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Mesozoic and Cenozoic plant evolution and biotic change: A symposium in honor of Ruth Stockey

Stull, Gregory [1], Adams, Neil [2], Manchester, Steven [3], Sykes, Dan [4], Collinson, Margaret [5].

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

The London Clay flora (Early Eocene, Ypresian) constitutes one of the most diverse Paleogene fruit and seed assemblages, with more than 350 species. The flora was originally monographed by E.M. Reid and M.E.J. Chandler and is notable not only for its diversity but also its quality of preservation; the fruits and seeds are largely preserved as pyrite permineralizations, which retain cellular detail and 3D morphology, thereby offering excellent taxonomic resolution. Since the original monographs by Reid and Chandler, our improved understanding of phylogenetic relationships and fruit morphology of many plant groups, coupled with technological advances in imaging/visualizing fossil material (e.g. X-ray micro-computed tomography), offers an excellent opportunity to revisit the systematics of the flora. The Icacinaceae, a pantropical family of trees, shrubs, and lianas including 23 genera and ca. 160 species, are a prime example of London Clay fossils deserving a detailed systematic revision. The family is one of the most diverse and abundant components of the flora, represented by at least seven genera and 25 species (according to the original works of Reid and Chandler). Although the family was, in the traditional sense, grossly polyphyletic, recent phylogenetic work has greatly clarified the composition of the family and relationships within it. Furthermore, ongoing studies of fruit morphology have highlighted characters useful for diagnosing clades within the family. We present a systematic revision of the Icacinaceae from the London Clay flora, based on examinations of new micro-CT (µCT) scans of 21 fossil species (mostly holotypes) in the context of new information on fruit morphology across all modern and fossil genera of the family. Virtual sections through the fossils (obtained using µCT datasets) revealed internal morphological features critical for generic determination, allowing us to revise the generic placements of multiple species (e.g., “Iodescorniculata, “Iodesmultireticulata, and “Natsiatumeocenicum). The new data also enabled recognition of a number of species that had been incorrectly attributed to this family. Collectively, this work provides a much-improved understanding of the evolutionary and biogeographic history of the Icacinaceae.

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1 - University of Florida, Florida Museum of Natural History, Dickinson Hall, 1659 Museum Rd, Gainesville, Florida, 32611-7800, USA
2 - Royal Holloway University of London, Department of Earth Sciences and Department of Geography, Egham, Surrey, TW20 0EX, UK
3 - University of Florida, Florida Museum of Natural History, Dickinson Hall, 1659 Museum Rd, Gainesville, Florida, 32611-7800, United States
4 - The Natural History Museum, Imaging and Analysis Centre, Cromwell Road, London, SW7 5BD, UK
5 - Royal Holloway University Of London, Geology Dept-Royal Holloway, Egham Hill, Royal Holloway University Of London, Egham, N/A, TW20 0EX, United Kingdom

London Clay

Presentation Type: Colloquium Presentations
Session: C6
Location: Salon 5/The Shaw Conference Centre
Date: Wednesday, July 29th, 2015
Time: 2:00 PM
Number: C6003
Abstract ID:643
Candidate for Awards:None

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