Temporary exposures of the Eocene London Clay Formation at Highgate, north London: rediscovery of a fossiliferous horizon ‘lost’ since the nineteenth century

Tracey, Steve; Donovan, Stephen K.; Clements, Diana; Jeffery, Paul; Cooper, John; Rye, Phil; Hensley, Caroline

doi:10.1016/s0016-7878(02)80037-2

Cited by 2 publications

(1 citation statement)

References 23 publications

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“…There is a large, well-illustrated field guide, covering the common elements of the biota (Rayner et al 2009). Marine invertebrates (e.g., Tracey et al 2002) include nautilids (Dzik and Gaź dzicki 2001) and teredinid bivalves, which bored into wood (Huggett and Gale 1995). Marine vertebrates include sharks (Casier 1966;Hooker et al 1980), teleost fish (e.g., Beckett and Friedman 2015), and turtles (Hooker et al 1980).…”

Section: Introductionmentioning

confidence: 99%

X-ray micro-computed tomography (micro-CT) of pyrite-permineralized fruits and seeds from the London Clay Formation (Ypresian) conserved in silicone oil: a critical evaluation

Collinson

Adams

Manchester

et al. 2016

Botany

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Pyrite-permineralized fruits and seeds from the London Clay Formation (Ypresian; England) in the NHMUK are stored in silicone oil to retard decay processes. X-ray micro-computed tomography (micro-CT) has revealed internal morphology for multiple holotypes (including severely cracked and encrusted specimens) scanned in the protective fluid. Silicone oil alone has a similar X-ray attenuation to parts of the specimens, causing minor uncertainty for digitally rendered surfaces, but key systematic characters are readily visualized. Further work is needed to optimize visualization of fine-scale cellular detail. Labelling and segmentation to visualize important structures is achievable with these micro-CT datasets. However, manual labelling of individual slices is required, and defining boundaries between features can be difficult due to differential pyritization and silicone oil permeation. Digital sections through specimens can be made in any orientation and digital locule casts can be produced for studies in virtual taphonomy. These achievements have been accomplished with minimal risk to specimens, which remained in silicone oil and were studied within the museum. The datasets provide a potentially permanent record of at-risk specimens, can be made widely available to researchers unable to visit the collections and to other interested parties, and they enable monitoring for future conservation.Key words: early Eocene, fossil plants, fruits and seeds, London Clay Formation, micro-CT, Natural History Museum, London (NHMUK). Résumé :Des fruits et des graines perminéralisées à la pyrite de la formation de London Clay (Yprésien ; Angleterre) sont conservés au NHMUK dans l'huile de silicone pour retarder le processus de dégradation. La micro-tomographie aux rayons-X assistée par ordinateur (micro-CT) a révélé la morphologie interne de plusieurs holotypes (y compris des spécimens sévèrement fissurés et incrustés) balayés dans le liquide protecteur. L'huile de silicone seule présente une atténuation des rayons-X similaire aux parties des spécimens, causant une incertitude mineure en ce qui concerne les surfaces interprétées de manière digitale, mais les caractères systématiques clés sont rapidement visualisés. Du travail supplémentaire est nécessaire afin d'optimiser la visualisation de détails cellulaires à échelle fine. Le marquage et la segmentation pour visualiser les structures importantes sont réalis-ables avec ces jeux de données en micro-CT. Cependant, le marquage manuel de sections individuelles est néces-saire et il peut être difficile de définir les frontières entre les éléments à cause de la pyritisation et la perméance

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