Diving into deep time

Our current First Animals exhibition is extending its run until 1 September, and to mark the extension our Research Fellow Imran Rahman takes a look at how animal life in the ancient oceans was brought to life in our Cambrian Diver interactive installation.

One of the biggest challenges in developing the First Animals exhibition lay in visualising rare fossil specimens as ‘living’ organisms, transforming them from two-dimensional imprints in the rock into three-dimensional animated computer models.

Many of the specimens on display in First Animals were collected from sites of exceptionally well-preserved fossils called Lagerstätten. These deposits preserve the remains of soft-bodied organisms that are almost never seen in the fossil record; things such as comb jellies and worms, as well as soft tissues such as eyes, gills and muscles. Even so, most of these fossils are flattened and two-dimensional, which makes it very difficult to reconstruct what they looked like in life.

Vetulicola cuneata from the Chengjiang fossil site had a large body with triangular openings on either side and a segmented tail. Its three-dimensional shape is uncertain.

To help exhibition visitors visualise the animals in a living environment we worked closely with Martin Lisec and his team at Mighty Fossils to create a set of detailed computer models of a key set of animals. We have worked with Martin before on the video of a Jurassic sea inhabited by plesiosaurs and other marine animals for our Out of the Deep display. That was very successful, but our idea for First Animals was even more ambitious: to create a unique interactive installation called the Cambrian Diver.

The material focused on the Chengjiang animals from the Cambrian of Yunnan province, China, which provides the most complete record of an early Cambrian marine community, from approximately 518 million years ago. Using fossil evidence of the organisms thought to have lived at the time we selected 12 species that were representative of the diversity of the Chengjiang biota.

The first phase was collecting as many materials as possible to be able to create 3D models. As usual, we started with rough models, where we set basic dimensions, shapes and proportions of body parts. Once approved, we moved to very detailed models for the animations, artworks and textures for less detailed models to be used within the interactive application. – Martin Lisec, Mighty Fossils

Images showing a preliminary 3-D model of the lobopodian Onychodictyon ferox in multiple views, with annotations in yellow highlighting changes suggested by Museum researchers.

To provide two-dimensional templates for Mighty Fossils to work from we scoured the scientific literature for the most recent accurate reconstructions available for each of the species.

The predatory arthropod Amplectobelua symbrachiata is a good example. We drew heavily upon a 2017 paper by Dr Peiyun Cong and colleagues, which included a very detailed reconstruction of the head region. This reconstruction shows that the underside of the head of Amplectobelua consisted of a rod-shaped plate, a mouth made up of two rows of plates, and three pairs of flaps with spiny appendages, all details that are included in our 3D model.

Scientific reconstruction (left) and our 3D model (right) of the arthropod Amplectobelua symbrachiata. Left-hand image modified from Cong et al. (2017).

Colour and texture were another consideration. To inform these we looked at living species that are thought to have similar modes of life today. For Amplectobelua, a free-swimming predator, we examined the colouration of modern marine predators such as sharks. Many sharks have countershading, with a darker upper side of the body and a lighter underside, which acts as camouflage, hiding them from potential prey.

We reconstructed our Amplectobelua model with similar countershading camouflage, with blue and red colouration inspired by the peacock mantis shrimp, a brightly coloured predatory arthropod that lives in the Indian and Pacific oceans.

3-D model of Amplectobelua in angled upper (top) and lower (bottom) views, showing countershading.

The next vital step was establishing how the animals moved and interacted with one another. This is a major challenge because in many cases there are no modern equivalents for these extinct early animals. For Amplectobelua we inferred that the flaps on the sides of the body were used for swimming, with the tail fan helping to stabilize the animal as it moved through the water. This agrees with previous interpretations of swimming in closely related animals such as Anomalocaris.

The models were built and textured by Mighty Fossils using the 3D gaming engine Unity. The video below is an accelerated sequence showing how the elements of the model are layered together.

The finished, animated and annotated Amplectobelua model is shown below, and can be zoomed and rotated. All the models generated by Mighty Fossils for the First Animals exhibition are gathered in a collection on our Sketchfab page.

Once animated models of all 12 species were created we placed them in a realistic marine environment. Study of the rocks preserving the Chengjiang fossils suggests these animals lived in a relatively shallow, well-lit sea, perhaps 50 metres deep and characterised by a flat, muddy seafloor. A continuous shower of organic particles is thought to have filled the water column, as in modern oceans.

Reconstruction of the Cambrian seafloor with ‘marine snow’

Based on present-day marine ecosystems, we infer that the number of immobile suspension feeders would have been much greater than the number of predators. As a result, we included multiple individuals of the suspension feeders Cotyledion, Saetaspongia and Xianguangia, which were tightly grouped together, but only a small number of the active predators Amplectobelua and Onychodictyon.

This scene is now populated with animals, including two predators: Amplectobelua (swimming) and Onychodictyon (centre)

The final step involved setting up a camera and user interface to allow visitors to discover the various animals in our interactive environment. For this we worked with creative digital consultancy Fish in a Bottle to identify eight locations, each focused on a different animal.

As the video above shows, users can navigate between locations by touching an icon on the screen, and when the Cambrian Diver sub arrives at a location information about the animal, its mode of life and its closest living relatives is presented on-screen. A physical joystick allows users a 360-degree rotation to look around the scene, and explore the ancient watery world.

This project was significantly bigger than the Out of the Deep work we had done previously with the Museum, mainly because of the complicated approval procedure needed for 20 individual 3D models. Along with three large illustrations, two animations and the interactive application this was a big workload! Fortunately, we managed to finish the whole project on time for the opening of the exhibition. – Martin Lisec

That’s Amore

By Laura Ashby and Megan MacLean, events managers

From cockroaches hissing alluringly to their mate, to smooth newts wafting intoxicating pheromones, and butterflies with eyes in their genitalia, the amorous pursuits of the natural world are enough to make St Valentine blush.

Valentine’s Day may conjure images of Cupid and his arrows, and indeed the romantic cherub of mythology has a brutal counterpart in nature. When the hermaphrodite Garden Snail (Helix aspersa) snuggles up to mate, both partners try to stab each other with love-darts in a mating duel. These darts are coated in chemicals that increase the chances of the dart-receiver’s eggs being fertilised. Love is a dangerous game: sometimes a dart misfires and hits a vital organ – a dart to the heart.

The hermaphrodite Garden Snail (Helix aspersa) fires love-darts as part of its mating ritual

Traditionally given as wedding presents in Japan, the lacy white deep-ocean glass sponge Euplectella, known as Venus’ flower basket, offers an interesting take on “…’til death do us part”. When a young shrimp pair enters the sponge to mate, they become trapped inside as they grow too large to escape. The couple then spend the rest of their lives together, caged in the sponge, whilst their offspring are small enough to leave through the small gaps and seek sponge-mates of their own.

The glass sponge Euplectella spp., also known as Venus’ flower basket

And if you forgot all about Valentine’s Day you will no doubt be panic-buying a bunch of overpriced roses on the way home, but be heartened that humans are not the only creatures that try to attract mates by presenting each other with gifts. The male Bowerbird builds a bower to attract females, decorating it with brightly coloured embellishments including flowers, leaves, stones, and even bits of plastic.

Objects from a Spotter Bowerbird bower, showing an interesting preference for white and green material

Meanwhile, male Empids (dance flies) offer a high-protein ‘nuptial gift’ – a gloopy sac called a spermatophore – for the female to eat during copulation. One theory is that females use the size of the gift as a way of choosing their mates…

Moving on from the natural world to natural historians, in 1835, Frederick William Hope married the wealthy heiress Ellen Meredith. He donated one of the founding collections to the Museum that they subsequently worked on together, the inspiration behind our current HOPE for the Future project. Meredith had recently rejected a marriage proposal from the future Prime Minister Benjamin Disraeli, stating that:

a life as the wife of a politician would have been a very dull one indeed

We at the Museum completely understand that weekends rootling around in dung for beetles with her entomologist husband seemed more appealing than stiff diplomatic receptions at Number 10.

Ellen Meredith and Frederick William Hope married in 1835

Fast forward to the modern day, and romance is in the air at the Museum, as many couples celebrate their marriages here each year. Every wedding has a different flavour, depending on the interests of the bride and groom, but natural history puns are guaranteed during the speeches, and dancing amongst the dinosaurs is a must!

A wedding in the Museum is surely the best start to a marriage

It may seem like a strange idea to tie the knot in a Museum, but perhaps 60-odd years of marriage seems comfortingly short in the context of 4.5 billion years of geological time?

If you are interested in talking with our events team about celebrating your wedding at the Museum of Natural History, contact Laura and Megan at venue@oum.ox.ac.uk / 01865 282780.

HOPE for the Future is supported by the National Lottery Heritage Fund. Find out more and get involved: https://www.oumnh.ox.ac.uk/hope-future

Top image: Gold-fronted Bowerbird, once thought to be extinct, but rediscovered in the Foja Mountains of Indonesia, painted by activist artist Jane Mutiny for the Conservation Optimism film festival at the Museum in 2019.

 

Oxford University Museum 1860

An ever-evolving museum

Oxford University Museum 1860

As we embark on our Life, As We Know It redisplay project – the first substantial changes to the permanent exhibits in more than 20 years – our Senior Archives and Library Assistant Danielle Czerkaszyn takes a look back at 160 years of an ever-evolving museum, in the first of a series of posts around the redisplay.

On 15 June 1860, Henry W. Acland, Regius Professor of Medicine at the University of Oxford, wrote:

The Oxford Museum slowly approaches completion. The building will shortly sink into insignificance when compared to the contents it will display, and the minds it will mould.

The University Museum at Oxford, as the Museum was originally known, was established to bring together scientific teaching and collections from across the University under one roof. The doors opened in June 1860, and soon after several departments moved into the building – Geometry, Experimental Physics, Mineralogy, Geology, Zoology, Chemistry, Astronomy, Human Anatomy, Physiology, and Medicine.

Ground floor plan 1866
Ground floor plan of the University Museum in 1866

When the University Museum opened, it was not simply a museum; each department got a lecture room, offices, work rooms and laboratories, as well as use of the library and display areas. According to Acland, a key figure in the Museum’s foundation, in 1860 the outer south aisle of the main court featured mineralogical specimens and chemical substances, while the inner aisle exhibited Oxfordshire dinosaurs.

Acland’s detailed descriptions of the central aisle highlighted zoological specimens with twelve parallel cases of taxidermy birds, four side cases of taxidermy animals, including animals on top of the cases, and six table cases down the centre showing shells, crabs, insects, corals and sponges, starfish and urchins. The inner north aisle presented reptiles and fish, while the outer aisle introduced the Ashmolean‘s zoology specimens, as well as anatomical and physiological collections.

The Museum in 1890
The Museum court in 1890

Although members of the public were welcome in the Museum from the start, the departments which inhabited the building were more concerned with teaching space, research facilities and the storage of their specimens than the needs of visitors. As a result, most of the early displays and cases were arranged in a systematic manner that focused on space-saving practicalities and communicating scientific knowledge, rather than aesthetics.

Geology specimens on the walls
Geology specimens displayed on shelves on the walls
Early Dodo display case
An early display focused around the Museum’s famous dodo specimen

Tracing through old annual reports it is clear that cases in the main court have been almost constantly refreshed and updated, with displays highlighting new specimens and changes to scientific understanding, or through practical improvements to lighting, electricity points and environmental monitoring. Nonetheless, the overall layout of the cases remained the same until the early 1980s.

The Museum court, unknown date
The Museum court, unknown date

From the early 1990s a focus on public engagement began to increase. Longer opening hours were introduced and displays were redesigned to link to both undergraduate teaching as well as the National Curriculum. Temporary exhibitions also regularly featured in the main court to increase the variety of specimens on display.

The Museum court in 1994
The Museum court in 1994
Megalosaurus temporary exhibition
A temporary exhibition about the Megalosaurus dinosaur in the 1990s

The turn of the millennium marked the start of a major project to update the main court displays. The central cases were reconfigured and a new set of introductory cases installed, including many themes familiar to visitors in recent years, such as exhibits on the Oxfordshire dinosaurs, Alice in Wonderland, and the Oxford Dodo.

T. rex makes its presence known

These showcases were complemented by the addition of an imposing cast of ‘Stan’ the Tyrannosaurus rex in the centre aisle, positioned behind the historic Iguanodon cast. The changes were well received and attendance in the month of July 2000 was the highest ever recorded. The Museum also introduced live insects for the first time in 2000, with Upper Gallery tanks containing Madagascan Hissing Cockroaches, South American Burrowing Cockroaches, a variety of stick insects, and some large tarantulas.

The project completed in late 2005 when the displays on Evolution, the History of Life, and Invertebrate Biodiversity were installed. Touchable specimens were also given their own permanent display area, allowing visitors the opportunity to physically interact with natural history material. These and other public engagement activities were recognised when the Museum won The Guardian newspaper’s Family Friendly Museum of the Year Award for 2005.

People around a table of touchable taxidermy specimens
New tables of touchable specimens were introduced for visitors in the 2000s.

The last substantial update to the fabric of the building took place in 2013, when the Museum closed for a year to fix the leaks in the glass roof. Taking advantage of the closure, a major piece of conservation work was undertaken on the seven whale specimens suspended from the roof. Having been on display for over 100 years, the whales were in need of considerable TLC.

A conservation team worked on the whale skeletons during the Museum’s closure for roof repairs in 2013.

Today, new and exciting changes are afoot as we embark on the first major changes to our permanent displays in almost 20 years. New high-end showcases will present displays under the concept of Life, As We Know It – beautiful presentations of the diversity of life, and the importance and fragility of biodiversity and human impact on the environment. The new exhibits will look at how the biological processes of evolution combine with the geological processes of our dynamic Earth to give rise to the immense, interconnected variety of the natural world.

Looking back across the decades we can see that the Museum is never static, but instead constantly changing and adapting, shifting from its foundation as a Victorian centre of academia to the accessible and engaging space we know and love today.

The Life, As We Know It redisplay project is supported by a generous gift from FCC Communities Environment.

On the trail of the Piltdown hoax

The latest display in our single-case Presenting… series takes a look at the famous Piltdown Man hoax, and Life Collections manager Mark Carnall tells us how the display came about…

Visiting researchers to the zoology collections at the Museum often give us an excuse to dig deeper into our own material, and one such recent enquiry led me into the intriguing story of the Piltdown Man hoax.

Professor Andrew Shortland from Cranfield University contacted us to enquire about the Piltdown Man material in our collections, as part of research for a book on hoaxes and forgeries in anthropology that he is writing with Professor Patrick Degryse of KU Leuven.

I knew we had some Piltdown material here thanks to this page written by Malgosia Nowak-Kemp, but I hadn’t had an excuse to investigate any further. The enquiry was also timely as we’d just transferred a collection of palaeoanthropology casts, models and reconstructions from our Earth collections to bring our human collections into one place. I knew from our move project team that there was some Piltdown material awaiting processing – perfect.

For those who don’t know the Piltdown Man story, a short history is in order. In the early 20th century, amateur fossil hunter Charles Dawson brought a collection of human remains excavated from gravel pits in Sussex to the attention of Arthur Smith Woodward, then Keeper of Geology at the British Museum (Natural History). Woodward and Dawson collected further material and presented the remains as those of Eoanthropus dawsoni (‘Dawson’s dawn man’), an important fossil human from Britain.

Group portrait of the Piltdown skull being examined. Back row (from left): F. O. Barlow, G. Elliot Smith, Charles Dawson, Arthur Smith Woodward. Front row: A. S. Underwood, Arthur Keith, W. P. Pycraft, and E. Ray Lankester. Charles Darwin looks on from a portrait on the wall. Image via Wikipedia.
R.F. Damon-produced endocast and associated label recording the presentation of this specimen to the Museum by Arthur Smith Woodward

The discovery looked set to put Britain on the map when it came to evidence of human evolution, but suspicions were quickly raised about the authenticity of the material. Such was the skill of the forgery – meticulous breaking, abrading and staining of various archaeological and historic specimens – that it wasn’t until dating techniques, chemical analyses and some experimental palaeoanthropology in 1953 that the hoax was conclusively put to bed.

In turned out that the Piltdown ‘remains’ were a mix of medieval bone, an orangutan jaw, and chimpanzee teeth maltreated to look like an evolutionary intermediate between humans and other apes.

For 40 years or so the hoax refused to go away and numerous casts, models and reconstructions of Piltdown Man were made, sold, exchanged and gifted to museums and universities. These included casts of the original material as well as reconstructions of the skull and even reconstructions of the endocast – a cast of the inside of the skull.

The Museum has a selection of this material, but as Professor Shortland examined the collections, two specimens stood out.

The first is an R. F. Damon-produced endocast presented to the Museum by Arthur Smith Woodward himself. Smith Woodward was known as an expert on fossil fish but published widely on zoological topics. As a scientist of some repute there’s been long-standing speculation about his role in the hoax. Was he wholly duped by Dawson, or was he in on the hoax from the beginning? If it’s the former, then the presentation of this endocast shows Smith Woodward disseminating research he presumably took some pride in. If it’s the latter, perhaps it was a way of cementing the hoax as legitimate by spreading specimens far and wide.

Joseph Weiner’s experimental fake created by modifying an orangutan jaw, alongside a cast of the Piltdown jaw

The second significant specimen is a worked orangutan jaw produced by Joseph Weiner, one of the three authors who debunked the hoax in a 1953 Nature paper titled The Solution of The Piltdown Problem. Weiner modified the orangutan jaw to replicate the original hoax specimen. Thanks to Professor Shortland’s knowledge of the hoax, he sent through a copy of Weiner’s book on the Piltdown Man where this exact specimen is pictured.

The Piltdown Man hoax wasn’t the first and certainly won’t be the last hoax, fake or forgery in the history of science, but it remains one of the most well-known and stands as a warning of the dangers of hubris in the discovery and description of the natural world.

The Weiner jaw and Damon endocast will be on display alongside other Piltdown Man material in our Presenting… case from 9 January to 8 March 2020.

First Impressions: exploring early life through printmaking

Dickinsonia by Claire Drinkwater

by Rachel Parle, public enagement manager

In each of our special exhibitions, we complement contemporary scientific research with contemporary art. In recent years this has included Elin Thomas’s crocheted petri dishes, Ian Kirkpatrick’s migration and genetics-themed installation, and who could forget the enormous E. coli sculpture by Luke Jerram?!

First Animals exhibition is on show until 24 February 2020

For our current exhibition, First Animals, we’ve taken this collaboration to a new level by commissioning original works from a total of 22 artists, all part of Oxford Printmakers Co-operative (OPC) – a group of over a hundred printmakers which has been running for more than 40 years.

First Animals looks at the very earliest evidence of life on Earth, dating back half a billion years. Some of the fossils on display are shallow impressions in the rock – the only direct evidence we have that life existed at that time.

Amplectobelua symbrachiata – one of the incredible Cambrian fossils from the Chengjiang site in China

To kick-start the project we ran a series of workshops for OPC artists to meet the Museum researchers working on the exhibition, and to see the fossils first hand. There were also opportunities to draw directly from these unique fossils, many of which have never been displayed in the UK before.

Discussions between researchers and artists revealed fascinating similarities between these ancient fossils and the process of printmaking. Sally Levell, of Oxford Printmakers Co-operative, explains:

I was completely fascinated by the fossil collection in the Museum, especially the fine specimens from Chengjiang and Newfoundland. They are preserved as mere impressions in the rock, so they are, in essence, nature’s prints.

Each printmaker partnered with a researcher who could answer questions, provide extra info and help the artist decide which specimen or subject to depict in their final print. It’s clear from talking to the printmakers that this direct contact with the experts was invaluable and made the work really meaningful.

Xianguangia by Charlie Davies

We couldn’t have worked without the patient explanations and “show and tell” sessions with the three main researchers – Dr Jack Matthews, Dr Imran Rahman and Dr Duncan Murdock. They were just excellent and their dedication to their work was an inspiration to all of us printmakers.

Sally Levell

Over a period of around seven months, ideas blossomed and printing presses were put into action, with the printmakers exploring the forms, textures and evolution of the fascinating first animals. The final result is First Impressions, an enticing art trail of twenty-five prints dotted around the Museum, both within the First Animals exhibition gallery and nestled within the permanent displays.

Ottoia by Jackie Conway

Such a large group of artists brings a huge variety of techniques and styles, all under the umbrella of printmaking; from a bright, bold screen print in the style of Andy Warhol, to a delicate collagraph created from decayed cabbage leaves! To take part in the art trail yourself, simply grab a trail map when you’re next in the Museum.

Workshop printers inking up their plates

But our foray into fossils and printmaking didn’t stop there. OPC member Rahima Kenner ran a one-day workshop at the Museum where participants made their own intaglio prints inspired by the First Animals fossils. The group of eight people featured artists and scientists alike, all keen to capture the unique fossils through print techniques.

Designs were scratched onto acrylic plates and inked up, before a professional printing press created striking pieces to take home. Participants also explored techniques such as Chine-Collé, the addition of small pieces of paper to create texture and colour underneath the print.

It was a delight to be able to share with the group our enthusiasm for these discoveries in the medium of making the drypoint prints and to share their enjoyment of learning and using the new techniques. Some lovely work was produced in a single day.

Rahima Kenner

A plate about to go into the press
A finished print, using intaglio and chine-colle

The First Impressions project has been transformative for the Museum team and for the Oxford Printmakers Co-operative. Catriona Brodribb describes its impact on the printmakers :

It’s been a great opportunity to challenge one’s own artistic boundaries in terms of stretching the imagination, and for our members to throw themselves into something new, and enjoy responding to such ancient material in a contemporary way.

The First Animals and First Impressions exhibitions are open until 24 February 2020 and are free to visit.

A grasp of the past

by Ricardo Perez-De-La Fuente, research fellow

Few creatures look weirder – or are cooler, in my opinion – than mantidflies. There are around 400 species of these small predatory insects known worldwide – a scarce diversity by insect standards.

Like praying mantises, mantidflies have long ‘necks’ and forelegs armed with powerful spines and other structures used to hunt their prey with a sudden lethal grasp. The unfortunate victims become immobilised until they are meticulously eaten alive – not the best way to spend your last minutes on Earth!

Mantidflies belong to the Neuroptera order of insects and so aren’t actually related to praying mantises, but to insects such as lacewings and antlions.

A new paper that a colleague and I have published presents a new fossil mantidfly from Spanish amber that is important in understanding the evolution of their gripping – or raptorial – forelegs. The finding is presented in the open access journal Scientific Reports today.

Although the discovery has just been published, we excavated the new fossil during the scorching summer of 2010 in Teruel, northeastern Spain.

Amber excavations are very romantic – while they take place we carefully store the amber, piece by piece, into muddy plastic bags, remaining oblivious of what creatures are being unearthed because the amber surfaces have become opaque during fossilisation. Later, in the laboratory, the surfaces of the amber pieces are polished and screened for inclusions. Then a first glimpse is gained into what has remained frozen in time for millions of years.

It is only when the amber inclusions are carefully examined and studied that the implications of the specimens that were dug up years earlier start to be revealed. In this case, a specimen that was preserved in fragments, nothing spectacular at first look, ended up being truly exceptional.

Foreleg of Aragomantispa lacerata, showing powerful spines and other structures adapted to strike and hold prey.

Extinct true mantidflies, particularly those preserved in amber, are extremely rare. Our new fossil, pictured above at the top of the article, is 105 million years old, from the Cretaceous period. It currently stands as the oldest true mantidfly known in amber. The new extinct species, named Aragomantispa lacerata, has allowed us to compare the structures of the raptorial forelegs between extinct and extant mantidflies with an unprecedented detail.

Comparison between the foreleg spine-like structures of the new fossil mantidfly (up), with those from a close modern species (bottom).

Present-day mantidflies have forelegs with spines that bear minute cones at their tip. These cones are sensory organs that elicit the striking reflex and feel the prey’s movements once captured and restrained by the mantidfly’s tight embrace.

The forelegs of Aragomantispa lack these cones at the spines’ tip, instead having larger, icicle-shaped tips. We do not know how sensitive the mantidfly forelegs were in the Cretaceous, but the spines of at least some of these insects seem to be not as specialised as those from their present-day relatives.

Some mantidflies have smaller, reclined hair-like structures forming an edge on the leg’s surface opposing the spines. These reinforced edges create a scissor effect that stuns prey when the forelegs strike. Although Aragomatispa has these structures on the forelegs, they are also different in shape to those found on extant mantidflies.

Reconstruction of Aragomantispa lacerata striking at a hypothetical prey on a fern in the Cretaceous Spanish forest.

The fossil record offers the only direct means to assess when and how the traits characteristic of a given animal group originated in time. However, this kind of fossil evidence appears very occasionally. Our discovery shows that the foreleg spine-like structures of recent mantidflies were not fully developed in at least some of their Cretaceous ancestors.

The most exciting part is to think that this story and literally thousands more lie waiting to be discovered – or otherwise forgotten forever – buried underground.