Elaine Charwat has been on a journey into the attic storerooms behind the scenes of the Museum to discover 19th-century wax models of parasites. A strange occupation you might think, but it’s all part of her doctoral research programme with the Arts and Humanities Research Council to learn about the use of models and replicas in science, past and present. In the podcast above Elaine meets Mark Carnall, Zoology Collections Manager at the OUMNH, who talks about the differences between models and the thousands of specimens he looks after, and Dr Péter Molnár, Assistant Professor of Biological Sciences at the University of Toronto, who offers important insights into current research using mathematical models.
Different types of models and replicas are everywhere in the Museum, and they tell us much about the organisms they represent or reconstruct, but even more about processes in research and science. Made to communicate and produce data, these larger-than-life objects are as fascinating as their subjects…
Top image: Wax models of Sarcoptes scabiei (itch mite) produced by Rudolf Weisker, Leipzig (Germany), probably late 1870s or early 1880s. These models are listed as having been on public display at the Museum in 1911, labelled: “Sarcoptes scabiei: enlarged wax models, male & female + mouth parts”.
Elsa Panciroli recently joined the Museum research team as an Early Career Leverhulme Research Fellow. Elsa is a Scottish palaeontologist, whose studies focus on the early evolutionary origins of mammals, working extensively on fossils from the Isle of Skye. Here she tells us how her work will combine studies of mammal evolution with stunning new fossil finds from Scotland.
We are mammals. This means we share a common ancestor with creatures as different as hippos, opossums and platypuses. All of us are united in one taxonomic group by a suite of characteristics in our bodies, but principally, that we feed our young on milk. Every mammal from a baboon to a blue whale produces milk for their offspring, and this makes us unique among animals alive on Earth today.
But not all mammals bring their young up in the same way; raising a kitten is nothing like raising a kangaroo or a platypus. Kittens are born stumbling around with their eyes closed, while platypus babies are laid in eggs – yes eggs – and when they hatch they look like little scampi. Both are underdeveloped at birth or hatching, but that’s nothing compared to kangaroos. They leave the womb only millimetres in length, and wriggle their way like living jellybeans toward a teat in the marsupial pouch, where they latch on. Only after two months of milk-drinking are they able to hop for themselves and leave the pouch.
The different ways that mammals are born and grow is a huge area of scientific research. But there are still some major questions to answer about the evolution of these growth patterns. When did the ancestors of mammals stop laying eggs? Were they born defenceless, or able to fend for themselves? How quickly did they grow up and how long did they live?
Over the next three years at the Museum, I’ll be looking for evidence in the fossil record to help us try and answer some of these questions. I’ll study living mammals to understand how they are born and grow, combining this information with data from some of the amazing fossils being found on the Isle of Skye. With collaborators in South Africa I’ll try and work out how the ancestors of mammals developed, and what this means for the bigger picture of the origin of mammals as a group.
Alongside my main research I hope to share lots of stories about our fossil past through the museum’s fantastic public engagement programme. I’m also very active on social media, and I write about science for online and in print publications. So if you see me on your next visit to the building, or find me online, feel free to ask about my research! I look forward to seeing you, and sharing more about the elusive and exciting origins of mammals – and ourselves.
Last week’s observations of the swift nest boxes in the Museum tower highlighted the drama the colony faces in the struggle for survival. This week’s survey made that struggle even more explicit…
Clambering through the darkened spaces of the Museum tower, lit faintly by the red lights that the swifts cannot see but which help give surveyors a dim view of the ladder rungs and observation platforms, I peered briefly into each nest box to count the birds and eggs.
In one box I came across a dead bird, alone and lying on its back. Carefully bagging up the body for later investigation I continued my count while pondering the cause of its death, the sadness relieved slightly with the discovery of new eggs in other boxes and the promise of new life to come.
Screams and banging from birds prospecting for nest sites are a regular backdrop to each survey. Birds call and swoop past the boxes only inches from my ears, separated by just a few roof slates. The birds within scream back in answer. But on this occasion, half way down the tower, I became aware of particularly loud and persistent screams and banging, coming from within a box.
A quick peek inside revealed a hectic struggle between at least three swifts, wings drawn back, wrestling and rolling around, pecking and slashing at each other with their sharp claws. It was actually impossible to see if the fight involved three or four birds as the struggle filled every inch of the small box with wings, beaks, claws and feathers.
David Lack first documented these fights in his excellent book Swifts in a Tower. He proposed that they were the result of birds entering an already occupied box in the struggle to find a suitable nest site.
Sitting and anxiously listening beside the box, I recorded the fight lasting 15 minutes from the time I became aware of it. Lack documented ‘gladiatorial shows’ that lasted five and three quarter hours; they were painful to watch, he admitted, as the swifts have a surprisingly strong grip and claws capable of drawing blood, but rarely resulted in death.
When the noise died down, I gently lifted the cloth blind to take another look. Only two birds remained, both looking exhausted and fiercely gripping each other’s feet, one lying under the other. A quick flurry and the upper bird disengaged and jumped from the nest box entrance.
Lack also mentions in his book that it is usually the bird underneath in these struggles that is the winner and I was relieved when the remaining bird picked itself up and returned to the two eggs, which had somehow remained in the nest, settled on top of them and preened itself. This suggested that the nest’s original occupant had won, driving off an intruder.
The screaming and banging outside the boxes is a check for a screamed response from within. It reveals whether a box is already occupied or empty, before the bird risks entry. Presumably, the fight I witnessed was the result of a bird not hearing a response or perceiving it as coming from another box.
The drama of the fight illustrates the incredible importance of nest sites and the fidelity the swifts have to them after a year on the wing. Nest sites are at a premium and swifts are almost totally dependent on nesting in old buildings as there are so few forests with suitably old, cavity filled trees remaining.
Once a nest is occupied the owners will fight furiously to defend it and David Lack did record occasional incidents of birds fighting to the death. So perhaps this was the cause of the dead bird I had found lying on its back, but that will have to wait for a later examination.
It is important to record nest sites and, if you can, put up nest boxes. RSPB’s Oxford Swift City project, which the Museum and Oxford City Council were involved in, annually surveys and records nesting sites so that development in these areas is restricted during the breeding season and developers must include plans to protect and provide new nest sites when repairs to property or new building takes place. If you would like to help with the work of conserving one of the most dramatic annual migrants to our shores visit the RSPB site.
We have our first eggs! After an earlier than usual return from the warmth of Africa, followed by a cold snap of north easterly winds, our swifts have begun to lay their first clutches of eggs in the tower.
Ten eggs were counted on 14 May, some in pairs and some lying singly on nests. Birds in other nests appear to be incubating as well, sitting in pairs and screaming out at any newcomers investigating possible nesting sites.
More swifts are arriving daily and screaming parties are urgently exploring for potential nesting locations. They buzz the tower’s nesting holes at speed and bang on the entrances with their wings like naughty teenagers playing a vociferous game of ‘knock and run’!
Typically, no bird has yet elected to nest in either of the boxes fitted with webcams. But as the weather warms and more swifts take up residence every day, we’re sure you’ll be able to follow all the drama of the Swifts in the tower very soon.
The delicate art of laying
Swifts tend to lay their eggs in the mornings, usually between 8am and 11am. The small, fragile eggs are white to reflect light, an adaptation shared by most cavity-nesting birds that makes the eggs more visible to adults in the dark of the nest.
The first eggs this year appear to be quite early in the season compared with the observations by David Lack in the 1940s and 50s. At that time, when the study of the Museum’s colony began, the first eggs were recorded on average between 17 and 22 May, but sometimes none was laid until the first week of June.
Egg production and laying in swifts are very closely tied to the weather, and production seems to be triggered by the availability of food. Swifts feed exclusively on small airborne insects, which are more abundant in the warm thermals and light winds we experience on good summer days.
It takes a swift five days to produce and then lay an egg. Five days before our first eggs were laid it was sunny and warm, just before the strong, cold north easterly winds swept down over the weekend and lowered the temperature. The warmer early start to the summer seems to have triggered this early laying; whether this is a trend that is increasing as the climate changes is something we should able to answer with long-term datasets provided by studies like this.
Dealing with the weather Whatever climate change has in store for us it is becoming clear that we won’t experience repeated hot summers. The unpredictability of the British summer reigns supreme.
Swifts have evolved several wonderful adaptations to deal with the vagaries of our weather. Their eggs can be left without an adult to keep them warm for several days. There are records of eggs being left unattended for almost a week and still developing normally. Although adults usually take it in turns to feed and brood the eggs, sometimes during the day the eggs are left unattended by both birds which are then able to forage far afield for food.
Unlike many songbirds which produce one egg a day until their clutch is completed, swifts are able to space out their laying. In a clutch of two or three eggs, the second or third may be laid two or three days after the first, depending on weather conditions. The birds will also limit the size of clutches, with clutches of three eggs the average in warm weather and two eggs the average in cold weather. This helps the adults to supply all of their young with enough food.
Finally, swifts may also eject eggs and lay a second clutch. Some studies have linked this behaviour to cold weather but this has not always been the case at the Museum colony and is a further line of investigation in the ongoing studies of these most secretive of birds.
From laying to hatching usually takes about 19 days, depending on the weather. So we should be seeing our first chicks at the very beginning of June, hopefully streaming live on the Swiftcam…
Screaming parties prospecting for nest sites are a good way for you to see if you have nesting swifts nearby. Any records really help with our understanding of the current population in the UK. You can help conservation and recording for the Oxford Swift City project, or use the RSPB’s Swift Mapper for the rest of the UK.
Amber, or fossilised plant resin, is a unique material to learn about the history of life on Earth. Its incredible preservation and ability to capture life “in action” are well known thanks to the Jurassic Park saga, but fewer people know where amber is found, what it looks like in the field, and how it is gathered.
Cretaceous amber, about 130 to 70 million years old, is the oldest amber that provides abundant fossils, specifically insects and spiders. Ecosystems drastically changed during this period due to global greenhouse conditions and the diversification of flowering plants, among other factors. Amber from that time has been discovered in Lebanon, Spain, France, Myanmar, eastern United States, Canada, and northern Russia.
My research team and I carry out regular amber excavations in northern Spain, working in teams of six to ten people. The outcrops that we excavate are often located next to roads and highways because amber is typically uncovered during roadworks. Excavations take place during the summer or fall to try and minimise the risk of rain, and we usually embark on one field trip each year.
The goal is to recover as much amber as possible – usually a few kilograms – from the muddy and sandy sediments. These materials were transported downstream tens of million of years ago by heavy rain and river swellings from the forests where the resin was produced, before being finally deposited in near-shore areas.
I find amber excavations quite romantic. In the field, amber has a dull appearance that makes it difficult to distinguish from rocks or woody remains. This is due to an opaque crust resulting from oxidation in the sediments and other processes.
This outer layer makes detecting potential fossils inside the amber highly unlikely while the excavation is ongoing. So, in the field we just gather as many amber pieces as possible, and hope for the best.
Only when amber is polished – or shows broken surfaces – does its distinct yellowish to reddish shine emerge, and any possible fossils within become evident. Some ambers are highly fossiliferous, while others are very poor in fossils.
Amber can be gathered by hand using regular tools such as hammers. However, the most efficient method to extract amber from soft sediments is with concrete mixers! This rather unsophisticated piece of equipment provides the best way to recover medium quantities of amber in the field.
We charge water and amber-bearing sediments into the mixer, and after stirring for a while amber floats to the top because it is less dense than muddy water. Then, the surface of the water containing the amber is poured into sieves, which separates even the tiniest pieces.
After fieldwork, many hours will be spent looking for fossils within the amber and preparing them. Gathering raw amber is just the first part of a process in unearthing the secrets held within – fragments of encapsulated time.
Top image: First amber excavation in the El Soplao outcrop, Cantabria, N Spain in 2008. Credit: IGME/UB.
Some of the very oldest complex, macroscopic communities on Earth appear in the fossil record about 570 million years ago and record the presence of a group of organisms – the rangeomorphs – with an unfamiliar body plan that, at their ultimate extinction, was lost from life’s repertoire.
Rangeomorphs are characterised by a strange frondose branching anatomy, where large primary branches host smaller branches which themselves host smaller branches again. This arrangement appears to maximise the surface-area to volume ratio of the organism, rather like a lung or a gill would today.
The smallest known rangeomorphs are less than a centimetre in length, but they grew huge and the largest records indicate they could stand more than two metres tall. There is no evidence to suggest that rangeomorphs were able to move around, rather, they lived stuck to the sea floor in the deep ocean, far below the reach of light.
Despite this strange set of characters, there is growing consensus that rangeomorphs likely represent very ancient records of animal life. However, they lived at such a remote time in Earth’s history that they do not possess any direct living descendants. Given all this, it may not be a surprise to hear that we know relatively little about how these organisms made their living and came to dominate the ancient seafloors.
In order to better understand them, my co-author Alex Liu and I travelled to Newfoundland, Canada to explore the rocks which host these remarkable fossils and over the past few years we have made an unexpected discovery. We found that fine filamentous threads connect rangeomorph fronds of the same species, in some cases over many meters, though they are typically between two and 40 centimetres long.
It is possible that these filaments were involved in clonal reproduction, like strawberry plants today, but they may have had additional functions such as sharing nutrients or providing stability in strong ocean currents.
The discovery of the filaments means that we have to reconsider how we define an individual rangeomorph, and may help us understand how rangeomorphs (seemingly) rapidly colonised deep-sea environments. Either way, some reassessment of the palaeobiology of these unique organisms is certainly required!