2017, Birmingham:

Talks:

• Project airless: addressing the problem of pyrite oxidation in a large fossil collection. Kieran Miles.
• Replicating the 1.8m long skull of Pliosaurus carpenteri for display. Nigel Larkin & Steven Dey.
• The remedial conservation and support jacketing of the neotype of the dinosaur Massospondylus carinatus. Mark Graham
• Finding and collecting a dinosaur in an open pit mine - the Fort McMurray nodosaur. Donald Henderson.
• Blood, sweat and vinegar: acetic acid preparation of cetacean fossils yields exceptional results. Tim Ziegler.

Posters:

• Recording the uncollectable with low cost low tech: Successful photogrammetry in the field using a mobile phone to create digital 3D models. Nigel Larkin & Steven Dey.

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The Remedial Conservation and Support Jacketing of the Neotype dinosaur Massospondylus carinatus.

Mark R Graham

In March 2017 the Neotype specimen of the Early Jurassic South African prosauropod dinosaur Massospondylus carinatus was appraised and condition reported at the Evolutionary Studies Institute, University of the Witwatersrand (WITS), Johannesburg, in readiness for remedial conservation and re-storage. The work was necessitated by deterioration of the specimen, which was caused by handling over a number of years and an inadequate and failing support mount. Formally numbered BP/1/4934, but more affectionately known to staff as ‘Big Momma’, the specimen was contained within several individual blocks on flimsy support bases and presented various conservation challenges. These included treatment of fractures and cracking across several surfaces of the fossil and the production of clam shell supports to allow for articulated display within the constraints of an existing display cabinet. Part of the brief was to facilitate safer handling and access for researchers. This project was led by the author (MRG) who also trained the curatorial and preparation staff at WITS in the methods and techniques employed. The visit was funded by the Palaeontological Scientific Trust (PAST), the DST/NRF Centre of Excellence in Palaeosciences and The University of the Witwatersrand (WITS).

Finding and collecting a dinosaur in an open pit mine – the Fort McMurray nodosaur

Donald M Henderson

In 2011 a shovel operator working in the Suncor Millenium Mine in northern Alberta bumped into an exceptionally preserved armoured dinosaur contained in a single, very large concretion. The force of impact of the bucket knocked many pieces off the concretion, resulting in a period of 2 days of searching by hand through rubble for small pieces before collection of the remaining fossil could begin. The position of the remainder, located 8m up in a vertical cliff, required the use of a variety of heavy equipment to expose the specimen before it could be collected. After partly exposing the concretion, a high-pressure water and vacuum system was used to remove the last of the softer matrix, and to undercut the concretion. The rapid development of the concretion around the carcass soon after the animal’s death, prevented the fossil from becoming permineralized. This unexpected lack of mechanical strength of the specimen, due to the very soft nature of the skeleton and armour, led to the collapse of the concretion into multiple pieces when it was lifted. The remaining pieces were then collected by stabilizing exposed surfaces with a penetrant stabilizer, and then using standard burlap and plaster jackets. Some of the larger, fractured pieces were held together with various webbing and ratchet-straps prior to jacketing. An 800km return trip by road to the Museum required novel packing and stabilizing methods to avoid abrasion and vibration problems.

Replicating the 1.8m long skull of Pliosaurus carpenteri for display.

Nigel R Larkin

The type specimen of Pliosaurus carpenteri from Westbury in Wiltshire is the most complete skeleton of its genus known, with an estimated body length of 8m. The whole skeleton was mounted for display at Bristol City Museum & Art Gallery in 2017 for the first time since its excavation in 1994. However, the skull is 1.8 m long, very heavy and consists of sixteen fragile pieces. Mounting the real skull in position would have required a large amount of unsightly supporting metalwork that would have obscured some very interesting pathology on the pallete. One option was to CT-scan the skull pieces and mount 3D prints of the subsequent digital models. This would present less risk to the specimen than traditional moulding and casting and could possibly be quicker and cheaper. Importantly, the process would also provide 3D morphological data of the skull’s internal anatomy for research for the first time. But would the resulting replica look real or horribly fake? After CT scanning the skull pieces, replicas were 3D-printed in gypsum and acrylic using a powder based 3D printer. After mounting these pieces together with internal metalwork, the replica was coloured with artists’ acrylic paints to match the fossil. Casts of the teeth were adhered in position, which would have been problematic if the real skull had been used. Satisfyingly, at the opening of the exhibition many well-known palaeontologists viewing the specimen failed to recognise that the skull they were looking at was in fact a replica. It passed.

 

Recording the uncollectable with low cost low tech: successful photogrammetry in the field using a mobile phone to create digital 3D models

Nigel Larkin¹ & Steven Dey²         

¹Cambridge University Museum of Zoology, UK, ²Thinksee3d Ltd,   Eynsham, UK

There are many different ways to record the three-dimensional morphology of a specimen in detail. Most techniques rely on expensive, cumbersome and delicate equipment requiring a power supply. However, if a very large and heavy fossil or geological feature in the field cannot easily be removed to a museum or is in danger of imminent loss it would be very useful to be able record the three-dimensional morphology of the find accurately and in detail there and then with readily available low-cost equipment and with simple techniques.  Fortunately, experimentation has shown that photogrammetry using a standard 5-megapixel mobile phone digital camera can produce very good quality digital 3D models of specimens in the field (such as short dinosaur trackways) that are useful for research. Unlike some scanning methods this also provides a photographic overlay to the morphological model creating, effectively, a 3D photographic record of the specimen and surrounding context. Even specimens larger than 1 m² can be recorded to a level of sub-millimetre resolution with such a device in reasonable lighting conditions and if the relevant photographic techniques and image processing techniques are well understood. The software required to convert the photographs into 3D models is readily available and low cost. Current mobile phone cameras can even produce results that are better than digital SLR cameras in some low light conditions and they are improving every year. As most people have a mobile phone with them on fieldwork, with a little training anyone can undertake scientifically useful 3D scans.

http://www.natural-history-conservation.com/PhotogrammetryPoster.pdf

Project Airless: addressing the problem of pyrite oxidation in a large fossil collection

Kieran Miles

The Natural History Museum in London holds around 7 million fossils, a diverse collection of huge scientific and historical importance. The Conservation Centre is responsible for a wide range of specimen care issues, including those affecting the palaeontology collections. One of the most serious of these problems is pyrite oxidation. Pyrite, a form of iron sulphide, can often be found in fossils or their surrounding matrix. Oxidation occurs when unstable pyrite, often in its microcrystalline form, reacts with atmospheric oxygen and water. This reaction is accelerated at relative humidity above 60%, and produces a variety of harmful by-products, usually comprising ferrous sulphate, hydrogen sulphide and sulphuric acid. Airless, a three year project that started in August 2015, aims to address this problem. The goal is to identify, treat and prevent pyrite oxidation in the Earth Science collections. A small team of conservation technicians are surveying the collections looking for signs of pyrite decay. Affected specimens are taken to a dedicated lab space where remedial treatments, such as dry brushing or ammonia vapour treatment, are carried out, before re-storage of specimens in anoxic microenvironments. These are individually hand-made using barrier film, with oxygen scavenging sachets added to remove oxygen from the sealed bag. In addition, the project has a digitisation aspect, with the use of web-based applications, improving the museum’s database with high-quality photographs that partly compensate for the reduced physical access to the specimens. To date, the team has completed work on nearly 3000 specimens, including ichthyosaurs, plesiosaurs and pterosaurs.

Blood, sweat, and vinegar: Acetic acid preparation of cetacean fossils yields exceptional results

Tim Ziegler, Erich MG Fitzgerald, Matthew R McCurry, James L Goedert

Apprehensions about long preparation time, cost of consumables and even personal safety often cause researchers and institutions to eschew the use of acid to prepare fossils in favour of a mechanical approach. Indeed, inconsistently applied chemical preparation protocols can rapidly permit irreversible fossil corrosion. This is seen as particularly pertinent in the preparation of cetacean fossils, which are vulnerable due to their large size, thin neocortex and abundant trabecular bone. We show these factors are mitigable by a methodology employing briefer acid immersions, longer neutralisation times and systematic consolidation and protection of exposed bone. Museums Victoria has accelerated a technical programme preparing Cenozoic marine tetrapods including cetaceans, pinnipeds and birds, following prior institutional advances in the preparation of three-dimensionally preserved Devonian placoderms and Cretaceous mammal microfossils. As an example, we present the cranium and tympanoperiotics of an allodelphinid odontocete, cf. Arktocara (NMV P252767), collected in a calcareous concretion by James L. Goedert from the Upper Oligocene Lincoln Creek Formation (Grays Harbor County, Washington, USA). Cetacean fossils from the North Pacific are notoriously difficult to prepare, due to bioerosion by siboglinid Osedax worms and subsequent tectonisation of sediments along the Pacific active margin. This specimen was prepared primarily with acetic acid over 13 months, with exceptional anatomical detail retained to a degree not achievable mechanically or by less-stringent acid protocols. This is shown by comparisons with examples of previously prepared North Pacific cetacean fossils, and of acid corrosion on an Australian Cretaceous ichthyosaur, Miocene marsupial megafauna, and an in-preparation Miocene odontocete.