SHORT COMMUNICATION Euarchontan affinity of Paleocene Afro-European adapisoriculid mammals and their origin in the late Cretaceous Deccan Traps of India Thierry Smith & Eric De Bast & Bernard Sigé Received: 28 October 2009 / Revised: 18 January 2010 / Accepted: 19 January 2010 / Published online: 20 February 2010 # Springer-Verlag 2010 Abstract The controversial family Adapisoriculidae, a group of shrew-sized Paleocene mammals, had proposed relation- ships with insectivores, marsupials and more recently to plesiadapiforms. Adapisoriculid remains are numerous in the early Paleocene locality of Hainin, Belgium, and allow us a test of these different phylogenetic hypotheses. Here, we identify the first tarsal bones of adapisoriculid mammals. The highly specialised bones indicate an arboreal mode of life with euarchontan affinity. Moreover, the tarsal bones are morphologically very close to those of the late Cretaceous Deccanolestes from the Deccan intertrappean beds of India, and also share several characters with the Paleocene plesiadapiforms and the extant cynocephalid dermopterans. The adapisoriculid affinities of Deccanolestes are also confirmed by tooth morphology, indicating that Deccano- lestes is a primitive member of this family. These phy- logenetic affinities suggest a paleobiogeographic scenario for the family with dispersal either via East Africa or across the Tethys area. Keywords Adapisoriculidae . Deccanolestes . Euarchonta . Mammalia . Paleocene . Belgium Introduction Adapisoriculids represent an enigmatic group of small mammals with an insectivore-like tooth morphology. Four genera are known from Paleocene localities of Europe and North Africa. The family seems to have disappeared during the early Eocene in Europe and North Africa (Gheerbrant 1993; Smith 1997). The dental morphology is relatively plesiomorphic, especially in the genus Afrodon that is present on the two continents (Gheerbrant and Russell 1989). The dental characteristics of the group are the development of stylar cusps and a progressive dilambdo- donty (V-shaped centrocrista) on the upper molars. The hypoconulid is progressively displaced lingually towards the entoconid and the crista obliqua starts to ascend on the trigonid wall of the lower molars. These derived characters are especially developed in Adapisoriculus. The genera Bustylus and Remiculus are morphologically intermediate between the primitive Afrodon and the advanced Adapisor- iculus (Gheerbrant and Russell 1991). The phylogenetic affinities of the Adapisoriculidae are uncertain and debated. Based on the late Paleocene Adapisoriculus minimus from Cernay, France, they have been considered as either insectivores, didelphid marsu- pials, leptictids or tupaiids (see Gheerbrant and Russell 1989). The early Paleocene Bustylus marandati from Hainin, Belgium was thought to belong to peradectid marsupials based on the rectodonty (straight centrocrista) combined with the presence of stylar cusps on the upper molars like in Didelphimorphia (Crochet and Sigé 1983). The description of the genera Afrodon and Bustylus, and the study of the dental evolution within the family suggested a relationship of adapisoriculids with lipotyphlan insectivores (Gheerbrant and Russell 1989, 1991). However, recently tiny limb bones with arboreal features from the late Electronic supplementary material The online version of this article (doi:10.1007/s00114-010-0651-5) contains supplementary material, which is available to authorized users. T. Smith (*) : E. De Bast Department of Palaeontology, Royal Belgian Institute of Natural Sciences, rue Vautier 29, 1000 Brussels, Belgium e-mail: thierry.smith@naturalsciences.be B. Sigé Université Claude Bernard–Lyon 1, boulevard du 11 novembre, 43–Bât. 402, 69622 Villeurbanne Cedex, France Naturwissenschaften (2010) 97:417–422 DOI 10.1007/s00114-010-0651-5