Auditory Region in North American Fossil Felidae: Its Significance in Phylogeny GEOLOGICAL SURVEY PROFESSIONAL PAPER 243-G Auditory Region in North American Fossil Felidae: Its Significance in Phylogeny By JEAN HOUGH SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1952, PAGES 95-115 GEOLOGICAL SURVEY PROFESSIONAL PAPER 243-G Detailed descriptions and illustrations of the ear region in some fossil and recent genera, and a proposed revision of superfamily classification of the Carnivora UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1953 UNITED STATES DEPARTMENT OF THE INTERIOR Douglas McKay, Secretary GEOLOGICAL SURVEY W. E. Wrather, Director For sale by the Superintendent of Documents, U. S. Government Printing Office Washington 25, D. C. - Price 20 cents (paper cover) CONTENTS Page Page Abstract ___________________________________________ 95 Generic descriptions—Continued Introduction. ______________________________________ 95 Subfamily Nimravinae________---___-_-___-_--__ 103 Acknowledgments_____ _ _____________________________ 97 Dinictis (Oligocene species)__________________ 103 General characters of the auditory region in Oligocene External characters _____________________ 103 Felidae. _________________________________________ 97 Internal structure of the bulla and middle ear. 103 Auditory bulla_ ________________________________ 97 Basicranial foramina. ___________________ 103 Basicranial foramina, ___________________________ 99 Dinictis cyclops Cope (John Day species) ______ 105 Generic descriptions _ _ _____________________________ 99 Nimravus- _________________________________ 106 Subfamily Machaerodontinae _ __________________ 99 Subfamily Pseudaelurinae______________________ 106 Hoplophoneus- _____________________________ 99 American genera.__________________________ 106 General characters- _______---__---__-___ 99 Asiatic and European genera.________________ 106 Auditory bulla_ ________________________ 99 Summary and conclusions______________________ 106 Basicranial foramina ____________________ 99 Homology of basicranial features of the Feloidea______ 107 99 Septum bullae_-_______-_--------__------------- 107 General characters. _____________________ 99 Form and position of the septum _____________ 1C7 Middle and inner ear structure- __________ 100 Mode of development of the bulla____________ 1C9 Basicranial foramina. __________^____.___ 100 Basicranial foramina._____-____-_______--:____-_ 110 Pliocene machaerodonts, ____________________ 100 Summary and conclusions________-____-_-___-__ 112 Smilodon __________________________________ 101 Evolution of the intracranial circulation _______ 112 General characters. _____________________ 101 Evolution of the auditory bulla_______________ 112 Internal structure of the auditory bulla____ 102 Proposed taxonomic changes_____-___-_--___- 113 Structure of the middle and inner ear_ 102 Summary of superf amilies and families ________________ 113 Basicranial foramina. _-___-_-__________- 102 Selected references-_________________________________ 115 ILLUSTRATIONS Page Pag« FIGURE 5. Hoplophoneus primaevus oreodontis---------- 98 FIGURE 10. Viverricula ind. rasse. ___ 10° 6. Smilodon californicus--.------------------- 100 11. Felis catus- ________-- ________________ 10° 7. Smilodon californicus.-- _________________ . 100 12. Cam's dingo. __________-_-_____-___-_-_-_ 110 8. Diniclis felina---------------------------- 104 13. Vulpes velox---------------------------- 111 9. Dinictis cyclops___________________________ 105 AUDITORY REGION IN NORTH AMERICAN FOSSIL FELIDAE: ITS SIGNIFICANCE IN PHYLOGENY By JEAN HOUGH ABSTRACT common fossa with the posterior lacerate foramen. Tv 3 The auditory region of the North American fossil Felidae is Arctoidea, on the other hand, have a simple, one-cham­ described in detail. In the Oligocene Felidae the characters of bered bulla, a large postglenoid foramen, a large condy­ this region, especially the foramina associated with the veins loid foramen quite distinct from the foramen lacerum and arteries of the head, are like those of the modern Canidae rather than the Felidae. On the contrary, all of the middle posterius, a well-developed bony canal for the carotid Miocene (post-John Day) and later genera have typical felid artery and a large posterior carotid foramen also dis­ characters in this part of the skull. This has profound sig­ tinct from the posterior lacerate foramen. The Cynoi­ nificance for the phylogeny and major taxonomy of the family. dea have some features of each group. There is a par­ If any of the species of Oligocene felids are ancestral to the tial septum, the postglenoid foramen is moderately modern forms, an evolution of both the venous and arterial large, the condyloid foramen is smaller than in the system of the head as well as the auditory bulla must have taken place. This is quite possible, for not only is there theoretical sup­ Arctoidea and the carotid canal less conspicuously de­ port for it in the ontogeny of modern genera, but there are species veloped. The posterior carotid foramen is a narrow that have characters linking the Paleofelides to the Neofelides. slit opening into the common fossa with the foramen Nevertheless, postulating such an evolution is a radical step as lacerum posterius. it throws doubt upon the validity of the current superfamial These characters were probably considered by classification of the Carnivora. This arrangement is based pri­ marily on the homology of the two-chambered bulla, and the Flower, and certainly by Turner (1848) who originated presence or absence of the postglenoid foramen. If, as this the idea, as no more than morphological correspond­ paper attempts to show, these structures are not homologous, ences the use of which gave a more natural classification but have evolved independently in the Viverridae and Felidae (sensu Dobzansky, 1941, p. 363) than the use of adap­ (and in other families), the categories Aeluroidea and Arctoidea tive characters of the limbs and teeth. Mivart, ho^- of Flower (Feloidea and Canoidea of Simpson) have no phylo- genetic significance, but are at best convenient divisions appli­ ever, in a series of papers (1882,1885,1890) elaborated cable to modern genera only. on the idea extensively, giving it an archetypal signifi­ cance by compiling long lists of features in the soft INTRODUCTION parts and skeleton linked, as he thought, with the key The threefold division of the Carnivora into Aeluroi­ characters of the basicranium. With the rise of the dea, Cynoidea and Arctoidea was based by Flower evolutionary theory, this archetypal concept of homol­ (1869) primarily on the characters of the auditory re­ ogy gave way in turn to a phylogenetic one. Homol­ gion, especially the presence or absence of a septum di­ ogy indicated common ancestry, proof of which was to viding the bulla into two chambers, and the arrange­ be sought first in ontogeny, and later, as the fossil ment of the basicranial foramina. In these features, record became better known, in paleontological history. the Aeluroidea (Viverridae, Felidae, Hyaenidae) repre­ The first result of this shift in zoological theory was sent one extreme, the typical arctoid Carnivora (Mus- the reduction of Flower's threefold classification to a telidae, Procyonidae, Ursidae) another. The Cynoidea twofold one. Flower had considered the partial sen- (Canidae) Flower thought intermediate between the turn found in many canids, and especially well devel­ two. In the Aeluroidea the interior of the bulla is di­ oped in Oanis yubatus homologous with the septum vided into two chambers by a septum which completely bullae of Felis, at least in the morphological sense. (It closes off the chambers except for a small opening just has the same position and where the bullae is well in­ below the fenestra cochleae; the postglenoid foramen is flated appears to be an intermediate stage in the evolu­ reduced or absent, the condyloid foramen concealed by tion of the typical felid septum.) Winge's studies the foramen lacerum posterius, the carotid canal re­ (1895) seem to show that the septum of Oanis was, in duced to a vestige and the posterior carotid foramen fact, homologous in mode of origin (not position) whh (where present at all) very inconspicuously placed in a the septae and rafters that radiate from the cris^a 95 96 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1952 tympani across the walls of the bulla in some mustelids. included in the Canoidea but on the basis, presumably, These are ossified from folds of the mucuous lining. of the dentition, or of an alleged canid ancestry. In spite of the fact that this homology was disputed'by Paleoprionodon and Paradaphoenus, wture basi­ Van Kampen (1905) who denied that the septum in cranial characters are almost exactly alike, ar?, placed Canis originated from mucous folds and considered it in different superfamilies, one in the Feloidea and the rather a part of the original wall become concave by other in the Canoidea presumably on the basis of den­ bone apposition on the outer side and simultaneous re- tition although the dental characters of Paleopriono­ sorption on the inner side, Winge's classification con­ don differ from those of Paradaphoenus in the same tinued to be universally accepted for over half a cen­ way that those of Poiana differ from Civetwtis—mod­ tury. This was in part due, however, to support ern viverrines included by Gregory (1939) in the same given to the idea of the homology of the basicranial subfamily. The basicranial foramina of the fossil characters