Abstract
The enamel microstructure in molars of Arsinoitherium is reinvestigated and a new modification of radial enamel (RE), ‘arsinoitheriid radial enamel (ARE)’, is defined. It is characterised by alternating stripes with different organisation of the interprismatic matrix but no prism decussation. Recognition of this new subtype leads to a reinterpretation of structure previously identified as modified radial enamel and of Hunter–Schreger bands in Arsinoitherium. The newly differentiated ARE of Arsinoitherium is more derived in relation to corresponding microstructures of Palaeoamasia and Crivadiatherium. A careful reinvestigation of RE in other Paenungulata will be required to provide additional data bearing on phylogenetic reconstruction. The enamel of Phenacolophus argues against inclusion of this genus in the Embrithopoda.
Acknowledgements
The idea to honour the late Wolf-Ernst Reif with this volume was advanced by Roger D.K. Thomas as a sign of deep friendship. The author is very grateful that he was invited to contribute to this Festschrift. In addition, he kindly improved the English text of this paper. The author very much indebted to all those colleagues who have contributed precious material for the (regrettably destructive) investigation of enamel microstructures. Especially, for this study, Wolf-Dieter Heinrich, MB, Berlin; Sevket Sen, Paris; Rodolphe Tabuce, UM 2, Montpellier; Reinhard Ziegler, SMNS, Stuttgart, generously provided fossil material from collections in their care.