Eric Delson Research Associate, Division of Paleontology American Museum of Natural History Professor of Anthropology, Lehman College and the Graduate School City University of New York Director, NYCEP Carl J. Terranova Assistant Professor of Anatomy Laboratory of Evolutionary Biology Howard University College of Medicine Washington DC 20059 William L. Jungers Professor of Anatomical Sciences State University of New York Stony Brook NY 11794-8081 Eric J. Sargis Graduate Student, NYCEP and Ph.D. Program in Anthropology City University of New York New York NY 10016 Currently Acting Assistant Professor of Anthropology Yale University New Haven CT 06520 Nina G. Jablonski Irvine Chair in Anthropology California Academy of Sciences Golden Gate Park San Francisco CA 94118-4599 Paul C. Dechow Professor of Biomedical Sciences Baylor College of Dentistry Texas A&M Health Science Center Dallas TX 75246 ANTHROPOLOGICAL PAPERS OF THE AMERICAN MUSEUM OF NATURAL HISTORY Number 83, 159 pp., 19 figures, 23 tables Issued December 29, 2000 Copyright American Museum of Natural History 2000 TABLE OF CONTENTS Abstract...4 Introduction...4 Institutional Abbreviations...6 Materials...7 Postcrania...7 Craniodental Data...9 Compiled Mass Data...10 Statistical Methods...16 Mass Estimation...16 Choice of Comparative Samples for Estimating Fossil Masses...17 Estimation Model Construction and Evaluation...18 Postcranial Sample...18 Craniodental Sample...18 Identifying Reliable Estimators...18 Evaluation of Estimator Variables...30 Comparing Estimator Performance Between Anatomical Regions...30 Comparison of Estimation Accuracy with Previous Studies...31 Scaling of Predictor Variables...38 Postcranial Scaling...43 Dental Scaling...46 Cranial Scaling...48 Implications for Estimating Body Mass...49 Estimated Mass in Fossil Cercopithecid Taxa...50 Colobinae...50 Africa...50 Eurasia...57 Cercopithecinae...62 Eurasia...62 Africa...67 Taxa other than Theropithecus...67 Taxa of the Theropithecus clade...77 Victoriapithecinae...82 Discussion...84 Some Theoretical and Methodological Questions...84 Selection of Variables...84 Selection of Models...86 The Form of the Answer...86 Interregional Estimation Comparisons...87 Paleobiological Applications of our Estimates...87 Sex Dimorphism...88 Evolution of Cercopithecid Mass through Time...88 Extinct Cercopithecid Mass and Energetics...92 Summary...93 Acknowledgments...97 References...98 Appendices...105 ABSTRACT Body size, as summarized especially by mass, is one of the simplest yet most significant aspects of an animal's adaptation and life history. Extant Cercopithecidae (Old World monkeys) present a range of mass from ca. 1-50 kg, and extinct species have been suggested to have weighed as much as 100 kg. The development of reliable methods for determining body size in extinct taxa is an important prerequisite to more detailed paleobiological analyses. Here we develop a series of equations to be used in such estimation as well as a protocol for the selection of the "best" such equations. Data were analyzed for 35 variables from the postcranium, dentition, and cranium in about 1500 individual cercopithecids (roughly half extant and half fossil). Bivariate relationships between each of the variables and mass were determined (using ordinary least squares regression) in a subset of taxa to obtain prediction equations. These equations were then tested on a smaller subset of taxa which had not been included in the previous step, in order to determine prediction accuracy, as judged by Mean Prediction Error. A final set of prediction equations was then developed for the highest-ranked variables in each of seven taxon-sex subgroups. The scaling of these variables with mass was examined in extant taxa using reduced major axis regression. We compared prediction accuracy in variables from the postcranium, skull, and dentition. Postcranial and dental variables yielded somewhat more accurate estimates than did cranial variables. In addition, we explored the relationships among correlation coefficients, mean prediction error, regression model choice, and scaling patterns with respect to estimation. We determined that 20% on either side of a point estimate of mass is an acceptable range of "answers", given the normal variation in mass in extant Old World monkey populations, the quality of our data, and the statistical methods used for estimation (bivariate OLS regression). Any greater claimed "precision" for a fossil mass estimate is an injustice to the estimation routine as well as to the reader. The prediction equations were finally applied to over 90 fossil taxa, using postcranial, dental, and cranial specimens from both sexes. As suggested previously, males of the largest population studied (Theropithecus from Olorgesailie, Kenya) may have averaged 85 kg, with some isolated teeth indicating a mass of 95 kg. Other taxa, such as Papio (Dinopithecus) ingens from Swartkrans (South Africa), were estimated to have had a far lower mass than predicted by other workers. The resulting mass estimates were used to examine sexual dimorphism, body size evolution, and energetics in extinct cercopithecids. In Theropithecus, for example, mass increased rather steadily through time, as noted previously by many workers. However, although the Olorgesailie population had an average (mixed-sex) mass of cat 62 kg, roughly contemporaneous populations from Tighenif and Hopefield averaged only 43 kg. This might have resulted from a late lineage split in this clade or factors relating to energetics. WHERE TO ORDER: Publications Department of Anthropology American Museum of Natural History Central Park West at 79th Street New York, NY 10024 Price: $16.50 a copy
URL: http://www.primate.wisc.edu/pin/review/bodymass.html
Page last modified:
October 9, 2001
Maintained by the WRPRC Library
Return to Review Copies Received
Return to PIN Home Page