On the trail of the evolution of mammals

Woman sitting on top of a large, layered rock formation

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.

Wareolestes rex is a Middle Jurassic mammal, illustrated here by Elsa Panciroli

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?

The Rock Hyrax (Procavia capensis) is a terrestrial mammal native to Africa and the Middle East

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.

Follow Elsa on Twitter at twitter.com/gssciencelady.

Drawn to life

A set of illustrated cartoons of the heads of eleven people with their names handwritten underneath

By Rachel Simpson

Worms, fish and … Greenland? Hugely different topics which all have one thing in common – the Museum’s First Animals exhibition online lecture series. Running every other Wednesday from May until September 2020, this series provided a fantastic insight into a wide range of topics about how the first animals lived, died, and are studied. And illustrator Rachel Simpson tells us how she drew her way through them all…

I came across this lecture series just before the first talk and I knew I had to sign up. Drawing along to lectures is a hobby I seem to have developed in the past few months as we went into lockdown and didn’t have much to do. It’s the perfect combination for me – an opportunity to listen to interesting topics and brush up on my live drawing skills at the same time. There’s no pause button, there’s no asking the webinar speaker to just go back a few slides and hold on a minute whilst I draw; it’s fast paced, it’s inspiring and it’s a great way to just create art.

Barma Booties used on the rocks at Mistaken Point, and my first drawing of the series.

I’ve done some illustration work with the Museum before so I knew that it was going to be fun. In 2018, I worked with Dr Jack Matthews illustrating Ediacaran Fossils as part of a collaborative university project between the University of Plymouth and the Museum. I was also lucky enough to be able to go to Newfoundland and see some of the fossils myself, again with Jack. This was such an incredible opportunity and opened up a whole new world of science/art collaborative work which I didn’t know about before.

The First Animals series kicked off with Jack’s talk titled Don’t walk on the rocks! – an interesting insight into how protective “Barma Booties” (some rather funky socks worn to protect fossil sites such as Mistaken Point, Newfoundland) might actually be damaging to the fossils they’re meant to be protecting. Having been to Mistaken Point myself and worn these socks, it was interesting to hear about their possible impact and to learn about the experiments conducted to prove this fact.

Of course, at the same time as Jack was talking, I was scribbling away in my sketchbook trying to form some sort of visual response to the talk. At the end of the hour I’d managed a portrait of Jack and a family of Barma-Booted tourists trampling on the fossil site. It was a start. The beginning of my lecture drawings and a point at which I can retrospectively say started a new hobby.

Annelid worms drawn with Tombow brush pens.

Over the following weeks we heard about worms from Dr Luke Parry; 3D reconstruction from Dr Imran Rahman; The Chronicles of Charnia by Dr Frankie Dunn; and the first animal skeletons from Dr Duncan Murdock. Luckily for me, all the speakers kindly included photos and descriptions of the topics they were discussing which meant that I was never short of visual inspiration for my drawings. After all, it’s hard to try and draw an annelid worm if you’ve never seen one before.

I love to look at the fossils being discussed and then try to draw a little character or creature inspired by them. They’re not scientifically accurate, nor are they always anatomically correct, but they have character and begin to bring to life the essence of something that’s been dead for many millennia. The fossils are obviously stone-coloured so I take as many liberties as possible when it comes to colour. I like to make them as vibrant and colourful as I can, so although they probably didn’t look like that, that’s how I like to think they looked.

Within my wider practice I like to use stamps as the basis of my illustrations. These however, are time consuming to make and therefore not very suitable for when I’m drawing along to lectures. As a result I’ve found myself using brush pens and pencils to make my lecture illustrations. If you’re interested in art, or thinking about getting into art, brush pens will be your best purchase. They create a wonderful quality of line and are quick and easy to use. Whereas a ballpoint pen will give you one line of a certain weight and thickness, brush pens are versatile and depending on the pressure applied, the line quality will change.

For the first few lectures I only used brush pens, but later on I decided to use coloured pencils as well, to add depth to the drawings. As I got more used to drawing in lectures I found that I was making more illustrations per talk. Early on, I managed to finish maybe a double page in my sketchbook but towards the end of the series I was filling four double pages! It’s amazing what a little bit of practice can do.

As the weeks went by the talks continued and we heard about the evolutionary origin of animals from Museum director Professor Paul Smith; an introduction to taphonomy, the study of fossilisation, by Professor Sarah Gabbott; and how the first animals moved by Professor Shuhai Xiao.

During this time I became a lot more confident drawing the specimens; looking back I can see that this was the period in which my work developed the most. My drawings began to have more character and life. The landscape drawings were slowly becoming more realistic and detailed. This was great news for me as this whole endeavour began as a way to practice my drawing skills in a timed environment.

Paul Smith’s lecture has to be my favourite of them all. He gave a wonderful talk all about the Evolutionary Origin of Animals and talked us through his fieldwork expedition to Greenland. How I would have loved to have been on that trip!

It was during Paul’s talk that I made one of my favourite drawings from the series – the plane – and coincidentally it was also at this point that I bought myself some new polychromo pencils. I started using these pencils in my illustrations on top of the Tombow brush pens. The pencils added a softer layer on top of the solid base colour from the brush pens and meant that I could add more details, shading and most importantly, the characterful eyes I love to add to my drawings.

Buoyed by this development in my drawings, and some lovely responses to my work on Instagram and Twitter, I raced through the next few weeks of talks and made twelve pages of drawings over the next four talks. Professor Derek Briggs told us all about extraordinary soft-bodied fossils; Professor Gabriela Mángano told us about the trace fossil record; and Professor Rachel Wood gave us her thoughts about what triggered the Cambrian Explosion.

Another of my favourite drawings from the series was from Derek Briggs talk about extraordinary soft-bodied fossils. Here, I made a small series of drawings based on some of the animals mentioned in the talk and as soon as I’d finished drawing them I wished that they were real and that I could pop them in a fish tank and keep them as pets. These drawings got the best response on social media too and it’s wonderful now to look back and compare these drawings to the work I was creating at the beginning of the series.

Two images of coloured drawings of extinct marine creatures side by side
Comparison between week 2, Luke Parry’s talk (left), and Week 9, Derek Briggs’ talk (right): What a difference 16 weeks of drawing practice makes!

The First Animals series may be over but keep your Wednesday evenings free because there are more talks to come! The next series, “Visions of Nature”, starts on 8 October so make sure you join us then! A huge thank you to all the speakers, to Jack for hosting and to the Museum for running the events.

To see more of Rachel’s illustrations visit www.rachelerinillustration.co.uk.

High-tech insect origami

By Dr Ricardo Pérez-de la Fuente, Research Fellow

Earwigs are fascinating creatures. Belonging to the order Dermaptera, these insects can be easily recognised by their rear pincers, which are used for hunting, defence, or mating. But perhaps the most striking feature of earwigs is usually hidden – most can fly with wings that are folded to become 15 times smaller than their original surface area, and tucked away under small leathery forewings.

With protected wings and fully mobile abdomens, these insects can wriggle into the soil and other narrow spaces while maintaining the ability to fly. This is a combination very few insects achieve.

I have been working on research led by Dr Kazuya Saito from Kyushu University in Japan, which presents a geometrical method to design earwig wing-inspired fans. These fans could be used in many practical applications, from daily use articles such as fans or umbrellas, to mechanical engineering or aerospace structures such as drone wings, antennae reflectors or energy-absorbing panels!

Dr Saito came to Oxford last year for a six-month research stay at Prof Zhong You’s lab, in the Department of Engineering Science at the University of Oxford. He introduced me to biomimetics, an ever-growing field aiming to replicate nature for a wide range of applications.

Biological structures have been optimised by the pressures of natural selection over tens of millions of years, so there is much to learn from them. Dr Saito had previously worked on the wing folding of beetles, but now he wanted to tackle the insect group that folds its wings most compactly – the earwigs.

He was developing a design method and an associated software to re-create and customise the wing folding of the earwig hind wing, in order to use it in highly compact structures which can be efficiently transported and deployed. Earwigs were required!

Here at the Museum we provided access to our insect collections, including earwig specimens from different species having their hind wings pinned unfolded. These were useful to inform the geometrical method that Saito had been devising.

Dr Saito was also interested in learning about the evolution of earwigs and finding out when in deep time their characteristic crease pattern established. Some fossils of Jurassic earwigs show hints of possessing the same wing structure and folding pattern of their relatives today.

However, distant earwig relatives that lived about 280 million years ago during the Permian, the protelytropterans, possessed a different – yet related – wing shape and folding pattern. That provided the chance to test the potential and reliability of Saito’s geometrical method, as all earwigs have very similar wings due to their specialised function.

The geometrical method turned out to be successful at reconstructing the wing folding pattern of protelytropterans as well, revealing that both this extinct group and today’s earwigs have been constrained during evolution by the same geometrical rules that underpin the new geometrical design method devised by Dr Saito. In other words, the fossils were able to inform state-of-the-art applications: palaeontology is not only the science of the past, but can also be a science of the future!

We were also able to hypothesise intermediate extinct forms – somewhere between protelytropterans and living earwigs – assuming that earwigs evolved from a form closely resembling the protelytropterans.

As a collaboration between engineers and palaeobiologists, this research is a great example of the benefits of a multidisciplinary approach in science and technology. It also demonstrates how even a minute portion of the wealth of data held in natural history collections can be used for cutting-edge research, and why it is so important to keep preserving it for future generations.

Soon these earwig-inspired deployable structures might be inside your backpacks or used in satellites orbiting around the Earth. Nature continues to be our greatest source of inspiration.

Original paper:  Saito et al. (2020). Earwig fan designing: biomimetic and evolutionary biology applications. Proceedings of the National Academy of Sciences of the United States of America.

When life got hard

By Dr Duncan Murdock, Research Fellow

Whether you’re a great white shark with a deadly conveyor belt of teeth, a deep sea snail with a coat of armour or a coral building the Great Barrier Reef one polyp at a time, mineralized skeletons are a crucial part of many animals’ way of life. These hard skeletons – shells, teeth, spines, plates and bones – are all around us.

The fossil record is full of the remains of the skeletons of long-extinct critters, so much so that entire layers of rocks can be composed almost completely of them. But this has not always been the case…

A piece of 425 million year old sea floor containing the skeletons of trilobites, brachiopods, bryozons, corals and gastropods preserved as limestone

Travel back some 570 million years to a time known as the Ediacaran and the picture is very different. Although there were large-bodied creatures that were possibly animals, they were entirely soft-bodied. Then, right at the end of the Ediacaran Period, the first animals with hard skeletons evolved, creating strange tubes, stacked cones, and other bizarre forms such as Namacalathus, which resembles a baby’s rattle!

Some of the first animals with skeletons, Cloudina and Namacalathus alongside the soft-bodied Ediacaran fauna. Reconstruction based on rocks from Namibia, Southwest Africa, from 543 million years ago. Image: Mighty Fossils.

 

In the following few tens of millions of years, in the early part of the Cambrian Period, a whole host of animals burst onto the scene baring their ‘teeth’, hiding in their shells, and bristling their spines. In fact, we can trace the origin of almost every kind of animal skeleton to this relatively short window of the Earth’s past.

In my research, I have compiled the evidence for how and when these skeletons first appear. Three key observations have emerged. First, skeletons evolved independently many times in different animal groups. Second, there is both direct and indirect evidence, such as exceptionally preserved fossils and trace fossils, for entirely soft-bodied examples of animal groups that later evolved skeletons. And lastly, the first animal skeletons are less complex and more variable than later examples.

Added to what we know about how living animals build their skeletons, this all points to one explanation: Animal skeletons evolved independently in different groups by utilising a common ‘toolkit’ of genes, inherited from their common ancestor but used in different ways in different skeletons.

In other words, the soft-bodied ancestors of animals with hard parts had inherited all they needed to build simple skeletons that were then honed into the array of shells, teeth, spines, plates and bones we see today. For these skeletal pioneers, armed with their genetic ‘toolkit’, the environmental and ecological pressures of the early Cambrian prompted the evolution of similar, but independent, responses to their changing world – when life got hard.

Murdock, DJE. 2020. The ‘biomineralization toolkit’ and the origin of animal skeletons, Biological Reviews, is available for free here.

Top image: Tiny fragments of early skeletons, shells and spines, from around 510-515 million years ago.

 

Excavating amber

First amber excavation in the El Soplao outcrop, Cantabria, N Spain in 2008. Credit IGME-UB.

By Dr Ricardo Perez-De-La Fuente, Research Fellow

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.

Manual extraction of amber. Credit IGME-UB
Manual extraction of amber in the El Soplao outcrop, Cantabria, northern Spain in 2008. Credit: IGME/UB.

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.

Amber pieces recovered in a sieve after washing
Amber pieces recovered in a sieve after having been “washed” from their sediment. First amber excavation in the La Manjoya outcrop, Asturias, northern Spain in 2017.

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.

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