Abstract Detail

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

Collinson, Margaret Elizabeth [1], Adams, Neil [1], Manchester, Steven [2], Stull, Gregory [3], Herrera, Fabiany [4], Smith, Selena Y. [5], Andrew, Mary J. [1], Kenrick, Paul [6], Sykes, Dan [6].

Re-examining the Early Eocene flora of the London Clay Formation, UK: micro-CT scanning of holotypes.

The Early Eocene (Ypresian) flora of the London Clay Formation, exposed in the south-east of the UK, contains over 350 named species of fruit and seed fossils. This diversity, the quality of the preservation (by pyrite permineralization) and almost 200 years of previous study (e.g., by Bowerbank, Reid and Chandler) make this fossil flora a global benchmark for studies of Early Eocene plants and vegetation, as well as for calibration of plant phylogenies. Unfortunately, the benefits of pyrite permineralization, for 3D morphological reconstructions and tissue and cellular studies, are offset by the ease with which pyrite breaks down in humid, oxygenated conditions. Consequently, some fossils have decomposed and the collections in the Natural History Museum in London are now housed in silicon oil to retard further decay. In view of the importance of this flora, the antiquity of some specimens including holotypes, the potential damage to specimens taken in and out of silicon oil for study and the future risks of pyrite decay, a long-term project has begun with the aim of scanning all of the holotypes using micro-computed tomography (micro-CT). If a complete holotype no longer exists, then the most complete figured specimen of the species, or other complete specimen, is selected for scanning. The ultimate aim is to make 3D renderings, digital sections and movies through the selected specimens, freely available to all. All genera and species in the families Anacardiaceae, Icacinaceae and Mastixiaceae have so far been studied. Many research benefits of using this X-ray approach are already evident. Different tissues can be readily recognised but pyrite permineralization is variable and external appearances can be misleading. Important systematic characters, which have never before been seen in the complete holotypes, are revealed (examples will be shown from Anacardiaceae and Mastixiaceae). Three-dimensional renderings of selected surfaces within the fossils (virtual taphonomy) can enable comparisons between preservation states (e.g., by producing digital locule casts). It is possible to retrieve key data from specimens that are already severely damaged, e.g., Choerospondias (Anacardiaceae). In addition, the datasets obtained provide important documentation of these specimens in their current state. Micro-CT scanning can therefore be used in the future to monitor the success of current and possible alternative conservation methods for these internationally significant but vulnerable fruits and seeds from the London Clay Formation.

1 - Royal Holloway University of London, Department of Earth Sciences, Royal Holloway University of London, Egham Hill, Egham, Surrey, TW20 0EX, UK
2 - Florida Museum of Natural History, University of Florida, Dickinson Hall, 1659 Museum Road, Gainesville, FL, 32611-7800, USA
3 - University of Florida, Florida Museum of Natural History, Dickinson Hall, 1659 Museum Rd, Gainesville, Florida, 32611-7800, USA
4 - Chicago Botanic Garden, Plant Science Center, 1000 Lake Cook Road, Uiversity Of Florida, Glencoe, Il, 60022, USA
5 - University of Michigan, Department of Earth and Environmental Sciences, 2534 CC Little Building, 1100 North University Avenue, Ann Arbor, MI, 48109-1005, USA
6 - The Natural History Museum, Department of Earth Sciences, Cromwell Road, London, SW7 5BD, UK

Keywords:
Computed Tomography
Eocene
London Clay
pyrite permineralization
Anacardiaceae
Mastixiaceae
Fruit
seed.

Presentation Type: Symposium Presentation
Session: SY14
Location: Salon 5/The Shaw Conference Centre
Date: Wednesday, July 29th, 2015
Time: 9:15 AM
Number: SY14004
Abstract ID:655
Candidate for Awards:None