Richard Frederick Kay

Richard Frederick Kay

Professor of Evolutionary Anthropology

External address: 
0013 Biological Sciences Building, 130 Science Drive, Durham, NC 27708
Internal office address: 
Duke Box 90383, Durham, NC 27708-0383
(919) 684-2143


I have two areas of research:1) the evolution of primates in South America; and 2) the use of primate anatomy to reconstruct the phylogenetic history and adapations of living and extinct primates, especially Anthropoidea.

1) Evolution of primates and mammalian faunal evolution, especially in South America. For the past 30 years, I have been engaged in research in Argentina, Bolivia The Dominican Republic, Peru, and Colombia with three objectives:a) to reconstruct the evolutionary history and adaptive patterns of South America primates and other mammals; b) to establish a more precise geologic chronology for the mammalian faunas between the late Eocene and middle Miocene (between about 36 and about 15 million years ago); and c) to use anatomy and niche structure of modern mammals as a means to reconstruct the evolution of mammalian niche structure in the Neotropics.

2) Primate Anatomy. I am working to reconstruct the phylogeny of primates based (principally) on anatomical evidence; and to infer the adaptations of extinct primates based mainly on cranial and dental evidence.

Field activities
Current fieldwork is focused on the study of terrestrial biotic change in Patagonia through the 'mid-Miocene Climate Optimum' when global climate was moderate and the subtropical zone, with primates and other typically tropical vertebrates, extended their ranges up to 55 degrees of South latitude.

In this collaborative research undertaking with colleagues at University of Washington and Boise State University, the geochronology of the Santa Cruz Formation at in extreme southern Argentina is being refined using radiometric dating. Stratigraphically-controlled collections have been made of vertebrates and plant macro- and microfossils. Climate change and its impact on the biota is assessed 1) using biogeochemical analysis of stable isotopes in fossil mammalian tooth enamel; 2) by documenting changes in mammalian community structure (richness, origination and extinction rates, and ecological morphology); and 3) by documenting changes in vegetation and floral composition through the study of phytoliths. These three independent lines of evidence in a refined geochronologic framework will then be compared with similar evidence from continental sequences in the Northern Hemisphere and oceanic climatic records to improve our understanding of the timing and character of climatic change in continental high latitudes during this temporal interval.

A second field project project in its early stages is the study of the fossil vertebrates of the Amazon Basin. The latter is a collaborative effort of biologists and geologists across schools at Duke (Nicholas School) and among six North American universities. My role is to direct the vertebrate paleontology component of this project in Brazil and Amazonian Peru. The hope is to recover primates from the Oligocene through Early Miocene. New material will shed light on the phylogenetic status of African Paleogene anthropoids, one of which may be the platyrrhine sister-taxon. Also, new remains of fossil primates will help to refine hypotheses about the origins of the modern families and subfamilies of platyrrhines, all of which trace back to an Early Miocene (17-21 Ma) common ancestor. Finally, new fossil primates may further constrain the time of entry of platyrrhines into South America.

Degrees & Credentials

  • Ph.D., Yale University 1973

  • M.Phil., Yale University 1971

  • B.S., University of Michigan at Ann Arbor 1969

Kay, R. F., and H. H. Covert. “Anatomy and behaviour of extinct primates..” Food Acquisition and Processing in Primates, edited by D. J. Chivers et al., Plenum Press, 1984, pp. 467–508.

Kay, R. F. “On the use of anatomical features to infer foraging behavior in extinct primates.” Adaptations for Foraging in Nonhuman Primates, edited by J. Cant and P. Rodman, Columbia University Press, 1984, pp. 21–53.

Kay, R. F., and E. L. Simons. “A reassessment of the relationship between later Miocene and subsequent Hominoidea.” New Interpretations of Ape and Human Ancestry, edited by R. L. Ciochon and R. S. Corruccini, Plenum Press, 1983, pp. 577–624.

Fleagle, J. G., and R. F. Kay. “New interpretations of the phyletic position of Oligocene hominoids.” New Interpretations of Ape and Human Ancestry, edited by R. L. Ciochon and R. S. Corruccini, Plenum Press, 1983, pp. 181–210.

Kay, R. F. “Ramapithecines and Human Origins.” McGraw-Hill Yearbook of Science and Technology, 1982, pp. 1–11.

Kay, R. F., and E. L. Simons. “Apidium and Parapithecus.” McGraw-Hill Yearbook of Science and Technology, 1981, pp. 103–05.

Simons, E. L., and R. F. Kay. “Aegyptopithecus and Propliopithecus.” McGraw-Hill Yearbook of Science and Technology, 1981, pp. 77–80.

Kay, R. F. “Platyrrhine origins: a reappraisal of the dental evidence..” Evolutionary Biology of the New World Monkeys and Continental Drift, edited by R. Ciochon and B. Chiarelli, Plenum Press, 1980, pp. 159–88.

Kay, R. F., and W. L. Hylander. “The dental structure of mammalian folivores wiht special reference to primates and Phalangeroidea (Marsupialia).” The Ecology of Arboreal Folivores, edited by G. G. Montgomery, Smithsonian Institution Press, 1978, pp. 173–91.

Kay, R. F. “Molar structure and diet in extant Cercopithecoidea.” Development, Function and Evolution of Teeth, edited by P. M. Butler and K. Joysey, Academic Press, 1978, pp. 309–39.


Vizcaíno, S. F., et al. “A baseline paleoecological study for the Santa Cruz Formation (late-early Miocene) at the Atlantic Coast of Patagonia, Argentina.” Palaeogeography, Palaeoclimatology, Palaeoecology, vol. 292, no. 3–4, Jan. 2010, pp. 507–19. Scopus, doi:10.1016/j.palaeo.2010.04.022. Full Text Open Access Copy

Williams, B. A., et al. “Darwinius masillae is a European middle Eocene stem strepsirrhine—a reply to Franzen et al..” Journal of Human Evolution, vol. 59, 2010, pp. 567–73.

Williams, B. A., et al. “Darwinius masillae is a European middle Eocene stem strepsirrhine..” Journal of Human Evolution, vol. 59, 2010, pp. 567–73.

Bargo, M. S., et al. “Predominance of orthal masticatory movements in the early Miocene Eucholaeops (Mammalia, Xenarthra, Tardigrada, Megalonychidae) and other megatherioid sloths.” Journal of Vertebrate Paleontology, vol. 29, no. 3, Dec. 2009, pp. 870–80. Scopus, doi:10.1671/039.029.0324. Full Text

Kay, R. F. “Much Hype and Many Errors.” Science, vol. 325, no. 5944, American Association for the Advancement of Science (AAAS), Aug. 2009, pp. 1074–75. Crossref, doi:10.1126/science.1177071. Full Text

Malinzak, M. D., and R. F. Kay. “Systematic characterization of locomotor head movements in Lemur catta.” American Journal of Physical Anthropology, WILEY-LISS, Jan. 2009, pp. 182–182.

Krueger, Kristin L., et al. “Technical note: Dental microwear textures of "Phase I" and "Phase II" facets..” American Journal of Physical Anthropology, vol. 137, no. 4, Dec. 2008, pp. 485–90. Epmc, doi:10.1002/ajpa.20928. Full Text

Bajpai, Sunil, et al. “The oldest Asian record of Anthropoidea..” Proceedings of the National Academy of Sciences of the United States of America, vol. 105, no. 32, Aug. 2008, pp. 11093–98. Epmc, doi:10.1073/pnas.0804159105. Full Text

Kay, R. F., et al. “Two new fossil vertebrate localities in the Santa Cruz Formation (late early - early middle Miocene, Argentina), ∼51° South latitude.” Journal of South American Earth Sciences, vol. 25, no. 2, Mar. 2008, pp. 187–95. Scopus, doi:10.1016/j.jsames.2007.07.003. Full Text

Kay, Richard F., et al. “The anatomy of Dolichocebus gaimanensis, a stem platyrrhine monkey from Argentina..” Journal of Human Evolution, vol. 54, no. 3, Mar. 2008, pp. 323–82. Epmc, doi:10.1016/j.jhevol.2007.09.002. Full Text


Madden, R., et al. Gran Barranca: the most complete South American middle Cenozoic sequence.. Vol. Abstracts and Program Book, 2004, p. P-39.

Kay, R. F., and T. R. T. Mitchell. “Cranial evidence for the timing of the platyrrhine-catarrhine divergence..” American Journal of Physical Anthropology, WILEY-LISS, 2003, pp. 127–127.

Madden, R., et al. Gran Barranca: the most complete South American middle Cenozoic sequence.. Vol. Abstracts and Program Book, 2003, p. P-39.

Heizler, M., et al. “Geochronologic age of the casamayoran fauna at Gran Barranca, Chubut Province, Argentina.” Congreso Argentino De Paleontologia Y Biostratigrafia, vol. VII, 1998.

Kay, R. F., and M. R. Sanchez-Villagra. “Skull of Hondalagus, an argyrolagid marsupial from the Middle Miocene of Bolivia.” Journal of Vertebrate Paleontology, 1997.

Ungar, P. S., et al. “Dental evidence for diets of Miocene apes.” American Journal of Physical Anthropology, vol. Suppl. 22, 1996, pp. 232–33.

Kay, R. F., et al. “Calibraciones de edades mamifero en la Gran Barranca del Lago Colhue Huapi, Provincia del Chubut, Argentina..” Simposio “Paleogeno De América Del Sur".  B. Aires, vol. 1 Octubre de 1996, 1996.