and yet Loxodonta is believed to embodymore generalized features than Elephas.25,40 From themedical standpoint, it is noted that generalized mam-mals (e.g., insectivores) are better adapted than special-ized mammals (e.g., horses) to cope with living in differ-ent habitats.3,4 It could be argued that generalizedmammals may be better adapted to fight diseases thanspecialized mammals. To test this hypothesis a survey ofdiseases known to occur in the African versus the Asianelephant should be conducted. It is predicted that theAfrican species (L. cyclotis and L. africana) would bemore resistant to diseases—including communicableand zoonotic diseases—than the Asian species (E. max-

imus). Recent investigators have demonstrated differentsusceptibilities to herpesvirus infection in captive Asianversus African elephants32 and the apparent increasedprevalence of uterine cystic endometrial hyperplasia2

and uterine leiomyomas17 in Asian elephants. These


7

Table 1.2. Major Differences Between the African and the Asian Elephant

studies, however, examined only captive individuals inwhich husbandry and management issues may con-found any genetic or taxonomic effect. Further researchin this area would be valuable in the practical manage-ment of elephant populations as well as enhancing ourgeneral understanding of the association between tax-onomy and the balance between health and disease.

Taxonomy’s importance in understanding the po-tential health problems of elephants is highlighted bythe work of Hagey15 who described the unique use ofbile alcohols in elephants and a few of their closest rela-tives, the manatee and hyrax. All other mammals pro-duce bile acids as a product of cholesterol metabolism.The presence of bile alcohols instead of acids may makeelephants more susceptible to bacterial invasion andcholelith formation.1

An understanding of taxonomy is also valuablewhen considering potential metabolic and physiologicsimilarities in drug metabolism.21,29 Similar digestivetracts or similar cholesterol metabolic pathways, for ex-ample, might be empirically expected to absorb orprocess a particular drug similarly, allowing veterinari-

ans to extrapolate drug doses from one species to an-other. Again, little research into the comparative phar-macology of nondomestic animals has been done forany species, including elephants. See Chapter 15 for fur-ther information.

The Loxodonta Group. Traditionally, the African ele-phant was divided into two subspecies: L. africana

africana (the bush African elephant) and L. a. cyclotis

(the forest African elephant, discussion in Grubb14

2000). Recent taxonomic revision within this group ismanifested in dividing the African elephant into twospecies: the forest African elephant (L. cyclotis), and thebush African elephant (L. africana; see Table 1.3, upper).This taxonomy is not agreed upon by all scientists.Grubb and Roca support the species concept,14,33

whereas Debruyne5 provides data in support of the tra-ditional subspecies, L. a. africana and L. a. cyclotis.Between the two African species, L. cyclotis is more prim-itive than L. africana (discussed in detail by Grubb; seealso footnotes to Table 1.3). In addition to the twospecies of African elephants, Eggert reported on what


Table 1.3. Major Differences Among Species and Subspecies of Elephants

Within the African Elephants, Loxodonta sp.*Bush Species Forest Species(L. africana) (L. cyclotis)

Weight 4,000–7,000 kilograms 2,000–4,500 kilograms(8,820–15,430 pounds) (4,410–10,000 pounds)

Height at shoulder 3–4 meters (10–13 feet) 2–3 meters (6 feet 7 inches–10 feet)Skin On average lighter On average darkerShape and size of ears Triangular, extend below line of neck Rounder, do not extend below line of neckSkull, cranium Much pneumatized Less pneumatizedSkull, mandible Shorter LongerTusks Curved out and forward, thicker Straighter, down-pointing, slenderNumber of naillike Forefeet 4 or 5 Forefeet 5structures (“toes”) Hindfeet 3, 4 or 5 Hindfeet 4 or 5in adults

Within the Asian Elephants, Elephas maximus**

Sri Lankan Subspecies Mainland Subspecies Sumatran Subspecies(E. m. maximus) (E. m. indicus) (E. m. sumatranus)

Weight 2,000–5,500 kilograms 2,000–5,000 kilograms 2,000–4,000 kilograms(4,410–12,125 pounds) (4,410–11,020 pounds) (4,410–8,820 pounds)

Shoulder height 2–3.5 meters 2–3.5 meters 2-3.2 meters(6 feet 7 inches– (6 feet 7 inches– (6 feet 7 inches–11 feet 6 inches) 11 feet 6 inches) 10 feet 6 inches)

Skin color Darkest, with large and distinct Color and depigmentation in Lightest with leastpatches of depigmentation on between the other two depigmentationears, face, trunk, and belly subspecies

Size of ears Most have large ears Vary in size Appear large compared tobody size

Tusks incidence Lowest Intermediate Possibly the highestNumber of ribs 19 pairs 19 pairs 20 pairs

*Loxodonta cyclotis is more primitive than L. africana for these reasons: forest dweller, smaller, slender, and down-pointing tusks andother skull characters discussed by Grubb 2000.

**Elephas maximus sumatranus is possibly the most primitive Asian subspecies for these reasons: forest dweller, smallest, has largestnumber of ribs, possibly has highest incidence of tusks, has least depigmented skin and other characters discussed by Deraniyagala 1955.

might be interpreted as a possible third species ofAfrican elephant for the populations of the forest andsavannah elephants of West Africa (these interpreta-tions are not widely accepted).7 These findings are basedon DNA extracted from dung of elephants in Ghana, theIvory Coast, Mali, and Cameroon. These elephants livein both forest and savannah habitats. The study suggeststhat, based on genetic data, the West African popula-tions have been isolated from other elephant popula-tions for as long as 2.4 million years.

The Elephas Group. We find less controversy in thetaxonomy of the Asian elephant (E. maximus), whereShoshani and Eisenberg (1982) recognized three sub-species: the Sumatran Asian elephant (E. m. suma-

tranus), the mainland Asian elephant (E. m. indicus),and the Sri Lankan Asian elephant (E. m. maximus).38

Evolutionary trend among these subspecies is sug-gested. Thus, E. m. sumatranus is said to be the mostprimitive of the three subspecies, E. m. maximus themost derived, and E. m. indicus an intermediate form.Evidence for this trend includes 20 pairs of ribs in E. m.

sumatranus and 19 pairs in E. m. maximus and E. m. indi-

cus.37,43 Other features include forested versus less-forested dwelling; small versus large body size; ear size; possibly high versus low incidence of tusks, tusksize, and shape (e.g., straight versus curved); and leastversus most skin depigmentation. Additional charac-ters and discussion on Asian elephant subspecies wereprovided by Deraniyagala.6 Table 1.3 summarizes thesedifferences betweeen the subspecies of the Asian ele-phant.

A recent study by Fernando8 concluded, based onDNA isolated from dung, that the elephants fromBorneo island (specifically the Malaysian states of Sabahand Sarawak) are “. . . genetically distinct, with molecu-lar divergence indicative of a Pleistocene colonization ofBorneo and subsequent isolation.” These authors sug-gest “. . . that a formal reinstatement of the E. m. bor-

neensis taxa await a detailed morphological analysis ofBorneo elephants and their comparison with other pop-ulations.” This author concurs with Fernando8 thatthere should also be morphological differences amongthe recognized Asian elephant subspecies. Additionally,it would also be a stronger argument for the proposedsubspecies if the recent findings of Fernando would berepeated and corroborated.8

CAN THE TWO LIVING SPECIESINTERBREED?

Traditionally, a species was defined as a group of animals(taxon) that possesses unique characters and does notinterbreed with other such groups (taxa) under naturalconditions.27 Since then it has been observed that hy-brid zones between distinct species in the wild havebeen reported for warm-blooded vertebrates, both

birds28 and mammals13. In captivity, however, the ani-mals are artificially placed together, and hybrids amonganimals that will never meet in the wild may occur.Such was the case of “Motty,” the only known hybridbetween a male African elephant, “Jumbolino”(“Bubbles”), and a female Asian elephant, “Sheba.” Thishybrid was conceived in Chester Zoo, England, in1978.18 Motty lived only 10 days; his skin is mounted atthe Natural History Museum (formerly British Museumof Natural History, London). Zoo authorities and otherpeople doubted whether it would have been possible forthe two elephant genera to hybridize. Unfortunately nosoft tissue samples were kept for future testing, but asample of small dry skin was collected from behind theear of Motty and was used in immunological experi-ments to test whether Motty was indeed a hybrid. Theresults confirmed that Motty’s tissue behaved like thatof a mule, corroborating that it was a hybrid betweenLoxodonta africana and Elephas maximus.24 These resultsare not totally surprising because the diploid chromo-somes number in somatic cells for both elephant speciesis 56.19

A SIMPLIFIED CLADOGRAM OF SELECTEDPROBOSCIDEANS

Evolutionary relationship can be depicted either as a“family tree” or as a cladogram (Fig. 1.1). A family treemay be compared to a genealogical family tree wherethe origins of the great-great-grandparents of an indi-vidual are being traced. In a family tree, such as the onegiven in Shoshani37 (pp. 26–27), the direct line of ances-try of Elephas (the animal at the center, top) is drawn aspassing through Primelephas, Gomphotherium, Palaeo-

mastodon, and “Ancestral proboscideans.” All other pro-boscideans depicted are side branches and are not a partof the main tree trunk. In this kind of illustration themain trunk is conceived as an evolutionary grade in-cluding taxa that are not necessarily phylogeneticallyrelated. In a cladogram, taxa are depicted successively assister taxa, and the common ancestors are recon-structed, not observed, presumed at the point of conver-gence of two sister taxa. For example, the common an-cestor of Mammuthus and Elephas in Figure 1.1 ispresumed at a point just above the tribe name Elephan-tini. The branch of the sister taxa Elephantini andLoxodontini are joined to form the subfamily Elephan-tinae. The common ancestor of Elephantini and Loxo-dontini may have been an animal that embodied char-acters similar to those of Primelephas.

To better understand this cladogram, examine Figure1.1 in tandem with the classification provided in Table1.1. In this table taxa are listed in the sequence as theywould appear on a cladogram from the most primitiveor generalized (listed first) to the most derived or spe-cialized (listed last). This is a simplified cladogram witha simplified table depicting only a portion of the


Proboscidea. When all the 44 genera of Proboscidea areincluded, the branching pattern of the cladogram is nolonger simple. It would be even more complicated if weinclude all 182 species and subspecies.

EVOLUTIONARY TRENDS AND MIGRATIONOF PROBOSCIDEANS

Evolutionary TrendsAs we proceed from the earliest proboscidean that livedin early Eocene epoch (about 55 million years ago) tothe present (Holocene), we observe these major evolu-tionary changes or trends: overall increase in body size;increase of tusk size; development of a trunk, or pro-boscis; and increase of trunk length (these trends are de-picted in Shoshani,37, pp. 26–27). Table 1.4 elaborateson these trends and includes information on gigantism(over 4 meters shoulder height) and dwarfism (only 1meter tall), coevolution of infrasonic communicationand the ability to store water in the pharynx, and hori-zontal displacement of premolars and molars as thoughthey were moving on a slow conveyor belt (Fig. 1.2).Phosphatherium, the earliest known proboscidean, wasabout the size of a dog (10–15 kg), but it was not a dwarf;it did not have a trunk, tusks, or horizontal displace-ment of premolars and molars (these features developedlater within the Proboscidea). Nevertheless, Phospha-

therium was a proboscidean since it possessed uniqueproboscidean characters such as a well-developed zygo-matic process of the maxillary bone.12

Migration of ProboscideansA map of migratory routes, as those depicted in Figure1.3, was constructed based on fossil material discoveredat different localities, at different geological times. Thus,the older the fossils, the closer they would appear to theplace of origin of the Proboscidea. For example, numi-dotheres (e.g., Phosphatherium, the earliest known pro-boscidean; Daouitherium; and Numidotherium) werefound in Morocco and Algeria, northwest Africa, in theearly-middle Eocene. Africa is believed to have been iso-lated from other continents during most of thePaleogene (Paleocene, Eocene, and Oligocene), and thusits fauna during these geological epochs was endemic.We are uncertain of the exact origin of Proboscidea.Emmanuel Gheerbrant (personal communication,2005) suggested: “Paleogene proboscideans are repre-sentative of the whole African province, proboscideansare of African origin” (see also 9,10). For this reason, mi-gration and dispersal patterns of the earliest pro-boscideans from northwest Africa during the Paleogeneare uncertain (thus the question marks on the map).However, one possibility emerges that the northernshores of the Mediterranean Sea (a remnant of the an-


Figure 1.1. A cladogram of se-

lected proboscideans (modified after

Shoshani and Tassy 2005, p. 14), to

be studied in tandem with Table 1.1.

Reprinted from Quaternary Interna-

tional, Volume 126-128, J. Shoshani

and P. Tassy, Advances in Probosci-

deans Taxonomy & Classification,

Anatomy & Physiology, and Ecology

& Behavior, page 14, copyright

(2005), with permission from

Elsevier.

cient Tethys Sea) might be postulated as the place of ori-gin of Proboscidea (for this discussion, members ofAnthracobunidae are excluded). Northeast Africa(Egypt, Libya) embodied environmental conditionswhere fossils of Moeritherium, Barytherium, Palaeomas-

todon, and Phiomia were found in the late Eocene toOligocene sediments. It seems plausible that northeast-ern African proboscideans may have migrated to theHorn of Africa (late Oligocene) and to East Africa (Mio-cene) where centers of radiation of some proboscideans(including deinotheres and gomphotheres) are believedto have taken place. Another center of radiation of ex-tinct gomphotheres is believed to have occurred in Asia

(a silhouette of Gomphotherium angustidens appears inFigure 1.1; details in Shoshani and Tassy).40 From theHorn of Africa (again following the geological evidencewe have thus far), it is suggested that some proboscideans(possibly gomphothere stock) migrated to what is todaythe Saudi Arabian peninsula (late Oligocene to earlyMiocene) and from there toward the general area of whatis today Pakistan. Like the classification and the evolu-tionary tree (and cladogram), this map is subject toconstant changes with the discovery of new fossilsand/or different interpretations of old material. Fromthis map of migration routes, we learn that Proboscideawas distributed in all the continents except Australia,


Table 1.4. Proboscideans Evolutionary Trends*

Increase in size—Earliest proboscideans were about the size of a dog; later taxa became giants, reaching over 4 meters at the shoulders.Dwarfism is observed in certain lineages, perhaps due to isolation (such as, but not limited to, islands); some were only 1 meter tall.

Lengthening of limb bones and development of short, broad feet

Growth of the skull to extraordinarily large size—This is particularly noticeable in the cranium, where greater surface for muscleattachment was possible. Enlargement of the cranium was facilitated by development of air cells (pneumatized bones), a feature thatprovides strength without added weight. Another possible function for the development of air cells is the need to protect the sensitivebrain tissues from extreme environmental temperatures. The external surface of an elephant cranium can be about 25 cm from thebrain; this physical protection with “padding” of air is probably a very important feature in the survival of certain proboscideanlineages.

Coevolution of infrasonic communication and the ability to store water in the pharynx—These developments appear to beassociated with cranial and otic changes, modified hyoid apparatus, and evolution of the proboscis.

Shortening of the neck—The skull and its associated structures (tusks and trunk) became large and heavy and the neck was reduced,probably as a mechanical advantage for leverage.

Elongation of the lower jaw (mandible) and secondary shortening of the cranium and mandible was an early primary

trait among proboscideans—Secondary shortening of the lower jaw (especially the area of the mandibular symphysis) and shift inthe center of gravity of the head posteriorly was a trend associated with parallel evolution in advanced proboscideans.

Development of a proboscis—This observation is based on the elevated position of the external naris, enlargement of the infraorbitalcanal, the connection between frontal and premaxilla bones, and the shapes and sizes of the premaxilla and nasal bones. It is believedthat the combination and elongation of the upper lip and nose have evolved to accommodate the distancing of the head from theground due to the increase in size of the animal. Subsequently, the proboscis is further elongated to form a very mobile trunk, possiblyhaving evolved independently in different lineages.

Forward or horizontal displacement of cheek teeth (premolars and molars)—The movement of teeth may be regarded asthough they were moving on a slow conveyor belt; the earlier teeth are smaller than later ones. This feature is present in all knownNeogene (Miocene through Pliocene epochs) proboscideans, from mammutid through elephantid species. The vast majority of othermammals, humans included, has vertical rather than horizontal tooth displacement.

Reduction in number of teeth from the full eutherian dentition—incisors 3/3, canines 1/1, premolars 4/4, molars 3/3—

Throughout the history of the Proboscidea, there is a decrease in the numbers of premolars, canines, and incisors. Living elephantshave this dental formula: 1/0 0/0 3/3 3/3.

Hypertrophy (excess growth) of the middle incisors to form tusks—Some of these were straight, curved downward, or upwardand helicoidal; they functioned in food gathering, defense, offense, and display. Enamel covering of tusks decreased to a longitudinallateral band and then disappeared. Tusks greatly increased in length and diameter; those of proboscideans are the largest known teethof animals, living or extinct.

In a cross section, tusks of advanced proboscideans (from members of Mammutidae to Mammuthus) exhibit Schreger

pattern, also known as “engine turning” or guillochage—In this system two sets of lines begin at the center and curve clock-wise and counterclockwise toward the periphery; at the point of crisscrossing each other they form small rhomboid-shaped areas visiblewith the naked eye. This pattern is also present in dentine of the cheek teeth.

Enlargement and specialization of the cheek teeth in proboscideans were achieved by increasing the number of cusps

such as central conules, conelets, and the numbers of cross-lophs, or lamellae (from the simple 2 transverse lophs in

the earliest members to 30 lophs in the most advanced taxa; large teeth of living elephants may weigh over 5 kg)—Thistrend was accompanied by molarizing the deciduous premolars and thinning of enamel; it began in the early stages of proboscideanevolution. Parallel evolution, in the increasing number of lamellae, is found among the three genera of Elephantinae (Loxodonta,

Elephas, and Mammuthus), and in Stegodon.Rate of evolution in the head, particularly the cheek teeth, has been faster than the rate of evolution of other organ

systems in the body, e.g., the digestive system, which is relatively primitive and lags behind dentition.

Increase in the value Encephalization Quotient (EQ)—One of the earliest proboscideans, the Moeritherium had an EQ of 0.2. Thisvalue increased during the 35–40 million of years and reached the value of up to 2.66 in modern elephantids.

*Slightly modified after Shoshani 1998, p. 484.

Antarctica, and some oceanic islands. Also included onthis map are locations of pygmy proboscideans and acomparison of a typical elephant to a pygmy individual.

CONCLUDING REMARKS

Biological classification involves categorization of or-ganisms by their unique characters; it provides a univer-sal language for laymen and scientists. Classification,cladograms, distribution maps, and suggested migra-tory routes will change as we discover new fossils orform different interpretations of previous data. Of theapproximately 180 species and subspecies of pro-boscideans that inhabited the earth since early Eocene(55 million years ago) only two or three remain todayand even these are in peril. We only begin to understandthe possible relationships between taxonomy and med-icine; it is plausible to hypothesize that the more gener-alized mammals may be better adapted to resist diseasesthan specialized mammals. Among elephants there issome evidence from captive animals that the Africanelephant (the more generalized or primitive species rel-ative to the Asian elephant) is less susceptible to her-pesvirus infection, uterine cystic endometrial hyperpla-sia, and uterine leiomyomas. Understanding taxonomymay help us better recognize the potential health prob-lems of elephants.

ACKNOWLEDGMENTS

Special thanks to the editors for inviting me to share themost recent findings. Heartfelt thanks to Gary H.Marchant for assistance with figure preparation. DalenAgnew, Emmanuel Gheerbrant, Sandra Shoshani, andPascal Tassy helped improve earlier versions of this man-uscript.

REFERENCES01. Agnew, D.W., Hagey, L. and Shoshani, J. In press. Cholelithi-

asis in a wild African elephant (Loxodonta africana). The ele-phants of Zoba Gash-Barka, Eritrea: Part 4. J Zoo Wildl Med.

02. Agnew, D.W., Munson, L. and Ramsay, E.C. 2004. Cystic en-dometrial hyperplasia in elephants. Vet Pathol 41:179–183.

03. Benton, M.J. 2000. Vertebrate Paleontology (2nd ed.). London,Blackwell Science, Ltd.

04. Carroll, R.L. 1988. Vertebrate Paleontology and Evolution.New York, W.H. Freeman and Company.

05. Debruyne, R. 2005. A case study of apparent conflict betweenmolecular phylogenies: the Interrelationships of African ele-phants. Cladistics 21:31–50.

06. Deraniyagala, P.E.P. 1955. Some extinct elephants, their rela-tives and the two living species. Colombo, Ceylon NationalMuseums Administration.

07. Eggert, L.S., Rasner, C.A. and Woodruff, D.S. 2002. The evolu-tion and phylogeography of the African elephant inferredfrom mitochondrial DNA sequence and nuclear microsatellitemarkers. Proc Royal Soc London B 269:1993–2006.


Figure 1.2. Diagrams depicting (a) cross-sections of isolated lamellae to reveal pattern of occlusal (chewing) surfaces, a tooth, and a left dentary in

a medial view with arrows indicating direction of horizontal tooth displacement; (b) right sides of mandibulae of Loxodonta africana depicting teeth

that are present at different ages (a, drawn from specimens by Gary H. Marchant; b, after Laws 1966, after Shoshani and Tassy 1996, p. 13).

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