Conservation – Page 2 – More Than A Dodo

Our conservator Bethany Palumbo tells us how she restored a beautiful 19th-century papier-mâché model of a honeybee hive, created by master model-maker and anatomist Louis Thomas Jérôme Auzoux

Although the Museum’s collections are mostly of organic specimens, we also hold a fascinating collection of scientific models made to represent the natural world, made from all types of materials, from wax and cardboard to plaster and paint.

We are lucky enough to own a model made by esteemed French anatomist Louis Auzoux (1797-1880), who in the late 19th century developed a method of building strong yet light papier-mâché models that could be taken apart and rebuilt, allowing internal elements such as tissues and organs to be studied in detail.

Model of a honeybee hive in box with six bees, by Louis Auzoux

While Auzoux made many models demonstrating human anatomy, he later expanded his business to include magnified models of plants and insects. The model we have is of a honeybee hive, containing six beautiful bees.

The hive, painted with a protein-based paint and varnished with gelatine, is large enough to allow the viewer to see the fine details of the hive, including individual chambers containing tiny larvae.

As you can see in the image at the top of the article, the bees themselves are also intricately painted, with rabbit hair used to simulate their natural fuzz, and delicate wings constructed from metal wire.

While there was much to admire about this model, it was in received in poor condition. Previous restoration attempts had introduced many materials that were now failing. There were fills, constructed of paper, applied to areas in an attempt to hide cracks in the original model. These were covered in oil paint, which was dripping over the original paintwork and had become brittle and discoloured.

Oil paint layers were peeling from the model

The whole hive was coated in a layer of cellulose nitrate film, a popular coating in the mid-20th century which was used as protection and to create a gloss finish. This coating doesn’t age well, resulting in peeling. It had also been applied to the bees themselves, clumping together the bee ‘fuzz’ and disguising the paintwork underneath.

The priority for treatment was to return the model to its original form while stabilising it for the future.

I undertook treatment in several stages over the course of six months. First, the cellulose nitrate film was removed from all areas using acetone, which could be applied with a cotton bud and fortunately didn’t affect the paint layer beneath.

Fill material used to cover previous damage had become discoloured

The next stage was to remove the discoloured oil paint from the hive. This was done manually using metal and wooden tools lubricated with white spirit, which were used to gently scrape the surface under magnification. This revealed old fills on the hive, made from a combination of plastic tape, paper and old adhesives which also needed to be removed. They were easily softened with water and gently peeled away.

Once all unstable introduced materials were removed, work began to stabilise the original model. The bees were suffering from paint cracking and peeling, as seen in the magnified photograph below.

We decided to consolidate this using gelatine as it would be in keeping with the original construction and could easily be reversed if necessary. Gelatine was mixed in water and warmed to make it a thin consistency, and then applied with a paintbrush. Once the paint flakes had softened they could be gently pressed down. Gelatine was also used with acid-free tissue to stabilise the cracks and areas of surface loss on the hive.

With the hive and bees now clean and stable, the quality of this piece and its incredible paintwork can really be admired. We hope to put it on display soon for all our visitors to enjoy!

12 October 20181 November 2018

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Restoring the Great Lizard of Stonesfield

by Paul Smith, Museum director

One of the unusual things about the collections in the Museum is that some of the specimens date back hundreds of years, and so have been researched by generation after generation. Sometimes these specimens have been damaged and repaired, and in some cases this has happened many times, leaving a complex history of research and conservation.

One high profile example is the type specimen of the theropod dinosaur Megalosaurus bucklandii – the world’s first scientifically described dinosaur. This specimen itself is the lower jaw, pictured above, which has been in the collections of Oxford University since 1797 at the latest.

Working with the Centre for Imaging, Metrology, and Additive Technology (CiMAT) at WMG, University of Warwick, we have been unraveling the conservation and repair history of the fossilised jaw using an innovative combination of modern technologies.

Identification of repair using X-ray computed tomography (XCT ) from the *Megalosaurus bucklandii* type specimen. The two colours indicate two different types of plaster material. Scale bar is 10 cm.

Earlier studies had mapped the presence of plaster used for repair, but X-ray CT scanning of the type used in medical procedures rapidly revealed a number of different phases of repair. In each of these repairs the plaster was of different composition and was used in different places.

One type, shown in red on the image above, was used to infill fractures and to make the specimen more robust; a second type, shown in green, was used to repair the teeth and, in some cases, to recreate the teeth. Interestingly, the extent of plaster revealed by the CT scanning is actually less than previously interpreted with the naked eye.

The two types of plaster were then analysed chemically to better understand their historical use, revealing quite different compositions. The more abundant ‘red’ plaster is mixed with quartz sand and calcite grains, possibly from the rock matrix surrounding the fossil, to make it look more similar.

Carbon is also abundant and grains rich in lead are present. Carbon is not common in the rock itself, and the carbon in the plaster has probably come from a varnish such as shellac being used to coat the repair. The presence of lead was more puzzling. Further analysis eventually showed that the grains were made of red lead – lead tetroxide – which was used historically as a pigment in paint. The red lead in the repair may have been used to colour the plaster, but it may also have been applied to make the density of the plaster more similar to that of the fossilized bone, and so replicate the weight of the specimen better.

Reconstruction of *Megalosaurus bucklandii* by Julius T. Csotonyi

The second type of plaster, used to repair the teeth, lacks the lead of the first type but contains barium. Barium hydroxide was often used as a consolidant and sealant for plaster, which would explain its use here.

Having a full understanding of the repair history and the position and extent of plaster helps us in a number of ways. It allows researchers to understand which parts of the lower jaw are original and anatomically reliable, and it helps the curators and conservators to know which parts of the specimen are more fragile during handling and display.

By combining cutting-edge scanning technologies with heritage material we are able to shed new light on the conservation history, and future, of important specimens such as Megalosaurus bucklandii.

Read the full paper here.

27 September 201812 October 2018

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Pieces of a plesiosaur

We’ve just opened a brand new, permanent display called Out of the Deep, featuring two beautifully preserved plesiosaur skeletons. Remarkably, both of these marine reptile fossils have skulls, which is more unusual than you might think. Dr Hilary Ketchum, collections manager in the Museum’s Earth Collections and curator of Out of the Deep, describes how the skull of the long-necked plesiosaur made it safely from a quarry to a museum display.

At the bottom of a clay pit in 2014, palaeontologists from the Oxford Clay Working Group discovered a 165-million-year-old fossil plesiosaur skeleton, and they knew they had found something special. Plesiosaur bones are fairly common in the quarry, but skeletons are rare. Skeletons with skulls are rarer still. Fantastically, at the end of their newly-found plesiosaur’s neck was a skull. Barely visible underneath the clay, only the tip of the snout and a few teeth were exposed.

Can you see the skull? Fossil hunting in the quarry takes time, patience and a good eye to distinguish between bones and clay. Image: Mark Wildman, Oxford Clay Working Group.

Plesiosaur skulls are usually made up of around 33 bones, not including the tiny bones from inside the eye sockets, called the sclerotic ring. The skull bones are among the smallest and most fragile in the entire skeleton. This means they are much less likely to be preserved, and less likely to be discovered, than the larger and more robust backbones and limb bones.

A plaster jacket was made around the skull while still in the quarry.
Image: Mark Wildman, Oxford Clay Working Group.

When the plesiosaur skeleton arrived in the Museum in 2015, the skull and some of the surrounding clay was encased in its protective plaster field jacket. As tempting as it was, instead of cracking open the jacket straight away, we decided on a more technological approach. Professor Roger Benson and Dr James Neenan took the specimen to the Royal Veterinary College to use their enormous CT scanner, normally used for scanning horses and other large animals, and took thousands of X-rays of the jacket. This allowed them to build up a 3D model of the fossil inside – our first tantalising glimpse of the whole skull!

The CT scan of the plaster jacket (left) revealed the location of the skull inside the jacket (middle). The jacket was then digitally removed (right) to reveal a 3D image of the skull.

Having the CT scan of the skull was like having a picture on a puzzle box
Juliet Hay, Earth Collections conservator and preparator

Although the CT scan was incredibly useful, we still had to proceed with the preparation with caution. It was possible that not all of the bones had not been detected by the scanner, especially the incredibly thin bones of the palate.

After opening the plaster jacket, Juliet began to carefully remove the clay from around the fossil bone.

Slowly and carefully, Juliet and I removed the soft clay from around the skull. The weight of clay pressing on top of the skull for millions of years had crushed it, breaking some of the bones into a lot of smaller pieces. In order to keep track of them we attached a number to each piece of bone and photographed it from several different angles before removing it from the jacket.

Each individual bone was mapped using a numbering system. The numbers were attached with the conservation adhesive Paraloid B72 in acetone, so that they could be easily removed later.

The plesiosaur’s pointed teeth being revealed.

When all the bones had finally been removed from the clay, we had over 250 pieces. Next came the challenge of the three-dimensional jigsaw!

With knowledge about plesiosaur skulls from my PhD, and some extra expert help from Roger Benson and Dr Mark Evans, Curator of Natural Science and Archaeology, New Walk Museum and Art Gallery, I was able to build up the skull, piece by piece, until it was nearly whole again.

After many months of painstaking work, the beautifully preserved skull of this long-necked plesiosaur can finally be seen in the *Out of the Deep* display.

Amazingly, the skull is even more complete and more beautifully preserved than we could tell from the CT scan. The sutures between the individual bones can be seen in exquisite detail, and even though I work with fossils every day, I still find it amazing that it is 165 million years old.

With special thanks to:

Oxford Clay Working Group: Mark Wildman, Carl Harrington, Shona Tranter, Cliff Nicklin, Heather Middleton, and Mark Graham, who uncovered and excavated the long-necked plesiosaur.

Forterra, for generously donating the plesiosaur skeleton to the Museum, after it was discovered in a Forterra quarry.

12 July 201824 July 2018

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Digging in the archives

by Danielle Czerkaszyn, Senior Archive and Library Assistant

Working day in, day out in the Museum of Natural History’s archive, we like to think we know a lot about our collections. The truth is, with the sheer number of items in our archive and the many nooks and crannies which exist in a historical building, we sometimes need some help rediscovering items in our collections. One such item is the engraved trowel used to set the Museum’s foundation stone.

The Earl of Derby lays the foundation stone at the 1855 ceremony. Engraving from *Illustrated London News.*

The story began when we received an enquiry from a museum enthusiast in America. He had read an article from an 1855 edition of the Illustrated London News, about the foundation stone ceremony. This was the moment that construction began on the Oxford University Museum, as it was then known. It seems that a small trowel was used as part of this ceremony. The article describes the trowel as follows:

The trowel, which is of silver and bronze, is highly finished, and novel in form. It is enriched by an engraved Gothic pattern on the upper, or silver, side. It was made by Skidmore, of Coventry, who has contracted for the foliated wrought-iron work which will decorate the quadrangle of the building. The trowel bears the following inscription-

Oxford University Museum. Chief Stone laid 20^th June, 1855, by the Right Hon. Edward Geoffrey Earl of Derby, Chancellor; Thomas Deane, Knt; Thomas N. Deane, and Benjamin Woodward, Architects.

Look carefully at the engraving from Ilustrated London News and you’ll see that children were also involved in the ceremony. They were likely to be Sarah and William Acland, the two eldest children of Dr. Henry Acland, who was instrumental in the founding of the Museum:

The trowel, borne on a cushion by two interesting children (the son and daughter of Dr. Acland), was then handed to the Earl.

The article does not say what happened to the trowel so our enquirer wanted to know; did the trowel end up in our archival collection or does it sit in the void under the stone?

Details from the Museum’s wrought iron roof decoration. Both the metalwork and the trowel were designed by Francis Skidmore.

As far as any of the Museum staff were aware, there was no trowel in our collections. With little to go on, we momentarily put the enquiry to one side and hoped for some good luck. The rediscovery came by accident just one week later, as we were rearranging boxes in the archive to make additional room for art storage. The trowel was spotted at the top of a box of items that had yet to be sorted and catalogued. With the recent enquiry on our minds, we recognised the trowel from its description and instantly knew what a special find this was.

Danielle Czerkaszyn holds the newly-discovered trowel. Her next challenge is to track down the missing silver handle.

Our enquirer was pleased to hear of the trowel’s rediscovery and thrilled to know the part that his enquiry played. Without his curious question, we might not have recognised the trowel for what it was. The trowel is now undergoing conservation treatment and cataloguing, and as an important part in the history of the Museum, it will hopefully be on display in the near future.

The Museum archive and library is open by appointment to anyone who would like to visit, and we welcome enquiries at library@oum.ox.ac.uk.

9 May 201822 May 2018

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Deal or no deal

by Darren Mann, Head of Life Collections

In a previous article on this blog I reported the discovery, in an insect collection, of the 21st British specimen of the ‘Regionally Extinct’ dung beetle Melinopterus punctatosulcatus. And since then, I’ve been on the hunt for more…

Heading out to numerous other museum collections I discovered more specimens, all collected in the same locality – Deal in Kent. In Ipswich Museum there are six, collected by C. Morley in 1896; there are two in the Natural History Museum, London, collected by G.C. Champion; and in the Museum of Zoology, Cambridge there are two collected by G.C. Hall in 1883.

But the earliest and most recent finds are both in the National Museum of Scotland – one from May 1871, in the G.R. Waterhouse collection, and one from 1923, in the T. Hudson-Beare collection. So now we know of 42 specimens of this beetle with data and we know that the species occurred at Deal for about 50 years. But why are there no records after this time?

The Deal sandhills in Kent were famous for their insects, but even as long ago as 1900 entomologists* were discussing the negative impact of “summer camping-out stations and the modern craze for the ‘Royal and Ancient Game of Golf'” on beetles and butterflies in the area.

Today, most of the sandhills are gone and there are no grazing animals other than a few rabbits. Most of the surrounding land is either developed as a golf course or under agricultural management. So, is the possible local extinction of this dung beetle due to habitat loss and a lack of dung?

To try and answer this question, naturally I went looking for poop in Deal. In a field in Sandwich Bay I could hear sheep bleating in the distance, although poo was scarce. Eventually I found a few old plops and inside were ten Calamosternus granarius, a small dung beetle. This was good, but my main target was Melinopterus punctatosulcatus.

Melinopterus punctatosulcatus edit — A specimen from the Museum of *Melinopterus punctatosulcatus,* previously listed as ‘Regionally Extinct’ in Britain, but now rediscovered in Deal, Kent

I probed the poop further. To my delight, crowded in the remaining squishy bit were four other species. On close inspection, one of these was hairy, so a male, and much darker than its close relatives. It fitted perfectly with my expectations for Melinopterus punctatosulcatus after seeing so many examples in museum collections. Success! This beetle, misidentified in museum collections for so long, and not seen since the 1920s in Deal, is indeed hanging on in Kent.

Disappointingly, after a further few days of searching, only a handful more specimens were seen. This suggests that either the species exists at low population levels, or that it was it was not the peak emergence period when I was there. Nonetheless, a species not recorded anywhere in the UK for over 70 years is actually still here.

Now hopefully we can encourage local land owners to help conserve this all-important dung fauna and flora.

* Walker, J.J. 1900. The Coleoptera and Hemiptera of the Deal Sandhill. Entomologist Monthly Magazine 36: 94-101.

20 April 20188 January 2019

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Who shot the Dodo?

By Scott Billings, Digital Engagement Officer

If ever the Oxford Dodo were to have squawked, its final squawk may have been the saddest and loudest. For the first time, the manner of death of the museum’s iconic specimen has been revealed: a shot to the back of the head.

This unexpected twist in the long tale of the Oxford Dodo has come to light thanks to a collaboration between the Museum and the University of Warwick. WMG, a cutting-edge manufacturing and technology research unit at Warwick, employed its forensic scanning techniques and expertise to discover that the Dodo was shot in the neck and back of the head with a 17th-century shotgun.

Mysterious particles were found in the specimen during scans carried out to analyse its anatomy. Further investigation of the material and size of these particles revealed them to be lead shot pellets of a type used to hunt wildfowl during the 1600s.

The Oxford Dodo specimen, as it has come to be known, originally came to the University of Oxford as part of the Tradescant Collection of specimens and artefacts compiled by father and son John Tradescant in London in the 17th century. It was thought to have been the remains of a bird recorded as being kept alive in a 17th-century London townhouse, but the discovery of the shotgun pellets cast doubt on this idea, leaving the bird’s origins more mysterious than ever.

Dodos were endemic to the island of Mauritius in the Indian Ocean. The first European accounts of the bird were made by Dutch explorers in 1601, after they rediscovered the island in 1598. The last living bird was sighted in 1662.

The story of the Oxford Dodo is especially significant because it represents the most complete remains of a dodo collected as a living bird – the head and a foot – and the only surviving soft tissue anywhere in the world.

This discovery reveals important new information about the history of the Oxford Dodo, which is an important specimen for biology, and through its connections with Lewis Carroll and Alice’s Adventures in Wonderland of great cultural significance too.
– Professor Paul Smith, Museum director

The Oxford Dodo represents the only soft tissue remains of dodo in the world. This iconic specimen was taken from the Museum to WMG at the University of Warwick for CT scanning.

WMG’s CT scans show that this famous symbol of human-caused extinction was shot in the back of the head and the neck, and that the shot did not penetrate its skull – which is now revealed to be very thick.

The discovery of such a brutal demise was quite a surprise as the scans were actually focused on discovering more about the Dodo’s anatomy, as well as how it lived and died. This work will continue, but we now have a new mystery to solve: Who shot the Dodo?

What’s the next step? It is possible that the isotope of lead in the shot could be analysed and traced to a particular ore field. This might tell us what country it was mined in, and perhaps what country is was made in, and ultimately reveal who shot the Dodo.

Category: Conservation

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