The Autochthonous North American Musk Oxen Bootherium, Symbos, and Gidleya (Mammalia: Artiodactyla: Bovidae) JERRY N. MCDONALD and CLAYTON E. RAY SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY • NUMBER 66 SERIES PUBLICATIONS OF THE SMITHSONIAN INSTITUTION Emphasis upon publication as a means of "diffusing knowledge" was expressed by the first Secretary of the Smithsonian. In his formal plan for the Institution, Joseph Henry outlined a program that included the following statement: “It is proposed to publish a series of reports, giving an account of the new discovenes in science, and of the changes made from year to year in all branches of knowledge." This theme of basic research has been adhered to through the years by thousands of titles issued in series publications under the Smithsonian imprint, commencing with Smithsonian Contributions to Knowledge in 1848 and continuing with the following active series: Smithsonian Contributions to Anthropology Smithsonian Contributions to Astrophysics Smithsonian Contributions to Botany Smithsonian Contributions to the Earth Sciences Smithsonian Contributions to the Marine Sciences Smithsonian Contributions to Paleobiology Smithsonian Contributions to Zoology Smithsonian Folklife Studies Smithsonian Studies in Air and Space Smithsonian Studies in History and Technology In these series, the Institution publishes small papers and full-scale monographs that report the research and collections of its various museums and bureaux or of professional colleagues in the world of science and scholarship. The publications are distributed by mailing lists to libraries, universities, and similar institutions throughout the world. Papers or monographs submitted for series publication are received by the Smithsonian Institution Press, subject to its own review for format and style, only through departments of the various Smithsonian museums or bureaux, where the manuscripts are given substantive review. Press requirements for manuscript and art preparation are outlined on the inside back cover. Robert McC. Adams Secretary Smithsonian Institution SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY • NUMBER 66 The Autochthonous North American Musk Oxen Bootherium, Symbos, and Gidleya (Mammalia: Artiodactyla: Bovidae) Jerry N. McDonald and Clayton E. Ray SMITHSONIAN INSTITUTION PRESS Washington, D.C. 1989 JUN o S ABSTRACT McDonald, Jerry N., and Clayton E. Ray. The Autochthonous North American Musk Oxen Bootherium, Symbos, and Gidleya (Mammalia: Artiodactyla: Bovidae). Smithsonian Contribu¬ tions to Paleobiology, number 66, 77 pages, 64 figures, 4 tables, 1989.—The history of taxonomy of the autochthonous genera of North American musk oxen— Bootherium, Symbos, and Gidleya —is reviewed. The bases upon which taxonomic judgments within the group have been made are identified. These bases are reevaluated in the light of current information on patterns of ontogenesis, sexual dimorphism, postmortem alteration of skeletal remains, and spatial and temporal distribution of musk ox records. The bases used by taxonomists in the past to justify separation of this musk ox group into multiple genera and species can be explained best as indices of sexual dimorphism or postmortem weathering and abrasion. All nominal species within Bootherium, Symbos, and Gidleya are, therefore, placed in synonymy with the senior name in the group, Bootherium bombifrons (Harlan, 1825). A revised diagnosis is provided for the monotypic species. OFFICIAL PUBLICATION DATE is handstamped in a limited number of initial copies and is recorded in the Institution’s annual report, Smithsonian Year. Series cover design: The trilobite Phacops rana Green. Library of Congress Cataloging in Publication Data McDonald, Jerry N. The autochthonous North American musk oxen. (Smithsonian contributions to paleobiology; no. 66) Bibliography: p. 1. Musk ox, Fossil—-North America—Classification. 2. Paleontology—North America. I. Ray, Clayton Ed¬ ward. II. Smithsonian Institution. III. Title. IV. Series. QE701.S56 no. 66 560 s [569'.73] 88-607937 [QE882.U3] Contents Page Introduction. 1 Acknowledgments. 2 History of Taxonomy of the Group. 3 The Content of Bootherium, Symbos, and Gidleya .24 The Relationship between Gidleya and Symbos .26 The Relationship between Bootherium and Symbos .27 Differences in the Size of Bootherium and Symbos Crania.28 Differences in the Characteristics of the Horn Cores.31 Differences in the Dorsal Surface of the Cranium.40 Differences in the Basioccipital-Basisphenoid Flexion.44 Differences in Depth of the Lacrimal Fossae.46 Differences in the Number of Bootherium and Symbos Specimens.46 Similarities in the Morphology and Distribution of Bootherium and Symbos Specimens. 47 Conclusions. 51 Systematic Hierarchy. 67 Bootherium bombifrons (Harlan, 1825). 67 Appendix I: Abbreviations for Institutional, Departmental, and Private Collections Used in This Study. 70 Appendix II: Chronology of Nominal Species Referable to Musk Oxen in the Genera Bootherium, Symbos, and Gidleya . 72 Appendix III: Radiocarbon Dates on Bootherium and Symbos Specimens.73 Literature Cited. 74 iii The Autochthonous North American Musk Oxen Bootherium, Symbos, and Gidleya (Mammalia: Artiodactyla: Bovidae) Jerry N. McDonald and Clayton E. Ray Introduction Five genera of musk oxen (low-horned ovibovines) presently are recognized from the Quaternary of North America. Two of these genera ( Ovibos and Praeovibos ) were Holarctic in distribution, whereas the other three ( Bootherium, Symbos, and Gidleya ) are known only from the Nearctic. Praeovibos Staudinger, 1908, at one time considered to be the earliest known representative of the musk ox group, is known from fossil skull material from at least 16 sites in Europe and Asia that date from the middle Pleistocene (i.e., the Giinz, Mindel, and possibly Riss stages, and their equivalents) (Kahlke, 1964; Sher, 1974; Cregut-Bonnoure, 1984; Moigne, 1984). Ovibos Blainville, 1816, however, is also known from deposits possibly of Giinz age at Sussenborn, East Germany (Kahlke, 1964; Kurten, 1968; Cregut-Bonnoure, 1984), and was considered by Kahlke (1975) to be the oldest genus of musk ox. Recently, skeletal remains assigned to Praeovibos sp. have been reported from Venta Micena, Spain, and Casa Frata, Italy (Moya-Sola, August!, Gibert, and Pons-Moya, 1981; De Giuli and Masini, 1983), both of which, along with at least one of the Kolyma Basin sites in Siberia, are reported as predating those at Sussenborn. The earliest records of Ovibos and Praeovibos from North America are from deposits presumed to be of Ulinoian age near Nome and Fairbanks, Alaska, respectively (Pewe and Hopkins, 1967; Harington, 1970a). Nearctic records of Praeovibos are restricted to eastern Beringia (Fairbanks area, Alaska, Old Crow Basin, Yukon Territory, and Porcupine River, Yukon-Alaska), whereas cranial records of Ovibos extend from Alaska southward to Montana, Wyoming, Nebraska, Iowa, Illinois, Ohio, and the continental shelf of New Jersey Jerry N. McDonald, P.O. Box 10308, Blacksburg, Virginia 24062. Clayton E. Ray, Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560. (Hay, 1923, 1924; Barbour, 1934; Harington, 1978; Walker, 1982; McDonald and Ray, unpubl. data). The North American autochthons, Bootherium (Harlan, 1825), and Symbos (Leidy, 1852), appear simultaneously in deposits usually assigned to the Ulinoian glaciation (= late Irvingtonian-early Rancholabrean land mammal ages). The earliest record of Bootherium is from Cripple Creek Sump (and possibly Gold Hill and Lower Cleary Creek) in the Fairbanks District, Alaska (Pewe and Hopkins, 1967; Pewe, 1975). Remains of Symbos of Ulinoian age also have been recovered from Cripple Creek Sump, as well as from the North Prong Quarry (Mullen local faunas), Cherry County, Nebraska, and equivocally from the Conard Fissure, Newton County, Arkan¬ sas (Brown, 1908; Jakway, 1961a; Pew6 and Hopkins, 1967; Martin, 1972). Both North Prong Quarry and Conard Fissure local faunas, however, present some problems of specimen identification or age assignment (see discussion, pp. 48- 51). A Symbos specimen from sediments tentatively assigned to the late Illinoian (i.e., middle Rancholabrean) has been reported from Booth Canyon, Bonneville County, Idaho (White, 1985). The single specimen of Gidleya (Gidley, 1906), from Black Rocks, McKinley County, New Mexico, was considered at one time to date from the early Pleistocene because of its association “with camels and horses, animals of early Pleistocene age” (Hay, 1924:179). Now, however, the Gidleya record, and all Bootherium and Symbos records from localities other than those just mentioned, are considered to be either Sangamonian or Wisconsinan in age. Praeovibos became extinct in Eurasia (Sher, 1974; Cregut- Bonnoure, 1984) near the end of the Middle Pleistocene (during the ?Riss glaciation). Praeovibos might have become extinct in North America before the Wisconsinan glaciation, but specimens assigned to this genus have been found at lower Cleary Creek, and have been identified tentatively from essentially late Wisconsinan faunules at Cripple Creek, Dome 1 2 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY Creek, Gold Hill, and lower Cleary Creek, Alaska. Bootherium, Symbos, and Gidleya appear to have become extinct by the end of the Wisconsinan glaciation. Ovibos became extinct in Eurasia around 3000 yr B.P., and survived into the historic period only in the higher latitudes of North America and Greenland (Allen, 1912, 1913; Harington, 1970a, 1970b; Cregut-Bonnoure, 1984). The taxonomy of the autochthonous North American musk oxen has been unstable since the earliest recognized taxa were described in the second and third decades of the 19th century. Questions about the relationship between Bootherium and Symbos arose soon after the group was first revised by Leidy (1852a,b) and have continued, unresolved, to the present (e.g.. Nelson and Neas, 1980; White, 1985; Nelson and Madsen, 1987). Another conspicuous taxonomic problem involving musk oxen concerns the status of Gidleya, a genus established originally as Liops on an extensively abraded partial cranium from New Mexico (Gidley, 1906). Although Gidleya has received attention from paleontologists throughout its eighty- year history (Cossmann, 1907; Allen, 1913; Troxell, 1915; Hay, 1922,1924; Ryziewicz, 1933,1955; Frick, 1937; Kretzoi, 1942; Harington, 1961; Romer, 1966), it has failed nonetheless to receive functional validation as a viable taxon. No less than 13 nominal species were erected within Bootherium, Symbos, and Gidleya between 1825 and 1942. Most of these species were established upon weak foundations—isolated teeth, isolated postcranial elements, or fragments of crania. Six of the 13 species already have been synonymized with more securely founded taxa, but the status of the remaining species also needs to be reevaluated. Much of the reason for taxonomic instability at the generic level of the autochthonous North American musk oxen can be attributed to either failure to recognize sexual dimorphism and individual variation or assess differential postmortem alteration of various specimens. This circumstance is in part a result of very few specimens being available at the time for study and comparison. Furthermore, the questions being asked often were different from those being asked today. The arguments that have characterized this debate have endured long past their time in great part because a comprehensive review of the North American fossil musk ox group has not been undertaken since Allen did so in 1913. The taxonomy of the group has not benefited from the information and ideas acquired or developed during the last 75 years, and consequently the uncertainties related to the conceptualization and use of the three recognized genera are based to a surprising but real extent upon 19th century information and ideas. Information acquired since 1913 relevant to the taxonomic status of Bootherium, Symbos, and Gidleya is herein updated and reevaluated. The 226 available specimens is much larger than the 16 or so known to Allen (who, apparently, personally examined only two of these). Consequently, patterns of morphological and geographical variation can be documented and analyzed with substantially greater resolution and confi¬ dence than was possible in 1913. More reliable dating methods and inter-site correlations permit more confident assessments of chronology and contemporaneity of the three nominal genera. Data obtained from taxa closely related to musk oxen permit comparisons of patterns of individual morphological variation, sexual dimorphism, differential preservation and collection of male and female skeletal elements, and geographi¬ cal distribution. Recent studies of taphonomy provide much useful information about the effects of weathering and abrasion processes on bones and teeth, and patterns of postmortem biological alteration of skeletal remains. Our purpose is to reassess the relationships among the genera Bootherium, Symbos, and Gidleya. We first review the taxonomic history of the group, directing particular attention to the specific questions that have characterized the instability. In this same section we identify the morphological characters and other data that have been invoked to support the diverse perspectives that have characterized the debate. Next we present our views on the status of the nominal species within each of the three genera. In a third section we consider the relationship between Gidleya and Symbos. Lastly, we examine the validity of the various elements of the arguments over the relationship between Bootherium and Symbos, incorporating modern data and insights derived from studies of individual variation, sexual dimorphism, ontogenetic change, and tempo¬ ral and spatial distribution patterns. In this paper the names Bootherium, Symbos, and Gidleya are used as though they represented distinct taxa until we establish and summarize our case for their synonymy in the final section. We have omitted use of the diaerisis in Bootherium in accordance with Article 27 of the 3rd edition of the International Code of Zoological Nomenclature. Abbreviations for institutional, departmental, and personal collections containing specimens used in this paper are identified in Appendix I. Acknowledgments.— The theme and scope of this paper was established in 1982 and 1983 during McDonald’s tenure as a Smithsonian Postdoctoral Fellow, working with Ray, in the Department of Paleobiology, National Museum of Natural History. The paper was written in 1984 and 1985, since which time it has remained essentially unchanged save for adding new records and references to newly published factual information. The ideas presented in this paper, however, have developed during our more than 30 years of combined research on musk and shrub oxen. During that period, we have benefited from the assistance and interest of many colleagues. For facilitating access to collections, for loaning specimens, for sharing unpublished information, and for conversation and debate, we thank the following people: William A. Akersten, Carol W. Allison, Donald Baird, Charles S. Bartlett, Jr., Stig M. Bergstrom, Robert C. Bright, Kenneth Caster, Charles S. Churcher, Vickie L. Clay, William A. Clemens, Jr., John Connaway, John P. Cook, Richard G. Corner, Richard A. Davis, A. Gordon Edmund, Ralph E. Eshelman, Anthony Fiorillo, Weldon D. Frankforter, Jr., Larry E. Freeman, Linda Gordon, Russell W. Graham, the late John E. Guilday, Carl E. NUMBER 66 3 Gustafson, R. Dale Guthrie, Mark S. Hafner, Charles A. Handley, Jr., C. Richard Harington, Toni Herrin, the late Claude W. Hibbard, Robert M. Hunt, Jr., Louis L. Jacobs, David R. Klein, George E. Lammers, Everett H. Lindsay, K. Don Lindsey, Ernest L. Lundelius, Jr., Janies E. Martin, Earl Manning, H. Gregory McDonald, Malcolm C. McKenna, Susanne J. Miller, John F. Neas, Michael E. Nelson, Sarah W. Neusius, John Palmquist, Ronald Parsley, the late Bryan Patterson, John D. Pinsof, Charles Potter, Mr. and Mrs. Don Rice, Ronald L. Richards, Judith A. Schiebout, Gary Selinger, Holmes A. Semken, Jr., L. Gay Shapiro, Morris F. Skinner, Theresa Skwara, Bob H. Slaughter, Robert E. Sloan, Charles L. Smart, Jr., Ralph Space, John E. Storer, Margot Surovik- Bohnert, Lloyd G. Tanner, Richard H. Tedford, Richard Thorington, Charles W. Totten, William D. Turnbull, John A. White, Frank C. Whitmore, Jr., Melissa C. Winans, and Susan L. Woodward. Richard A. Davis, H. Gregory McDonald, John D. Pinsof, and Theresa Skwara provided us with unpublished manuscripts and permitted us to refer to specimens described in those manuscripts. Robert S. Hoffmann provided us with a copy of John Neas’s M.A. thesis on 2 November 1987. C. Richard Harington, James H. Madsen, Jr., John F. Neas, Michael E. Nelson, and John A. White presendy share our research interest in the systematic relationship among Boo- therium, Symbos, and Gidley. We have benefited from interaction with these colleagues. The photographs used herein were taken by Victor A. Krantz, and the illustrations were prepared by Mary Parrish. Gladwyn B. Sullivan was always available when called upon for preparing, casting, photographing, transporting, and pack¬ ing specimens; throughout his years of dependable service “Tutt’s” “happy hands” made our work easier, more efficient, and more pleasant than it otherwise might have been. Holmes A. Semken, Jr., and Frank C. Whitmore, Jr.,read and provided critical comments about an earlier version of this paper. We wish to express our deep appreciation for their assistance, but we accept full responsibility for the information and views contained herein. History of Taxonomy of the Group The first published record of a fossil musk ox from North America was Wistar’s description and figures of a cranium with horn cores (ANSP 994; Figures 1-4) collected at Big Bone Lick, Kentucky, by William Clark in 1807 (Wistar, 1818; Rice, 1951). Wistar recognized the resemblance between some characters in his specimen and those of domestic cattle, sheep, and goats, and especially bison, but he gave no indication of having compared the specimen with the tundra musk ox, descriptions of which were available at that time (e.g., Jeremie, 1720; Pennant, 1781,1784; Blainville, 1816). Although Wistar realized that the cranium from Big Bone Lick was “very different from that of any animal now known here” (Wistar, 1818:379), he did not name this newly documented form of life (Wistar, 1818). Seven years later, Harlan (1825), in Fauna Americana, described Bos bombifrons on the basis of the Big Bone Lick cranium (ANSP 994: Figures 1-4). This species shared the genus Bos with B. americanus (now Bison bison ) and the new species B. latifrons (now Bison latifrons ); the tundra musk ox ( Ovibos moschatus) was retained as a monotypic genus, following Blainville (1816). Both Wistar and Harlan placed the Big Bone Lick specimen near Bison because the skulls of both were similar in size, and the horn cores of each were rounded and projected laterally from the cranium distinctly anterior to the occipital crest. Harlan apparently overlooked the remnant lacrimal depression on the left side of the Big Bone Lick skull, for one diagnostic criterion of his genus Bos (and, erroneously, Ovibos ) was the absence of a “lachrymal depression” (Harlan, 1825:264,267). In 1828, De Kay described and figured a second fossil musk ox specimens partial cranium with the bases of the horn cores, discovered at New Madrid, Missouri, following the famous earthquake of 1812. This specimen, too, was originally identified as “a petrified occiput, and the horn processes of the American Bison” but, in De Kay’s opinion, “none of that genus are now to be found in our country, whose crania in the slightest degree resembles the one under consideration” (De Kay, 1828:285). Placing emphasis upon the flattened horn cores, De Kay correctly removed this specimen from the bison group and placed it with the musk oxen. Upon comparing the New Madrid specimen with Cuvier’s description of Ovibos moschatus, however, De Kay recognized important differences in the character of the dorsal surface of the frontals (although De Kay allowed that his specimen, with its conspicuously roughened surface, could have been damaged or have lost the entire dorsal surface), the depth of the occipital surface (being greater in his specimen than in Ovibos ), and “the most remarkable differ¬ ence” (De Kay, 1828:287)—the position of the horns. The bases of the horn cores suggested to De Kay (1828:287,289) that the longest axis of the horns has been in the same direction with the bones of the face ... or to speak more definitely, the axis of the longest diameter of the horns, is parallel with the bones of the palate. These observed and inferred differences between the New Madrid specimen and existing descriptions of Ovibos mos¬ chatus led De Kay to consider affinities with fossil specimens from Siberia originally described by Pallas (1773) and Ozeretskovsky (1811), as reported by Cuvier in an unidentified edition of his Recherches. De Kay found sufficient support in Cuvier’s comments about the Siberian specimens to erect a new species, Bos pallasii, to accommodate “the fossil crania of Pallas and Ozeretskovsky, and provisionally, the specimen from the banks of the Mississippi” (De Kay, 1828:291; our emphasis). The Siberian specimens of Pallas, however, earlier had been named Ovibos pallantis by Smith (1827), making Bos pallasii a junior synonym of the former. The New Madrid specimen was later referred to Bootherium cavifrons by Leidy SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 5 cm FIGURE 1.—Holotype of Bos bombifrons Harlan, 1825 (ANSP 994), in dorsal view. 5 cm FIGURE 2.—Holotype of Bos bombifrons Harlan, 1825 (ANSP 994), in right lateral view. NUMBER 66 5 FIGURE 3.—Holotype of Bos bombifrons Harlan, 1825 (ANSP 994), in ventral view. FIGURE 4.—Holotype of Bos bombifrons Harlan, 1825 (ANSP 994), in caudal view. 6 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY (1852b), and, although this specimen has been lost or destroyed, Leidy’s decision seems to have been correct. De Kay’s contribution to the nomenclatural history of the Pleistocene musk oxen of North America was that he was the first to recognize the occurrence of a fossil musk ox in North America, and he correctly identified the major morphological differences between Ovibos and what would become Booth- erium (in part, then Symbos). Leidy reviewed the extinct North American oxen in 1852. At that time, the only known specimen of Bos bombifrons was the holotype from Big Bone Lick, while at least 12 crania of the kind described by De Kay were known (Leidy, 1852b). In May 1852, Leidy (1852a:71) noted that both forms of musk oxen possessed large larmiers or lachrymal depressions, as in the deer, and if these are possessed by the Ovibos moschatus, the two fossils would belong to the same genus as Ovibos bombifrons and O. cavifrons; but if they are not possessed by Ovibos, as is stated to be the case by Desmarest, the two latter species would form a new genus, for which the name Bootherium is proposed. The genus Bootherium, containing two species (B. bom¬ bifrons and B. cavifrons ), was erected in the formal review (Leidy, 1852b: 12) on the basis of three diagnostic characteris¬ tics: 1. The os frontis rises into a hump, or forms a prominent process, from the sides of which arise the hom-cores. 2. The latter arise above and posterior to the orbits, but considerably in advance of the inion, and curve downwards in their course, but do not turn up at the tips, as in Ovibos. 3. The species possess lachrymal depressions, or larmiers, as well developed as in cervine animals. The holotype for B. cavifrons (ANSP 12995; Figures 5-8) is a relatively well-preserved cranium lacking only the distal tip of the left horn core. This cranium was secured by Thomas Kite of Cincinnati, Ohio, “in the hut of an Indian, in which it was used as a seat and he was informed it was found in a neighboring gravelly bluff, near Fort Gibson, on the Arkansas River” (Leidy, 1852b: 13) in what was then Indian Territory (now Oklahoma). Leidy’s descriptions of this specimen and the B. bombifrons holotype are extensive and detailed, but he did not indicate explicitly those criteria considered to be specifi¬ cally diagnostic. In the description of B. bombifrons, Leidy stated that the base of the cranium “is sufficiently well preserved to exhibit the peculiarities which associate it in the same genus with Bootherium cavifrons” (Leidy, 1852b: 18), but he did not identify those unifying characteristics. More¬ over, he did not mention one of the most conspicuous shared characters—the outward, downward, and forward curvature of the horn cores, clearly evident in both type specimens. (Leidy also did not comment on a small circular scar on the holotype of B. cavifrons located on the dorsal surface of the right frontal, above the orbit, resulting from a pathologic condition. This injury healed before the death of the individual, and resculpting restored the bone surface to near-normal configuration. This condition is apparent in fig. 1, pi. Ill of Leidy, 1852b, and in our Figure 5.) Leidy’s review was important in that it transferred Harlan’s Bos bombifrons from the bison group to the musk ox group and placed both forms of fossil musk oxen in the same genus. However, Leidy did not establish the distinctiveness and integrity of Bootherium with the three diagnostic criteria he proposed. His first criterion actually consisted of two charac¬ ters—either a hump or a prominent process of the frontal region—and he did not establish any reason why these two expressions should be shared within the same genus, or that each was species specific (although this is implied by his descriptions of the two specimens). The second and third criteria are characteristics of all low-horned musk oxen and, therefore, are not generically diagnostic. Certainly, the inade¬ quacy of Leidy’s generic diagnoses can be attributed to the fact that he had very little information about the structure of the skull of Ovibos moschatus, and that some of what had been published elsewhere was erroneous. Subsequent information about the morphology of Ovibos proved that the genus did have lacrimal depressions and its horn cores did not turn upward at the tips. In 1854, Leidy repeated his belief that the presence of lacrimal depressions in Bootherium separated that genus from Ovibos, and that B. cavifrons was further separated from 0. moschatus by differing frontal characteristics—the presence of a deep fissure separating the bases of the horn cores in the latter whereas the horn core bases joined together and covered the entire length and breadth of the frontals in the former (Leidy, 1854). A new species, Ovibos maximus, was named by Richardson in 1852 on a damaged fossil axis (HM 90/2; Figure 9) found at Eschscholtz Bay, Alaska. Richardson compared the fossilized axis with that of a young male Ovibos moschatus and concluded that the two bones, being of different sizes, represented different species. Without stating reasons, Richard¬ son considered that the fossilized axis might belong to the same taxon that Leidy had called Bootherium cavifrons and thus proposed the synonymy of 0. maximus and B. cavifrons (Richardson, 1852). Leidy quickly and effectively refuted Richardson’s decision, and explicitly stated his opinion that there were no reasonable grounds for considering Ovibos and Bootherium to be synonymous (Leidy, 1854). Riitimeyer (1865) and Dawkins (1867) referred Leidy’s genus Bootherium to Ovibos on the grounds that Ovibos, like Bootherium, possessed lacrimal depressions. Riitimeyer (1865) further considered B. cavifrons and B. bombifrons to be actually male and female of the same taxon, and created a new species, O. priscus, to accommodate the pair. Leidy acknowl¬ edged that Bootherium might possibly belong within Ovibos, but he did not concur that the two forms were conspecific (Leidy, 1869). In 1872, Dawkins concluded that Leidy’s B. cavifrons and B. bombifrons were conspecific and gave them the new combination Ovibos cavifrons (a name proposed earlier by Leidy), despite the fact that bombifrons was the senior specific epithet (Dawkins, 1872). The idea that the two forms were conspecific received mixed reception, some authors—including Lydekker (1885, 1898)—agreeing with NUMBER 66 7 FIGURE 5.—Holoiype of Bootherium cavifrons Leidy, 1852 (ANSP 12995), in dorsal view. FIGURE 6.—Holotype of Bootherium cavifrons Leidy, 1852 (ANSP 12995), in left lateral view. 8 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY FIGURE 7.—Holoiype of Bootherium cavifrons Leidy, 1852 (ANSP 12995), in ventral view. FIGURE 8.—Holoiype of Bootherium cavifrons Leidy, 1852 (ANSP 12995), in caudal view. NUMBER 66 9 FIGURE 9.—Holotype of Ovibos maximus Richardson, 1852 GEM 90/2), in A, ventral, B, caudal, and c, right lateral views. Riitimeyer and Dawkins, and others not (e.g., Rhoads, 1895; Osgood, 1905a; Allen, 1913). Riitimeyer (1865), however, had raised a major question about the relationship between B. cavifrons and B. bombifrons and, whether other authors agreed with him or not, none offered systematic arguments against either his or Dawkins’ (1872) positions. Rhoads identified another species of musk ox from a small cranial fragment found in a cave in Durham County, Pennsylvania (ANSP 29; Figures 10, 11). The specimen was considered initially to be part of the left horn core and adjacent frontal of a new species of bison to which Rhoads gave the name Bison appalachicolus (Rhoads, 1895). Reexamination of 10 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY FIGURE 10.—Hololype of Bison appalachicolus Rhoads, 1895 (ANSP 29), in A, ventral, and B, rostral views. FIGURE 11.—Holotype of Bison appalachicolus Rhoads, 1895 (ANSP 29), in A, dorsal, and B, caudal views. the specimen led Rhoads to conclude that it belonged to a musk ox, not bison, so he changed the name to Ovibos (Boolherium?) appalachicolus (Rhoads, 1897). Osgood (1905a) reversed the trend toward synonymyzing Bootherium/Ovibos bombifrons and Bootherium/Ovibos cavi- frons when he created Scaphoceros to accommodate a nearly complete skull (USNM 2555; Figures 12-15) from the Yukon Territory that he described as Scaphoceros tyrrelli. Osgood transferred Bootherium cavifrons to Scaphoceros as S. cavi- frons. Osgood rejected Rutimeyer’s Ovibospriscus as spurious and reinstated B. bombifrons, leaving it in a genus separate from Scaphoceros. (Following publication, Scaphoceros was found to be preoccupied and was replaced by Symbos; Osgood, 1905b). Osgood (1905a: 181-183) justified and elaborated upon his decisions on the following grounds: Since bombifrons and cavifrons have been considered by several authors as being not only congeneric but conspecific, the establishment of a separate genus for each may appear surprising. While it may be possible, from examination of Figures only, to construct a hypothesis to the effect that cavifrons represents the male and bombifrons the female of one species, it is inconceivable that any modem taxonomist would reach such a conclusion after comparing the original types. These are now before me and with them are specimens of S. tyrrelli and of both sexes and young of Ovibos moschatus. From comparisons of these it is evident that, unless the disparity between the sexes in this case was vastly greater than in the recent genus Ovibos, cavifrons and bombifrons do not respectively represent the male and female of one species. Neither is bombifrons the young of any species, for the type gives every evidence of maturity. The hom cores of the female Ovibos are essentially of the same character as those of the male. They are excessively flattened and directed downward close to the skull just as those of the male. Their bases approach each other over the top of the frontals increasing with age as in the male, the space between them being merely relatively greater than in the male. They are attached to the frontals only it is true,but this is the case with the immature male. Therefore the skull of the female has all the essential characters of the male but they are not as highly developed. The skull of Bootherium bombifrons , on the contrary, differs not in degree but in actuality from that of Scaphoceros cavifrons and S. tyrrelli. The hom cores are not flattened but are actually round or as nearly round as may be in a rough surfaced structure; they are directed away from the skull at a different angle; their attachment to the skull is entirely different; their bases do not approach each other in the least but on the contrary stand out from the skull on pedicels and have a distinct burr as in Bison. The frontal region between the hom pedicels is not flattened as in the female Ovibos, but is elevated and convex. The under side of the skull of the type of bombifrons is much injured but one conspicuous character is shown in which it differs from all the other species. This is found in the basisphenoid which is not deflected but has its lower surface in the same horizontal plane as that of the basioccipilal and it has a sharp median ridge. The hom cores of bombifrons are essentially like those of Bison except that they turn downward instead of upward. However, other characters, notably the possession of deep lacrymal fossae, serve to distinguish it from Bison. In consideration of these various characters, the genus Bootherium with Bos bombifrons as the type seems to merit recognition. Thus far, only one specimen of this genus, the original type, has been found. Specimens of S. cavifrons and S tyrrelli, however, have been secured at various localities among which are the following: Fort Gibson, Indian Territory; Council Bluffs, Iowa; New Madrid, Mo.; St Louis, Mo.; Benton Co., Mo.; Trumbull Co., Ohio; Brook Co., W. Va.; Pennsylvania; Anvik, Alaska, and Bonanza Creek, near Dawson, Yukon Territory. In this large number of specimens, if there were any females at all it is probable that there would be more than one. In order to give any semblance of certainty to the supposition that the differences between bombifrons and cavifrons are sexual, it is necessary to show that these differences are relatively the same that obtain NUMBER 66 Figure 12.—Holotype of Scaphoceros lyrrelli Osgood, 1905 (USNM 2555), in dorsal FIGURE 13.—Holotype of Scaphoceros lyrrelli Osgood, 1905 (USNM 2555), in right lateral view FIGURE 14.—Holotype of Scaphoceros tyrrelli Osgood, 1905 (USNM 2555), in ventral view FIGURE 15.—Holotype of Scaphoceros tyrrelli Osgood, 1905 (USNM 2555), in caudal view NUMBER 66 13 between the sexes in living species. This cannot be done, therefore it seems safer to treat the two animals as distinct. A much more reasonable assumption would be that S. cavifrons represents the male and S. tyrrelli the female of one species. The present objection to this is the fact that both have not been found in the same region. From the foregoing excerpt, it can be seen that Osgood (1905a,b) considered the following facts important in separat¬ ing Symbos and Bootherium: 1. The dimorphism between skulls of Bootherium and Symbos (Osgood’s Scaphoceros ) was greater than that between skulls of female and male Ovibos moschatus. (No number of specimens available was given, nor were quantitative compari¬ sons of the dimorphism made.) 2. The shape of horn cores and the manner of their attachment to and development over the frontals differed qualitatively between Bootherium and Symbos. 3. The frontal region in B. bombifrons was elevated and convex, whereas that of Symbos “between bases of horn cores (was) surmounted by a prominent exostosis with an anterior bounding rim and a deep median excavation” (Osgood, 1905a: 174). 4. The basisphenoid of B. bombifrons was not deflected from the basioccipital, and it contained a sharp median ridge on the ventral surface, whereas the basisphenoid in Symbos was deflected conspicuously and did not exhibit a sharp median ridge. 5. The sex ratio of skulls recovered (Osgood implied) should closely approximate the sex ratio of living wild populations. (No allowance was made for differential preserva¬ tion or recovery of male and female skulls.) Although Osgood had few specimens with which to work, including only a single specimen of the form he returned to Bootherium bombifrons, his ideas nonetheless have had great influence upon the study of Pleistocene musk oxen during the 20th century. A new genus and species of musk ox was erected in 1906 by Gidley upon a partial cranium (USNM 5100; Figures 16-18) found during the construction of an irrigation dam near Black Rocks, McKinley County, New Mexico. Gidley (1906:165) acknowledged that “its incompleteness and poor condition make it a rather unsatisfactory type, yet there are sufficient distinctive characters preserved to warrant its description” which he gives as follows (Gidley, 1906:165-167): LIOPS, new genius, [sic] Generic characters. —Hom cores set wide apart and well back, as in Ovibos, but much less drooping; continuous with the frontals laterally, with no burrs or rugosities at base; smooth throughout. Parietals forming a large part of the occiput, which is high and narrow above. No true lambdoidal crest. Foramen magnum about one and one-half times greater in diameter than in Ovibos. Occipital condyles set widely apart, with their borders continuous with the surrounding bones. Tympanic bone roughly triangular in shape, very smooth and flat, with no bulla, and tightly inclosed by the surrounding elements. Post-glenoid process reduced to a low rounded knob. LIOPS ZUNIENSIS, new species. Type, top and back portion of skull. Cat. No. 5100, U.S.N.M. collection. A striking feature of the portion of the skull preserved is its extreme smoothness. Its angles are free from rugosities, and there are no sharp or roughened processes even in the tympanic and mastoid region. The hom cores are relatively longer, less robust, and less drooping than in Ovibos or Sunbos [sic], the latter standing directly intermediate between Liops and Ovibos in this respect. Another striking feature is the position of the relatively large foramen magnum, which is confined entirely to the back or occipital face of the skull. Gidley named the new genus Liops, with Liops zuniensis as the type species. Liops was twice preoccupied and, apparently, Gidley tried to change the generic name to Lissops in 1908. By that time, however, Cossmann had suggested replacing Liops with the valid name Gidleya which remains in current use (Cossmann, 1907; Gidley, 1908). Gidley named two other extinct musk oxen in 1908 when he founded Ovibos yukonensis upon a partial skull (USNM 5728) from the Palisades along the Yukon River in Alaska and Bootherium sargenti upon a partial cranium (dorsal surface, part of left nasal, most of left horn core, and all of right horn core: GRPM 11-423-3101; Figures 19-21) from Moorland Swamp near Grand Rapids, Michigan. The Alaska specimen was correctly assigned to Ovibos and will not be considered further in this paper. Of Bootherium sargenti, Gidley (1908:683-684) said: Species-characters. —Size about two-thirds that of Ovibos moschatus, somewhat larger than B. bombifrons-, horn-cores comparatively large, well rounded, long and slender, horn-cores at base horizontally directed at right angles to the skull as in Plate LEX, fig. a, but curving downward and forward in graceful semi-spirals, ending in slender anteriorly directed tips (see Plate LIX, fig. b); orbits comparatively large, depressed below the arching frontals, with thin gently shelving borders,not tubular as in Ovibos. In the general form and contour of the skull and horn-cores this species, together with B. bombifrons, is strikingly different from other known species of the Ovibovenae [sic]. The type of B. sargenti, compared with that of B. bombifrons, shows the following resemblances: (1) The fragment preserved indicates a skull but little larger in size and of the same general proportions; (2) the position, form, and contour of the orbits as well as (3) the general appearance of the facial and posterior portions of the cranium (see Plate LIX, fig. c) are essentially alike. The horn-cores are also similarly placed, but the differences in their relative size, form and proportions are very marked. In B. sargenti the base of the horn-core is relatively heavier, is angular in front, and its superior border approaches much nearer the median frontal suture than in B. bombifrons. In addition, characteristic rugosities and markings on the frontals indicate that the horn-covering extended much beyond the horn-core base, nearly or quite meeting the one from the opposite side in the median line. In B. bombifrons the inter-hom space was apparently covered by a wide skin-band as in Bos. The hom characters seem sufficiently different to separate these species genetically, but the other cranial characters denote generic relationship. Moreover it is possible that the extreme difference in type of hom-core may be due in part at least to difference in sex. NOTES ON THE RELATIONSHIPS OF THE GENUS BOOTHERIUM LEIDY. The genus Bootherium has for some time been considered as closely allied to Ovibos, and by some authorities as synonymous with that genus. But in 1905 Mr. W. H. Osgood re-defined Bootherium, selecting B. bombifrons as the type, and transferred the remaining species, B. cavifrons, to a new genus, Scaphoceros, of which S. tyrrelli is the type. In the publication first cited Mr. Osgood has shown with good reason the untenability of the opinion held by Rutimeyer and others regarding the types of B. bombifrons and Ovibos (, Symbos ) cavifrons, which they considered the female and male, respectively, of the same, or closely related, species. He has also pointed out that the type of B. bombifrons does not represent an immature male, but a fully adult 14 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY FIGURE 16.—Holotype of Liops zuniensis Gulley, 1906 (USNM 5100), in dorsal view. individual. By an analogy similar to that employed by Osgood it is equally clear that the type of B. sargenli can not be referred on these grounds to any species of Ovibos or Symbos. The validity of the genus Bootherium therefore seems to be well established. The separation of the two species originally referred to this genus permits the study of its relationships in a new light. As now known the genus presents quite as many bovine as ovibovine characters, and if referable to the Ovibovinae it is far removed from the other known genera of the group. From present evidence it seems probable that the finding of more complete material will show that, whether, genetically distinct from each other or not, the species B. bombifrons and B. sargenti represent a distinct group, or subfamily, of the Bovidae. To this group may belong also the genus Lissops Gidley. Since, however, so little is known of the species of the group as a whole, owing to the lack of good material, it would be unwarrantable to separate them at present from the Ovibovinae. A new species, Symbos australis, was erected upon three teeth (RM2, Lm2, Lm3: AMNH 11828; Figure 22) collected by Barnum Brown in 1904 at Conard Fissure, Newton County, Arkansas (Brown, 1908). Other ovibovine remains collected at the fissure and referred to S. australis included three premolars, an atlas, one or two proximal phalanges, and an ungual phalanx. (Brown reported one proximal phalanx on p. 203, but referred to two on p. 204. We arc aware of only one such element among the ovibovine material from Conard Fissure described by Brown.) Brown determined that the three molars were too large to belong to Ovibos, and sent the RM2 and the atlas to Osgood for comparison with the type specimens of B. bombifrons, S. cavifrons, and 5. tyrrelli. Osgood concluded (Brown, 1908:203): They evidently belong to a species different from the one on which I am working, Symbos ( Scaphoceros ) tyrelli (sic). The tooth is somewhat smaller in my specimen, although the difference in condition makes it difficult to get an exact comparison. The atlas is much too small to fit on the condyle of my specimen or on that of the type of Ovibos cavifrons Leidy, with which I compared it in Philadelphia. The type of O. bombifrons is also in Philadelphia, but is very different from any of the other specimens and hardly needs to be considered. Allen revised the North American musk oxen in 1913. Although his treatment of the fossil taxa was relatively superficial, he followed Osgood (1905a) in considering Bootherium and Symbos to be valid separate genera (Allen, 1913:209), which, in the light of present knowledge, prove to be not only not congeneric, but not very closely allied. This interesting discovery is due to Osgood, whose paper on the status and relationships of Bootherium is entitled to high praise. Allen (1913:210) considered that the following character FIGURE 19. —Holotype of Bootheriu/n sargenli Giilley, 1908 (GRPM 11-423-3101), in dorsal view. FIGURE 20. —Holotype of Boolherium sargenli Gidlcy, 1908 (GRPM 11-423-3101), in right lateral view. differences satisfactorily separated Boolherium and Symbos: 1. Boolherium had Bison-\\ke (round or sub-rounded) horns, whereas the horns of Symbos, unlike those of Bison, were flattened. 2. Boolherium had a smooth and sharply convex dorsal frontal surface, whereas the same surface in Symbos was an elongated trough covered with exostosis. 3. The ventral surface of the basisphenoid was continuous with that of the basioccipital in Boolherium, and it supported a high ridge, whereas in Symbos the ventral surface of the basisphenoid was deflected from that of the basioccipital. 4. Boolherium had small but deep and sharply defined lacrimal fossae, whereas those of Symbos were shallow and less well defined. 5. Boolherium was much smaller than Symbos, based on the assumption that the holotype of Boolherium bombifrons was the skull “of a very old male, with all the sutures of the preserved part of the skull wholly obliterated by anchylosis.” NUMBER 66 17 FIGURE 21. —Holotype of Boolherium sargenti Gidley, 1908 (GRPM 11-423-3101), in caudal view. Allen went on to say, however, that Boolherium did resemble Symbos in some characters, including those of the occipital condyles, the occipital plane, and the length and depth of the skull. Nonetheless, he concluded that Boolherium and the recently described shrub ox Prepioceras (Furlong, 1905) were “not closely related, but more nearly so than is either to any other known genus” (Allen, 1913:212), a decision that was based more upon the superficial impression of horn core similarity than a thorough systematic comparison of cranial structure in the two forms. Boolherium sargenti, however, was transferred from Boo¬ lherium to Symbos by Allen (1913:215). The species was founded on an imperfect skull . . . found in a swamp near Grand Rapids, Michigan. In the description comparison is strangely made with Boolherium bombifrons, with which it shares no essential feature. The homcores are attached to the skull as in the female of Ovibos, with about the same relative area of exostosis extending from the base over the lateral third or more of the fronlals and not, as in Boolherium, supported on a pedicel and terminating in a burr as in Bison. The relationship of Boolherium sargenti is entirely with Symbos, and well fulfills the conditions that would be expected in the female of S. cavifrons. Allen did not specify what conditions would be expected in the female of Symbos, nor did he consider the possibility, when discussing S. tyrrelli, that this form could be the female of S. cavifrons. Allen did, however, refer S. australis to S. cavifrons “as probably representing the female of that species” (Allen, 1913:215). Allen upheld the distinctiveness of Gidleya (which he discussed under Hops). His description of the specimen (Allen, 1913:216) reads, in part, as follows: The dense smooth natural surface of the bone is preserved over the greater part of the dorsal aspect of the skull, except laterally in the postorbital region; the surface elsewhere consists of the cancellous structure of abraded bone, the abrasions being in places quite superficial, as in the case of the homcores and upper surface of the skull, and elsewhere so deep as to greatly obscure or wholly obliterate important features, as the condyles, the characters of the mastoid and tympanic regions, and the occipital angles. The unabraded dorsal surface of the skull shows that it must have been that of an old animal, and probably that of a male, the sutures being entirely obliterated by anchylosis. Continuing, Allen (1913:216) acknowledged that Hops was nearer Symbos than any other taxon, as Gidley (1906) had suggested. A sinking difference between Liops and both Symbos and Ovibos is the smoothness of the surface of the basal portion of the homcores and the entire absence of exostosis between the horn bases over the top of the skull, which is here smooth, with the same dense surface as that of the interorbital and preorbital portions. The ventral, caudal, and lateral surfaces of the skull, Allen stated, were greatly abraded. Hay (1915) erected Boolherium nivicolens on the basis of a partial cranium (USNM 23241; Figure 23) from Eschscholtz Bay, Alaska, that possessed character states he considered different from or midway between B. bombifrons and B. sargenti. Most important among these were the outward orientation of the horn cores and the way in which they had burrs situated on distinct pedicels, as in B. bombifrons. The specimen also had exostosis extending over the dorsal surface of the pedicel onto the lateral edges of the dorsal surface of the frontals, as in B. sargenti. Hay also rejected Allen’s syn- onymizing of B. sargenti and S. cavifrons, arguing that it was unlikely that, among the 25 or so skulls known and assigned to S. cavifrons, only one would have belonged to a female. More likely, Hay maintained, the smaller specimens with exostosis- covered frontals and more feebly developed horn cores that were assigned to Symbos probably represented females. Hay (1915:527) also pointed out that one of the characteristic features of Boolherium, as identified by Allen, was the abrupt downward slope of the dorsal outline of the skull posterior to the horn cores. The type skull of B sargenti has a slope of the same region which lacks but a few degrees of being equal to that found in Boolherium .... Elsewhere, Hay (1915:527) stated: Notwithstanding the immense development of the horn-cores of the males of Symbos cavifrons, there is no such elevation of the region behind the orbits as we see in the case of B. sargenti .... Four new species of Pleistocene musk oxen were named SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY FIGURE 22.—Type of Symbos australis Brown, 1908 (AMNH 11828): RM2 in A, lingual, B, occlusal, and C, labial views; Lm2 in D, labial, E, occlusal, and F, lingual views; and Lm3 in G,labial, H. occlusal, and I, lingual views. NUMBER 66 19 Figure 23.—Holotype of Bootherium nivicolens Hay, 1915 (USNM 2324), in dorsal view. A B C l£!T FIGURE 24.—Holotype of Symbos promplus Hay, 1920 (USNM 9120), in A, labial, B, occlusal, and C, lingual views. from 1920 to 1942. Symbos promplus was founded upon an upper left third molar (USNM 9120; Figure 24) from near Afton, Oklahoma, the diagnosis given as simply “Upper molars with the external styles less strongly developed than in S. cavifrons; the fossetts less angular” (Hay, 1920:125). Barbour (1934) named Symbos convexifrons upon a nearly complete skullcap and right horn core (UNSM 39001; Figures 25-28) found in the North Prong Quarry in southern Cherry County, Nebraska. “The brow of this specimen is notably convex, and this, coupled with the slope, length, and sweep of the horn cores, constitutes the main feature of this new species” (Barbour, 1934:295). ?Ovibos giganteus was created by Frick (1937) with a large right humerus (PAM 30498; Figure 29) from near Fairbanks, Alaska, as the holotype. Frick probably was stimulated to name this species after seeing what was (probably erroneously) then identified as the humerus of a -V SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY FIGURE 25.—Holotype of Symbos convexifrons Barbour, 1934 (UNSM 39001), in dorsal view. FIGURE 26.—Holotype of Symbos convexifrons Barbour, 1934 (UNSM 39001), in right lateral view NUMBER 66 21 FIGURE 27.—Holotype of Symbos convexifrons Barbour, 1934 (UNSM 39001), in ventral view. FIGURE 28.—Holotype of Symbos convexifrons Barbour, 1934 (UNSM 39001), in caudal view. giant ovibovine from near the American Falls Reservoir, Idaho (Frick, 1937). The last North American musk ox to be named was Bootherium brazosis, erected upon a damaged partial cranium with partial horn cores (TAMC 2553; Figures 30-32) that was found in Brazos County, Texas (Hesse, 1942). Hesse considered his specimen to resemble B. bombifrons more than any of the other nominal taxa, but it was differentiated from B. bombifrons by minor differences, some of which undoubtedly resulted from Hesse’s having misoriented the specimen during study. Hibbard and Hinds initiated a resurgence of attention to the relationship among Bootherium and Symbos species that has SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY FlGL'RE 29.—Holotype of ?Ovibos giganleus Frick, 1937 (AMNH F:AM 30498), in A, cranial and B, caudal views. NUMBER 66 23 FIGURE 30.— Holotype of Boothenum brazosis Hesse, 1942 (TAMC 2553), in dorsal view. Figure 31.—Hololype of Boothenum brazosis Hesse, 1942 (TAMC 2553), in ventral view. FIGURE 32.—Holotype of Boothenum brazosis Hesse, 1942 (TAMC 2553), in caudal view. 24 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY continued to the present. These authors stated “it is very likely that Bodtherium is the female woodland musk ox since all specimens of Symbos based on skulls are considered as those of bulls” (Hibbard and Hinds, 1960:107). Harington (1961) disagreed, instead favoring Hay’s (1915) separation of the two genera. Semken, Miller, and Stevens (1964) apparendy adopted Allen’s views, concluding that Boot her ium bombifrons was not a female Symbos but that B. sargenti, which was erroneously placed within Bootherium, might be. Ray evaluated the status of B. appalachicolus and B. brazosis and concluded that both were better considered junior synonyms of B. sargenti than separate species. Ray also acknowledged the merit of the suggestions that B. sargenti could represent the female of S. cavifrons, and stated that failure to allow for weathering damage had vitiated much comparison and unwarranted differentiation in the past (Ray, 1966a,b). By 1977, Harington had come to accept the synonymy of S. cavifrons and B. sargenti, but “presuming the specimen of Bodtherium bom¬ bifrons does not represent an abnormal individual, that species is probably not closely related to Bodtherium sargenti or Symbos cavifrons ” (Harington, 1977:880-881). Regarding the synonymy of B. sargenti and S. cavifrons, Harington (1977:882-883) wrote: .. .the evidence supporting this view is very strong. The similar basic conformation of the homcores (as far as orientation and curvature are concerned); the smaller, thinner-roofed cranium; and the broad space between the homcore bases in the former species parallel the differences between male and female Ovibos moschatus: thus Sargent’s muskox resembles what a female Symbos cavifrons would be expected to look like. In addition, Bodtherium sargenti and Symbos cavifrons had similar geographic and habitat preferences (e.g. Alaska, Yukon Territory, Indiana, Michigan, Virginia (using Bodtherium sp.), Utah, Missouri and Nebraska), and sometimes even from the same site and deposit (e.g. near Great Salt Lake, Utah, in the Bonneville sands and gravels (Stokes and Hansen 1937,p. 63), and evidently in the Goldstream Formation of Wisconsin age near Fairbanks, Alaska). In the conterminous United States, both species are concentrated within the same latitudinal range—usually south of the late Wisconsin fossil localities of the tundra muskox, Ovibos moschatus. Unlike Soergelia, Praeovibos, and Ovibos, which had Holarctic distributions during the Pleistocene, Bodtherium sargenti and Symbos cavifrons are only known from North America. Geochronologically, both species appear during the Dlinoian and become extinct near the close of the Wisconsin glaciation. In the preceding excerpt, Harington advocated the compari¬ son of patterns of both sexual dimorphism (without demanding exact duplication of character states between the sexes, as had earlier writers) and geographic and chronologic distribution in assessing the relationships between these two taxa. Nelson and Madsen (1978) and Nelson and Neas (1980) recognized Bootherium and Symbos as distinct genera, but acknowledged that the status of most nominal species within Bootherium was still uncertain. Following Harington, Kurten and Anderson (1980) placed B. sargenti in S. cavifrons while allowing B. bombifrons to stand, although with the admonition that “The status of the genus Bootherium is in doubt; it has often been considered to be congeneric with Symbos, but this is undemonstrated” (Kurten and Anderson, 1980:334). Nelson and Madsen (1987) concurred with Harington (1977) and Kurten and Anderson (1980) in synonymizing S. cavifrons and B. sargenti (as S. cavifrons ) while maintaining the validity of B. bombifrons as a distinct taxon. Neas has reversed his opinion held in 1980 that Bootherium and Symbos were distinct taxa and, with McDonald and Ray, views all nominal taxa within Bootherium, Symbos, and Gidleya as synonyms of Bootherium bombifrons (McDonald, 1986; Neas, 1986; McDonald and Ray, 1987, in press; Neas and Hoffmann, 1987; Neas and Parker, 1987). The Content of Bootherium, Symbos, and Gidleya Twelve nominal species of autochthonous North American musk oxen were erected between 1825 and 1942 within, or are referable to, the genera Bootherium, Symbos, and Gidleya. Bootherium, in the modern sense, at one time or another contained the five species B. (= Bos) bombifrons (1825), B. (= Bison) appalachicolus (1895), B. sargenti (1908), B. nivicolens (1915), and B. brazosis (1942). Ray placed B. appalachicolus and B. brazosis in synonymy with B. sargenti, and Harington did the same with B. nivicolens (Ray, 1966a,b; Harington, 1977). Allen (1913) attempted to place B. sargenti in synonymy with Symbos cavifrons, but this decision has met with mixed acceptance and the status of B. sargenti must, therefore, be reevaluated. Bootherium bombifrons was consid¬ ered conspecific with Symbos cavifrons by Riitimeyer (1865), Dawkins (1872), and their followers during the late part of the 19th century, but the two taxa have been considered generically distinct for most of their history. At present, most workers tend to recognize only a single species of Bootherium, B. bom¬ bifrons, while acknowledging that uncertainty in the taxonomic status of the group, and especially of B. sargenti, clearly exists. Symbos has contained six species during its 135-year history, including Symbos (= Bootherium) cavifrons (1852), 5. tyrrelli (1905), S. australis (1908), S. promptus (1921), 5. convexifrons (1934), and S. (= ?Ovibos) giganteus (1937). Allen (1913) placed S. australis in synonymy with S. cavifrons, and Jakway (1961b) did the same for S. convexifrons. Among the remaining four species, only S. cavifrons is in use. Gidleya has contained only a single species, G. (= Liops, Lissops) zuniensis (1906). Although this taxon has been recognized by several paleontologists since it was established, it has never received validation as a viable taxon. The relationship of Ovibos maximus is uncertain; this taxon probably is properly placed within Ovibos, although conclusive determination of that fact must await further comparative study of the axes of the various ovibovine genera. At present, then, there are seven nominal species standing within the three genera, five of the 12 named species having been placed previously, without subsequent rejection, in synonymy (Appendix II). The standing species are B. bombifrons (Harlan, 1825); S. cavifrons (Leidy, 1852); S. tyrrelli Osgood, 1905; Gidleya zuniensis (Gidley, 1906); B. sargenti Gidley, 1908; S. promptus Hay, 1920; and S. (= ?Ovibos) giganteus (Frick, 1937). We are of the opinion that B. (= Bos) bombifrons, B. NUMBER 66 25 (= Bison) appalachicolus, B. sargenti, B. nivicolens, and B. brazosis are conspecific. Bootherium appalachicolus, B. bra- zosis, and B. nivicolens have been synonymized with B. sargenti by Ray (1966a,b) or Harington (1977). Bootherium bombifrons and B. sargenti may be considered conspecific on the basis of morphological similarity of their cranial and horn core structure, especially (1) horn core size, shape, orientation, and cranial attachment, and (2) frontal configuration (Figures 1-3,19-21). Aside from modest differences in the exact shape and size of character states—all of which can be attributed more satisfactorily to individual variation than to taxonomic distinctiveness—there are no significant morphological fea¬ tures present on the holotypes of these taxa sufficient to justify their taxonomic separation. Despite numerous statements and implications to the contrary, the differences in the size, shape, surface details, and orientation of character states between B. sargenti and S. cavifrons are much greater, qualitatively and quantitatively, than are those between B. bombifrons and B. sargenti. Detailed comparisons of character state differences, and discussions of the reasons for those differences among individuals and between sexes and taxa, are presented below (pp. 25-51). We also are of the opinion that all nominal species within Symbos (including ?Ovibos giganteus ) should be considered conspecific. Symbos convexifrons was established upon the dorsal half of a cranium and nearly complete right horn core (Figures 25-28). The dorsal surface of the right half of the braincase is preserved, whereas the frontoparietal sinuses are exposed on the left side (in ventral view). Several small fragments of bone have been reattached to the cranium with plaster. The diagnostic characters for S. convexifrons were the “notably convex” dorsal surface of the cranium, coupled with the slope, length, and sweep of the horn cores. Barbour (1934:295) also noted that “the horns rise from the side of the head.” Jakway (1961b), following Frick (1937:562), referred S. convexifrons to S. cavifrons on the grounds that (1) all other remains of Symbos from the North Prong Quarry and other sites in Nebraska were assignable to S. cavifrons, and (2) the “convexity between the horncores, the supranuchal, and the internal surface of the cranium” seemed to be pathological instead of taxonomically significant variations (Jakway, 1961b: 115). The holotype of S. convexifrons appears to represent a mature individual, based on the size of the specimen, the density of the horn core, and the absence of unfused sutures. This specimen is unusual, however, in several respects. (1) The horn core possesses a distinct burr line which delimits the horn core proper from the exostosis covering the intercornual surface of the cranium. (2) The base of the remaining horn core is situated abnormally low on the side of the cranium and the horn core emanates from the cranium at an unusually low angle but, based on differences in the planes of secondary bone medial to the bases of the horn cores, the left core was neither situated as low nor did it emanate at such an unusually low angle. (3) The longitudinal profile of the dorsal surface of the cranium is flexed to an unusual degree. (4) The transverse profile of the dorsal surface of the cranium is asymmetrical. (5) The exostosis is distributed rather thinly and uniformly across the intercornual region. The exostosis extends rostrally only a short distance from the level of the horn cores and caudally only a short distance onto the parietal surface. No rim-like or shelf-like build-up of secondary bone is present at either the caudal or rostral edges, respectively, of the exostosis. (6) The horn core attaches only to the frontal bone. We are of the opinion that the asymmetry of the transverse profile of the dorsal surface of the cranium in the holotype of S. convexifrons is probably attributable to a pathology of the right horn core. We were unable to locate any other natural asymmetries and consider the cranium—excluding the horn pathology and subsequent atypical development of the intercor¬ nual boss and associated exostosis—to be normally developed. Two fragments of the cranium—one including the insertion surface for the left M. semi spinalis capitis and the other a portion of the left frontoparietal bones—were reattached at the wrong location during restoration. These artificial errors probably contributed to Jakway’s recognition of asymmetries in the supranuchal ridge and internal surface of the cranium. Aside from the asymmetry of the dorsal surface of the cranium in transverse profile and the low level of emanation of the right horn core, the holotype of S. convexifrons strongly resembles a cranium with horn cores (USNM 23548) found in the Ohio River below Augusta, Bracken County, Kentucky. The Kentucky specimen has a similarly flexed (longitudinally) dorsal surface of the cranium and—over the caudal part of the dorsal surface—a similar pattern of exostosis development. Other crania identified as S. cavifrons (e.g., AMNH F:AM 33129 from Lower Goldstream, Fairbanks District, Alaska) also exhibit marked flexion of the longitudinal profile of the dorsal surface, as do specimens identified as Bootherium (e.g., ANSP 994 from Big Bone Lick, Kentucky; USNM 23264 from Saltville, Virginia). We believe that the holotype of S. convexifrons represents a pathologic adult male with abnormal placement and orientation of the right horn core and the development of the keratinous boss over the dorsal surface of the cranium. When the evidence of this pathologic condition is put aside, we see nothing to justify recognition of S. convexifrons as a valid taxon distinct from S. cavifrons. Allen’s (1913) referral of S. australis (founded upon three associated teeth, AMNH 11828; Figure 22) is reasonable, in part, but not conclusive. The RM2 and Lm2 are undifferen- tiable from the equivalent teeth in other specimens of S. cavifrons. The Lm3, however, differs somewhat from other m3s assigned to S. cavifrons. Specifically, the shape of the enamel border of the entoconulid-hypoconulid is conspicu¬ ously rounded (i.e., elliptical) in the holotype of S. australis (Figure 22). The same character in other m3s of Symbos is more complexly shaped, with an undulating lingual surface and a distinct terminal stylid at the caudal end. The unusual shape of the entoconulid-hypoconulid in the S. australis m3 could represent (1) an atypical tooth of Symbos, (2) a character state 26 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY typical of early Symbos that subsequently changed to the form found in late Wisconsinan Symbos, or (3) a tooth belonging to another large ovibovine, such as Euceratherium. (The teeth that constitute the type of 5. australis are within the size range of the teeth of Euceratherium. The breadth of the occipital condyles in the holotype of Euceratherium collinum is 103 mm, and the breadth of the cranial articular cavities in the atlas from Conard Fissure is 107 mm.) Dental variation within the ovibovines, and especially shrub oxen, is not known sufficiently well to conclusively determine the identity of the teeth of the S. australis type specimen. The possibility exists that the three teeth forming the type of S. australis might represent more than one animal and, perhaps, more than one taxon. We feel that S. australis should be left in synonymy with S. cavifrons for now, but we also recognize that some or all of these teeth might, at some later date, be assignable to one or more other taxon/taxa. Symbos tyrrelli was erected upon a nearly complete but unusually small skull (USNM 2555, the smallest skull for which quantitative information was available in 1905; Figures 12-15) from Bonanza Creek, Yukon Territory, at a time that few Symbos crania were known (Osgood, 1905a). Osgood used three character states to differentiate the Bonanza Creek specimen from S. cavifrons: the relatively small size, restricted development of exostosis, and shallow depth of the frontoparietal region. The holotype does not, however, possess any character of taxonomic significance that would set it apart, qualitatively or quantitatively, from S. cavifrons as that species is now conceived, based upon more than 150 known specimens. Specifically, the size of the skull and its various characters, the degree of exostosis development, and the depth of the frontoparietal sinus region of the Bonanza Creek specimen are all within the range of variation known for S. cavifrons. We feel that S. tyrrelli is conspecific with S. cavifrons. Symbos prompt us was founded upon an upper left third molar (USNM 9120; Figure 24) from near Afton, Oklahoma (Hay, 1920). This tooth is well worn; about one-third of the crown remains. The two criteria upon which the species was founded were the less extensive lateral development of the buccal styles and the more crescentic, less angular shape of the enamel border of the internal fossettes, relative to other known teeth of Symbos. Apparently, Hay compared the tooth from Afton only with two other specimens—the upper right second molar in the S. australis type tooth series and the superior molars in a Symbos cavifrons skull from near Manchester, Michigan (Hay, 1920). The tooth from Afton was worn more than either of the teeth with which it was compared. As wear progresses in the superior molars of Symbos cavifrons, the lateral extension of the buccal styles is reduced and the shape of the enamel border of the fossettes changes from a more angular or chevron shape to a more rounded or crescentic shape. The tooth from Afton is within the size range of the teeth of Symbos cavifrons (the size of the M3 of Bootherium is still unknown), and appears to be nothing more than a relatively well worn tooth assignable to that taxon. We feel that S. promptus is properly a junior synonym of S. cavifrons. Frick erected ?Ovibos giganteus upon a right humerus (AMNH F:AM 30498; Figure 29) from an unidentified site in the Fairbanks District, Alaska (Frick, 1937). Frick gave no reason for considering the holotype to be other than Symbos or Bootherium, nor were any diagnostic criteria given in the type description. Some of the incentive for establishing this species probably came from the discovery by J.W. Gidley, in 1929 and 1930, of what were considered to be remains of a giant ovibovine from southern Idaho. Two crania of Symbos cavifrons possessing unusually large horn cores were found in a gravel quarry near the American Falls Reservoir, and these might have inspired some notion of gigantic ovibovines from that area. In addition, a robust radioulna and an unusually long humerus from southern Idaho were also identified as ovibo¬ vines. The humerus was shown to Frick by Gidley, and might have been the specific stimulus that led Frick to recognize an extinct taxon of giant musk ox from Alaska. Actually, the radioulna (figure 26 in Gidley, 1930) was probably Bison latifrons and the humerus was probably Camelops sp. In the collection of fossils from southern Idaho in the National Museum of Natural History (USNM), there are no ovibovine limb bones, but there is a large Bison radioulna (USNM 13710) that can be identified as the one in Gidley’s figure 26 and a Camelops humerus (USNM 392114) of similar size to that mentioned by Frick from Idaho (length estimated by Frick: 470 mm; length of USNM 392114, whose proximal end is abraded slightly: 458 mm). The humerus from near Fairbanks is ovibovine, it is similar in size and morphology to the humerus of an associated partial skeleton (F:AM A-204-4254) of Symbos cavifrons from Little Eldorado Creek, Alaska, and we refer it to that species. Gidleya zuniensis was founded upon an extensively abraded cranium and carries only a single specimen, its holotype (USNM 5100; Figures 16-18). The seven standing species of musk oxen within the genera Bootherium, Symbos, and Gidleya have been reduced to three species in three monolypic genera: Bootherium bombifrons, Symbos cavifrons, and Gidleya zuniensis. In the next two sections of this paper, we evaluate the relationships between the genera (1) Gidleya and Symbos and (2) Bootherium and Symbos, respectively. The Relationship between Gidleya and Symbos The genus Gidleya (= Liops, Lissops, sensu Gidley, 1906, 1908) was founded upon a partial skull (USNM 5100; Figures 16-18) found in 1905 during the construction of an irrigation dam on the Zuni Indian Reservation at Black Rocks, McKinley County, in western New Mexico. This specimen, along with a small collection of other vertebrate fossils (including Mam- muthus columbi, Equus sp. indet., and camel) was salvaged by the site engineer John B. Harper and transferred to the Smithsonian Institution through the efforts of F.E. Leupp, Commissioner of Indian Affairs. NUMBER 66 27 The musk ox specimen from Black Rocks had been damaged extensively by abrasion. Most of the occipital surface is missing, both of the horn cores have been shortened and reduced in diameter by the loss of surface bone, the dorsal surface of the cranium has been abraded to the extent that several of the parietal and frontal sinus cells are exposed. The remainder of the specimen has had most surface detail completely removed or extensively rounded by abrasion. Most of the dense outer bone appears to have been removed prior to the time this specimen was unearthed, leaving cancellous bone exposed over much of the surface. The cells of the cancellous bone apparently filled with a fine grained chemical precipitate during or prior to the last phase of abrasion, giving the specimen an unnaturally smooth surface. Other parts of the remaining surface are not smooth, probably because of damage incurred during the excavation, drying, and handling of the specimen. (The smooth surface bone easily separates from the deeper bone at a nearly uniform depth.) The poor condition of the specimen was acknowledged by Gidley in his type description of the genus (as Liops ) and its sole species G. (= Liops) zuniensis (Gidley, 1906). The characters that Gidley considered to be taxonomically signifi¬ cant were all products of post-mortem alteration—the “extreme smoothness” of the skull, its angles “free from rugosities,” and absence of “sharp or roughened processes even in the tympanic and mastoid region,” horns “relatively longer, less robust and less drooping” than in Ovibos or Symbos, and “the relatively large foramen magnum, which is centered entirely to the back or occipital face of the skull” (Gidley, 1906:166-167). With uncharacteristic oversight, Allen apparently regarded the abraded dorsal surface as being natural, writing “The dense smooth natural surface of the bones is preserved over the greater part of the dorsal aspect of the skull, except laterally in the postorbital region” (Allen, 1913:216). Allen correctly pointed out that Gidley had failed to recognize the extent to which the caudal, lateral, and ventral surfaces of the skull had been damaged, and that as a result Gidley had introduced errors into his generic diagnosis. Allen also noted that, while the Black Rocks specimen was about one-half the size of Symbos (Allen personally had examined only one Symbos specimen, AMNH 14365 from Hebron, Porter County, Indiana), its proportions were similar to those of Symbos (Allen, 1913). Patterson commented further upon the insecure foundation of Gidleya in some unpublished notes that he prepared after he received a cranium of Symbos cavifrons from near Grand Mesa, Delta County, Colorado (McDonald, 1985a), that was abraded somewhat like the type specimen of Gidleya zuniensis: On comparing this (i.e., the Colorado) fragment with specimens of Ovibos and with published figures and descriptions of the various Pleistocene forms I was struck by its resemblance to Gidley’s '‘Liops 1 ’ zuniensis (Gidleya zuniensis Cossman [sic], 1907). The type of this species was found near Zuni, New Mexico and was also uncovered, curiously enough, during excavations for a dam. Dr. C. Lewis Gazin kindly arranged for a loan of the specimen, U. S. N. M. no. 5100. Careful comparison of the two specimens permits no doubt that they are congeneric and little doubt, despite the somewhat larger size of the Colorado specimen, that they are conspecific. The type is about as waterwom as is possible for a fossil to be and yet retain some character, so scoured is it that some portions could almost be described as polished. It is quite evident that Gidley completely underestimated the extent of the abrasion and was therefore badly led astray. I quote his diagnosis here, placing brackets around those “characters” that are certainly artificial. Horn cores set wide apart and well back, as in Ovibos, but much less drooping, [continuous with the frontals laterally, with no burrs or rugosities at base; smooth throughout.] Parietals forming a large part of the occiput, which is high and narrow above. [No true lambdoidal crest.] Foramen magnum [about one and one half times] greater in diameter than in Ovibos. [Occipital condyles set widely apart, with their borders continuous with the surrounding bones.] Tympanic bone roughly triangular in shape [very smooth and flat with no bulla and tightly inclosed by the surrounding elements. Post-glenoid process reduced to a low rounded knob]. None of the characters that remains after this elimination distinguishes Gidleya from Symbos (Osgood 1905A and B) (Notes attached to letter: B. Patterson to C. E. Ray, 4 November 1968). Gidley originally described this taxon under the name Liops (Gidley, 1906), but that name was preoccupied so Cossmann (1907) suggested replacing it with Gidleya. Gidley, perhaps realizing Liops was unavailable and not knowing of Coss- mann’s replacement, inserted—without explanation or refer¬ ence to a specific specimen—the name Lissops in a subsequent manuscript when he alluded to the genus based on the Black Rocks specimen (Gidley, 1908). Allen (1913) and Troxell (1915) retained use of Liops, but most subsequent authors have referred to the genus as Gidleya (e.g.. Hay, 1922, 1924; Ryziewicz, 1933, 1955; Kretzoi, 1942; Harington, 1961; Romer, 1966). Frick’s placement of Gidleya zuniensis in Ovibos, as O. zuniensis, was done without explanation and has had no following (Frick, 1937). Although, based upon usage of the name, Gidleya has been considered a viable genus, the literature gives no indication that any specimen other than the holotype of G. zuniensis has ever been placed in the genus. If allowance is made for the extensive loss of bone by battering and fine abrasion, the cranium upon which Gidleya was founded is undifferentiable from crania that would routinely be assigned to S. cavifrons. As Allen (1913) suggested and Patterson (n.d.) stated emphatically, the propor¬ tions and configuration of the vestigial characters are like those in Symbos cavifrons. The Black Rocks specimen is smaller than average (a condition exaggerated by its abraded condition), but it is still clearly within the range of variation for cranial characters of S. cavifrons. At least two other crania of S. cavifrons are now known from the Colorado Plateau (Mc¬ Donald, 1985a; McDonald, Neusius, and Clay, 1987), so— although the Black Rocks specimen is a boundary record—it was found near the otherwise documented range of the species. We conclude that the Black Rocks specimen is simply an extensively abraded cranium representing Symbos cavifrons. Gidleya zuniensis should, therefore, be considered a junior synonym of Symbos cavifrons. The Relationship between Bootherium and Symbos The uncertainty about the biological relationship between Bootherium and Symbos is a direct result of different 28 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY interpretations of (1) morphological and preservational differ¬ ences exhibited in the known skull characters and (2) sample sizes of representatives of the two groups. Most of the debate about the relationship of these two forms has involved a few specific morphological features of the cranium, the horn cores, and the lacrimal bones—all features that were known as early as Leidy’s technical description of Bootherium cavifrons and Bootherium bombifrons (Leidy, 1852b). Specifically, the morphological characteristics that have been invoked to support opinions about the relationship between Bootherium and Symbos include (1) the general size of adult crania (Osgood, 1905a; Allen, 1913); (2) the size, shape, attachment, direction, and angle of emanation of the horn cores (Osgood, 1905a; Allen, 1913; Hay, 1914); (3) the configuration of the dorsal surface of the cranium (Leidy, 1852b; Osgood, 1905a; Allen, 1913; Hay, 1914, 1915); (4) the degree of flexion between the ventral surfaces of the basisphenoid and basioc- cipital bones at their junction, and the configuration of the ventral surface of the basisphenoid (Osgood, 1905a; Allen, 1913); and (5) the relative depth of the lacrimal fossae (Allen, 1913). In addition, the pronounced difference in the number of recovered Bootherium and Symbos skulls has been used as a basis for declaring the two forms taxonomically distinct (Osgood, 1905a; Hay, 1914). Presently, three arrangements of the relationship among nominal taxa within Bootherium and Symbos are advocated by different writers, including (1) Bootherium (including all nominal species) and Symbos (including all nominal species) are taxonomically distinct; (2) Bootherium bombifrons is taxonomically distinct from Symbos (including all nominal taxa in Symbos, as well as B. sargenti and its synonyms); and (3) Bootherium and Symbos are sexually dimorphic forms of the same taxon (at least genus, possibly species). In essence, the morphological bases for the debate have not changed since Leidy’s initial revision of the North American fossil oxen (Leidy, 1852b). Additional information on the cranial morphology of Bootherium and Symbos that has been produced since Leidy’s time has served, instead, to document better the ranges of variation found within any given character rather than to identify new differences. Likewise, the larger number of specimens now known has allowed a better documentation of the distribution of the two forms without altering significantly the disproportionate numerical represen¬ tation of the two forms. The position taken by specific authors who have been active in the debate has been reviewed in the second section of this paper. Here, we consider the various specific issues separately, first by reviewing the argument(s) as used by the principal advocate(s) and then discussing the validity of the argument in the light of currently available information. Differences in the Size of Bootherium and Symbos Crania Difference in the size of crania of Bootherium and Symbos has been interpreted as representing both sexual dimorphism and a taxonomic characteristic. Although Leidy placed the two forms in different species, he did not mention that size difference alone was a specific consideration in leading him to do so. Rutimeyer (1865) and Dawkins (1872) attributed the size difference to sexual dimorphism. Dawkins (1872:29) stated that the skull of B. bombifrons bears exactly the same relation to that of B. cavifrons, as the male to the female [sic; he has these reversed] Musk Sheep. It is therefore highly probable that B. cavifrons and B. bombifrons are the male and female of the same species. Osgood, however, concluded that the disparity in size between the two forms “was vastly greater than in the recent genus Ovibos" (Osgood, 1905a: 182) and proceeded to separate the two forms into Bootherium and Symbos. Allen (1913) accepted Osgood’s conclusion about the taxonomic distinctive¬ ness of Bootherium (as represented by B. bombifrons) and Symbos, but he moved the recently named B. sargenti (Gidley, 1908) to Symbos, stating “the relationship of B. sargenti is entirely with Symbos, and well fulfills the condition that would be expected in the female of S. cavifrons" (Allen, 1913:215). Allen did not enumerate the expected conditions, but he clearly was aware that the female skull should be smaller than that of the male. Hay (1914,1915) felt that the range of sizes among specimens assigned to Symbos was adequate to accommodate both male and female individuals, and rejected Allen’s placement of B. sargenti with Symbos. Hibbard and Hinds, however, returned to the position of Rutimeyer (1865) and Dawkins (1872) when they wrote “it is very likely that Bootherium is the female woodland musk ox since all specimens of Symbos based on skulls are considered those of bulls” (Hibbard and Hinds, 1960:107). All of the positions reviewed above were based upon the qualitative differences observed in available crania, which in most cases consisted of relatively few specimens or, in the cases of Rutimeyer and Dawkins, illustrations only. Hay probably used the largest sample, which included some 25 specimens assigned to Symbos and four specimens assigned to Bootherium. None of these authors supported their position with focused discussions of patterns expected in sexually dimorphic forms of the same species. Neither did they quantify comparisons of Bootherium and Symbos, nor compare such patterns with those of dimorphism found in Ovibos or other closely related taxa. Sexual dimorphism of the skeleton is an expected character¬ istic among species of Artiodactyla, with the skeleton of males typically being larger than that of females (Glucksmann, 1978; Nowak and Paradiso, 1983). Patterns of size distribution within known or inferred single-sex populations have been described for samples of crania representing species such as Bison latifrons, Bison antiquus, Bison bison, Ovis catclawensis, and Rupicapra rupicapra caucasica (Corner, 1977; McDonald, 1981; Koubck and Hrab£, 1983). Patterns of size distribution recorded for historic and fossil populations of Ovibos moschatus, and Bootherium and Sym¬ bos, are presented in Figures 33 to 37. These histograms and scatterplots show that the Bootherium and Symbos samples possess about the same quantitative relationship to each other as do female and male Ovibos moschatus. NUMBER 66 29 CO O) Recent ft Ovlbos moschatus Recent *?Ovlbos moschatus 10 0 12 5 ISO 1 7 5 200 100 125 150 175 200 POSTORBITAL WIDTH OF FRONTALS (in mm) FIGURE 33. —Histogram showing distribution of measurements of postorbital width of frontals in Boolherium, Symbos, and fossil and Recent samples of male and female Ovibos moschatus. Symbos Bootherlum 175 225 275 325 375 75 225 2 7 5 J 2 5 J/5 Fossil 9 Ovlbos R e c e n t 9 O vi b o s moschatus LENGTH OF HORN CORE (in mm) FIGURE 34. —Histogram showing distribution of measurements of length of horn core in Boolherium, Symbos, and fossil and Recent samples of male and female Ovibos moschatus. (The small sample of Ovibos moschatus is due to the fact that most modem specimens still have the horn sheaths attached, making examination of the horn core impossible.) 30 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY S ym b o s o <5 - 2 CM — 110 - 100 - 90 - X o o o 80 75 yrs: F (N=5) 160.2° M (N=22) 150.2° Osgood and Allen mentioned is a variable character that appears on all of the Bootherium crania for which the character can be assessed. A trace of a ridge occurs on the ventral surface of the basisphenoid of some female Ovibos moschatus. This character appears to be typical of specimens assigned to Bootherium, but we consider it of no taxonomic value. Differences in Depth of the Lacrimal Fossae Leidy observed the presence of lacrimal fossae in both Bootherium cavifrons and Bootherium bombifrons, describing that of the former as “a deep lenticular depression, or larmier, such as exists in the Deer and Sheep” and that of the latter as “a remarkably deep fossa, or larmier, which appears to have been hemispherical, but, in the specimen, the lower portion is broken away” (Leidy, 1852b: 13,18). One characteristic of Bootherium given by Allen (1913:210) was “the presence of small but deep and sharply defined lacrymal fossae.” These are the only allusions to this character in a taxonomic context of which we are aware. The specific shape and size of the lacrimal fossae are variable among individuals, but generally they are larger and better defined in specimens assigned to Symbos than those assigned to Bootherium. We consider differences in the size of the lacrimal fossae to be of no taxonomic value. Differences in thi Number of Bootherium and Symbos Specimens The number of known specimens referred to Symbos increased slowly but continuously during the 19th century and the early part of the 20th Century. Although De Kay (1828) had but a single cranial specimen, Leidy (1852b) had access to eight such specimens, Allen (1913:214) acknowledged knowing of “at least 11” localities from which Symbos specimens had been reported (actually only eight of these localities had produced Symbos remains, and they a total of 12 whole or partial crania), and Hay claimed to have examined 25 specimens by 1915 (Hay, 1914, 1915). The only Bootherium cranium known to exist with certainty for some 90 years was the holotype for Bootherium bombifrons (Wistar, 1818; Harlan, 1825; Leidy, 1852b). A second specimen was described by Rhoads in the 1890s, originally as Bison appalachicolus, then Ovibos (Bootherium?) appalachicolus (Rhoads, 1895, 1897). Gidley described a third specimen as Bootherium sargenti in 1908. Other records followed, but always fewer than Symbos. Both Osgood (1905a) and Hay (1914, 1915) invoked the difference in the number of specimens of Bootherium and Symbos as probable evidence that the two forms represented different taxa. Osgood, noting that Symbos specimens had been reported from 10 localities by the time of his writing, stated as one reason that Bootherium should be separated from Symbos: “In the large number of specimens, if there were any females at all it is probable that there would be more than one” (Osgood, 1905a:183). Hay objected to Allen’s (1913) putting Booth¬ erium sargenti in Symbos and defended this position by writing “If the Grand Rapids skull is the female of Symbos cavifrons, it is very remarkable that only one female should be discovered among 25 specimens” (Hay, 1914,1915:527). Many additional crania referred to either Bootherium or Symbos have been found since 1915. The most productive locality has been the Fairbanks, Alaska, mining district where, from 1937 to 1960, Otto Geist collected literally thousands of vertebrate fossils for Childs Frick and, to a lesser extent, the University of Alaska (Keim, 1969). Isolated specimens or small numbers of specimens have, however, been collected at numerous other localities throughout much of the United States and western Canada. The proportion of Symbos to Bootherium records, however, has not changed substantially. We have examined 175 Symbos and 51 Bootherium crania for use in this paper. Our Bootherium.Symbos ratio of .29 is not greatly different from Allen’s (3:12; .25) ratio. Among bovids the skull of females typically is smaller, lighter, and less strongly fused by suturing than is the skull of males. These differences in size and structure render the female skull more susceptible than that of the male to destruction by weathering, abrasion, decomposition, carnivory, gnawing, or trampling. Three female and 38 male records of fossilized crania of Ovibos moschatus are known from North America, giving a female:male sex ratio of .08 for a group whose sexual dimorphism is well documented and widely accepted (Mc¬ Donald, unpubl. data). Howard Hutchison (pers. comm.) observed in the Canadian arctic that the skulls of female Ovibos moschatus were more easily and readily destroyed by wolves than were the skulls of males. If female skulls are the more easily destroyed, then it is reasonable to expect them to be recovered less often than male skulls. There also appears to be a general collecting bias against salvaging the smaller, possibly NUMBER 66 47 FIGURE 62.—Histograms showing the distribution of measurements of the angle of divergence between the basioccipital and basisphenoid bones in Bootherium, Symbos, and male and female samples of fossil and Recent Ovibos moschatus. more fragmented female skull. This has been observed among some collectors of Bison bison crania in Texas, and museum collections of some modern taxa often are biased against females. The National Museum of Natural History collections of Bison bison, Budorcas taxicolor, and Ovibos moschatus, for example, are biased in favor of males (11$ : 27cf males, adult sample only; 5$ : lid"; 11$ : 23d\ respectively) (McDonald, 1981,unpubl. data). Sex ratios for other samples of Recent and fossil bovids are given in Table 2. Based upon the sex ratio of samples in published reports and museum collections known to us, there are typically fewer females than male specimens in collections of bovid crania. It is our opinion that the ratio of Bootherium.Symbos crania is within the limits of what could be expected as a sex ratio for a randomly collected sample of fossil crania in a single taxon. Certainly, the Booth- erium:Symbos ratio presents no valid, persuasive basis for claiming that the two forms are taxonomically distinct. Similarities in the Morphology and Distribution of Bootherium AND Symbos SPECIMENS Even though the debate over the relationship between Bootherium and Symbos focused upon characters that differed between Bootherium and Symbos, several characters have been 48 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY Table 2.—Sex ratios for selected samples of bovid crania. Sample No. of females No. of males F:M ratio Source Bison bison bison 39 153 .254 McDonald, 1981 Bison antiquus occidentalis 30 115 .260 McDonald, 1981 Bison antiquus antiquus 31 107 .288 McDonald, 1981 Bison latifrons 10 80 .125 McDonald, 1981 Ovibos moschatus (Recent) 15 36 .417 McDonald, unpubl. Ovibos.noschalus (Recent) 26 31 .839 Allen, 1913 Ovibos moschatus (Fossil) 3 38 .079 McDonald, unpubl. Rupicapra rupicapra caucasica 13 30 .433 Koubek and Hrabe, 1983 Ovis calclawensis 2 4 .500 Comer, 1977 identified in the literature that are similar in the two forms. Comparison of the technical descriptions of Bootherium cavifrons and Bootherium bombifrons provided by Leidy (1852b) indicates many similarities between the types of his two species, including the longitudinal growth form of the horn cores, the lateral emanation of the horn cores and their placement about midway between the levels of the orbits and the occipital plane, the shape and surface detail of the occiput, the presence of lacrimal fossae and grooves, the shape of the temporal fossae, the foramen magnum and processes of the ventral surface of the cranium, and the configuration and relative size of the occipital condyles. Allen (1913) conceded that several important characters were similar in Bootherium and Symbos, including the occipital condyles, the surface of the occiput, and the general proportions (great depth and length relative to breadth) of the skull. Additional characters can be added to the list of similarities shared by Bootherium and Symbos. The frontoparietotemporal suture in both Symbos and Bootherium typically exhibits the same rostrocaudal orientation (i.e., roughly horizontal). The crania of male and female Ovibos moschatus share a common orientation of this suture line, but the orientation differs between Ovibos moschatus and Bootherium!Symbos. The mandibular dentition of Bootherium is now known from a mummified carcass collected by Otto Geist in 1940 at Fairbanks Creek, Alaska (McDonald, 1984b). Although this individual was a subadult (~2.3 years of age) at death and all permanent teeth had not developed, those that are present are indistinguishable from the teeth of Symbos. In addition to morphological similarities between the crania of Bootherium and Symbos, the two forms share a similar pattern of spatial and temporal distribution. The spatial distribution of Bootherium and Symbos crania, based almost entirely upon specimens we have examined personally or from photographs, are shown in Figures 63 and 64. (Provenience data are presented in Tables 3 and 4.) These illustrations include all boundary records of which we are aware. Records without figures are not included in our data set; their inclusion would change only the density, not the spatial extent, of records. The major features of similarity between the distribu¬ tion of records of Bootherium and Symbos include (1) their concentration in Alaska and the mid-latitude belt of ~35°-45° N; (2) their southernmost extent on the coastal plain of Texas and Louisiana; (3) their absence in the extreme southeastern and southwestern corners of the continental United States; and (4) their absence over most of the glaciated northeastern one-third of the continent. Bootherium and Symbos are known only from the United States and Canada. Although Harington has noted that the holotype of Ovibos recticornis, from Radotin, Czechoslovakia, closely resembles Symbos (Ryziewicz, 1933; Harington, 1977), we suspect that this poorly known species is referable to Praeovibos. The temporal distribution of Bootherium and Symbos is also broadly similar, but reliable stratigraphic and chronologic information exists for relatively few specimens. Available information indicates that Bootherium and Symbos were essentially Rancholabrean in age. Both Bootherium and Symbos have been found in the Cripple Creek Sump loess in central Alaska, a mass of loess (possibly rebedded) of Illinoian age that was deposited on a down-warped or down-faulted surface of auriferous gravel beneath the present valley of Cripple Creek in the Fairbanks district.... (Pewe and Hopkins, 1967:269). Symbos remains also have been reported from deposits of Illinoian age (and assigned to the late Irvingtonian) in Nebraska and Arkansas, but both of these records arc weak. Jakway (1961a,b) reported Symbos in the Mullen local fauna, which he assigned to the early Illinoian. Jakway regarded this fauna as mixed, including some elements that predated the Illinoian and, possibly, some that post-dated the early Illinoian. Martin subsequently reported that, based upon restudy of the Mullen fauna and additional excavations at the locality (UNSM Cr-10), “the reworking was more extensive than Jakway had supposed” (Martin, 1972:174). Martin recognized at least two separate faunas within the Mullen assemblage,based upon the microtine rodent component: Mullen I, which he assigned tentatively to the early Kansan, and Mullen II, which was assigned to the early Illinoian. Martin did not discuss the status of Symbos within his revision of the fauna, but Kurten and Anderson (1980) report that Symbos, along with Bison and Alces, were probably intrusives that post-dated Mullen II. The Conard NUMBER 66 51 Fissure local fauna is considered to represent a single biostratigraphic unit assigned tentatively to the Irvingtonian, but—according to Kurten and Anderson (1980:26), who did not enumerate the reasons for their position—this age assesment is “in dispute.” This local fauna was originally described by Brown (1908). Graham later collected and studied new material—primarily Blarina, with other small mammals— from this site, and considers its assignment to the late Irvingtonian to be correct (Graham, 1972, and pers. comm.). The ovibovine remains from Conard Fissure include three molars which were made the type of a new species, S. australis, along with some premolars and postcranial elements that were referred to S. australis by Brown (1908). Most of the teeth reported by Brown are of the size and configuration of those of Symbos, and their assignment to that genus was reasonable, but one (the Lm3) differs in detail from the corresponding tooth in other specimens assigned to Symbos and all are within the size range of corresponding teeth of Euceratherium. In addition, a tooth row collected at Conard Fissure by James H. Quinn is more similar to what are presumed to be the teeth of Soergelia than to those of any other known ovibovine taxon. The unequivocal presence of Symbos remains in both the pre- Rancholabrean fraction of the Mullen, and the Conard Fissure, local faunas is, therefore, not established. Most specimens of Symbos and Bootherium are known or considered to date from the late Wisconsinan (Tables 3 and 4, Appendix III). The geologically youngest record of Symbos, based upon a radiocarbon-dated fourth lumbar vertebra from the associated skeleton (including skull) found near Scotts, Kalamazoo County, Michigan, is 11,100 + 400 yr B.P. (M- 1402)(Semken, Miller, and Stevens, 1964). A date of 10,370 ± 160 yr B.P. (1-8582) on Bison bone has been obtained on the Lost Chicken Creek fauna, which includes Symbos. Equus bone from the same fauna, however, yielded a date of 26,760 ± 300 yr B.P. (SI-355), and no dates have been obtained directly on remains of Symbos from the site (Harington, 1978). The only radiocarbon dates obtained direedy from Bootherium specimens were determined from hair (SI-454:17,210± 500 yr B.P.) and scalp tissue (SI-455:24,140± 2200 yr B.P.) from the frozen carcass of a subadult (F:AM A-293-5268) found at Fairbanks Creek, Alaska, in 1940 (Pewe, 1975; McDonald, 1984b) and from a horn sheath (SI-292:22,540 ± 900 yr B.P) on a cranium from the same locality (Pewe, 1975). Although not derived from the tissue of the animal itself, a radiocarbon date of 17,200 ± 600 yr B.P. (W-1617) was obtained on matrix from the cranial cavity of the holotype of Bootherium bombifrons (from Big Bone Lick, Kentucky). The geologically youngest radiocarbon date associated with Bootherium remains is 13,130 ±330 yr B.P. (A-2985) obtained on spruce wood from the base of a lacustrine mud at Saltville, Virginia, in which the remains of both Bootherium and Symbos have been found (McDonald, 1984a). Specimens of Symbos and Bootherium have been found together at several sites (Tables 3 and 4), including at least eight of the Fairbanks district sites (Cripple Creek and Cripple Creek Sump, Dome Creek, Engineer Creek, Ester Creek, Fairbanks Creek, Gold Hill, lower Goldstream, and upper Cleary Creek); Lost Chicken Creek, Alaska; the Provo Formation near Slate Canyon, Utah County, Utah (Stokes and Hansen, 1937), Natural Trap Cave, Wyoming (Gilbert and Martin, 1984), Big Bone Lick, Kentucky, and Saltville Valley, Virginia (Ray, Cooper and Benninghoff, 1967; McDonald and Bardett, 1983; McDonald, 1984a). These localities are widely distributed throughout the Bootherium/Symbos range, and both forms have been recovered from other deposits that are known or considered to be contemporaneous. Bootherium and Symbos were, therefore, contemporaneous as well as sympatric. Conclusions In the preceding sections we have reviewed the history of taxonomy of the autochthonous genera of musk oxen in North America, and the arguments that have been invoked during the past 135 years to justify decisions about the relationships between the nominal genera Bootherium and Symbos (includ¬ ing Gidleya). We have also discussed each issue individually in the light of current information and modern concepts, and presented evidence that allows the interpretation of all issues as characteristics or functions of sexual dimorphism. Specifically, we re-evaluated differences in the absolute size of crania; the size, shape, attachment, direction, and angle of emanation of the horn cores; the configuration of the dorsal surface of the cranium; the degree of flexion between the ventral surfaces of the basisphenoid and basioccipital bones at their junction; the relative depth of the lacrimal fossae; and the absolute number of recovered skulls of Bootherium and Symbos. In addition, we have introduced new perspectives on the relationship between these two forms—including similarities in the primary mor¬ phology of the cranium and horn cores in Bootherium and Symbos, and morphological parallels between Bootherium / Symbos and Ovibos —and attempted to show that these perspectives, too, allow recognition of the two nominal genera as sexually dimorphic forms of a single genus. Symbos, therefore, must be suppressed as a junior synonym of Bootherium, leaving Bootherium as the sole genus of musk oxen autochthonous to North America. There is presently no strong evidence that more than one species exists within Bootherium. The range of quantitative variation within the male and female samples is continuous, as is most qualitative variation, presenting patterns of variation harmonious with that expected in a representative sample population of a large mammal taxon that ranged over half of North America for some 500,000 years. The caution that the collective sample of Symbos (now male Bootherium) crania might represent more than one species (McDonald, 1985b) is still applicable, since some qualitative differences (e.g., shape of the frontoparietotemporal suture; depth of the frontoparietal sinus region; configuration of the basioccipital bone) do occur among crania of both male and female Bootherium. Instances of atypical characters are rare, and appear to be randomly 52 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY TABLE 3.—Records of Bootherium mapped in Figure 63. Locality Specimen No. Name No. Description Provenience 1 Eschscholtz Bay, Alaska USNM 2324 skullcap with both horn cores on the shores of Eschscholtz Bay, probably at Elephant Point 2 Fairbanks area, Alaska A-284-2044 left horn core with adjacent frontal Cripple Creek 2 Fairbanks area, Alaska A-284-8280 partial cranium with partial horn cores Engineer Creek 2 Fairbanks area, Alaska A-284-8281 skullcap with hom cores Engineer Creek 2 Fairbanks area, Alaska A-293-5268 mummified carcass Fairbanks Creek; 64 IJ 58 , .N, 147°ll/W 2 Fairbanks area, Alaska A-325-8392 partial left hom core Engineer Creek 2 Fairbanks area, Alaska A-459-2014 partial left hom core with adjacent frontal Cripple Creek 2 Fairbanks area, Alaska A-521-4247 right hom core with adjacent frontal Cripple Creek 2 Fairbanks area, Alaska F:AM 30499 partial cranium with base of right hom core Upper Cleary Creek 2 Fairbanks area, Alaska F:AM 30500 skullcap with hom cores and supra¬ orbital region ? 2 Fairbanks area, Alaska F:AM 30508 cranium with hom cores with both sheaths largely intact creek near Fairbanks (Pewe, 19 /5) 2 Fairbanks area, Alaska F:AM 33101 skullcap with partial hom cores Cripple Creek 2 Fairbanks area, Alaska F:AM 33102 right hom core Cripple Creek Sump 2 Fairbanks area, Alaska F:AM 33103 partial skullcap with partial right hom core Cripple Creek Sump 2 Fairbanks area, Alaska F:AM 33194 skullcap with partial hom cores Dome Creek 2 Fairbanks area, Alaska F:AM 33195 cranium with hom cores Ester Creek 2 Fairbanks area, Alaska F:AM 33196 partial skullcap and left hom core Fairbanks Creek 2 Fairbanks area, Alaska F:AM 33197 skullcap with partial hom cores Fairbanks Creek 2 Fairbanks area, Alaska F:AM 33198 skullcap with partial hom cores Fairbanks Creek 2 Fairbanks area, Alaska F:AM 33199 cranium with hom cores Fairbanks Creek 2 Fairbanks area, Alaska F:AM 33207 cranium with partial hom cores; part of face Fairbanks Creek 2 Fairbanks area, Alaska F:AM 33208 skullcap with base of left hom core Gold Hill 2 Fairbanks area, Alaska F:AM 33220 skullcap with partial hom cores bank opposite Fox—Goldstream 3 Lost Chicken Creek, Alaska UAF V-54-158 cranium with hom cores near head of Lost Chicken Creek; 64°03'N, 141°53'W 4 Old Crow River, Yukon Territory NMC 10536 partial right hom core and adjacent frontal bank of Old Crow River; 67°47'N, 139°57'W 5 Benton County, Washington WSU uncataloged cranium with partial hom cores Umatilla Mammoth Site, near Wal- lula Gap, on Columbia R. -1 mi upstream from Umatilla, Oregon 6 Minidoka County, Idaho LACM 16888 cranium with partial hom cores from 12' depth, gravel pit 1 mi W of Minidoka Dam, N side of Snake R. (LACM loc. 6671); NE 'A, Sec. 1, T9S, R25E, Lake Walcott Quad, USGS 7.5' series 7 Power County, Idaho UVP 083 skullcap with hom cores intersection of Oregon Trail and Ele¬ vator Streets, American Falls; NE ’/■i, Sec. 29, T7S, R31E, American Falls Quad, USGS 7.5' series 8 Bannock County, Idaho IMNH 17124 skullcap and hom cores from 12' depth, Arimo Gravel Pit; SE >/4, SW l /4, Sec. 19, T10S, R37E, Arimo Quad, USGS 7.5' series 9 Utah County, Utah lost; no number partial skullcap and partial left hom core near Pleasant Grove 10 Utah County, Utah BYUG 834 cranium with partial hom cores about 50' below surface, Provo City Upper Gravel Pits, near Slate Can¬ yon; SW 'At, Sec. 8, T7S, R3E, Provo Quad, USGS 7.5' series 11 Big Horn County, Wyoming KUMNH 6135 skullcap and hom cores Natural Trap Cave NUMBER 66 Table 3.—Continued. (Locality/Specimen No. repeated from left half of table for ease of reference.) 53 Locality Specimen Principal published No. No. Stratigraphic unit Geologic age description(s) 1 USNM 2324 Hay, 1915 (pi. 31: fig. 1) 2 A-284-2044 unpublished 2 A-284-8280 unpublished 2 A-284-8281 unpublished 2 A-293-5268 radiocarbon age: 17,210 + 500 yr (SI- Guthrie, 1972:300 (photograph 454: on hair) and 24,140 ± 2,200 yr (SI-455; on muscle) B.P. McDonald, 1984b 2 A-325-8392 unpublished 2 A-459-2014 unpublished 2 A-521-4247 unpublished 2 F:AM 30499 unpublished 2 F:AM 30500 unpublished 2 F:AM 30508 radiocarbon age: 22,540 ± 900 yr B.P. unpublished (SI-292 on horn sheath) 2 F:AM 33101 unpublished 2 F:AM 33102 unpublished 2 F:AM 33103 unpublished 2 F:AM 33194 unpublished 2 F:AM 33195 unpublished 2 F:AM 33196 unpublished 2 F:AM 33197 unpublished 2 F:AM 33198 unpublished 2 F:AM 33199 unpublished 2 RAM 33207 unpublished 2 F:AM 33208 unpublished 2 F:AM 33220 unpublished 3 UAF V-54-158 unpublished 4 NMC 10536 Harington, 1977 (fig. 83) 5 WSU uncataloged (?)Late Wisconsinan (probably dates unpublished “shortly after 13,000 yr B.P,” Lyman and Livingston, 1983) 6 LACM 16888 Late Pleistocene White, 1985 7 UVP 083 ?Equivalent to B layer (= Rainbow ?~26,500 ± 500 yr B.P. Nelson and Madsen, 1987 (fig. 1) Beach Section), American Falls Formation 8 IMNH 17124 Lake Bonneville gravels White, 1985 (figs. 2 a, 3a) 9 lost; no number unpublished 10 BYUG 834 (?)Provo Formation (?)Lake Bonneville age Stokes and Hansen, 1937 (fig. 1, bottom) 11 KUMNH 6135 Late Wisconsinan Nelson and Madsen, 1987 (fig. 7) 54 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY TABLE 3.—Records of Bootherium mapped in Figure 63 (continued). Locality Specimen No. Name No. Description Provenience 12 Sheridan County, Nebraska UNSM 9-418-39 left horn core Pit 4, Johndreau Quarry 1. E ’/ 2 , Sec. 25.T31N, R41W 12 Sheridan County, Nebraska UNSM 10-419-39 partial cranium with base of left horn core Pit 4, Johndreau Quany 1. E ] / 2 , Sec. 25.T31N, R41W 13 Hitchcock County, Nebraska UNSM 18-11-36 cranium with partial horn cores Trenton Gravel Pit 14 Cuming County, Nebraska UNSM 603-46 cranium with hom cores gravel pit at W edge West Point (UNSM loc. Cm-3); SW ’A, NW l /4. Sec. 34, T22N, R6E 15 (?)Douglas County, Nebraska UNSM 193-25-5-27 cranium with partial hom cores (?)near Omaha 16 Atchinson County, Missouri KUMNH Cast 345 left hom core from gravel bar -4 mi SW of Fairfax; SE '/a, SE '/4, Sec. 36, T64N, R41W 17 Cooper County, Missouri Widel collection skullcap with partial hom cores dredged from Lamine R. (?)14 mi S of Blackwater, Sec. 22, T46N, R19W 18 Brazos County, Texas TAMC 2553' partial cranium with partial hom cores from sandbar in or along Brazos R. at Pitts Bridge 19 Bolivar County, Mississippi McKay collection partial cranium with partial hom cores from sand bar in Mississippi R. near Rosedale 20 Muskegon County, Michigan GRPM 11-423-3101 dorsal cranium and hom cores about 2'- 3' deep. Moorland Swamp, Charles McKay Farm, 3 mi NE of Moorland. NE '/4,Sec. 16, T10N, R14W 21 Gibson County, Indiana USNM 24885 skullcap with partial hom cores; asso¬ ciated occiput and basicranium probably of same individual at 5'-20' depth in gravel pit “some¬ where” east of East Mt. Carmel 22 Boone County, Kentucky ANSP 994 cranium with hom cores and orbital region Big Bone Lick (Clark-Jefferson Col¬ lection) 22 Boone County, Kentucky UNSM 1111 fragmentary skullcap and hom cores Big Bone Lick (University of Ne¬ braska collection) 23 Smyth County, Virginia USNM 23264 cranium with partial hom cores Saltville Valley 23 Smyth County, Virginia USNM 392115 fragment of proximal right hom core Saltville Valley 23 Smyth County, Virginia Space collection fragment of frontal bone with base of left hom core 2 Saltville Valley 23 Smyth County, Virginia Stephens collection fragment of frontal with base of left hom core Saltville Valley 24 Dare County, North Carolina USNM 347315 cranium with partial hom cores and parts of face in surf, Oregon Inlet 25 Bucks County, Pennsylvania ANSP 29 small part of right hom core and adjacent cranium from a closed limestone crevice in Durham Cave, along bank of Dela¬ ware R. near Riegelsville 'This specimen is now a part of the collections of the Texas Memorial Museum, University of Texas, Austin, Texas. 2 This specimen was in the Rufus Pickle collection when it was examined by Ray in 1965. The Pickle collection was subsequently sold to Ralph Space of Sussex, New Jersey. This specimen could not be located when the Space collection was examined by McDonald in December 1984. NUMBER 66 55 Table 3.—Continued. (Locality/Specimen No. repeated from left half of table for ease of reference.) Locality No. Specimen No. Stratigraphic unit Geologic age Principal published description(s) 12 USNM 9-418-39 unpublished 12 USNM 10-419-39 Middle Pleistocene (Yarmouthian) unpublished 13 USNM 18-11-36 unpublished 14 USNM 603-46 Middle to Late Wisconsinan unpublished (Frankforter, 1950:45) 15 USNM 193-25-5-27 Barbour, 1931 (fig. 146) 16 KUMNH Cast 345 Neas and Parker, 1987 (fig. 1) 17 Widel collection Holmes, 1960 (fig. 225) 18 TAMC 2553 Hesse, 1942 (pi. 18); Ray, 1966b (figs. 1,2) 19 McKay collection unpublished 20 GRPM 11-423-3101 Gidley, 1908 (pi. 59) 21 USNM 24885 unpublished 22 ANSP 994 matrix from cranium radiocarbon Wistar, 1818 (pi. 9: figs. 10,11) dated at 17,200 ±600 yrs B.P. (W- 1617) 22 USNM 1111 (?)Late Wisconsinan unpublished 23 USNM 23264 (?)Unit W4 (Late Wisconsinan fluvial radiocarbon age of Unit W4: between Ray, Cooper, and Benninghoff, 1967 gravels) (McDonald, 1984a) 3 27,000+900 (A-2986) and (pi. 65: figs. 2,3; pi. 66: figs. 1-3) 14,480 ± 300 (Beta-5701) yrs B.P. 23 USNM 392115 (?)Late Wisconsinan unpublished 23 Space collection (?)Late Wisconsinan unpublished 23 Stephens collection (?)Late Wisconsinan unpublished 24 USNM 347315 Ray, 1983:3 (photographs) 25 ANSP 29 Rhoads, 1895,1897; Ray, 1966a 3 Based on information obtained from excavations at Saltville since October 1980, all known vertebrate fossils from this locality are presumed to date from the late Wisconsinan or Holocene. No remains of extinct vertebrate taxa have been found in deposits of Holocene age, and no vertebrate fossil bearing deposits have been found that date >27,000 yr B.P. (McDonald, 1984a). 56 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY Table 4.—Records of Symbos mapped in Figure 64. Locality Specimen No. Name No. Description Provenience 1 Anvik, Alaska USNM 2378 partial right hom core Anvik 2 Point Barrow, Alaska BM(NH) 10462 cranium with partial hom cores Port (= Point) Barrow 3 Lillian Creek District, Alaska BLM uncataloged cranium with hom cores Tucker Mine, Lillian Creek 4 Fairbanks area, Alaska A-204-4254 cranium with hom cores and left maxillary, left mandible, and sev¬ eral postcranial elements Little Eldorado Creek 4 Fairbanks area, Alaska F:AM 30501 cranium with left hom core; part of face lower Cleary Creek; found in place 9Cf below surface 4 Fairbanks area, Alaska F:AM 30505 cranium with hom cores ? 4 Fairbanks area, Alaska F:AM 30506 cranium with partial hom cores ? 4 Fairbanks area, Alaska F:AM 33124 skull lacking nasals, part of premaxil- laries; still has hom sheaths upper Cleary Creek 4 Fairbanks area, Alaska F: AM 33125 cranium with partial hom cores Lower Goldstream Creek 4 Fairbanks area, Alaska F:AM 33126 skullcap with partial hom cores lower Goldstream Creek 4 Fairbanks area, Alaska F:AM 33127 cranium with partial hom cores lower Goldstream Creek 4 Fairbanks area, Alaska F:AM 33128 cranium with bases of hom cores lower Goldstream Creek 4 Fairbanks area, Alaska F:AM 33129 cranium and base of right hom core lower Goldstream Creek 4 Fairbanks area, Alaska F:AM 33130 cranium with partial hom cores lower Goldstream Creek 4 Fairbanks area, Alaska F:AM 33131 cranium with partial hom cores Fairbanks Creek 4 Fairbanks area, Alaska F:AM 33132 partial cranium with partial hom cores Fairbanks Creek 4 Fairbanks area, Alaska F:AM 33133 cranium with bases of hom cores Fairbanks Creek 4 Fairbanks area, Alaska F:AM 33134 cranium with partial hom cores Fairbanks Creek 4 Fairbanks area, Alaska F:AM 33135 cranium with partial right hom core Fairbanks Creek 4 Fairbanks area, Alaska F:AM 33136 cranium with partial hom cores Fairbanks Creek 4 Fairbanks area, Alaska F:AM 33137 cranium with partial hom cores Fairbanks Creek 4 Fairbanks area, Alaska F:AM 33138 cranium with bases of hom cores Fairbanks Creek 4 Fairbanks area, Alaska F:AM 33139 left hom core and part of cranium Fairbanks Creek 4 Fairbanks area, Alaska F:AM 33140 cranium with partial hom cores Fairbanks Creek 4 Fairbanks area, Alaska F:AM 33141 cranium with partial hom cores Fairbanks Creek 4 Fairbanks area, Alaska F:AM 33142 cranium with hom cores Fairbanks Creek 4 Fairbanks area, Alaska F:AM 33143 cranium with partial hom cores Engineer Creek 4 Fairbanks area, Alaska F:AM 33144 cranium with bases of hom cores Engineer Creek 4 Fairbanks area, Alaska F:AM 33145 cranium Engineer Creek 4 Fairbanks area, Alaska F:AM 33146 cranium with partial left hom core Engineer Creek 4 Fairbanks area, Alaska F:AM 33147 partial cranium Engineer Creek 4 Fairbanks area, Alaska F:AM 33148 cranium with hom cores Engineer Creek 4 Fairbanks area, Alaska F:AM 33149 skullcap with bases of hom cores Engineer Creek 4 Fairbanks area, Alaska F:AM 33150 cranium with bases of hom cores Cripple Creek 4 Fairbanks area, Alaska F:AM 33153 cranium with partial hom cores Engineer Creek 4 Fairbanks area, Alaska F:AM 33154 cranium with partial hom cores Engineer Creek 4 Fairbanks area, Alaska F:AM 33155 cranium with partial hom cores Cripple Creek 4 Fairbanks area, Alaska F:AM 33156 skullcap with partial hom cores Cripple Creek 4 Fairbanks area, Alaska F:AM 33157 cranium with left hom core Cripple Creek 4 Fairbanks area, Alaska F:AM 33158 skullcap with hom cores Cripple Creek 4 Fairbanks area, Alaska RAM 33159 cranium with hom cores; partial face Cripple Creek 4 Fairbanks area, Alaska F:AM 33160 cranium with partial hom cores Cripple Creek 4 Fairbanks area, Alaska F:AM 33161 cranium Cripple Creek 4 Fairbanks area, Alaska F:AM 33162 cranium with partial hom cores Cripple Creek 4 Fairbanks area, Alaska F:AM 33164 cranium with right hom core Cripple Creek 4 Fairbanks area, Alaska F:AM 33167 skullcap Cripple Creek 4 Fairbanks area, Alaska F:AM 33168 cranium with partial hom cores Cripple Creek Sump 4 Fairbanks area, Alaska F:AM 33169 cranium with bases of hom cores Cripple Creek Sump NUMBER 66 57 Table 4.—Continued. (Locality/Specimen No. repeated from left half of table for ease of reference.) Locality Specimen No. No. Principal published Stratigraphic unit Geologic age description(s) 1 USNM 2378 unpublished 2 BM(NH) 104 unpublished 3 BLM uncataloged unpublished 4 A-204-4254 radiocarbon age: >40,000 yr B.P. unpublished (SI-291: on fecal pellets) 1 4 F:AM 30501 unpublished 4 F:AM 30505 unpublished 4 F:AM 30506 unpublished 4 F:AM 33124 radiocarbon age: 25,090 ±1070 yr unpublished B.P. (SI-850: on horn sheath) 4 F:AM 33125 unpublished 4 F:AM 33126 unpublished 4 F:AM 33127 unpublished 4 F:AM 33128 unpublished 4 F:AM 33129 unpublished 4 F:AM 33130 unpublished 4 F:AM 33131 unpublished 4 F:AM 33132 unpublished 4 F:AM 33133 unpublished 4 F:AM 33134 unpublished 4 F:AM 33135 unpublished 4 F:AM 33136 unpublished 4 F:AM 33137 unpublished 4 F:AM 33138 unpublished 4 F:AM 33139 unpublished 4 RAM 33140 unpublished 4 F:AM 33141 unpublished 4 F:AM 33142 unpublished 4 F:AM 33143 unpublished 4 RAM 33144 unpublished 4 RAM 33145 unpublished 4 RAM 33146 unpublished 4 F:AM 33147 unpublished 4 F:AM 33148 unpublished 4 F:AM 33149 unpublished 4 F:AM 33150 unpublished 4 RAM 33153 unpublished 4 F:AM 33154 unpublished 4 F:AM 33155 unpublished 4 RAM 33156 unpublished 4 RAM 33157 unpublished 4 F:AM 33158 unpublished 4 RAM 33159 unpublished 4 F:AM 33160 unpublished 4 F:AM 33161 unpublished 4 RAM 33162 unpublished 4 RAM 33164 unpublished 4 F:AM 33167 unpublished 4 F:AM 33168 unpublished 4 RAM 33169 unpublished 'Several fecal pellets resembling those of Ovibos moschatus were found associated with this skeleton, parts of which were articulated by mummified connective tissue. The skeleton, however, does contain three Bison bones and one ?Ovibos moschatus rib, so the association between the Symbos skeleton and the fecal matter, although probable, is not established with certainty. 58 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY TABLE 4.—Records of Symbos mapped in Figure 64 (continued). Locality Specimen No. Name No. Description Provenience 4 Fairbanks area, Alaska F:AM 33170 cranium with partial horn cores Cripple Creek Sump 4 Fairbanks area, Alaska F:AM 33171 partial cranium with bases of horn cores Cripple Creek Sump 4 Fairbanks area, Alaska F:AM 33172 skullcap and partial left horn core Ester Creek 4 Fairbanks area, Alaska F:AM 33173 partial cranium with partial horn cores Ester Creek 4 Fairbanks area, Alaska F:AM 33174 skullcap with partial hom cores Ester Creek 4 Fairbanks area, Alaska F:AM 33175 cranium with partial hom cores Ester Creek 4 Fairbanks area, Alaska F:AM 33176 cranium with base of right hom core Little Eldorado Creek 4 Fairbanks area, Alaska F:AM 33177 cranium with partial hom cores Little Eldorado Creek 4 Fairbanks area, Alaska F:AM 33178 cranium with partial right hom core Little Eldorado Creek 4 Fairbanks area, Alaska F:AM 33179 cranium with partial hom cores Livengood Creek 4 Fairbanks area, Alaska F:AM 33180 cranium with partial hom cores Livengood Creek 4 Fairbanks area, Alaska F:AM 33181 skullcap with partial hom cores Bear Creek 4 Fairbanks area, Alaska F:AM 33182 cranium with hom cores; part of face Dawson Cut, Engineer Creek 4 Fairbanks area, Alaska F:AM 33183 cranium with partial hom cores Dawson Cut 4 Fairbanks area, Alaska F:AM 33184 cranium with bases of hom cores Dawson Cut 4 Fairbanks area, Alaska F:AM 33185 cranium with hom cores Dome Creek 4 Fairbanks area, Alaska F:AM 33186 cranium with partial hom cores Dome Creek 4 Fairbanks area, Alaska F:AM 33188 cranium with hom cores (?)Flatt Creek 4 Fairbanks area, Alska F:AM 33189 cranium with right hom core Gold Hill 4 Fairbanks area, Alaska F:AM 33190 cranium with partial left hom cores Gold Hill 4 Fairbanks area, Alaska F:AM 33191 skullcap Gold Hill 4 Fairbanks area, Alaska F:AM 33192 cranium with partial hom cores Tofty 4 Fairbanks area, Alaska F:AM 33193 skull ? 4 Fairbanks area, Alaska F:AM 34610 cranium with partial hom cores (?)Chat. (= Chatam?) 4 Fairbanks area, Alaska F:AM 34611 cranium with partial hom cores Ester Creek 4 Fairbanks area, Alaska F:AM 34612 cranium with partial hom cores ? 4 Fairbanks area, Alaska F:AM 34613 cranium with right hom core ? 4 Fairbanks area, Alaska F:AM 34614 cranium with partial hom cores ? 4 Fairbanks area, Alaska F:AM 34615 cranium with partial hom cores Ester Creek 4 Fairbanks area, Alaska F:AM 34616 cranium with bases of hom cores; part of face Goldstream Creek 4 Fairbanks area, Alaska F:AM 34617-A cranium with bases of hom cores ? 4 Fairbanks area, Alaska F:AM 34617-B cranium with partial left hom core ? 2 4 Fairbanks area, Alaska F:AM 34617-C partial cranium with bases of hom cores ? 4 Fairbanks area, Alaska F:AM 34617-D cranium and partial right hom core ? 4 Fairbanks area, Alaska F:AM 34617-F skullcap and left hom core ? 4 Fairbanks area, Alaska F:AM 34617-G partial cranium ? 4 Fairbanks area, Alaska F:AM 34617-1 skullcap with bases of hom cores upper Cleary Creek 4 Fairbanks area, Alaska F:AM 34617-? cranium with partial right hom core (?)upper Cleary Creek 3 5 Lost Chicken Creek, Alaska NMC 25892 cranium with partial hom cores near head of Lost Chicken Creek; 64 o 03X141°53'W 5 Lost Chicken Creek, Alaska UAF V-54-197 cranium with hom cores near head of Lost Chicken Creek 5 Lost Chicken Creek, Alaska USNM 372807 dorsal cranium with partial hom cores; caudal part of face Lost Chicken Creek 6 Dawson area, Yukon Territory NMC 8837 cranium with hom cores Dawson area, exact locality unknown 6 Dawson area, Yukon Territory NMC 29229 cranium with partial hom cores Dawson area 6 Dawson area, Yukon Territory USNM 2555 70' below surface in gravels, Lovett Gulch, Bonanza Creek 6 Dawson area, Yukon Territory USNM 2556 partial cranium with partial hom cores Bonanza Creek 6 Dawson area, Yukon Territory USNM 12135 partial skullcap with base of right hom core note with specimen: “From Dan Coate, Dawson. Y.T.” 2 The abbreviation “Cl.” is written on this specimen, but it is faint and additional information about provenience could be missing. 3 What appears to be the abbreviation “U. Cl.” is written on the specimen, but it is faint and additional information about provenience could be missing. NUMBER 66 59 Table 4.—Continued. (Locality/Specimen No. repeated from left half of table for ease of reference.) Locality Specimen No. No. Principal published Stratigraphic unit Geologic age description(s) 4 F:AM 33170 unpublished 4 F:AM 33171 unpublished 4 F:AM 33172 unpublished 4 F:AM 33173 unpublished 4 F:AM 33174 unpublished 4 F: AM 33175 unpublished 4 F:AM 33176 unpublished 4 F:AM 33177 unpublished 4 F:AM 33178 unpublished 4 F:AM 33179 unpublished 4 F:AM 33180 unpublished 4 F:AM 33181 unpublished 4 F:AM 33182 unpublished 4 F:AM 33183 unpublished 4 F:AM 33184 unpublished 4 F:AM 33185 unpublished 4 F:AM 33186 unpublished 4 F:AM 33188 unpublished 4 F:AM 33189 unpublished 4 F:AM 33190 unpublished 4 F:AM 33191 unpublished 4 F:AM 33192 unpublished 4 F:AM 33193 unpublished 4 F:AM 34610 unpublished 4 F:AM 34611 unpublished 4 F:AM 34612 unpublished 4 F:AM 34613 unpublished 4 F:AM 34614 unpublished 4 F:AM 34615 unpublished 4 F:AM 34616 unpublished 4 F:AM 34617-A unpublished 4 F:AM 34617-B unpublished 4 F:AM 34617-C unpublished 4 F:AM 34617-D unpublished 4 F:AM 34617-F unpublished 4 F:AM 34617-G unpublished 4 F:AM 34617-1 unpublished 4 F:AM 34617-? unpublished 5 NMC 25892 radiocarbon age: 20,500 ± 390 yr B.P. Harington, 1980 (figs. 13-15) (1-10649: on bone) 5 UAF V-54-197 unpublished 5 USNM 372807 unpublished 6 NMC 8837 Harington, 1977 (fig. 84) 6 NMC 29229 Harington, 1977 (fig. 85) 6 USNM 2555 Osgood, 1905a (pi. 37: fig. 2; pi. 38: fig. 2; pi. 39: fig. 1; pi. 40: fig. 2) 6 USNM 2556 unpublished 6 USNM 12135 unpublished 60 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY Table 4.— Records of Symbos mapped in Figure 64 (continued). Locality Specimen No. Name No. Description Provenience 7 Dease Lake, British Columbia BCPM 680 cranium from alluvium in the vicinity of Dease Lake 8 Saanich Peninsula, British Columbia BCPM 69:014 partial cranium with partial horn cores from Butler Brothers gravel pit at Keatings Cross Road, N of Victo¬ ria, on Saanich Peninsula, Vancou¬ ver Island, 48°33'54"N, 123°25'05"W 9 Ft. Saskatchewan, Alberta UA1 uncataloged cranium with partial horn cores at Steele Brothers of Canada gravel pit, -3 mi SW of Ft. Saskatchewan. SE »/4, Sec. 14, T54, R33, W4; 53°39'40"N, 113°17'W 10 Saskatoon, Saskatchewan GMUS VM462 cranium with partial hom cores 11 Fort Qu’Appelle, Saskatchewan NMC 11859 skull Bliss Gravel Pit, Fort Qu’Appelle 11 Fort Qu’Appelle, Saskatchewan SMNH PI00.63 partial cranium with partial hom cores Bliss Gravel Pit, Fort Qu’Appelle; SWVt.SWS, 7T.21R, 13W.2 11 Fort Qu'Appelle, Saskatchewan SMNH PI 00.84 partial cranium with partial hom cores (?)Bliss Gravel Pit, Fort Qu’Appelle 11 Fort Qu’Appelle, Saskatchewan SMNH PI675.1 cranium with partial hom cores Sangsten Gravel Pit, Fort Qu’Ap¬ pelle. 14T.21R, 14W, 2 12 Modoc County, California UCMP 58219 cranium with hom cores; part of left maxillary John St. Gravel Pit, -5—6 mi N of Cedarville; SW >/4, NW >/■», Sec. 17, T43N, R16E 13 Minidoka County, Idaho IMNH 2598 cranium with hom cores Acequia Gravel Pit, 2.5 mi E of Acequia; NE 1 /4, Sec. 8, T9S, R25E, Acequia Quad, USGS 7.5' series 14 Power County, Idaho USNM 13694 partial skull with partial hom cores gravel quarry near east end of Ameri¬ can Falls Dam 14 Power County, Idaho USNM 13695 cranium with partial hom cores gravel quarry near east end of Ameri¬ can Falls Dam 15 Salt Lake County, Utah UUVP 8540 skull with hom cores Hardman Gravel Pits,N edge of Salt Lake City. NE '/a, Sec. 32, TIN, R1E, Fort Douglas Quad, USGS 7.5' series 15 Salt Lake County, Utah UUVP 8536 cranium with hom cores from -6' beneath surface in sands and gravels, (?)91 East South Temple, Salt Lake City; SW 'At, TIN, R1E, Salt Lake City North Quad, USGS 1.5' series 4 16 Salt Lake County, Utah YPM uncataloged partial cranium with hom cores Salt Lake City 17 Utah County, Utah BYUG 102 cranium with hom cores from -15' beneath terrace surface in gravels and sands, Provo City Upper Gravel Pits, near Slate Can¬ yon. SW '/a. Sec. 8, T7S, R3E, Provo Quad, USGS 7.5' series 18 Utah County, Utah BYUG 103 partial cranium with hom cores from -120' below terrace level, in built deposits of upper Lake Bon¬ neville shoreline, Grant Lloyd Gra¬ vel Pit at Utah Bay, -2 mi E of Sanlaquin 18 Utah County, Utah USNM 17914 partial cranium and hom cores from sand lens within gravel deposit, southern Utah Valley, 1 mi NE of Santaquin 4 The provenience data refer to a specimen reported by Chadboume (1871). Nelson and Madsen (1978) presumed UUVP 8536 to be that specimen, but definitive identification of the specimen as that described by Chadboume is lacking. NUMBER 66 61 Table 4.—Continued. (Locality/Specimen No. repeated from left half of table for ease of reference.) Locality No. Specimen No. Stratigraphic unit Geologic age Principal published description(s) 7 BCPM 680 Harington, 1968 (figs. 1-3) 8 BCPM 69:014 from lower half of Saanichton gravels -19,000 yr b.p. (Harington, 1975; after Halstead, 1968:1411) Harington, 1975 (figs. 7-10) 9 UA1 uncataloged probably of late Pleistocene age (Har¬ ington, 1977:901) Harington, 1975 (figs. 3,4) 10 11 11 GMUS VM462 NMC 11859 SMNH PI00.63 Riddell Member, Floral Formation 4th gravel bed, Echo Lake Gravels probably Sangamonian probably Sangamonian, possibly Wisconsinan interstadial, in age. Molluscs from sand overlying 4th gravel bed radiocarbon dated >30,000 yr B.P. (GSC-987) probably Sangamonian Skwara and Walker, in press Khan, 1970 (pis. 23-25) Khan, 1970 (pis. 28,29) 11 SMNH PI00.84 unpublished 11 SMNH PI 675.1 Khan, 1970 (pis. 26,27) 12 UCMP 58219 unpublished 13 IMNH 2598 White, 1985 (figs. 2c, 3c) 14 USNM 13694 White, 1985 14 USNM 13695 White, 1985 15 UUVP 8540 Alpine Formation Early Lake Bonneville age Nelson and Madsen, 1978 (figs. 2-5) 15 UUVP 8536 (?)Provo Formation (?)Late Lake Bonneville age Hay, 1927 (pi. 1: fig. 3) 16 17 YPM uncataloged BYUG 102 (?)Provo Formation or (?)post-Provo sediments (?)Late Lake Bonneville age (Bissell, 1963) 5 unpublished Stokes and Hansen, 1937 (fig. 1, top specimen) 18 BYUG 103 (?)Bonneville Formation (?)Medial Lake Bonneville age (Bis¬ sell, 1963) unpublished 18 USNM 17914 Alpine Formation Early Lake Bonneville age (Bissell, 1963) unpublished 5 Stokes and Hansen (1937) reported this specimen to be from gravels and sands of late Bonneville age (- Provo Formation), but Nelson and Madsen (1978), following Bissell (1963), consider the specimen to have come from fan sediments of post-Bonneville age. 62 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY Table 4.—Records of Symbos mapped in Figure 64 (continued). Locality Specimen No. Name No. Description Provenience 19 Delta County, Colorado PM 526 cranium with bases of horn cores along or near Oak Creek. Sec. 14 or 15, T13S, R96W Hells Kitchen Quad, USGS 7.5' series 20 Montezuma County, Colorado DAP 23 partial cranium with partial horn cores, complete cervical vertebral series and most of thoracic verte¬ bral series from loess on Grass Mesa. NE 'A, Sec. 7, T38N, R15W, Trimble Point Quad, USGS 7.5' series 21 McKinley County, New Mexico USNM 5100 cranium with partial horn cores Black Rocks irrigation dam site, 4.5 mi E of Zuni. Zuni Quad, USGS 7.5' series 22 Custer County, Montana Payes collection partial cranium with partial left horn core from gravel pit -12 mi E of Miles City 23 Bennett County, South Dakota Rice collection cranium with partial horn cores and caudal part of face from fine gravel lens in loess on Don Rice farm, Tuthill; NE ’A, Sec. 8, T37N.R35W 24 Aurora/Douglas County, South Dakota WHOM 18661 cranium with hom cores from gravel pit -4 mi N of Corsica 25 Cherry County, Nebraska UNSM 39000 skull from North Prong Quarry (UNSM loc. Cr-102), N side of North Branch of Middle Loup River,-12 mi NW of Mullen; NW 'A, Sec. 18, T25N, R34W 25 Cherry County, Nebraska UNSM 39001 skullcap with right hom core from North Prong Quarry (UNSM loc. Cr-102), N side of North Branch of Middle Loup River, -12 mi NW of Mullen; NW 'A, Sec. 18, T25N.R34W 26 Frontier County, Nebraska UNSM 1108-48 cranium with partial hom cores Medicine Creek Dam 27 Red Willow County, Nebraska UNSM 1112 cranium with hom cores from gravel pit near McCook 28 Furnas County, Nebraska UNSM 4-10-95 cranium with partial hom cores found during construction of Chi¬ cago, Burlington and Quincy Rail¬ road, 2 mi E of Cambridge 29 Franklin County, Nebraska UNSM uncataloged right hom core ? 30 Clay County, Nebraska UNSM 4-10-30 6 cranium with partial hom cores from sand pit on Spring Ranch 31 Cuming County, Nebraska UNSM uncataloged cranium with partial hom cores East Pit, West Point 32 Otoe County, Nebraska UNSM 20-10-04 cranium with hom cores from gravel bed-1' thick, 32' beneath surface, Eugene Munn farm 5 mi S of Nehawka and 15 mi NW of Nebraska City. NW *A, Sec. 1, T9N.R13E 33 Gage County, Nebraska UNSM 22-11-30 cranium with partial hom cores from coarse gravel, 12' beneath sur¬ face, G.O. McClung farm, 4 mi E and 2 mi S of Beatrice 34 Jefferson County, Nebraska UNSM 15-11-00 partial cranium with partial hom cores near Endicott 35 Pottawattamie County, Iowa SUI 107 cranium with hom cores from loess 12' beneath surface, 130' above Missouri R. at Council Bluffs 36 Wyandotte County, Kansas KUVP 54004 cranium with partial hom cores from N bank of Kansas R. NW ’A, SE ’A, Sec. 29T11S.R24E 36 Wyandotte County, Kansas KUVP 58013 cranium with partial hom cores from channel of Kansas R. NW 'A, Sec. 5, T12S.R23E 37 Ellsworth County, Kansas AMNH 12699 cranium with bases of hom cores (?)near Wilson 7 38 Russell County, Kansas FHSM 11545 skullcap and partial hom cores from a sand and gravel quarry along a tributary of Big Creek, 3 mi S and 3 mi E of Gorham, SW 'A, T14S, R15W 6 This specimen is a cast of the original in the Hastings Museum, Hastings, Nebraska. 7 This specimen was purchased from Jacob Fowler at Wilson, Kansas, by Charles Sternberg for E.D. Cope. There is no indication that the specimen was found at or near Wilson. NUMBER 66 63 TABLE 4.—Continued. (Locality/Specimen No. repeated from left half of table for ease of reference.) Locality Specimen No. No. Stratigraphic unit Geologic age Principal published description(s) 19 20 PM 526 DAP 23 Mesa Verde (= Sage Plain) Loess found (probably redeposited) in sedi¬ ments that were probably of Holo¬ cene age radiocarbon age: 15,970 ± 155 yr B.P. (SI-6137: on bone) McDonald, 1985a (figs. 2-6) McDonald, Neusius, and Clay, 1987 (fig- 5) 21 USNM 5100 Gidley, 1906 (figs. 1-3) 22 Payes collection unpublished 23 Rice collection unpublished 24 WHOM 18661 Pleistocene Pinsof, 1986 (fig. 15) 25 UNSM 39000 (?)Crete Sand and Silt from Terrace 4 fill □linoian (Jakway, 1961a,b); (?) post- Hlinoian (Kurten and Anderson, 1980:32) unpublished 25 UNSM 39001 (?)Crete Sand and Silt from Terrace 4 fill Hlinoian (Jakway, 1961a,b); (?)post- Ulinoian (Kurten and Anderson, 1980:32) Barbour, 1934 (figs. 173,174) 26 27 28 UNSM 1108-48 UNSM 1112 UNSM 4-10-95 unpublished Comer, 1977 (fig. 3 b) Barbour, 1931 (fig. 140) 29 30 31 32 UNSM uncataloged UNSM 4-10-30 8 UNSM uncataloged UNSM 20-10-04 Grand Island Formation Kansan (Schultz, 1934) unpublished Barbour, 1931 (fig. 144) unpublished Barbour, 1931 (fig. 142) 33 UNSM 22-11-30 Barbour, 1931 (fig. 143) 34 UNSM 15-11-00 Barbour, 1931 (fig. 141) 35 SUI107 unpublished 36 KUVP 54004 Nelson and Neas, 1980 (fig. 3 a) 36 KUVP 58013 Nelson and Neas, 1980 (fig. 4 a) 37 38 AMNH 12699 FHSM 11545 Late Pleistocene unpublished Nelson and Neas, 1980 (fig. 5 b) 8 This specimen is a cast of the original in the Hastings Museum, Hastings, Nebraska. 64 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY TABLE 4.—Records of Symbos mapped in Figure 64 (continued). Locality Specimen No. Name No. Description Provenience 39 Comanche County, Kansas FHSM 8138 cranium with partial horn cores along Salt Fork of Arkansas R., 12 mi S of Coldwater. Either NW '/4,NW V4,T34S,R18W orNE ’A.NE’Ai, T34S, R19W 40 (?)Muskogee County, Oklahoma ANSP 12995 cranium with hom cores reportedly collected by an Indian from a gravelly bluff on the Arkan¬ sas R., near Fort Gibson 41 Kaufman County, Texas SMU-SMP 69127 cranium with bases of hom cores from shallow fluvial deposit along E side of Little Brushy Creek, -2.24 km WSW of City Hall, Kaufman 42 West Feliciana Parish, Louisiana LSUMZ 17814 partial cranium and base of left hom core from stream sediments along E side of Bayou Sara, near mouth of Gales Creek 43 Bolivar County, Mississippi WMHS 85.14 cranium with partial hom cores from gravel bar in Mississippi R. W of Scott 44 Coahoma County, Mississippi Connaway collec¬ tion (#284) partial cranium with bases of hom cores from gravel bar in Mississippi R. at Friars Point 45 New Madrid County, Missouri uncataloged (lost) cranium with partial hom cores New Madrid, probably from alluvium on floodplain of Mississippi R.; specimen was “ejected by the shock of an earth quake in 1812” 46 Benton County, Missouri ANSP 12996 partial cranium (?)along Osage R., near (?)Tackner 46 Benton County, Missouri ANSP 12997 partial cranium (?)along Osage R., near (?)Tackner 46 Benton County, Missouri ANSP 12998 partial cranium (?)along Osage R., near (?)Tackner 46 Benton County, Missouri ANSP 12999 partial cranium (?)along Osage R., near (?)Tackner 46 Benton County, Missouri ANSP 13000 partial hom core (?)along Osage R., near (?)Tackner 47 Lafayette County, Missouri USNM 8361 cranium from bed of recently abandoned chan¬ nel of Missouri R., Wellington 48 Mississippi River, Missouri or Illinois unknown cranium with bases of hom cores dredged from Mississippi R. a few mi S of Grand Tower, Illinois 49 Sangamon County, Illinois Broughton collec¬ tion partial cranium with partial right hom core from gravel p>ool surrounded by clay -65' beneath surface, Sangamon Valley Sand and Gravel Company gravel pit 8.5 mi E of Springfield. SW '/4, Sec. 36, T16N, R4W, Springfield East Quad, USGS 7.5' series 50 Mason County, Illinois USNM 7800 cranium with hom cores Manito. Sec. 22, T23N, R6W, Manito Quad, USGS 15' series 51 Kenosha County, Wisconsin PM 14679 skullcap with partial left hom core near Wilmot 52 Newaygo County, Michigan GRPM 12539 cranium with left hom core and dorsal parts of face from marl pit between Croton Dam and Newaygo 53 Washtenaw County, Michigan UMMP 3450 skull from bog, 4' beneath surface of deposit, William J. Schlicht farm, about 0.5 mi NW of Manchester. Near center of NW V4, NW 1 /4, Sec. 1.T4S.R3E 54 St. Joseph County, Michigan Yoder collection skull recovered by dragline from beneath Marl Lake, on Ray Yoder property, 3 mi SE of White Pigeon. Sec. 17, T8S.R11W 55 Kalamazoo County, Michigan KPM A2146- 61:379 skull, part of right mandible, and all or part of 10 postcranial elements from marl deposit 0.5 mi S of Scotts. Sec. 25, T3S, R9W 56 La Grange County, Indiana uncataloged cranium with hom cores and parts of face from p>eat bog on Lester Egli farm, 2.5 mi N of Wolcottville. NE >/4, NE '/4, SE ’/4, Sec. 21, T36N, R10E, Wolcottville Quad, USGS 1.5' series 57 St. Joseph County, Indiana ? ? from 0.6 mi W of North Liberty NUMBER 66 65 Table 4.—Continued. (Locality/Specimen No. repeated from left half of table for ease of reference.) Locality Specimen Principal published No. No. Stratigraphic unit Geologic age description(s) 39 FHSM 8138 Late Pleistocene Nelson and Neas, 1980 (fig. 5 a) 40 ANSP 12995 Leidy, 1852b (pi. 3, pi. 4: fig. 1) 41 SMU-SMP 69127 Wisconsinan, probably dating to be¬ McDonald, 1985b (figs. 2-5) tween 24,000 and 21,000 yrs B.P., perhaps to as much as 75,000 yr B.P. 42 LSUMZ 17814 probably redeposited from sediments McDonald and Corkum, 1987 (fig. 2) of medial to late Wisconsinan age (-38,000-10,000 yrs B.P.) 43 WMHS 85.14 unpublished 44 Connaway Collec¬ unpublished tion (#284) 45 uncataloged (lost) De Kay, 1828 (pi. 6: figs. 1-3) 46 ANSP 12996 unpublished 46 ANSP 12997 unpublished 46 ANSP 12998 unpublished 46 ANSP 12999 unpublished 46 ANSP 13000 unpublished 47 USNM 8361 unpublished 48 unknown Galbreath, 1974 (fig. 1) 49 Broughton collec¬ Ray, Wills, and Palmquist, 1968 tion 50 USNM 7800 Ray, Wills, and Palmquist, 1968 51 PM 14679 unpublished 52 GRPM 12539 Frankforter, 1966 (pi. 2) 53 UMMP 3450 Case, 1915 (pis. 1,2) 54 Yoder collection Semken, Miller, and Stevens, 1964 (pi. 129: fig. 2) 55 KPM A2146- radiocarbon age: 11,100 ± 400 yr B.P. Semken, Miller, and Stevens, 1964 61:379 (M-1402: on bone) (pi. 129: fig. 3: pi. 130) 56 un cataloged Rarick and Wayne, 1969 (photo¬ graphs, pp. 10,11) 57 ? Lyon, 1926 (fig. 1) 66 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY Table 4.—Records of Symbos mapped in Figure 64 (continued). Locality Specimen No. Name No. Description Provenience 58 Kosciusko County, Indiana CMNH 11744 partial skullcap with partial horn cores found in ditch being dug in swamp near North Webster 59 Porter County, Indiana AMNH 14365 skull from -7' beneath surface in mixture of sand and clay, -6 mi E of Hebron 60 Miami County, Indiana MCHS 170.56 skull from muck on Homer Fenters farm.S of Macy, Allen Township. S '/ 2 , Sec. 24 or NE ’A, Sec. 25, T29N, R3E, Macy Quad, USGS 7.5' se- 60 Miami County, Indiana USNM 8574 skull ries Union Township 61 Montgomery County, Indiana USNM 14428 skull from fluvial sediments along Mill Creek, on Ingersol farm, Ripley Township 62 Bartholomew County, Indiana AMNH 13830 cranium washed from alluvium overlying 10'-20' of glacial gravel along East Fork of White River, near Wales- boro 63 (?)Hamilton County, Ohio UCM 37882 cranium with left horn core from “local gravels” in or near Cin¬ cinnati 64 Hamilton County, Ohio CM P55 cranium with partial horn cores from -10' beneath surface in outwash gravels, SE ’A, NE 'A, SE ’A, Sec. 10, TIN, R1E, Hooven Quad, USGS 7.5' series 65 Warren County, Ohio CM P54 cranium with partial hom cores from -14' beneath surface in gravels, near Little Miami River, S of Foster 66 Bracken County, Kentucky USNM 23548 cranium with hom cores from Ohio R. below Augusta 67 Nicholas County, Kentucky YPM 13133 cranium with bases of hom cores Blue Licks region 68 Boone County, Kentucky Be-Cr uncataloged cranium with right hom core Big Bone Lick 68 Boone County, Kentucky MCZ9117 cranium with partial hom cores Big Bone Lick (Shaler collection) 69 Spencer County, Kentucky USNM 1988 partial cranium with partial hom cores along Salt River 70 Smyth County, Virginia Space collection (#3144) cranium with partial hom cores Saltville Valley 70 Smyth County, Virginia Space collection (#3145) cranium with partial hom cores Saltville Valley 70 Smyth County, Virginia USNM 23577 cranium with partial hom cores Saltville Valley 71 Continental Shelf off New Jersey PU 16340 partial left hom core and frontal Continental Shelf, 40 mi SE of Atlan¬ tic City distributed in time and space; they do not cluster in a biologically or taxonomically meaningful way. At present, then, we consider the autochthonous North American musk oxen to be monotypic, consisting only of Boolherium bom- bifrons. Boolherium bombifrons is the largest known Pleistocene musk ox of North America—heavier, longer limbed, and proportionately shorter (craniocaudally) than Ovibos mos- chatus and, probably, Praeovibos spp. The degree of sexual dimorphism appears to have been relatively great within this species, but a more nearly definitive assessment of this condition must await the comparative study of postcranial specimens representing both sexes. The skull of B. bombifrons is relatively longer and deeper than that of Ovibos; the dorsal half of the cranium is narrow relative to the ventral half; and the orbits protrude little relative to those of Ovibos and Praeovibos. The horn cores of males are longer and deflected downward more than are those of females. The bases of the horn sheaths extended over the dorsal surface of the cranium and fused at the midline in males, but probably extended only slightly over the dorsal surface of the cranium, if at all, in females. Technical descriptions of the cranium of males (given as Boolherium cavifrons or Symbos cavifrons ) have been presented by Leidy (1852b) and Semken, Miller, and Stevens (1964); the female skull (as Bootherium bombifrons) has been most thoroughly described by Leidy (1852b). Technical descriptions of parts of the adult male postcranial skeleton have been provided by Semken, Miller and Stevens (1964), McDonald and Bartlett (1983), and McDonald, Neusius, and Clay (1987). NUMBER 66 67 Table 4. —Records of Symbos mapped in Figure 64 (continued). (Locality/Specimen No. repealed from left half of table for ease of reference.) Locality No. Specimen No. Stratigraphic unit Geologic age Principal published description (s) 58 CMNH 11744 unpublished 59 AMNH 14365 Hay, 1912 (figs. 49,50) 60 MCHS 170.56 Richards and Wepler, 1985 (fig. 1) 60 USNM 8574 unpublished 61 USNM 14428 Lyon and Hall, 1937 (pis. 1,2) 62 AMNH 13830 unpublished 63 UCM 37882 McDonald and Davis, in press (fig. 2) 64 CM P55 Wisconsinan McDonald and Davis, in press (fig. 3) 65 CM P54 Wisconsinan Anonymous, 1965:31 (photo); Me- Donald and Davis, in press (fig. 4) 66 USNM 23548 unpublished 67 YPM 13133 unpublished 68 Be-Cr uncataloged (?)Late Wisconsinan unpublished 68 MCZ9117 (?)Late Wisconsinan unpublished 69 USNM 1988 unpublished 70 Space collection unpublished (#3144) 70 Space collection unpublished (#3145) 70 USNM 23577 unpublished 71 PU 16340 Parris, 1983 (fig. 4) Systematic Hierarchy Class Mammalia Linnaeus, 1758 Order ARTIODACTYLA Owen, 1848 Family Bovidae Gray, 1821 Genus Bootherium (Harlan, 1825) Bootherium bombifrons (Harlan, 1825) “A head very different from any now known here... .An animal nearly allied to the bison,” Wistar, 1818:379-380. Bos bombifrons Harlan, 1825:271. Ovibos bombifrons. —Leidy, 1852a:71. Ovibos cavifrons Leidy, 1852a:71. [New synonymy.) Bootherium cavifrons (Leidy).—Leidy, 1852b: 12. [New synonymy.) Bootherium bombifrons. —Leidy, 1852b: 17. Ovibos priscus Riitimeyer, 1865:328. Bison appalachicolus Rhoads, 1895:248. Ovibos (Bootherium?) appalachicolus Rhoads, 1897:492. Scaphoceros tyrrelli Osgood, 1905a:173. [New synonymy.) Scaphoceros cavifrons. —Osgood, 1905a: 182. [New synonymy.) Symbos lyrelli. —Osgood, 1905b:224 [misspelling]. [New synonymy.) Symbos cavifrons. —Osgood, 1905b:224. [New synonymy.) Symbos tyrrelli. —Gidley, 1906:682. [New synonymy.) Liops zuniensis Gidley, 1906:166. Gidleya zuniensis. —Cossmann, 1907:64. [New synonymy.) Bootherium sargenli Gidley, 1908:683. Lissops zuniensis (Gidley, 1908:684). [New synonymy.) Symbos australis Brown, 1908:203. Bootherium nivicolens Hay, 1915:523. Symbols promptus? Hay, 1920:109 [misspelling]. [New synonymy.) Symbos promptus Hay, 1920:115. [New synonymy.) Symbos convexifrons Barbour, 1934:295. ?Ovibos giganteus Frick, 1937:556. [New synonymy.) 68 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY ?Ovibos zuniensis. —Frick, 1937:557. [New synonymy.] Bootherium brazosis Hesse, 1942:78. Bootherium appalachicolus. —Ray, 1966:4. Symbos giganteus. —McDonald and Bartlett, 1983:454. [New synonymy.] ? Ovibos australis. —McDonald and Bartlett, 1983:458. Original Description. —C. Wistar provided an informal description of what later became the holotype for Bootherium bombifrons in 1818 in the paper “An Account of Two Heads Found in the Morass, Called the Big Bone Lick, and Presented to the Society, by Mr. Jefferson” (Wistar, 1818). The scientific name Bos (= Bootherium) bombifrons was created by Richard Harlan in 1825 in Fauna Americana (Harlan, 1825:271). Type Specimen and Repository. — Bootherium bom¬ bifrons is monotypic. The holotype is ANSP 994, a cranium with the greater parts of both horn cores. This specimen is located in the Department of Geology, Academy of Natural Sciences, Philadelphia, Pennsylvania. Type Locality. —Big Bone Lick, Boone County, Ken¬ tucky. Distribution. — Bootherium bombifrons was the most widespread of the musk oxen to inhabit North America during the Quaternary; the other taxa were Praeovibos spp. and Ovibos moschatus. Of these taxa, only Bootherium bombifrons was autochthonous to North America. Bootherium bombifrons is known from about the Irving- tonian-Rancholabrean boundary (or, from -500,000 yr B.P.) to about 10,000 yr B.P. Remains of this species have been recovered from throughout Anglo-America except the north¬ eastern quarter, and the extreme southwestern and southeastern corners, of the region. Diagnosis. —Horn cores subcircular to semielliptical in cross section at the base—ventral surface semicircular in rostrocaudal cross section, dorsal surface semicircular through flat to concave in rostrocaudal cross section. Horn cores emanate from lateral edge of dorsal surface of cranium, approximately midway between occipital and orbits. Horn cores emanate in lateral direction, then trend downward, forward, and outward becoming more nearly round distally. Tips terminate rostral to level of bases of horn cores, near or at level of orbits. Diameter of base of horn core along rostrocaudal axis ranges from 61 mm to 146 mm (N = 121). Length of horn core, base (burr line) to tip along dorsal surface, ranges from 210 mm to >400 mm (N = 16). Dorsal surface of cranium flexed; point of flexion near parietofrontal juncture. Orbits situated below level of dorsal surface of frontals, and extend but little beyond postorbital margin of frontals. Mean postorbital widthiorbital width ratio is .64 (N = 33). Line of frontoparietotemporal sutures is typically relatively straight and oriented horizontally. Nasofrontal suture line shaped like flat-bottomed V. Occipital surface about as deep as wide; silhouette of occipital surface is bell-shaped. (In ventral view, basioccipital typically is in shape of pentagonal shield with caudal half of lateral edges lying nearly parallel to each other and the midline, and the rostral half of lateral edges converging rostrally toward the midline. A ridge of bone oriented rostrocaudally typically occurs over part of the midline. The shape and surface configuration of the basioccipi¬ tal bone is often considered to be diagnostic, but specimens of Bootherium bombifrons are known in which the basioccipital is indistinguishable from the same element in typical specimens of Ovibos moschatus. Conversely, specimens of Ovibos moschatus are known that possess basioccipital bones indistin¬ guishable from the same element in specimens of Bootherium bombifrons .) Superior molars typically are without (1) cementum, (2) accessory style or rib external to enamel wall between protocone-hypocone, and (3) accessory internal fossette within dentine field at juncture of protocone-hypocone. (Exceptions to 1 and 2 are rare, and to 3 are uncommon.) Differential Diagnosis of Males. —Horn cores semiel¬ liptical in cross section at base—dorsal surface flat to concave in rostrocaudal cross section. Bases of horn cores fused to both frontal and parietal bones, and burr line typically blurred by deposits of secondary bone. Diameter of base of horn core along rostrocaudal axis ranges from 86 mm to 146 mm (N = 94; x = 109 mm). Length of horn core, base (burr line) to tip along dorsal surface, ranges from 206 mm to >400 mm (N = 16; x = 266 mm—this mean is based on a range of 206-369 mm; the longest horn cores known are incomplete, with remaining sections being about 400 mm in length). Dorsal surface of cranium typically covered with deposits of secondary bone (both dense and exostotic bone) from about level of orbits to about level of occiput. Differential Diagnosis of Females.— Horn cores sub¬ rounded to semielliptical in cross section at base—dorsal surface semicircular to flat in rostrocaudal cross section at base. Bases of horn cores fused with frontals only, and preserve distinct burr line. Diameter of horn core at base along rostrocaudal axis ranges from 61 mm to 96 mm (N = 27; x - 74 mm). Length of horn core, base (burr line) to tip along dorsal surface, ranges from 210 mm to 356 mm (N = 5; x = 263 mm). Dorsal surface of cranium with little or no deposits of secondary bone. If present, secondary bone is more extensive at level of rostral edge than at medial or caudal edge of base of horn cores. Differential Diagnosis of Other North American Musk Oxen. —Horn cores of Ovibos moschatus compressed dorsoventrally; elliptical to semielliptical in cross section at base along rostrocaudal axis; emanate in ventro-lateral direc¬ tion; and are straight. Tip of horn core terminates below, or just rostral to, level of base of horn core. Diameter of base of horn core along rostrocaudal axis ranges from 62 mm to 204 mm (N = 41). Length of horn core, base (burr line) to tip along dorsal surface, ranges from 180 mm to 311 mm (N = 16). Dorsal surface of cranium not markedly flexed between occiput and level of orbits; secondary bone typically does not coalesce over midline. Tubular orbits extend relatively far lateral to postorbi¬ tal edges of frontal bones. Mean postorbital width:orbital width ratio is .54 (N = 34). Nasofrontal suture line shaped like the letter W. Silhouette of occipital surface is semielliptical; NUMBER 66 69 transverse width typically is greater than dorsoventral depth. Superior molars typically (1) lack cementum, (2) contain accessory rib between protocone-hypocone, and (3) contain circular accessory enamel eyelet within dentine field near juncture of protocone-hypocone. Horn cores of Praeovibos spp. are triangular to subelliptical (with long axis oriented dorsocaudally-ventrorostrally) in cross section at the base. Base of horn core is fused with dorsolateral angle of cranium, and rises above dorsal surface of cranium. Horn cores emanate in a ventrolateral and rostral direction; straight or curved slightly rostrad; tips are below, or rostral to, level of base of horn core. Little or no secondary bone is deposited on dorsal surface of cranium medial to base of horn core. Frontoparietal sinuses are shallow. Dorsal surface of cranium is not markedly flexed between occiput and level of orbits. Orbits are markedly tubular and extend far lateral to postorbital edges of frontals. The postorbital width:orbital width ratio in the only specimen for which measurements are available is .45. Appendix I Abbreviations for Institutional, Departmental, and Private Collections Used in This Study A AMNH ANSP BC BCPM BLM BM(NH) BYUG CM CMNH DAP RAM FHSM GMUS GRPM HM IMNH KPM KUMNH LACM LSUMZ Institutional Collections Frick Collection (field numbers). Depart¬ MCHS ment of Vertebrate Paleontology, Ameri¬ can Museum of Natural History, New MCZ York, New York American Museum of Natural History, New NMC York, New York Academy of Natural Sciences of Philadel¬ PM phia, Philadelphia, Pennsylvania Behringer-Crawford Memorial Museum, Covington, Kentucky British Columbia Provincial Museum, Victo¬ ria, British Columbia Fairbanks District, Bureau of Land Manage¬ PU ment, Fairbanks, Alaska ROM British Museum (Natural History), London, England SMNH Department of Geology Museum, Brigham Young University, Provo, Utah Cincinnati Museum of Natural History, Cin¬ SMU-SMP cinnati, Ohio Carnegie Museum of Natural History, Pitts¬ SUI burgh, Pennsylvania Anasazi Heritage Museum, Cortez, Colorado Frick Collection (cataloged specimens). Department of Vertebrate Paleontology, TAMC American Museum of Natural History, UA1 New York, New York Sternberg Memorial Museum, Fort Hays UAF State University, Hays, Kansas Geology Museum, University of Saskatche¬ UCM wan, Saskatoon, Saskatchewan Grand Rapids Public Museum, Grand Rap¬ UCMP ids, Michigan Haslar Museum, England UMMP Idaho Museum of Natural History, Idaho State University, Pocatello, Idaho UNSM Kalamazoo Public Museum, Kalamazoo, Michigan Museum of Natural History, University of Kansas, Lawrence, Kansas USNM Natural History Museum of Los Angeles County, Los Angeles, California UUVP Museum of Zoology, Louisiana State Uni¬ versity, Baton Rouge, Louisiana UVP Miami County (Indiana) Historical Society Museum, Courthouse, Peru, Indiana Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts National Museum of Natural Sciences, Ot¬ tawa, Ontario Field Museum of Natural History, Chicago, Illinois Princeton University Museum of Natural History, Princeton University, Princeton, New Jersey (vertebrate paleontology col¬ lections now at Peabody Museum of Natural History, Yale University, New Haven, Connecticut) Royal Ontario Museum, Toronto, Ontario Museum of Natural History, Regina, Saskatchewan Shuler Museum of Paleontology, Depart¬ ment of Geology, Southern Methodist University, Dallas, Texas Museum of Natural History, University of Iowa, Iowa City, Iowa Texas A&M College (now University) col¬ lections (vertebrate paleontology collec¬ tions now at Texas Memorial Museum, University of Texas, Austin, Texas) University of Alberta, Edmonton, Alberta Otto Geist Museum, University of Alaska, Fairbanks, Alaska Department of Geology Museum, University of Cincinnati, Cincinnati, Ohio Museum of Paleontology, University of California, Berkeley, California Museum of Paleontology, University of Michigan, Ann Arbor, Michigan University of Nebraska State Museum, Uni¬ versity of Nebraska, Lincoln, Nebraska former United States National Museum, collections deposited in the National Mu¬ seum of Natural History, Smithsonian Institution, Washington, D.C. Utah Museum of Natural History, University of Utah, Salt Lake City, Utah Antiquities Section, Division of State His¬ tory, Salt Lake City, Utah 70 NUMBER 66 71 WHOM W.H. Over State Museum, Vermillion, South Dakota WMHS Winterville Mounds Historic Site, Green¬ ville, Mississippi WSU Laboratory of Anthropology, Washington State University, Pullman, Washington YPM Peabody Museum of Natural History, Yale University, New Haven, Connecticut Private Collections (Most recent date of record in parentheses) Broughton Robert D. Broughton, Springfield, Illinois (1967) Connaway John Connaway, Archaeological Survey, Mississippi Department of Archives and History, Clarksdale, Mississippi (1988) McKay McKay Collection, Archaeological Survey, Mississippi Department of Archives and History, Clarksdale, Mississippi (1988) Payes Mitchell L. Payes, Tucson, Arizona (1974) Rice Don Rice, Tuthill, South Dakota (1985) Space Ralph Space, Sussex, New Jersey (1984) Stephens Garland S. Stephens, Wytheville, Virginia (1965) Widel Phillip Widel, Blackwater, Missouri (1967) Yoder Ray Yoder, White Pigeon, Michigan (1964) Appendix II Chronology of Nominal Species Referable to Musk Oxen in the Genera Bootherium, Symbos, and Gidleya 1. Bos (= Bootherium, Ovibos ) bombifrons Big Bone Lick, Kentucky ANSP 994; cranium with partial horn cores Harlan, 1825 Stands as senior name in the group. 2. Bootherium (= Ovibos, Scaphoceros, Symbos) cavifrons Near Fort Gibson, Oklahoma ANSP 12995; cranium with partial horn cores Leidy, 1852b Referred, this paper, to B. bombifrons. 3. Ovibos maximus Eschscholtz Bay, Alaska HM 90/2; abraded axis Richardson, 1852 Stands; generic identity uncertain, but probably Ovibos. 4. Bison (= Bootherium, Ovibos) appalachicolus Durham Cave, Bucks County, Pennsylvania ANSP 29; cranial and right horn core fragment Rhoads, 1895 Referred to B. sargenti by Ray, 1966a. 5. Scaphoceros (= Symbos) tyrrelli Bonanza Creek, Yukon Territory USNM 2555; nearly complete skull Osgood,1905a Referred, this paper, to B. bombifrons. 6. Liops (= Gidleya, Lissops, Ovibos) zuniensis Black Rocks, New Mexico USNM 5100; extensively abraded cranium with partial horn cores Gidley, 1906 Referred, this paper, to B. bombifrons. 7. Bootherium sargenti Moorland Swamp, Michigan GRPM 11-423-3101; skull cap with horn cores Gidley, 1908 Referred to S. cavifrons by Allen, 1913; returned to Bootherium by Hay, 1914; referred, this paper, to B. bombifrons. 8. Symbos (= ?Ovibos) australis Conard Fissure, Arkansas AMNH 11828; 3 molar teeth Brown, 1908 Referred to S. cavifrons by Allen, 1913. 9. Bootherium nivicolens Eschscholtz Bay, Alaska USNM 2324; skullcap with horn cores Hay, 1915 Referred to B. sargenti by Harington, 1977. 10. Symbos prompt us Afton, Oklahoma USNM 9120; upper left third molar Hay, 1920 Referred, this paper, to B. bombifrons. 11. Symbos convexifrons Cherry County, Nebraska UNSM 39001; skullcap with right horn core Barbour, 1934 Referred to S. cavifrons by Jakway, 1961b. 12. Ovibos (= Symbos) giganteus Near Fairbanks, Alaska AMNH F:AM 30498; right humerus Frick, 1937 Referred, this paper, to B. bombifrons. 13. Bootherium brazosis Brazos River, border of Brazos County, Tfexas TAMC 2553; partial cranium with partial horn cores Hesse, 1942 Referred to B. sargenti by Ray, 1966b. 72 Appendix III Radiocarbon Dates on Bootherium and Symbos Specimens Bootherium SI-851 1. a. A-293-5268 Fairbanks Creek, Alaska 17,695 ± 445 yr B.P P6w6,1975 Hair SI-454 17,210 ± 500 yrB.P. Pewe, 1975; McDonald, 1984b 4. NMC 25892 Lost Chicken Creek, Alaska Bone 1-10649 b. A-293-5268 Fairbanks Creek, Alaska 20,500 ± 390 yr B.P. Harington, 1980 Tissue from beneath scalp SI-455 24,140 ±2,200 yrB.P. Pewe, 1975; McDonald, 1984b 5. DAP 23 Grass Mesa, Colorado Bone SI-6137 2. RAM 30508 Creek near Fairbanks 15,970 ± 155 yr B.P. McDonald, Neusius, and Clay, 1987 Symbos Horn sheath SI-292 22,540 ± 900 yr B.P. Pewe, 1975 6. KPM A2146-6L379 Scotts, Michigan Bone M-1402 11,100 ±400 yr B.P. 1. A-204-4254 Semken, Miller, and Stevens, 1964 Little Eldorado Creek, Alaska Fecal material SI-291 >40,000 yr B.P. Pewe, 1975 7. UMMP 34124 Climax, Michigan Bone M-639 13,200 ± 600 yr B.P. 2. RAM 33124 Upper Cleary Creek, Alaska Horn sheath SI-850 25,090 ± 1070 yr B.P. Pewe, 1975 Hibbard and Hinds, 1960 Notes: This number was given to three vertebrae (atlas, axis, and 3rd cervical) of a large musk ox that was determined to be Symbos cavifrons on the basis of the large atlas fitting the Symbos cavifrons skull (UMMP-3450) from the Schlecht farm in 3. RAM A-651-3006 Dome Creek, Alaska Horn sheath Washtenaw County, Michigan. The atlas was considered to be too large for Ovibos and Booth¬ erium (Hibbard and Hinds, 1960). 73 Literature Cited Allen, J. A. 1912. The Probable Recent Extinction of the Muskox in Alaska. Science, new series, 36(934):720-722. 1913. Ontogenetic and Other Variations in Muskoxen, with a Systematic Review of the Muskox Group, Recent and Extinct. Memoirs of the American Museum of Natural History, new series, 1(4): 101-226, plates 11—18,45 figures, 21 tables. Anonymous 1965. Muskox Skull, Killer Wasps Donated to Museum Here. Cincinnati Post and Times-Star, 5 September^ 1,1 figure. Barbour, E.H. 1931. The Musk-oxen of Nebraska. The Nebraska Slate Museum Bulletin, 1 (25):211—233,15 figures. 1934. A New Ovibovine, Symbos convexifrons, sp. nov. The Nebraska State Museum Bulletin, 1 (37):295—298,2 figures. Bensley, B.A. 1923. A Muskox Skull from Iroquois Beach Deposits at Toronto: Ovibos proximus, sp. nov. University of Toronto Studies, Biological Series, 23: 11 pages, 2 plates, 1 table. Bis sell, H J. 1963. Lake Bonneville: Geology of Southern Utah Valley, Utah. United States Geological Survey Professional Paper, 257-B:101-130, figures 23-27, plate 5,12 tables. 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The Extinct Mammalian Fauna of Dakota and Nebraska, Including an Account of Some Allied Forms from Other Localities, Together with a Synopsis of the Mammalian Remains of North America. Journal of the Academy of Natural Sciences of Philadelphia, series 2, 7 : 472 pages, 1 figure, 30 plates, tables. [Presented to Academy meeting, 25 January 1870.] 76 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY Lonnberg, E. 1900. On the Structure and Anatomy of the Musk-Ox ( Ovibos moschatus). Proceedings of the Zoological Society of London, 1900(19 June):686-718,10 figures, 1 table. Lydekker, R. 1885. Catalogue of the Fossil Mammalia in the British Museum (Natural History), Part II: Containing the Order Ungulata, Suborder Artiodac- tyla. xxii + 324 pages, 39 figures. 1898. Wild Oxen, Sheep, and Goats of All Lands, Living and Extinct, xiv + 318 pages, 61 figures, 27 plates. London: R. Ward. Lyman, R.L., and S.D. Livingston 1983. Late Quaternary Mammalian Zoogeography of Eastern Washington. Quaternary Research, 20:360-373,1 figure, 5 tables. Lyon, M.W., Jr. 1926. A Specimen of the Extinct Musk-ox, Symbos cavifrons (Leidy) from North Liberty, Indiana. Proceedings of the Indiana Academy of Science, 35(for 1925):321-324,1 figure, 1 table. Lyon,M.W.,Jr., and F.T. Hall 1937. Skull of Musk-ox, Genus Symbos, from Montgomery County, Indiana. American Midland Naturalist, 18(4):608-611, plates 1-2,1 table. Martin, L.D. 1972. The Microtine Rodents of the Mullen Assemblage from the Pleistocene of North Central Nebraska. Bulletin of the University of Nebraska State Museum, 9(5): 173—182,3 figures, 1 table. McDonald, H.G., and R.A. Davis In press. Fossil Musk-oxen of Ohio. Canadian Journal of Zoology. McDonald, J.N. 1981. North American Bison: Their Classification and Evolution, xii + 316 pages, 38 plates, 104 figures, 75 tables. Berkeley: University of California Press. 1984a. The Saltville, Virginia, Locality: A Summary of Research and Field Trip Guide. 45 pages, 5 figures, 1 table. Charlottesville: Virginia Division of Mineral Resources. 1984b. An Extinct Muskox Mummy from near Fairbanks, Alaska: A Progress Report. In D.R. Klein, R.G. White, and S. Keller, editors. Proceedings of the First International Muskox Symposium, Biologi¬ cal Papers of the University of Alaska, Special Report, 4:148-152, 2 figures, 1 table. 1985a. Symbos cavifrons (Artiodactyla: Bovidae) from Delta County, Colorado. Great Basin Naturalist, 45(3):455-461,6 figures, 1 table. 1985b. A Record of Symbos (Artiodactyla: Bovidae) from Kaufman County, Texas. Texas Journal of Science, 37(4):311-320,5 figures, 1 table. 1986. Classification and Zoogeography of the North American Ovibovines [Abstract]. AAG '86—Twin Cities, Abstracts, 50. Washington, D.C.: Association of American Geographers. McDonald, J.N., and C.S. Bartlett, Jr. 1983. An Associated Musk Ox Skeleton from Saltville, Virginia. Journal of Vertebrate Paleontology, 2(4):453-470,10 figures, 6 tables. McDonald, J.N., and K.C. Corkum 1987. A Woodland Musk Ox, Symbos cavifrons (Artiodactyla: Bov¬ idae), from Bayou Sara, Louisiana. Southwestern Naturalist, 32(1): 139-143,2 figures, 1 table. McDonald, J.N., S.W. Neusius.and V.L. Clay 1987. An Associated Partial Skeleton of Symbos cavifrons (Artiodactyla: Bovidae) from Montezuma County, Colorado. Journal of Paleontol¬ ogy, 61(4):831—843, 8 figures, 5 tables. McDonald, J.N., and C.E. Ray 1987. Bootherium bombifrons, the Autochthonous Low-Homed Musk Ox of Pleistocene North America [Abstract]. Second International Muskox Symposium, Abstracts, P22. Saskatoon: Western College of Veterinary Medicine and University of Saskatchewan. In press. Bootherium bombifrons, the Autochthonous Musk Ox of Pleistocene North America. Proceedings of the Second International Muskox Symposium. Moigne, A.-M. 1984. The Giant Muskox of the Arago Cave, Tautavel, France. In D.R. Klein, R.G. White, and S. Keller, editors, Proceedings of the First International Muskox Symposium. Biological Papers of the Univer¬ sity of Alaska, Special Report, 4:145-147,2 figures. Moya-Sola,S., J. Agusti, J. Gibert.and J. Pons-Moya 1981. El yacimiento cuatenario de Venta Micena (Espana) y su importan- cia dentro de las asociaciones faumsticas del Pleistoceno inferior europeo. Paleontologia i Evolucio, 16:39-53,2 plates, 5 tables. Neas, J.F. 1986. A Systematic Review of Symbos and Bootherium (Artiodactyla, Bovidae), with Notes on Bootherium from Natural Trap Cave, Wyoming, iv + 84 pages, 14 figures, 2 tables. Master’s thesis, Department of Systematics and Ecology, University of Kansas. [Thesis defended 28 August 1985.] Neas, J.F., and R.S. Hoffmann 1987. Budorcas taxicolor. Mammalian Species, 277(27 February): 7 pages, 3 figures. Neas, J.F., and G. Parker 1987. A Specimen of Bootherium bombifrons (Artiodactyla, Bovidae) from Northwest Missouri. Current Research in the Pleistocene, 4:116-118,1 figure. Nelson, M.E., and J.H. Madsen, Jr. 1978. Late Pleistocene Musk Oxen from Utah. Transactions of the Kansas Academy of Science, 81(4):277-295,5 figures,3 tables. 1987. Occurrence of the Musk Ox, Symbos cavifrons, from Southeastern Idaho and Comments on the Genus Bootherium. Great Basin Naturalist, 47(2):239-251,14 figures. Nelson, M.E., and J. Neas 1980. Pleistocene Musk Oxen from Kansas. Transactions of the Kansas Academy of Sciences, 83(4):215-229,6 figures, 2 tables. Nowak, R.M., and J.L. Paradiso 1983. Walker's Mammals of the World. 4th edition, 2 volumes. Baltimore, London: Johns Hopkins University Press. [Volume I: xlvi, 1—568, xlvii-lxi; volume II: x, 569-1362, xi-xxvii.] Osgood, W.H. 1905a. Scaphoceros tyrrelli, an Extinct Ruminant from the Klondike Gravels. Smithsonian Miscellaneous Collections, 48(1589): 173— 185, plates 37-42,1 table. 1905b. Symbos, a Substitute for Scaphoceros. Proceedings of the Biological Society of Washington, 18:223—224. Ozeretskovsky.N. 1811. R6marques sur le crane du bison musque. Memoires de TAcademie des Sciences de St. Petersburg, 3:215-219,1 plate. [Not seen.] Pallas, S.P. 1773. De reliquiis Animalium exoticorum per Asiam borealem repertis complementum. Novi commentarii Academiae scientiarum imperi- alis Petropolitanae, 17:576-606, plates 15-17. [Not seen.] Parris, D.C. 1983. New and Revised Records of Pleistocene Mammals of New Jersey. The Mosasaur, 1:1-21,4 figures, 1 table. Pennant, T. 1781. History of Quadrupeds. Volume I, xxiv + 284 pages, 32 plates. London: B. White. [Third edition, 1793, seen.] 1784. Arctic Zoology. Volume I, Introduction, Class I: Quadrupeds. [12] + CC + [6] + 186 pages, 8 plates, frontispiece. London: Henry Hughs. Peterson, O. A. 1926. The Fossils of the Frankstown Cave, Blair County, Pennsylvania. Annals of the Carnegie Museum, 16(2):249—314, plates 17-25, 10 figures, 3 tables. P6w6, T.L. 1975. Quaternary Geology of Alaska. United Slates Geological Survey Professional Paper, 835: v + 145 pages, 45 figures, 1 plate, 14 tables. Pewe, T.L., and D.M. Hopkins 1967. Mammal Remains of Pre-Wisconsin Age in Alaska. In D.M. NUMBER 66 77 Hopkins, editor, The Bering Land Bridge, pages 266-270, 1 table. Stanford: Stanford University Press. Pinsof, J.D. 1986. The Pleistocene Vertebrate Fauna of South Dakota, xvii + 298 pages, 16 figures, 27 tables. Master’s thesis, Department of Geology and Engineering, South Dakota School of Mines and Technology. Rarick.R.D., and WJ. Wayne 1969. The Wolcottville Skull. Outdoor Indiana, 34(1):10—11,2 figures. Ray.C.E. 1966a. The Identity of Bison appalachicolus. Notulae Naturae, 384: 7 pages, 2 figures. 1966b. The Status of Boolherium brazosis. Texas Memorial Museum, The Pearce-Sellards Series, 5: 7 pages, 2 figures. 1983. Outerbank Ovibovine Adds Link to Musk Ox Research. Whale¬ bones, 15:3,1 figure. Ray.C.E., B.N. Cooper,and W.S. Benninghoff 1967. Fossil Mammals and Pollen in a Late Pleistocene Deposit at Saltville, Virginia. Journal of Paleontology, 41(3):608-622, plates 65-66,4 figures, 6 tables. Ray, C.E..D.L. Wills, and J.C. Palmquist 1968. Fossil Musk Oxen of Illinois. Illinois State Academy of Science Transactions, 61(3):282-292,5 figures. Rhoads, S.N. 1895. Distribution of the American Bison in Pennsylvania, with Remarks on a New Fossil Species. Proceedings of the Academy of Natural Sciences of Philadelphia, 47:244—248. 1897. Notes on Living and Extinct Species of North American Bovidae. Proceedings of the Academy of Natural Sciences of Philadelphia, 49:483-502, plate 12. Rice, H.C., Jr. 1951. Jefferson’s Gift of Fossils to the Museum of Natural History in Paris. Proceedings of the American Philosophical Society, 95(6):597- 627, 15 figures, 1 table. Richards, R.L., and W.R. Wepler 1985. Extinct Woodland Muskox, Symbos cavifrons, Cranium from Miami County, North Central Indiana. Proceedings of the Indiana Academy of Science, 94:667-671,1 figure, 1 table. Richardson, J. 1852. The Zoology of the Voyage of HM.S. Herald, under the Command of ' Captain Henry Kellett,RN., CJJ., during the Years 1845—51: Fossil Mammals. 140 pages, 24 plates, tables. London: Reeve and Co. [Complete work, including living vertebrates, and three additional pages on fossil mammals, published 1854.] Romer, A.S. 1966. Vertebrate Paleontology. Third edition, ix + 468 pages, 443 figures, 4 tables. Chicago: University of Chicago Press. Riitimeyer, L. 1865. Beitrage zu einer Palaeontologischen Geschichte der Wiederkauer, Zunachst an Linne’s Genus Bos. Verhandlungen der Naturforschen- den Gesellschaft in Basel, 4(2):299-354. [Received at Smithsonian Institution 2 April 1866.] Ryziewicz, Z. 1933. Ovibos recticornis n. sp. ein Beitrag zur Systematik der Unterfamilie Ovibovinae. Bulletin de I'Academie Polonaise des Sciences el des Lettres, Classe des Sciences Mathematiques el Naturelles, Series B (Sciences Naturelles) (2), 1-5:71-87, plate 5,5 tables. 1955. Systematic Place of the Fossil Musk-ox from the Eurasian Diluvium. Prace Wroclawskiego Towarzyslwa Nauto we go, series B, 49: 74 pages, 55 figures, 51 tables. Schultz, C.B. 1934. The Pleistocene Mammals of Nebraska. Bulletin of the Nebraska State Museum, 1(41 ):357—393,2 tables. Semken, H.A., B.B. Miller, and J.B. Stevens 1964. Late Wisconsin Woodland Musk Oxen in Association with Pollen and Invertebrates from Michigan. Journal of Paleontology, 38(5):823-835,2 figures, plates 129-132,4 tables. Sher.A.V. 1974. Pleistocene Mammals and Stratigraphy of the Far Northeast USSR and North America. International Geology Review, 16(7): 1-89; (8):90—121; (9):122-206; (10):207-284, i-vi, 43 figures, plates 1-30, 40 tables. Skwara, T.,and E.G. Walker In press. Extinct Muskox and Other Additions to the Late Pleistocene Riddell Fauna (Riddell Member, Floral Formation; Late Ranchola- brean). Saskatoon, Canada. Canadian Journal of Earth Sciences. Smith, C.H. 1827. Supplement to the Order Ruminanlia. In Edward Griffith, Charles Hamilton Smith, and Edward Pidgeon, The Class Mammalia Arranged by the Baron Cuvier, with Specific Descriptions, 4:33— 428,51 plates. [Reprint 1978, New York: Amo Press.] Staudinger, W. 1908. Praeovibos priscus, nov. gen. et nov. sp.,ein Vertreter einer Ovibos nahestehenden Gattung aus dem Pleistocan Thiiringens. Centralblatt fur Mineralogie.Geologie und Palaontologie, 1908(16):481—502,4 figures, 2 tables. Stokes, W.L., and G.H. Hansen 1937. Two Pleistocene Musk-Oxen from Utah. Utah Academy of Sciences, Arts and Letters, 14:63-65,1 figure. Tener, J.S. 1965. Muskoxen in Canada: A Biological and Taxonomic Review. Canadian Wildlife Service Monograph, 2: 166 pages, 7 photographs, 1 figure, 72 tables, 1 map. Troxell, E.L. 1915. A Fossil Ruminant from Rock Creek, Texas, Preptoceras mayfieldi sp. nov. The American Journal of Science, 40:479-^182,3 figures, 1 table. Walker, D.N. 1982. A Late Pleistocene Ovibos from Southeastern Wyoming. Journal of Paleontology, 56(2):486-491,4 figures, 1 table. White, J. A. 1985. Late Pleistocene Musk Oxen from Southern Idaho. Tebiwa, 22:64-71,4 figures, 2 tables. Wistar.C. 1818. An Account of Two Heads Found in the Morass, Called the Big Bone Lick, and Presented to the Society, by Mr. Jefferson. Transactions of the American Philosophical Society, new series, 1 (31):375-380, plates 10-11. 6 U.S. GOVERNMENT PRINTING OFFICE: 1989-241-726/60050 REQUIREMENTS FOR SMITHSONIAN SERIES PUBLICATION Manuscripts intended for series publication receive substantive review (conducted by their originating Smithsonian museums or offices) and are submitted to the Smithsonian Institution Press with Form SI-36, which must show the approval of the appropriate authority designated by the sponsoring organizational unit. Re¬ quests for special treatment—use of color, foldouts, case-bound covers, etc.—require, on the same form, the added approval of the sponsoring authority. 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