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, RF. "On the use of anatomical features to infer foraging behavior in extinct primates." Adaptations for Foraging in Nonhuman Primates. Ed. J Cant and P Rodman. New York: Columbia University Press, 1984. 21-53.

Kay, RF, and Simons, EL. "A reassessment of the relationship between later Miocene and subsequent Hominoidea." New Interpretations of Ape and Human Ancestry. Ed. RL Ciochon and RS Corruccini. New York: Plenum Press, 1983. 577-624.

Fleagle, JG, and Kay, RF. "New interpretations of the phyletic position of Oligocene hominoids." New Interpretations of Ape and Human Ancestry. Ed. RL Ciochon and RS Corruccini. New York and London: Plenum Press, 1983. 181-210.

Kay, RF. "Ramapithecines and Human Origins." McGraw-Hill Yearbook of Science and Technology. 1982. 1-11.

Simons, EL, and Kay, RF. "Aegyptopithecus and Propliopithecus." McGraw-Hill Yearbook of Science and Technology. 1981. 77-80.

Kay, RF, and Simons, EL. "Apidium and Parapithecus." McGraw-Hill Yearbook of Science and Technology. 1981. 103-105.

Kay, RF. "Platyrrhine origins: a reappraisal of the dental evidence." Evolutionary Biology of the New World Monkeys and Continental Drift. Ed. R Ciochon and B Chiarelli. New York: Plenum Press, 1980. 159-188.

Kay, RF, and Hylander, WL. "The dental structure of mammalian folivores wiht special reference to primates and Phalangeroidea (Marsupialia)." The Ecology of Arboreal Folivores. Ed. GG Montgomery. Washington, D. C.: Smithsonian Institution Press, 1978. 173-191.

Kay, RF. "Molar structure and diet in extant Cercopithecoidea." Development, Function and Evolution of Teeth. Ed. PM Butler and K Joysey. London: Academic Press, 1978. 309-339.

Fleagle, JG, and Kay, RF. "New interpretations of the phyletic position of Oligocene hominoids." New Interpretations of Ape and Human Ancestry. Ed. RL Ciochon and RS Corruccini. New York: Plenum Press, 1978. 181-210.


Goin, FJ, Abello, A, Bellosi, E, Kay, RF, Madden, RH, and Carlini, AA. "Los Metatheria sudamericanos de comienzos del Neógeno (Mioceno temprano, Edad-mamífero Colhuehuapense). Parte 1: Introducción, Didelphimorphia y Sparassodonta." Ameghiniana 44 (2007): 29-71. (Academic Article)

Kay, RF, and Cozzuol, MA. "New platyrrhine monkeys from the Solimões Formation (late Miocene, Acre State, Brazil)." J Hum Evol 50.6 (June 2006): 673-686. Full Text

Fleagle, JG, and Kay, RF. "A new humerus of Homunculus from the Santa Cruz Formation, (early-middle Miocene, Patagonia)." Journal of Vertebrate Paleontology 26 (2006): 62A-.

Tafforeau, P, Boistel, R, Boller, E, Bravin, A, Brunet, M, Chaimanee, Y, Cloetens, P, Feist, M, Hoszowska, J, Jaeger, J-J, Kay, RF, Lazzari, V, Marivaux, L, Nel, A, Nemoz, C, Thibault, X, Vignaud, P, and Zabler, S. "Applications of X-ray synchrotron microtomography for non-destructive 3D studies of paleontological specimens." Applied Physics A: Materials Science and Processing 83.2 (2006): 195-202. Full Text

Forasiepi, AM, Sánchez-Villagra, MR, Goin, FJ, Takai, M, Shigehara, N, and Kay, RF. "A new species of Hathliacynidae (Metatheria, Sparassodonta) from the middle Miocene of Quebrada Honda, Bolivia." Journal of Vertebrate Paleontology 26.3 (2006): 670-684. Full Text

Vizcaíno, SF, Bargo, MS, Kay, RF, and Milne, N. "The armadillos (Mammalia, Xenarthra, Dasypodidae) of the Santa Cruz Formation (early-middle Miocene): An approach to their paleobiology." Palaeogeography, Palaeoclimatology, Palaeoecology 237.2-4 (2006): 255-269. Full Text

Kay, RF, Vizcaino, S, Tauber, AA, Bargo, MS, Williams, BA, Luna, C, and Colbert, MW. "Three newly discovered skulls of Homunculus patagonicus support its position as a stem platyrrhine and establish its diurnal arboreal folivorous habits." AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY (2005): 127-127.

Kay, RF, Campbell, VM, Rossie, JB, Colbert, MW, and Rowe, TB. "Olfactory fossa of Tremacebus harringtoni (platyrrhini, early Miocene, Sacanana, Argentina): implications for activity pattern." Anat Rec A Discov Mol Cell Evol Biol 281.1 (November 2004): 1157-1172. Full Text


Madden, R, Carlini, A, Vucetich, MG, Kay, R, Heizler, M, Vilas, F, Re, G, Kohn, MJ, Zucol, A, and Bellosi, ES. "Gran Barranca: the most complete South American middle Cenozoic sequence." Symposium on the Paleogene, Belgium, 25-28 August. 2003.

Heizler, M, Kay, RF, Madden, RH, Mazzzoni, MM, Re, G, Sandeman, H, and Vucetich, MG. "Geochronologic age of the casamayoran fauna at Gran Barranca, Chubut Province, Argentina." 1998.

Ungar, PS, Kay, RF, Teaford, MF, and Walker, A. "Dental evidence for diets of Miocene apes." 1996.

Madden, RH, Guerrero, J, Kay, RF, Flynn, JJ, Swisher/III, CC, and Walton, AH. "The Laventan Stage and Laventan Age; New Chronostratigraphic and geochronologic units for the Miocene of South America." VI Congreso Argentino de Paleontologia y Bioestratigrafia. Trelew, Chubut, Argentina, 1994.

Williams, BA, and Kay, RF. "Phylogenetic analysis of Eocene primates suggests Omomyidae is not a monophyletic group." XIV International Congress of Primatology. Strasbourg, France, 1992.