Revision of Icacinaceae from the Early Eocene London Clay flora based on X-ray micro-CT

Gregory W. Stull, Margaret Collinson

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The Early Eocene (Ypresian) London Clay Formation contains one of the most important fruit and seedassemblages from the Paleogene, including a large diversity of taxa (>350 spp.) preserved as pyrite permineralizationsretaining 3D structure as well as anatomical detail. Despite the importance of the flora for understanding angiospermbiogeographic and evolutionary history, the majority of the fossil material has not been revisited since the originaltaxonomic treatments by E.M. Reid and M.E.J. Chandler. Given subsequent advances in our understanding of angiospermphylogeny and fruit morphology, coupled with technological advances in imaging/visualizing fossil material,many of the taxa represented in the flora deserve further study. Here we present a revision of the pantropical familyIcacinaceae using X-ray micro-computed tomography (micro-CT) images of 21 species from the flora. Based on theresults, four new combinations are made, a new fossil-genus is established for a distinctive species with affinities to thePhytocreneae, and emended diagnoses are provided for eight taxa. Of the seven genera recognized from the flora, onlyone, Iodes Blume, is extant. This study offers important insights on the biogeographic and evolutionary history ofIcacinaceae, which is one of the most abundant and diverse components of the flora from the London Clay Formation.
Original languageEnglish
Pages (from-to)713-745
Number of pages33
Issue number9
Early online date7 Sept 2016
Publication statusPublished - Sept 2016

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