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Typeset in India by Techset Composition Limited, Salisbury, UK. Printed by Latimer Trend, Plymouth. Cover image: Wildebeest, a species of African antelope, grazing in the Maasai Mara National Reserve, Kenya. Diets of antelopes can be This paper meets the requirements of ISO 9706:1994(E) and ANSI/NISO Z39.48-1992 (Permanence of Paper) effective with volume 247, issue 1318, 1992. inferred from the characteristic wear on their teeth, which is correlated with the isotopic signature of the plants they consume. Proceedings of the Royal Society B (ISSN 0962-8452) is published twice a month for $3336 per year by the Royal Society, and is distributed in the USA by Agent named Air (See pages 4441–4446; image courtesy of J. Louys.) Business, C/O Worldnet Shipping USA Inc., 149-35 177th Street, Jamaica, New York, NY11434, USA. US Postmaster: Send address changes to Proceedings of the Royal Society B, C/O Air Business Ltd, C/O Worldnet Shipping USA Inc., 149-35 177th Street, Jamaica, New York, NY11414.