THE TAXONOMIC SIGNIFICANCE OF THE TONGUE MUSCULATURE OF PASSERINE BIRDS Item Type text; Dissertation-Reproduction (electronic) Authors George, William Gordon, 1925- Publisher The University of Arizona. Rights Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. Download date 05/10/2021 15:17:28 Link to Item http://hdl.handle.net/10150/284412 This dissertation has been 61-3328 microfilmed exactly as received GEORGE, William Gordon, 1925- THE TAXONOMIC SIGNIFICANCE OF THE TONGUE MUSCULATURE OF PASSERINE BIRDS. University of Arizona, Ph.D., 1961 Zoology University Microfilms, Inc., Ann Arbor, Michigan THE TAXONOMIC SIGNIFICANCE OF THE TONGUE MUSCULATURE OF PASSERINE BIRDS by William G. George A Dissertation Submitted to the Faculty of the DEPARTMENT OF ZOOLOGY In Partial Fulfillment of the Requirements For the Degree of DOCTOR OF PHILOSOPHY In the Graduate College THE UNIVERSITY OF ARIZONA 1961 THE UNIVERSITY OF ARIZONA GRADUATE COLLEGE I hereby recommend that this dissertation prepared under my direction by Wllllaa G. George entitled The Taxonoalc Significance of the Tongue Musculature of Passerine Birds be accepted as fulfilling the dissertation requirement of the degree of Doctor of Philosophy Dissertation Director / Date After inspection of the dissertation, the following members of the Final Examination Committee concur in its approval and recommend its acceptance:* *This approval and acceptance Is contingent on the candidate's adequate performance and defense of this dissertation at the final oral examination. The inclusion of this sheet bound Into the library copy of the dissertation is evidence of satisfactory performance at the final examination. STATEMENT BY AUTHOR This dissertation has been submitted in partial fulfillment of requirements for an advanced degree at The University of Arizona and is deposited in The Uni­ versity Library to be made available to borrowers under rules of the Library. Brief quotations from this dissertation are allowable without special permission, provided that ac­ curate acknowledgment of source is made. Requests for permission for extended quotation from or reproduction of this manuscript in whole or in part may be granted by the head of the major department or the Dean of the Grad­ uate College when in their judgment the proposed use of the material is in the interests of scholarship. In all other instances, however, permission must be obtained "from the author. SIGNED; . ^ ^ ^ ^ APPROVAL BY DISSERTATION DIRECTOR This dissertation has been approved on the date shown below: Joe T. Marshall, Jr. ABSTRACT This is a study of the hyoid bones of 501 species, and of the tongue muscles of 259 species, of perching birds. Hyoidean variations of alternative kinds are re­ ported to occur in the shape of the basihyale and the ceratobranchiale, in the manner of insertion of the M. hypoglossus posterior and M. ceratoglossus posterior, and in the origin of the M. stylohyoideus. These vari­ ations are described in detail and illustrated, and an attempt is made to establish their functional as well as their taxonomic significance. Evidence is developed to show that the Orepaniidae possess the hyoidean adaptations of cardueline finches, and that the Olive Warbler (Peucedramus taenlatus) has the hyoid bones, hyoid muscles and jaw muscles of an Old World warbler. It is strongly suggested that Peucedramus be removed from the Parulidae and placed in the Sylviidae. i CONTENTS Page Introduction 1 Obj ect 5 Methods and Materials 6 Acknowledgements 9 Results 11 The Hyoid Bones 11 The Hyoid Muscles 17 Observations on Tongue Function 36 Discussion 71 Taxonomic Analysis of Hyoidean Variation . 76 Disposition of Taxonomic Problems 83 Summary and Conclusions 90 Literature Cited 92 Appendix 128 ii ILLUSTRATIONS AND TABLES Figure Page 1A Typical passerine hyoid, ventral view 97 IB Cross section of basihyale in typical primaried passerine. 1C Cross section of basihyale in typical New World Nine-primaried Oscines. 2A Typical tongue musculature of passerines, 99 superficial dissection, ventral view. 2B Origin on the skull of stylohyoideus. 2C Dual origin of stylohyoideus. 3 Tongue musculature of typical passerine, 101 deep dissection, ventral view. 4 Tongue musculature of typical passerine, 103 deep dissection, dorsal view. 5 Comparative size of muscles in Brewer's 105 Sparrow and Audubon's Warbler. 6 Tongue musculature of Carpodacus cassinii. 107 7 Diagrammatic cross sections of the four 109 alternative conditions of hypoglossus posterior. iii Ventral view of the four alternative 111 conditions of hypoglossus posterior. 9 Dorso lateral view of relationship of 113 hypoglossus posterior, basihyale and paraglossalia. 10 Cross sections of ceratobranchiale of 115 seedhuskers. 11 Cross sections of basihyale in six species. 117 12-15 Photographs of hypoglossus posterior in 119-127 five species. Table 1. 38-70 iv INTRODUCTION Anatomical characters of value in classifying passerine birds at the suprageneric level are badly needed. Few such characters have been discovered, probably because few internal structural features of the perching birds have been thoroughly investigated. Since one can foresee, however, that perhaps every anatomical characteristic of nearly all living birds will be studied sooner or later, I wish not to comment here on past neglect of the comparative anatomy of the passerines; nor need I, for both Beecher (1953) and Bock (1960) have given us good accounts of this. I wish to point out, instead, that comprehensive anatomical knowledge of the 5000 species of perching birds will not be gained until museums have assembled very large spirit col­ lections of passerine specimens and have made the specimens available for dissection. The museums accordingly face a great responsibility and a tremendous task. Present inter­ est in passerine comparative anatomy surely shall decline if the present supply of specimens is not soon greatly ex­ panded. The internal structures which I shall describe and 1 2 discuss in this study are the tongue bones and tongue muscles of the perching birds. The study began when I noted striking interfamilial differences in the fundamental shape of one of the bones of the hyoid apparatus, the basihyale (Pig. 1A). A subsequent preliminary survey of passerine hyoid musculature revealed that two of the hyoid muscles, the M. stylohoideus and M. hypoglossus posterior, vary among species in alternative and highly uuggestive ways. The ne­ cessity for determining the functional significance of these variations, so that evolutionary interpretation of the vari­ ations could at least be attempted, led to investigation of the function of the tongue. Neither the bones nor the muscles of the passerine hyoid have been much studied in the past. Lucas (1896) superficially surveyed the hyoid bones, and Furbringer (1922) figured the hyoids of a number of species. Bates (1930) alone has employed the bones in a taxonomic study; he assigned the Hylliidae to a phylogenetic position next to the Nectariniidae on the basis of the singular morph­ ology of the hyoid horns shared by the birds of the two groups. Shufeldt (1890) described the tongue muscles of the Raven. Moller (1930-31) reported on the tongue muscles 3 of four passerine species, and Engels (1938) made a very fine study of the tongue musculature of nineteen species; he also corrected Shufeldt's errors, synonymized the hydoidean myological terminology, and observed: "Some dif­ ferences in detail have been noted; the finches especially, exhibit well-defined variations and seem most likely to repay a comparative, functional or blologlsch-anatomische study." I have borrowed the muscle nomenclature employed by Engels. It is important to consider here the anatomical plan and functional role of the hyoid apparatus. Essential­ ly, the hyoid apparatus is a Y-shaped skeleton of small bones (Fig. 1A); its posterior parts (the ceratobranchialia and epibranchialia) curl upward over the ventro-posterior surface of the cranium, while the anterior parts (the basihyale and paraglossilia) lie in the mouth. This funda­ mental skeleton is secured to the sides of the mouth by two muscles (M. branchiomandibularis and M. stylohyoideus), and to the ventral midline of the trachea by two muscles (M. tracheohyoideus and M. thyreohyoideus). Additonally, con­ nective tissue secures the apparatus to the trachea by lash­ ing the latter to the urohyale. The tongue itself consists of the tissues enfolded 4 around the tinest and most anterior of the hyoid bones, the paraglossalia. The paraglossalia articulate with the anterior end of the basihyale. Clearly, when the bones of the hyoid apparatus change position, the tongue changes position. Contraction of the hyoid muscles causes the hyoid apparatus to change position, and then we say the tongue has moved. OBJECTIVES The aims of this study are: 1) to survey the hyoid bones and muscles of perching birds and record all notice­ able variation between species; particularly, to determine the fundamental shape of the basihyale and the origin and insertion of the M. stylohyoideus and M. hypoglossus pos­ terior in as many passerine species as possible, 2) to de­ termine the function of the tongue bones and tongue muscles, 3) to establish the taxonomic significance of hyoidean variation, and 4) to use taxonomically