AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 86229-241 (1991 1 Dental Development of Known-Age Chimpanzees, Pan troglodytes (Primates, Pongidae) ROBERT L. ANEMONE, ELIZABETH S. WATTS, AND DARIS R. SWINDLER Department of Anthropology, State University of New York, Geneseo, New York 14454 (R.L.A.); Department of Anthropology, Tulane University, New Orleans, Louisiana 701 18 (E.S. WJ; Department of Anthropology, University of Washington, Seattle, Washington 98195 (D.R.S.) KEY WORDS and development Dental standards, Mandibular dentition, Growth ABSTRACT Interpretation of dental development of fossil hominids re- quires understanding of and comparison with the pattern and timing of dental development among living humans and pongids. We report the first study of crown and root calcification in the lower permanent molar teeth among chimpanzees (Pan troglodytes) of known chronological age. A series of 99 lateral head radiographs of 16 captive-born chimpanzees were analyzed. Radiographs were taken at irregular intervals throughout the entire postnatal period of dental development from birth to 13 years of age. Permanent mandibular molars were rated on an eight-point maturation scale from initial radiographic appearance through crown and root calcification and apical closure of the root canals. In addition, we were able to document initial crown calcification and completion, as well as root completion and apical closure in incisors, canines, and premolars. Our results show several differences from the widely cited developmental schedule for pongid dentitions of Dean and Wood (Folia Primatol. 361111-127, 1981). We found a much greater degree of temporal overlap in calcification of the crowns of adjacent molars, a pattern very unlike that usually seen in human dental development, which is charac- terized by delays between the onset of crown calcification in the molar series. Also, the ages and durations of crown and root formation in our chimp sample differ from the estimates proposed by Dean and Wood. By more clearly establishing the nature of developmental schedules and the timing of major events in the pongid dentition, these results should aid in the ongoing controversies concerning the human or pongid nature of dental development among Plio-Pleistocene hominids. During the past few years there has been a resurgence of interest among physical an- thropologists in understanding the pattern and timing of dental development among Plio-Pleistocene hominid fossils (Lewin, 1987; Dean, 1987a, Beynon and Dean, 1988). Attention has been focused on ascertaining whether early hominids resembled modern great apes or humans in their characteristic schedules of dental development, including tooth calcification and eruption sequences (Dean, 1985; Smith, 1986,1987;Grine, 1987; Conroy and Vannier, 1987, 1988; Mann et al., 1987; Mann, 1988; Wolpoff et al., 1988). Independent approaches utilizing the pres- ence of incremental growth markings in den- tal enamel have been used to ascertain the timing of events in the dental development of fossil hominids (Bromage and Dean, 1985; Bromage, 1985, 1987; Dean et al., 1986; Beynon and Wood, 1986,1987; Dean, 1987b; Beynon and Dean, 1987). The point of depar- ture for much of this research is Mann’s Received March 5,1990; accepted November 21,1990. Address reprint requests to Robert L. Anemone. Department of Anthropology, Tulane University, New Orleans, LA 70118. @ 1991 WILEY-LISS,INC