Login
Fruit morphology and anatomy are critical for delimitation of tribes and genera within Juglandaceae. In this study, we re-examined the holotypes of Juglandicarya cantia E.Reid et M.Chandler 1933 from the Early Eocene London Clay flora of England and J. simplicarpa Manchester 1987 from the Middle Paleocene of the Fort Union Formation of Wyoming, USA using micro-CT scanning to uncover additional morphological and anatomical characters and reassess their affinities relative to extant genera. These fossils are significant as they are among the earliest known large, wingless nuts in the fossil record of Juglandaceae. Although They resemble modern Juglans and Carya in overall nut morphology, key anatomical differences distinguish them from the extant genera. Micro-CT analysis reveals that the nutshell of J. cantia consists of densely packed isodiametric sclereids and lacks lacunae, unlike extant species of Juglans. Nuts of both J. cantia and J. simplicarpa lack internal longitudinal ribs and have only a weakly developed to absent secondary septum differentiating them from extant species of Carya. The genus Juglandicarya, as traditionally circumscribed, is non-monophyletic, and the morphological traits of J. cantia and J. simplicarpa differ significantly from those of the lectotype, J. lubbocki E.Reid et M.Chandler. We therefore propose a new genus, Zodicarya gen. nov., and establish the new combinations Zodicarya cantia (E.Reid et M.Chandler) M.Deng, M.E.Collinson et Manchester comb. nov. and Z. simplicarpa (Manchester) M.Deng et Manchester comb. nov. By analogy with extant Juglans, Carya, and Alfaroa, we infer that the large, wingless nuts of Zodicarya were adapted for animal-dispersal, indicating that these traits, which are not known in Cretaceous members of the family, evolved in the early Cenozoic. We also summarize the biogeographic history of Zodicarya in Europe and North America during the Paleogene.
Full Text of the Article
