READINGS ON THE EVOLUTION OF THE HORSE

The following are the technical publications which form the background of information used to compileboth “evolution” articles posted here at the ESI Knowledge Base. This is by no means a completebibliography of all the published research that has been done upon fossil horses, but nevertheless it isbetter than 30 pages long. The study of the evolution, biogeography, anatomy, embryology,classification, and functional morphology of horses is not only an old field but one that has fascinatedmany workers. It is best to regard this list as a sample which shows:

Who the major workers have been, both in the past and recently

Workers who have had long and productive careers (published over a long period of time)

Areas of controversy (similar titles by multiple authors at nearly the same time)

The names of the most important journals (where it would be productive to go for furtherreading)

If you want to pursue the technical literature, you should print this bibliography out and take it to thelibrary with you; you may find that this saves you a great deal of time.

The ordinary public library probably will not have, or be able to locate, most of these listings; you willhave to access either a University library or a library within a large Museum of Natural History, such asthe American Museum in New York City, the British Museum in London, the National Museum ofCanada in Toronto, the National Museum of Mexico in Mexico City, The University of California atBerkeley, The University of Florida at Gainesville, The University of Michigan at Ann Arbor, TheUniversity of Kansas at Lawrence, The University of Nebraska at Lincoln, or the U.S. NationalMuseum/Smithsonian Institution in Washington, D.C. Visiting a major museum is a good plan, anyway,if the subject of horses and their fossil and living relatives fascinates you.

Online Internet listings will also be of assistance. Major sources:

The Library of Congress: http://catalog.loc.gov/

The American Museum of Natural History library: http://digitallibrary.amnh.org/dspace/

The University of California Libraries: http://libraries.universityofcalifornia.edu/search/

The British Museum (Natural History) Earth Science Library: http://www.nhm.ac.uk/research-curation/library/earth-science-library/index.html

The Geological Society of America publications index: http://www.geosociety.org/pubs/

See also the Society of Vertebrate Paleontology (SVP) website: http://www.vertpaleo.org/publications/palaeontologia.cfm

Abusch-Siewert, S. 1983. Gebissmorphologische Untersuchungen an eurasiatischen Anchitherien(Equidae, Mammalia) unter besonder Berücksichtigung der Fundstelle Sandelzhausen, CourirForschungsinstitute Skenenberg 62:1-361.

Agassiz, L. and A. Gould. 1851. Principles of Zoology. Gould and Lincoln Publishers, Boston.

Allen, J.A. 1878. The geographical distribution of mammals. U.S. Geological Survey 4:313-376.

Anderson, E. 1984. Who’s who in the Pleistocene: a mammalian bestiary, in P.S. Martin and R.G. Klein,eds., Quaternary Extinctions: A Prehistoric Revolution, The University of Arizona Press, Tucson, pp.40-89.

Arambourg, C. and J. Piveteau. 1929. Les vertébrés du Pontian de Salonique. Ann. Paléont. 18:59-138.

Archibald, J.D., P.D. Gingerich, E.H. Lindsay, W.A. Clemens, D.W. Krause, and K.D. Rose. 1987.First North American land mammal ages of the Cenozoic era, in M. O. Woodburne, ed., CenozoicMammals of North America: Geochronology and Biostratigraphy, University of California Press,Berkeley, pp. 24-76,

Axelrod, D.I. 1937. A Pliocene flora from the Mount Eden beds, southern California. Carnegie Instituteof Washington Publication no. 476: 127-183.

Ayala, F.J. 1988. Can “progress” be defined as a biological concept? in M.H. Nitecki, ed., EvolutionaryProgress, University of Chicago Press, Chicago, pp. 75-96.

Azzaroli, A. 1982. On Villafranchian Palaearctic Equus and their allies, Palaeontographica Italia, NewSeries 72:74-97.

Azzaroli, A. 1988. On the equid genera Dinohippus Quinn 1955 and Pliohippus Marsh 1874. Boll. Soc.Paleont. Italiana 27:61-72.

Azzaroli, A. 1990. The genus Equus in Europe, in E.H. Lindsay, V. Fahlbusch, and P. Mein, eds.,European Neogene Mammal Chronology, Plenum Press, New York, pp. 339-356.

Bader, R.S. 1956. A quantitative study of the Equidae of the Thomas Farm Miocene. Bulletin of theMuseum of Comparative Zoology, 115:47-78.

Barbour, E.H. 1914. A new fossil horse, Hypohippus matthewi. Nebraska Geological Survey Bulletin,4(10):169-173.

Barry, J.C., E.H. Lindsay, and L.L. Jacobs. 1982. A biostratigraphic zonation of the middle and upperSiwaliks of the Potwar Plateau of northern Pakistan. Palaeogeography, Palaeoclimatology,Palaeoecology. 37:95-130.

Bennett, D.K. 1980. Stripes do not a zebra make, Part I: A cladistic analysis of Equus. SystematicZoology, 239(2):271-294.

Bennett, D.K. 1984. Cenozoic rocks and faunas of north-central Kansas, with an appendix concerningtaxonomy and evolution in the genus Equus. The University of Kansas Department of Systematics andEcology, thesis in partial fulfillment of the requirements for the Ph.D., Lawrence, Kansas.

Bennett, D.K. 1988. The ring of muscles. Equus Magazine, 121:36-42.

Bennett, D.K., and R.S. Hoffmann. 1999. Equus caballus, Mammalian Species of the AmericanSociety of Mammalogists, no. 628 pp. 1-14.

Benton, M.J. 1990. Vertebrate Paleontology. Unwin-Hyman, London.

Berger, J. 1983. Ecology and catastrophic mortaligy in wild horses: implications for interpreting fossilassemblages. Science 220:1403-1404.

Berger, J. 1987. Reproductive fates of dispersers in a harem-dwelling ungulate: the wild horse, in B.D.Chepko-Sade and Z.T. Halpin, eds., Mammalian Dispersal Patterns: The Effects of Social Structure onPopulation Genetics, The University of Chicago Press, Chicago, pp. 41-54.

Berggren, W.A., and J.A. VanCouvering. 1974. The late Neogene: biostratigraphy, geochronology andpaleoclimatology of the last 15 million years in marine and continental sequences. Palaeogeograpy,Palaeoclimatology, Palaeoecology, 16:1-216,

Berggren, W.A., D.V. Kent, J.J. Flynn, and J.A. VanCouvering. 1985. Cenozoic geochronology,Bulletin of the Geological Society of America, 96:1407-1418.

Berggren, W.A., D.V. Kent, C.C. Swisher III, and M.-P. Aubry. 1995. A revised Cenozoicgeochronology and chronostratigraphy, in W.A. Berggren, D.V. Kent, M.-P. Aubry and J. Hardenbol,eds., Geochronology, Time Scales and Global Stratigraphic Correlation: A Unified TemporalFramework for an Historical Geology. Society for Economic Paleontology and Mineralogy SpecialPublication, Tulsa, Oklahoma, 54:129-212.

Bernor, R.L. 1985. Systematics and evolutionary relationships of the hipparionine horses fromMaragheh, Iran (late Miocene, Turolian Age). Palaeovertebrata 15(4): 173-269.

Bernor, R.L. and S.T. Hussain. 1985. An assessment of the systematic, phylogenetic andbiogeographic relationships of Siwalik hipparionine horses. Journal of Vertebrate Paleontology, 5(1):32-87.

Bernor, R.L. and H. Tobien. 1989. Two small species of Cremohipparion (Equidae, Mammalia) fromSamos, Greece. Mitt. Bayer. Staatsslg. Paläont. Hist. Geolo. 29:207-226.

Bernor, R.L., H. Tobien, and M.O. Woodburne. 1990. Patterns of Old World hipparionineevolutionary diversification and biogeographic extension, in E. Lindsay, V. Fahlbusch, and P. Mein, eds.,European Neogene Mammal Chronology. Plenum Press, New York, pp. 263-320.

Bock, W.J. 1973. Philosophical foundations of classical evolutionary classification. Systematic Zoology,22:375-392.

Boné, E.L., and R. Singer. 1965. Hipparion from Langebaanweb, Cape Province and a revision of thegenus in Africa. Ann. South African Museum. 48:273-397.Bowler, P.J. 1976. Fossils and Progress: Paleontology and the Idea of Progressive Evolution in theNineteenth Century. Science History Publications, New York.

Bowler, P.J. 1989. Holding your head up high: degeneration and orthogenesis in theories of humanevolution, in J.R.Moore, ed., History, Humanity, and Evolution, Cambridge University Press,Cambridge, Massachusetts, pp. 329-353.

Bown, T.M. and A.J. Kihm. 1981. Xenicohippus, an unusual new hyracothere (Mammalia,Perissodactyla) from lower Eocene rocks of Wyoming, Colorado, and New Mexico. Journal ofPaleontology 55:257-270.

Brooks, C.E.P. 1928. Climate Through the Ages: A Study of the Climatic Factors and their Variation.Yale University Press, New Haven.

Burmeister, H. 1875. Los Caballos Fósiles de la Pampa Argentina. La Tribuna, Buenos Aires,Argentina.

Butler, P.M. 1952a. Molarisation of premolars in Perissodactyla. Proceedings of the Zoological Societyof London, 121:819-843.

Butler, P.M. 1952b. The milk-molars of Perissodactyla, with remarks on molar occlusion. Proceedingsof the Zoological Society of London 121:777-817,

Cain, A.J. 1954. Animal Species and Their Evolution. Hutchinson’s University Library, London.

Camp, C.L., and N. Smith. 1942. Phylogeny and functions of the digital ligaments of the horse.University of California Memoirs, 13:69-124.

Carroll, R.L. 1988. Vertebrate Paleontology and Evolution. Freeman Brothers, New York.

Chaney, R.W. and M.K. Elias. 1936. Late Tertiary floras from the High Plains. Carnegie Institution ofWashington Publication no. 476:1-72.

Chow, M., and T. Qi. 1978. Paleocene mammalian faunas from Nomogen Formation of InnerMongolia, Vertebrata Palasiatica, 16:77-85.

Chubb, S.H. 1934. Frontal protuberances in horse: an explanation of the so-called “horned” horse.American Museum Novitates, 740:1-9.

Churcher, C.S. and M.L. Richardson. 1978. Equidae, in V.J. Maglio and H.B.S. Cooke, eds.,Evolution of African Mammals. Harvard University Press, Cambridge, Massachusetts, pp. 379-442.

Cifelli, R.L. 1981. Patterns of evolution among the Artiodactyla and Perissodactyla (Mammalia).Evolution 35:433-440.

Colbert, E.H. 1935. Distributional and phylogenetic studies on Indian fossil mammals. II. Thecorrelation of the siwaliks of India as inferred by the migrations of Hipparion and Equus. AmericanMuseum Novitates 797:1-15.

Colbert, E.H. 1980. Evolution of the Vertebrates: A History of the Backboned Animals Through Time.Wiley & Co., New York.

Cope, E.D. 1878. On some of the characters of the Miocene fauna of Oregon. Proceedings of theAmerican Philosophical Society, 18:1878-1880.

Cope, E.D. 1879. A new Anchitherium. American Naturalist, 13(7):462-463.

Cope, E.D. 1881. On the origin of the foot structure of the ungulates. American Naturalist, 15(4): 271-273.

Cope, E.D. 1884. The Vertebrata of the Tertiary Formations of the West, Book 1. U.S. GeologicalSurvey, Washington, D.C.

Cope, E.D. 1887. The Perissodactyla. American Naturalist, 21(12): 940-1069.

Cope, E.D. 1889. A review of the North American species of Hippotherium. Proceedings of theAmerican Philosophical Society, 26:430-449.

Cracraft, J. 1981. Patterns and process in paleobiology: the role of cladistic analysis in systematicpaleontology. Paleobiology 7:456-468.

Crusafont, M. and P. Sondaar. 1971. Une nouvelle espece d’Hipparion du Pliocene terminald”Espagne. Palaeovertebrata, 4:28-37.

Cuvier, G. 1825. Des dents des mammiferes, considerées comme caractères zoologiques, in F.G.Leverault, ed., Dictionnaire des Sciences Naturelles, GUAHEO, Paris, 20:1-572.

Cuvier, G. 1836. Recherches sur les Ossemens Fóssiles. Edmond D’Ocagne, Paris.

Dalquest, W.W. 1978. Phylogeny of American horses of Blancan and Pleistocene age. Acta Zool.Fennica 15:191-199.

Dalquest, W.W. 1988. Astrohippus and the origin of Blancan and Pleistocene horses. OccasionalPapers of the Museum of Texas Tech. University, 116:1-23.

Dashzeveg, D. 1979. On an archaic representative of the equoids (Mammalia, Perissodactyla) from theEocene of central Asia. Trans. Joint Soviet-Mongolian Paleontol. Exped. 8:10-22.

DeCristol, A. 1832. Fossil horse remains from Mt. Leberon, southern France. Ann. Sci. Indust. Du Midide France, Vol. 1:215.

Deperet, C. 1917. Monographie de la faune de mammiféres fóssiles du Ludien inferieur d’Euzetles-Bains (Gard). Ann. L’Univ. Lyon, I, Sciences, Médecine, 40:1-274.

DePorta, J. 1960. Los equidos fósiles de la Sabana de Bogotá. Bol. Geol., Univ. Industrial Santander(Colombia), 4:51-78.

Desmond, A. 1982. Archetypes and Ancestors: Palaeontology in Victorian London 1850-1875.University of Chicago Press, Chicago.

Devillers, C., J. Mahe, D. Ambrose, R. Bauchot, and E. Chatelain. 1984. Allometric studies on theskull of living and fossil Equidae (Mammalia: Perissodactyla). Journal of Vertebrate Paleontology4:471-480.

Donoghue, M.J., J.A. Doyle, J. Gauthier, A.G. Kluge, and T. Rowe. 1989. The importance of fossilsin phylogeny reconstruction. Annual Review of Ecology and Systematics, 20:431-460.

Downs, T. 1961. A study of variation and evolution in Miocene Merychippus. Los Angeles CountyMuseum Contributions to Science, 45:1-75.

Durham, J.W. 1959. Paleoclimates, in L.H. Ahrens, ed., Physics and Chemistry of the Earth, Vol. 3.Pergamon Press, New York.

Edinger, T. 1948. Evolution of the horse brain, Memoirs of the Geological Society of America, 25:1-177.

Edinger, T. and D.B. Kitts. 1954. The foramen ovale. Evolution, 8:389-404.

Eisenberg, J.F. 1981. The Mammalian Radiations: An Analysis of Trends in Evolution, Adaptations, andBehavior. The University of Chicago Press, Chicago.

Eisenmann, V. 1975. Nouvelles interprétations des restes d’Équidés (Mammalia, Perissodactyla) deNihowan (Pléistocène Inférieur de la Chine du Nord): Equus teilhardi nov. sp. Géobios 8:125-134.

Eisenmann, V. 1977. Les Hipparions africains: Valeur et signification de quelques caractères desjugales inférieures. Bull. Mus. Natl. Hist. Nat. (France) 438:69-86.

Eisenmann, V. 1980. Les chevaux (Equus senso lato) fossiles et actuels: crânes et dents jugalessupérieures. Cahiers de Paleont., Cent. Natl. Recherche Sci. 1-186.

Eisenmann, V. 1981. Étude des dents jugales inférieures des Equus (Mammalia, Perissodactyla) actuelset fossiles. Palaeovertebrata 10:127-226.

Eisenmann, V. 1982. La phylogénie des Hipparion (Mammalia, Perissodactyla) d’Afrique d’après lescaractères crâniens. Koninklijke Nederlandse Akademie van Wetenschappen, Proc. Ser. B, 85(2):219-227.

Eisenmann, V. 1986. Comparative osteology of modern and fossil horses, half-asses, and asses, in R.H.Meadow and H.-P Uerpman, eds., Equids in the Ancient World, D.R. Ludwig Reichart Verlag,Wiesbaden, pp. 67-116.

Eisenmann, V., M.T. Alberdi, C. deGiuli, and U. Staesche. 1988. Studying Fossil Horses, Vol. 1:Methodology. E.J. Brill, Leiden.

Eldredge, N. and S.J. Gould. 1972. Punctuated equilibria: an alternative to phyletic gradualism, inT.J.M. Schopf, ed., Models in Paleobiology. Freeman, Cooper and Co., San Francisco, pp. 82-115.

Emry, R.J., L.S. Russell, and P.J. Bjork. 1987. The Chadronian, Orellan, and Whitneyan NorthAmerican Land Mammal Ages, in M.O. Woodburne, ed., Cenozoic Mammals of North America:Geochronology and Biostratigraphy, The University of California Press, Berkeley, pp. 109-127.

Evander, R.L. 1985. Middle Miocene horses of North America, Ph.D. dissertation, ColumbiaUniversity, New York, pp. 1-483.

Evander, R.L. 1986. The taxonomic status of Merychippus insignis Leidy. Journal of Paleontology60(6):1277-1280.

Evander, R.L. 1989. Phylogeny of the family Equidae, in D.R. Prothero and R.M. Schoch, eds., TheEvolution of Perissodactyls, Clarendon Press, Oxford, pp. 109-127.

Ewart, J.C. 1894. The development of the skeleton of the limbs of the horse, with observations onpolydactyla. Journal of Anatomy and Physiology, London, 28:22-48.

Falconer, H. and P. Cautley. 1845-1849. Fauna Antiqua Sivalensis, Being the Fossil Zoology of theSiwalik Highlands in the North of India. Pt. 9. Smith, Elder and Co., London, pp. 1-92.

Ferrusquía-Villafranca, Ismael. 2003. Mexico’s Middle Miocene Mammalian Assemblages: AnOverview, , in: B.J. MacFadden, ed., Vertebrate Fossils and Their Context: Contributions in Honor ofRichard H. Tedford. Bulletin of the American Museum of Natural History, no. 29, pp. 321-346.

Filhol, H. 1888. Études sur les vertébres fossiles d’Issel (Aude). Mem. Soc. Geol. France, 3(5):1-188.

Fischer, M.S. 1989. Hyracoids, the sister-group of Perissodactyls, in D.R. Prothero and R.M. Schoch,The Evolution of Perissodactyls, Clarendon Press, Oxford, pp. 37-56.

Flower, W.H. 1892. The Horse: A Study in Natural History. D. Appleton and Co., New York.

Forsten, A.-M. 1968. Revision of the Palearctic Hipparion. Acta. Zoologica Fennica, 119:1-134.

Forsten, A.M. 1970. Variation in and between three populations of Mesohippus bairdi Leidy from theBig Badlands, South Dakota. Acta Zool. Fennica 126:1-16.

Forsten, A.-M. 1973. Size and shape evolution in the cheek teeth of fossil horses. Acta. Zool. Fennica,137:1-31.

Forsten, A.-M. 1975. The fossil horses of the Texas Gulf Coastal Plain: a revision. Pearce-SellardsSeries, Texas Memorial Museum 22:1-86.

Forsten, A.-M. 1982a. The taxonomic status of the Miocene horse genus Sinohippus. Palaeontology25:673-679.

Forsten, A.-M. 1982b. The status of the genus Cormohipparion Skinner and MacFadden (Mammalia,Equidae). Journal of Paleontology, 56:1332-1335.

Forsten, A.-M. 1983. The preorbital fossa as a taxonomic character in some Old World Hipparion.Journal of Paleontology, 57:686-704.

Forsten, A.-M. 1986. Chinese fossil horses of the genus Equus. Acta Zool. Fennica 181:1-40.

Forster-Cooper, C. 1932. The genus Hyracotherium: A revision and description of new specimensfound in England. Philosopihical Transactions of the Royal Society of London, Series B., 221:431-448.

Fortelius, M. 1985. Ungulate cheek teeth: developmental, functional, and evolutionary interrelations.Acta Zoologica Fennica, 180:1-76.

Franzen, J.L. 1976. Exceptional preservation of Eocene vertebrates in the lake deposit of grube Messel(West Germany). Philosophical Transactions of the Royal Society of London, Series B, 311:181-186.

Froehlich, J. 1989. A small hyracothere from the San Jose Formation (Lower Eocene) of New Mexico.Journal of Vertebrate Paleontology 9:21A.

Gaffney, E.S. 1979. An introduction to the logic of phylogeny reconstruction, in J. Cracraft and N.Eldredge, eds., Phylogenetic Analysis and Paleontology, Columbia University Press, New York, pp. 79-111.

Galusha, T. 1975. Childs Frick and the Frick Collection of fossil mammals, Curator, 18:5-15.

Garces, M., L. Cabrera, J. Agusti, and J.M. Pares. 1997. Old World first appearance datum of“Hipparion” horses: Late Miocene large-mammal dispersal and global events. Geology 25(1): 19-22.

Gazin, C.L. 1936. A study of the fossil horse remains from the Upper Pliocene of Idaho. Proceedings ofthe U.S. National Museum, 83:281-319.

George, M., and O.A. Ryder. 1986. Mitochrondrial DNA evolution in the genus Equus. MolecularBiology and Evolution, 3:535-546.

Getty, R., ed. 1975. Sisson and Grossman’s The Anatomy of the Domestic Animals. W.B. Saunders Co.,Philadelphia.

Gidley, J.W. 1903. A new three-toed horse. Bulletin of the American Museum of Natural History, 19(8):467-476.

Gidley, J.W. 1906. A new genus of horse from the Mascall beds, with notes on a small collection ofequine teeth in the University of California. Bulletin of the American Museum of Natural History,22(22):385-388.

Gidley, J.W. 1907. Revision of the Miocene and Pliocene Equidae of North America. Bulletin of theAmerican Museum of Natural History, 23(25):865-934.

Gillette, D.D. and E.H. Colbert. 1976. Catalog of type specimens of fossil vertevbrates, Academy ofNatural Sciences, Philadelphia. Part II: Terrestrial Mammals. American Journal of Science, 128:25-28.

Gingerich, P.D. 1976. Paleontology and phylogeny: patterns of evolution at the species level in earlyTertiary mammals. American Journal of Science, 276:1-28.

Gingerich, P.D. 1977. Patterns of evolution in the mammalian fossil record, in A. Hallam, ed., Patternsof Evolution as Illustrated by the Fossil Record, Elsevier, Amsterdam, pp. 469-500.

Gingerich, P.D. 1981. Variation, sexual dimorphism, and social structure in the early Eocene horseHyracotherium (Mammalia, Perissodactyla). Paleobiology 7:443-455.

Gingerich, P.D. 1982. Time resolution in mammalian evolution: sampling, lineages, and faunalturnover. Proceedings of the 3rd North American Paleontological Convention, Vol. 1, 205-210.

Gingerich, P.D. 1983. Rates of evolution: effects of time and temporal scaling. Science, 222:159-161.

Gingerich, P.D. 1984a. Smooth curve of evolutionary rate: a psychological and mathematical artifact(response to comment by S.J. Gould). Science 226:995.

Gingerich, P.D. 1984b. Punctuated equilibria – where is the evidence? Systematic Zoology 33:335-338.

Gingerich, P.D. 1987a. Simpson as a model. Palaios 2:111.

Gingerich, P.D. 1987b. Evolution and the fossil record: patterns, rates, and processes. CanadianJournal of Zoology 65:1053-1060.

Gingerich, P.D. 1989. New earliest Wasatchian mammalian fauna from the Eocene of northwesternWyoming: composition and diverstiy in a rarely sampled high-floodplain assemblage. University ofMichigan Papers in Paleontology, 28:1-97.

Glen, W. 1986. Continental Drift and Plate Tectonics. Charles E. Merrill Co., Columbus, Ohio, pp. 1-188.

Goldschmidt, R. 1940. The Material Basis of Evolution. Yale University Press, New Haven.

Gould, S.J. 1983. Hen’s Teeth and Horse’s Toes. Norton Press, New York.

Gould, S.J. 1984. Smooth curve of evolutionary rate: a psychological and mathematical artifact. Science226:994-995.

Gould, S.J. 1987a. Bushes all the way down. Natural History 96(5):20, 22-25.

Gould, S.J. 1987b. Life’s little joke: the evolutionary histories of horses and humans share a dubiousdistinction. Natural History 96:16-25.

Gould, S.J. 1988. On replacing the idea of progress with an operational notion of directionality, in M.H.Nitecki, ed., Evolutionary Progress, University of Chicago Press, Chicago, pp. 319-338.

Gould, S.J. 1989. Wonderful Life: The Burgess Shale and the Nature of History. Norton Press, NewYork.

Gould, S.J. 1991. Fall in the house of Ussher: How foolish was the archbishop’s precise date forCreation? Natural History, 100(11):12-21.

Gould, S.J. and N. Eldredge. 1977. Punctuated equilibria: the tempo and mode of evolutionreconsidered. Paleobiology 3:115-151.

Gould, S.J. and R.C. Lewontin. 1979. The spandrels of San Marco and the Panglossian paradigm: acritique of the adaptionist programme, in Proceedings of the Royal Society of London, Ser. B., 205:581-598.

Granger, W.A. 1908. A revision of the American Eocene horses. Bulletin of the American Museum ofNatural History, 24:221-264.

Grayson, D.K. 1989. The chronology of North American late Pleistocene extinctions. Journal ofArchaeological Science 16:153-166.

Gregory, J.T. 1942. Pliocene vertebrates from Big Spring Canyon, South Dakota. University ofCalifornia Publications, Bulletin of the Department of Geological Science, 26:307-446.

Gregory, J.T. 1979. North American Vertebrate Paleontology, 1776-1976, in C.J. Schneer, ed., TwoHundred Years of Geology in America: Proceedings of the New Hampshire Bicentennial Conference onthe History of Geology, University Press of New England, Hanover, New Hampshire, pp. 305-335.

Gregory, W.K. 1910. The orders of mammals. Bulletin of the American Museum of Natural History,27:1-524.

Gregory, W.K. 1920. Studies in comparative myology and osteology, no. V: On the anatomy of thepreorbital fossae of Equidae and other ungulates. Bulletin of the American Museum of Natural History,42:265-284.

Gromova, V. 1952. Le genre Hipparion (translated from Russian by St. Aubin). Bureau of Resources ofMineralogy and Geology, 12:1-288.

Groves, C.P. and D.P. Willoughby. 1981. Studies on the taxonomy and phylogeny of the genus Equus.1: Subgeneric classification of the recent species. Mammalia 45:321-355.

Gunnell, G.F. 1990. Cenogram analysis of the Bridger B mammalian fauna (middle Eocene). Journal ofVertebrate Paleontology 10:26A.

Harris, J.M. and G.T. Jefferson, eds. 1985. Rancho La Brea: Treasures of the Tar Pits. Los AngelesCounty Museum of Natural History, Science Series no. 31.

Hay, O.P. 1902. Bibliography and catalogue of the fossil Vertebrata of North America. Bulletin of theU.S. Geological Survey 179:1-868,

Hennig, W. 1966. Phylogenetic Systematics. University of Illinois Press, Urbana.

Higuchi, R., B. Bowman, M. Freiberger, O.A. Ryder, and A.C. Wilson. 1984. DNA sequences fromthe quagga, an extinct member of the horse family. Nature 312:282-284.

Hildebrand, M. 1974. Analysis of Vertebrate Structures, John Wiley, New York.

Hildebrand, M. 1984. The mechanics of horse legs. American Scientist, 75:594-601.

Hoffstetter, R. 1950. Some observations on the fossil horses of South America, Amerhippus gen. nov.Bolivian Information Service, Natural History, Ecuador, 3:426-454.

Hoffstetter, R. 1952. Les Mammifères Pléistocènes de la République de L’Équateur. Soc. Géol. France,Mém. 66:1-391.

Hooker, J.J. 1984. A primitive ceratomorph (Perissodactyl, Mammalia) in the English early Eocene.Bulletin of the British Museum (Natural History), Geology, 33:101-114.

Hooker, J.J. 1989. Character polarities in early perissodactyls and their significance for Hyracotheriumand infraordinal relationships, in D.R. Prothero and R.M. Schoch, eds., The Evolution of Perissodactyls,Clarendon Press, Oxford, pp. 79-101.

Hsü, K.J. 1986. The Great Dying: Cosnmic Catastrophe, Dinosaurs, and the Theory of Evolution.Ballantine Books, New York.

Hulbert, R.C., Jr. 1982. Population dynamics of the three-toed horse Neohipparion from the lateMiocene of Florida. Paleobiology 8:159-167.

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