Brigham Young University Science Bulletin, Biological Series Volume 8 | Number 3 Article 1 12-1966 A comparative osteological study of two species of Colubridae: (Pituophis and Thamnophis) Robert E. Bullock Lethbridge College, Lethbridge, Alberta, Canada Wilmer W. Tanner Department of Zoology and Entomology, Brigham Young University, Provo, Utah Follow this and additional works at: https://scholarsarchive.byu.edu/byuscib Part of the Anatomy Commons, Botany Commons, Physiology Commons, and the Zoology Commons Recommended Citation Bullock, Robert E. and Tanner, Wilmer W. (1966) "A comparative osteological study of two species of Colubridae: (Pituophis and Thamnophis)," Brigham Young University Science Bulletin, Biological Series: Vol. 8 : No. 3 , Article 1. Available at: https://scholarsarchive.byu.edu/byuscib/vol8/iss3/1 This Article is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Brigham Young University Science Bulletin, Biological Series by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. A/ |Y^ Brigham Young University Science Bulletin -^^OWP^ zc UNIVERSITY A COMPARATIVE OSTEOLOGICAL STUDY OF TWO SPECIES OF COLUBRIDAE (PITUOPHIS AND THAMNOPHIS) by ROBERT E. BULLOCK and WILMER W. TANNER BIOLOGICAL SERIES — VOLUME VIII, NUMBER 3 ^y DECEMBER, 1966 I BRIGHAM YOUNG UNIVERSITY SCIENCE BULLETIN BIOLOGICAL SERIES Editor: Dorald M. Allred, Department of Zoology and Entomology, Brigham Young University, Provo, Utah Associate Editor: Eabl M. Christensen, Department of Botany, Brigham Yoimg University, Provo, Utah Members of the Editorial Board: Bacteriology J. V. Beck, C. Lynn HArwAUD, Zoology W. Derby Lavs^s, Agronomy Howard C. Stutz, Botany WiLMER W. Tanner, Zoology, Chairman of the Board David L. Hanks, Botany Ex officio Members: Rudger H. Walker,> Dean, College of Biological and Agricultural ScienceSciences Ernest L. Olson, Chairman, University PubHcations The Brigham Young University Science Bulletin, Biological Series, publishes acceptable papers, particularly large manuscripts, on all phases of biology. Separate numbers and back volumes can be purchased from University Publications, Brigham Young University, Provo, Utah. All remittances should be made payable to Brigham Young University. Orders and materials for library exchange should be directed to the Division of Gifts and Exchange, Brigham Young University Library, Provo, Utah. Brigham Young University Science Bulletin A COMPARATIVE OSTEOLOGICAL STUDY OF TWO SPECIES OF COLUBRIDAE (PITUOPHIS AMD THAMNOPHIS) by ROBERT E. BULLOCK and WILMER W. TANNER BIOLOGICAL SERIES — VOLUME VIII, NUMBER 3 DECEMBER, 1966 TABLE OF CONTENTS Page INTRODUCTION 1 MATERIALS AND METHODS 2 VERTEBRAL COLUMN 3 Atlas 7 Axis 7 First Thoracic Vertebra 7 Other Thoracic Vertebrae 9 Lumbar Vertebrae 9 Anterior Caudal Vertebrae 9 Middle Caudal Vertebrae 13 Posterior Caudal Vertebrae 13 Ribs 13 SKULL 15 Premaxilla 15 Nasals 15 Septomaxillae 15 Vomers 15 Frontals 15 Prefrontals 17 Parietals 17 Postorbitals 17 Supraoccipital 17 Prootics - 17 Exoccipitals 19 Basioccipital 19 Basisphenoid 19 MaxiUae 19 Ectopterygoids 19 Palatines 19 Pterygoids 21 Supratemporals 21 Quadrates 21 Mandible ^ 21 Stapes 22 Hyoid Apparatus 22 OSTEOLOGICAL COMPARISONS 22 Vertebral Column 22 Skull .. 23 DISCUSSION 25 SUMMARY AND CONCLUSIONS 27 LITERATURE CITED 28 ABBREVIATIONS USED IN PLATES 28 LIST OF FIGURES Figure Page 1. Atlas 4 2. Axis 5 3. First Thoracic and Thoracic Vertebrae 6 4. Thoracic and Lumbar Vertebrae 8 5. Anterior Caudal Vertebra 10 6. Middle Caudal Vertebra 11 7. Posterior Caudal Vertebra and Rib 12 8. Skull, Dorsal View 14 9. Skull, Lateral View 16 10. Skull, Ventral View 18 11. Hyoid Apparatus, Mandible, and Cranium 20 A COMPARATIVE OSTEOLOGICAL STUDY OF TWO SPECIES OF COLUBRIDAE {PITUOPHIS AND THAMNOPHIS) by Robert E. Bullock' and Wilmer W. Tanner- INTRODUCTION Snake anatomy has been genei-ally neglected. relative abundance. One of them (P. catenifer) Although some early writers recorded observa- cxjnstricts its prey. other T. radix ) The ( swallows tions on the anatomy of snakes, no attempt has it alive. This difference in mode of feeding may been made to undertake a comprehensive study, be responsible for some structural modifications. and Cole (1944) has rightfully referred to this Although it is not the purpose of this study section of vertebrate anatomy as an "almost vir- directly to resolve any phylogenetic or ta.xonomic gin field." Snakes deserve more intensive in- problems, it is hoped that it will encourage other vestigation because of the considerable number anatomical studies of reptiles, add to our present of adaptations demonstrated by them, their understanding of homologies, and indicate im- peculiar types of locomotion, and methods of portant internal phylogenetic and taxonomic feeding. It is important to comprehend their structures as suggested by Robinson and Tanner anatomical specializations if we are to under- (1962). stand the evolutionary trends among modern Although no previous investigator has studied reptiles. It also is evident that comparative de- the osteology of the two species included in this scriptions of serpents, thus far based mainly on study, the general gross anatomy of various external characteristics, need to be supplemented other snakes has been known for a long time. by accounts of their internal anatomy. Ahrenfeldt (1955) stated that as far back as 1573 there were some fragmentary accounts of The purpose of this study is threefold: snake anatomy published in Europe, but Cole (1) To work out in detail the osteology of ( 1944 ) mentioned that it was not until 1683 that two common members of the family the first workmanlike and relatively accurate Colubridae. description of serpent anatomy was made by (2) To compare the bones and bone struc- Edward Tyson on a "Timber Rattlesnake" said tures of the two species in order to de- to have been collected in the West Indies. Owen ( gave one of the first termine their anatomical similarities and 1866 ) detailed differences, and to use these comparisons accounts of the osteology and myology of snakes in determining the different speciahza- based on his work with the species Crotalus tions that have been made by two com- horridtis, Pijthon tigris. Boa constrictor, Naja mon serpents. tripudians, and Deirodon scaber. Although Owen's work on this section of the vertebrates (3) To relate the structural differences of is a general account by our standards, in his these genera, as far as possible, to some time it was a major contribution to this area of of the other generic groups previously anatomy. Another work dealing with reported. snake anatomy is a laboratory dissecting guide by Kel- Our original intent was also to include the licott (1898) for the genus Heterodon. Unfor- myology of the head, neck, and anterior tnmk tunately, the descriptions lack detail and are region (first 10 vertebrae). This proved to be a therefore somewhat superficial and in many major effort in itself, and such a report will ap- areas incomplete. pear separately at a later date. Huxley (1871), Gegenbaur (1878), Hoffman The gopher snake, Pituophis catenifer Blain- (1890), Sedgwick (1905), Wiedersheim and N'ille, and the plains garter snake, Thamnophis Parker (1907), VVilliston (192,5), Kingsley radix (Baird and Girard), were chosen for this (1917), Goodrich (1930), and Versluys (1937) study because of their moderately large size and were some of the early textbook writers who ^Lethbridge College. Lethbridge, AJberta, Canad ^Department of Zoology and Entomology, Brigha Young University, Provo, Utah. Brigham Young University Science Bulletin dealt with the subject of snake osteology. Most describes and compares the development of the of these writers restricted their studies to the cranial muscles and associated skeletal structures skull of serpents, and on occasion included one in forms ranging from the fishes to the mam- or more generalized vertebrae. Romer's "Osteo- mals. Haas (1930) and Cowan and Hick (1951) logy of the Reptiles" (1956) deals only briefly also dealt with the musculature of snakes, but with serpents, but does bring some of the termi- included skeletal structures as well. Albright and nology and many of the homologies up to date. Nelson ( 19.59 ) dealt with the cranial osteology Two volumes by Ludicke (1962, 1964) de- and the musculature of the colubrid snake voted entirely to the anatomy of serpents deal Elaphe obsolcta quadrivittata. rather extensively with the developmental and Perhaps more osteology has been done with adult anatomy of several species of snakes, in- venomous species, particularly with the teeth cluding a few colubrid species. Many of the (fangs) and sk-ull. The work of Klauber (1956: descriptions and comparisons in these works are 712-743) is a good example. of a general nature and, therefore, are of limited We made no major attempt here to e.xhaust value in making comparisons with the colubrid the references which may refer to snake anat- species involved in this study. omy. Those referred to above represent some of Sood (1941, 1948) published two papers the more important works that we have seen. dealing with the vertebral column of serpents. We were greatly surprised when we found rela- The first is concerned with the caudal vertebrae tively few studies dealing with either of the two of the sandsnake, Eryx johnii (Russell), and