Fossil nuts of Carya from the Oligocene and Miocene of Europe have been studied by micro-CT scanning to augment traditional morphological and anatomical methods to assess their relationships relative to extant Carya species of North America and Asia.  The course of vascular bundles within the nutshell and primary septum, the presence or absence of lacunae, the degree of development of secondary septum, the extent of development of internal longitudinal nutshell ribs, as well thickness and anatomy of the nutshell and ornamentation on the exterior of the nutshell provide characters suitable for distinguishing clades that are also recognized from molecular characters.  We found that two of the European fossils, namely the Czech Oligocene species C. costata (C.Presl ex Unger) Unger and the widespread eastern European Miocene species Carya ventricosa (Sternb. ex Brongn.) Unger correspond closely to extant east Asian tropical species, C. kweichowensis Kuang & A.M.Lu and C. poilanei (A. Chev.) Leroy, but with some specific differences.  On the other hand, the German Miocene fossil, C. hauffei Kirchh., has features indicating closest relations to the eastern North American species C. aquatica (F.Michx.) Elliott.  These findings implicate the southern Turgai route as well as the North Atlantic land bridge as likely corridors for the spread  of Carya throughout the northern hemisphere prior to its Plio-Pleistocene extinction from Europe that led to the current eastern North American-eastern Asian disjunct distribution of the genus.