Talk abstracts

Preparing a fish
by Richard Forrest

An Oxford Clay nodule with fish material showing on the surface was collected by Darren Withers and almost immediately started to disintegrate. In spite of this, the preservation appeared to be good, making detailed preparation desirable. The morphology of the scales suggests that it is Lepidotes, though this needs to be confirmed by someone more familiar with Oxford Clay fishes.

The surface of the nodule has a crust of light brown material caused by weathering. This contains some of the material but most is in the limestone matrix. Initial stages of preparation could be carried out using scalpels, dental picks and probes of various kinds, but most needed more aggressive methods because of the extreme hardness of the limestone.

Principal tools used were Zoic-Palaeotech TR and MR air pens, the former with a chisel tip on portions of matrix which don’t contain bone, the latter with a fine needle tip to expose fine the detail of bone within the body. Most of the work was carried out under a binocular microscope because of the small size and fragility of the bones. Paraloid was used to glue some of the pieces together, and as a coating to hold tiny bones in place. Mixed with glass beads it was also used to fill cracks made as the nodule fractured and to provide additional support to potentially fragile portions. The specimen has been mounted in three blocks in a fibreglass cushion mount to give access for researchers.

 

The Triceratops skeletons of the Dutch Naturalis natural history museum

By Martijn D. Guliker and Yasmin Grooters

Naturalis Biodiversity Center, Leiden, The Netherlands

Between 2015 and 2019, an aspiring team of Dutch preparators and paleontologists excavated six Triceratops horridus skeletons in Wyoming, USA. Currently, these skeletons are being prepared in an open lab setting in the Naturalis Biodiversity Center, the National Natural History Museum of The Netherlands.

Five out of six of the individuals were found mixed together in the same layer, which means that they at least got covered in the same sedimentation event, but it may imply something about the possible gregarious behaviour of these animals. Research about this hypothesis is ongoing, and is happening in tandem with the preparation efforts.

The sixth individual was found in isolation of the other five. Therefore, preparation was started on this individual, and this individual, nicknamed Dirk, is finished. Presented here are the various preparation techniques that were used to restore Triceratops Dirk to its former glory. These include removing the bones from their field plaster jackets, solidifying them using various glues and resins, removing remaining sediment using air scribes and micro-abrasive sandblasting.

Perhaps most progressive, though, is the inclusion of 3D-modelling as a preparation technique. We feel 3D-modelling and -printing is in many ways superior to molding and casting of missing parts of a skeleton, and we are currently using the same techniques to resurrect the five other Triceratops skeletons, which are expected to awe our visitors in late 2024.

 

Significant effects of fossil preparation using sodium bicarbonate air abrasion on dental microwear

Kayleigh A. Johnson

South Dakota School of Mines and Technology, Rapid City, South Dakota, United States of America

Dental microwear refers to microscopic pits and scratches found on wear surfaces of teeth and is used to interpret the diet of an animal, typically herbivorous mammals. Microwear has a high turnover rate and therefore can be sensitive to changes in diet and taphonomic processes. Techniques commonly used in preparing fossil vertebrate material can also be destructive and can potentially alter microwear patterns. Here, I test for significant changes in microwear counts before and after treatment with sodium bicarbonate air abrasion, a common preparation technique, on fossil Nannippus sp. and modern Bos taurus teeth. Using a low magnification method to photograph clear casts of teeth for microwear counts before and after treatment, I found a significant change in the number of scratches and no significant change in pit counts. On average, the number of scratches decreased after treatment and although pits did not change statistically, I observed that the original pits were erased, and new ones appeared with treatment. A microwear analysis also shows that both Nannippus sp. and Bos taurus are inferred to be grazers before treatment but browsers afterwards. These results reveal that air abrasion treatment using sodium bicarbonate can alter microwear patterns and affect dietary analysis, calling into question previous work that did not account for preparation methods used on the fossil teeth examined. In addition, more care should be taken in the future to document preparation methods used on fossils to allow researchers to control for the potential effects on dietary analysis.

The Durfort mammoth at the Muséum National d’Histoire Naturelle, Paris : a specimen that accounts for 150 years of consolidation treatments

Véronique Rouchon^1*, Alice Gimat¹, Christine Argot², Marc Herbin³, Vincent Pernègre³, Cécile Colin-Fromont³, Gaël Clément²

¹ Centre de Recherche sur la Conservation (UAR3224, CNRS, MNHN, MC), Muséum National d’Histoire Naturelle, Paris

² Centre de Recherche en Paléontologie – Paris (UMR7207, CNRS, SU, MNHN), Muséum National d’Histoire Naturelle, Paris

³ Muséum National d’Histoire Naturelle, Paris

The Durfort mammoth (Mammuthus meridionalis, MNHN.F.DUR1022) is one of the largest mammoth fossils known in the world. It is named after its place of discovery (Durfort, Gard, South France) and is housed at the Palaeontology gallery of the Muséum National d’Histoire Naturelle (MNHN), Paris. Excavated between 1869 and 1873, it was transported in July 1873 to Paris and was first mounted in a room specifically built for it at the jardin des plantes, yet not open to visits. End of 1884, it was moved to the Gaudry's Hangar where it was exhibited to the public. Finally it joined the new Palaeontology gallery building, inaugurated in 1898, and remained there since. It is today in poor condition and necessitates a conservation treatment.

From the very beginning, the skeleton was mentioned to be highly fragile. From its excavation to today, it has also undergone many consolidation interventions. Several sorts of adhesives and filling materials have obviously been used. Some of them were sampled for analyses by infrared spectroscopy and gas chromatography, showing the presence of beeswax, plaster (gypsum), gelatine, pine resin, polyacrylate and epoxy resins. These results, crosschecked with some recipes found in the correspondence of Mr Stahl, head of the moulding workshop at the time of the mammoth discovery, give a better insight into the history of preparation techniques used at the MNHN over a period of approximately 150 years.

 

Past, Present, & Future: What the current state of pyrite tells about historic conditions and means for the decision-making

By Kathryn Royce

University of Oxford

Pyrite is infamously unstable, with a long track record of complaints against it. Yet even after centuries, we remain uncertain just how it deteriorates, especially in the museum environment. A novel, semi-quantitative collection surveying method was designed to gather further evidence. Surveys were performed at four UK museums: Oxford University Natural History Museum (OUNHM), National Museum Cardiff (NMC), National Museums Liverpool (NML), and the Sedgwick Museum of Earth Science. This survey was created specifically to identify the types of changes seen in a given mineral species and correlate patterns in these phenomena to relevant agents of change. In addition to quantifying just how deteriorated specimens actually are, the survey’s results provide insight into the efficacy of various storage options, and the likely deterioration pathways of pyrite in the museum context.

Surveyed specimens varied in age, from recent acquisitions to those collected more than 300 years ago. Yet similar patterns of deterioration were observed in damaged specimens, regardless of age. All museums (save NML) retain specimens accessioned prior to the adoption of climate-controlled facilities. Their existence evidences that stable pyrite can withstand fluctuating indoor conditions when stored in wooden cabinetry. Additionally, correlating specimen state to locality indicates which habits are relatively more stable and suggests which locations produce them. This is affected by the geochemistry of the localities themselves, such as formation conditions and elemental impurities. It is clear from this work that the surveying methodology provides ample information about specimen state, which in turn can be used to make decisions about specimen storage and acquisition.