Category: Earth Collections

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The Evolution of Plants

To mark Plant Appreciation Day today, Lauren Baker and Chris Thorogood of the University of Oxford Botanic Garden and Arboretum take us on a quick tour of the evolution of plants: from primitive water-dwelling algae to the colonisation of land, and the eventual success of angiosperms – the flowering plants.

The Earth formed around 4.6 billion years ago, and around 2.7 billion years ago the very first plants evolved. These were the algae, a diverse group that live mainly in water. The ancestor of all modern algae – and the first organisms to photosynthesise – were cyanobacteria. Green algae evolved from these cyanobacteria and are the ancestors to all modern plants.

We owe the air we breathe to plants. With the production of oxygen through photosynthesis came a drastic climatic shift around 2.4-2.0 billion years ago. Known as the Great Oxygenation Event, it dramatically increased oxygen and decreased carbon dioxide in the atmosphere.

  • Red-coloured, irregular shaped fossil imprint on pale stone
    Fossil of Margaretia dorus, a 500 million year old algae from Utah, USA
  • Algae growing in the Outdoor Water Lily Pond at Oxford Botanic Garden

Non-flowering plants

Jump ahead 1.5 billion years and the evolution of plants really takes off. To leave the water, plants needed to develop protection from drying out. The group that colonised the land is called the bryophytes, and includes the liverworts, hornworts and mosses.

Bryophytes are simple plants that lack true roots or ‘plumbing’ vascular tissue such as xylem or phloem. Bryophytes may have evolved from green algae in shallow, fresh water and developed the ability to survive on land when these pools dried out: 470 million years on, you can still see many bryophytes growing in damp habitats today.

A living bryophyte: Marchantia species growing in the Carnivorous House at Oxford Botanic Garden

The first vascular plants appear around 430 million years ago. One of the earliest examples was Cooksonia, consisting of a simple branching stalk without leaves.

  • Fossilised Cooksonia, one of the earliest vascular plants. This 420-million-year-old fossil is from Lower Wallop in Shropshire. OUMNH C.31324.
  • Fossilised Cooksonia, one of the earliest vascular plants. This 420-million-year-old fossil is from Lower Wallop in Shropshire. OUMNH C.31324.

Lycophytes, which evolved around 350 million years ago, also have vascular systems that enable water and nutrients to be moved around the plant. This drove the evolution of more complex, multicellular plants.

The ability to pump water allowed lycophytes to grow to heights of 45 m and they formed vast forests. Their remains also make up the coal, oil, and natural gas we use for energy today. More than 1,200 species of lycophytes exist now, grouped into three orders: the club mosses, quillworts and spike mosses.

  • Repeated pattern fossil imprint on dark grey stone
    Fossilised remains of Lepidodendron, an extinct genus of primitive lycophytes
  • Living lycophytes: Selaginella, growing in the Cloud Forest House at Oxford Botanic Garden

A ‘living fossil’ that can be seen growing at the Botanic Garden is Equisetum, commonly called the horsetail. Horsetails evolved around 350 million and although the species alive today are herbaceous, extinct horsetails such as Calamites once formed large trees. The fossilised remains of Calamites in the collections of the Museum show the vascular tissues that would have carried water and nutrients up the vast trunk of the tree.

  • Striated fossil imprint on dark grey stone
    Extinct horsetails such as this Calamites once formed large trees. This 300 million year old fossil is from Rhondda Valley, Wales 
  • Horsetail today at Oxford Botanic Garden

​Cycads also evolved around the same time as the lycophytes and horsetails. They could easily be confused with palms, but unlike palms they are not flowering plants. Cycads belong to a group of plants called the gymnosperms, a name that literally means ‘naked seed’, and refers to the plants’ reproduction with seeds that are not encased in an ovary. Cycads can survive for over 1,000 years and are very slow growing. Today, the majority of the 200 surviving species are threatened with extinction.

  • Cycas revoluta, a cycad, growing in the Conservatory at Oxford Botanic Garden
  • Other living gymnosperms that evolved alongside cycads include the conifers, of which there are many, and ginkgos, of which today there is just one surviving species: Ginkgo biloba, pictured growing at Oxford Botanic Garden

​Another ancient and unusual group of gymnosperms that evolved alongside cycads and lycophytes are Gnetophytes, which include plants such as Ephedra, Welwitschia, and Gnetum. There are about 40 living species of Gnetum, and they are tropical evergreen trees, shrubs and lianas. Before DNA sequencing technology, they were believed to be the closest living relatives of flowering plants due to the sugary sap they produce to attract pollinating insects, like the nectar produced by flowers.

Fossils of Ephedra date back as long as 120 million years ago. They are pollinated by both wind and insects, and are found across all continents except for Australia. With small, scale-like leaves they are highly adapted to arid environments, growing in sandy soils with direct sun exposure.

But perhaps the most familiar gymnosperms are the conifers. Conifers include the world’s oldest tree, the bristlecone pine, and the world’s largest tree, the giant Sequoia. There are over 615 species of conifers, most belonging to the pine family, Pinaceae.

  • Branching pattern fossil imprint on brown stone
    Brachyphyllum expansum, an extinct conifer which belonged to the family Araucariaceae – famous for including the monkey puzzle tree
  • A monkey puzzle tree, Araucaria araucana, at Oxford Botanic Garden

Flowering plants​

The evolution of flowering plants – the angiosperms – 125 million years ago, was the start of a global botanical competition with gymnosperms, and it changed the appearance of our planet forever. The fossil record shows the earliest flowering plants bloomed alongside the dinosaurs, and probably looked something like a magnolia.

Magnolia stellata blooming at Oxford Botanic Garden

Unlike the gymnosperms, the angiosperms reproduce with flowers and their seeds are contained within protective ovaries. Despite their relatively late emergence, the diversity of flowering plant species was accelerated by their evolution alongside insect pollinators. Today, of the roughly 350,000 known plant species, 325,000 are flowering plants.

  • Fossil leaf imprint on pale stone
    Whilst more famously known for their foliage, acers are also angiosperms. This fossil of Acer tricuspidatum is 30 million years old, from Oeningen, Switzerland 
  • One of the many Acer species showcasing its autumn colour at Harcourt Arboretum
Bright pink and purple flower
Large, open yellow flower
Red and yellow flower
Orange sunflower head
Red, orange, yellow flower
Purple plants with bees

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Railway Geology part 2: Read all about it

By Nina Morgan – geologist, science writer and Honorary Associate of the Museum
Picture research by Danielle Czerkaszyn, Librarian and Archivist

The expansion of the railways in the 19th century offered more than just faster travel times. The growing rail network opened up the potential for introducing the wonders of geology, scenery and history to the travelling public at large. It also made it possible for geologists working in the field to import the comforts of home. And it spawned a new form of popular science and travel writing – describing geology and scenery from the train.

The geologist John Phillips, then based in York but later first Keeper of the Museum, was among the first to recognise these advantages. In 1841 he was on assignment mapping with the fledgling geological survey in southwest Wales. He expected the project to last several months, so rented a house in Tenby and – missing his home life – asked his sister Anne, along with Mary, her maid, and Cholo, their dog, to travel from York to Tenby join him.

Letter from John Phillips to his sister Anne, 28 April, 1841 (OUMNH Archive)

It was a marathon journey. In a long letter to Anne written on 28 April 1841, he provided her with detailed instructions about how to achieve it. Although it is clear that Phillips had become very familiar with the train timetables, he was not so sure about the rules for travelling with dogs. Two days later he wrote again to Anne to say:   

“How you will bring poor Cholo I do not even conjecture. Perhaps they will let him be with you in the carriage…. Pray have a good courage  then all will go right.”

 John Phillips’s popular railway guidebook, 2nd edition, 1855 (OUMNH collection)

Phillips’s book, Railway Excursions from York, Leeds and Hull, first published in 1853, was a popular success. It went through several editions and was republished several times under various titles.  Along with references to geology, the book included much historical background about the buildings, sights to be seen, and advice on the top ‘tourist destinations’ and how to reach them.

Phillips’s book inspired other geologists to jump onto the platform, and as new lines opened, so new railway geology guidebooks began to appear. Notable examples include the Geology of the Hull and Barnsley Railway by Edward Maule Cole, which appeared in 1886; and Yorkshire from a Railway Carriage Window, included as Part 2 in the massive Geology of Yorkshire by Percy Fry Kendall, Emeritus Professor of Geology at Leeds University, and Herbert Wroot, Honorary secretary of the Yorkshire Geological Society, which was published in 1924.

 Illustrations from Geology from a Railway Window, part 2 of The Geology of Yorkshire by Percy Fry Kendall and Herbert B. Wroot, 1924 (OUMNH collection)

Network rail

As the railway network expanded throughout Britain, so did the number of authors keen to describe the geology of their part of the country from the windows of a train. In 1878, the Geologists’ Association organised an excursion to examine the geology exposed in railway cuttings along the Banbury and Cheltenham District Railway from Chipping Norton to Hook Norton. Participants were advised to take the train from Paddington to Chipping Norton, with luggage directed to The White Hart, Chipping Norton.

In 1886, Sir Edward Poulton, later Hope Professor of Zoology at the University of Oxford, published an account of The Geology of the Great Western Railway journey from Oxford to Reading. Then in 1945, the Oxford geologist W.J. Arkell published his classic paper, Geology and Prehistory from the train, Oxford to Paddington; and in 2005 Philip Powell, a former curator and now Honorary Associate at the Museum, paid tribute to Arkell’s methods of observation by adding a final chapter outlining the geology that can be seen when travelling on part of the Cotswold Line from Moreton in Marsh to Reading, to his 2005 book, The Geology of Oxfordshire.

Meanwhile, the geologist Eric Robinson, now retired from University College London, prepared numerous handouts for his students and amateur guides describing the geology that can be seen from trains leaving from various London stations.

Left: Edward Bagnall Poulton, Oxford-based entomologist and evolutionary biologist, 1856–1943
(OUMNH Archive) ; Centre: The Geology of Oxfordshire by Philip Powell, 2005 (available from www.gravestonegeology.uk, and the OUMNH shop); Right: W.J. Arkell, Oxford-based geologist and palaeontologist, 1904–1958 (OUMNH Archive)

Times past

Along the way all of the ‘railway geologists’ painted vivid pictures both of the geology and the countryside as they saw it, and their descriptions – especially those from the earlier publications – provide a valuable insight into landscapes and railway lines now lost.

“A railway tour is life in a hurry,” Phillips proclaimed in his pioneering railway book. He clearly enjoyed the rush, and so did the many other geological authors and lovers of the countryside who followed in his tracks. Even today, with a railway geology book in hand, those delays along the line can turn into a real pleasure – depending where you’re held up, of course!

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Railway Geology Part 1: The flying steed

By Nina Morgan – geologist, science writer and Honorary Associate of the Museum
Picture research by Danielle Czerkaszyn, Librarian and Archivist

The introduction and growth of the railway network in the first half of the 19th century not only revolutionised travel and transport of goods for many, but it also had a profound effect on the science of geology.  Not only did it make it easier for geologists to cover the ground quickly – but the railway cuttings for the new lines revealed rock outcrops that had never before been seen.

John Phillips as a young man

One of the first to take advantage of the new possibilities was John Phillips (1800–1874), the first Keeper of the Museum, and nephew of William Smith, often referred to as the Father of English Geology. Phillips was orphaned at the age of eight, along with his younger sister Anne, and their younger brother, Jenkin.

John was educated at Smith’s expense and learned about geology at his uncle’s knee. He was reunited with Anne in 1829.  Neither married and they lived together until her death, with Anne serving as John’s housekeeper, moral support, confidant and geological companion. John went on to become a skilled palaeontologist, field geologist and prolific author.  He also became a great train enthusiast.

Anne Phillips photographed in 1860
(© Royal Institution London)

On 23 July 1835, John wrote to Anne with this vivid description of his first train journey – travelling on a ‘flying steed of Iron,’ from Manchester to Liverpool on his way to Dublin.

“…My dear Annie, You must certainly come to feel the strange impression of this flying Steed of Iron. It does so hurry & flurry on, you shake & sleep & start & wonder at the gliding Houses, trees & Churches, — the trains which meet & pass you’ like the swiftest birds with a rushing sound & the Master power (Steam) & a confused picture of colours & forms not at all distinct as Men[,] Women, Carriages &c that it is all like magic & can not be understood by a mere description. Then you are dragged through a tunnel full of gas lamps, then laid hold of by ruffian porters & crammed into an Omnibus whether you will or no & whirled away the man who guides (only) knows whither. “

Phillips quickly became a convert to train travel. He was often travelling from his then base in York to earn money by giving lecture courses by subscription to members of the various newly formed Philosophical societies, so enjoyed the relative convenience and faster travel times railways offered – even though, as he wrote to Anne in March 1841, the trains were not always punctual. 

Black and white image of railway station on postcard.
Liverpool and Manchester Railway commemorative postcard
(author’s collection)

“I found the Train of yesternight very good travelling till we entered on the Leeds & Manchester line at Normanton. Then began this singular amusement: to lose time so as to arrive in 4 hours from Leeds, the time really required being 2 1/2 hours.  We did this odd railway feat by stopping 5 minutes each at about 10 stations & using all possible precautions not to go too fast.  This is said to be on account of the recent embankments not allowing of rapid transit: but some of the trains are faster. We reached Manchester at 10:30, that is to say in 4 hours from York.”

Sound familiar?!

Scan of handwritten letter.
Letter from John Phillips to his sister Anne, 30 March 1841 (OUMNH Archive)

In the second part of Railway Geology, Nina will take a look at how the expansion of the railway network spawned a new form of popular science and travel writing.

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Rare Jurassic mammal fossil from Scotland is new species

By Elsa Panciroli, Research Fellow

This week my colleagues and I announced the discovery of a new species of mammal from the time of dinosaurs. It is one of two rare skeletons we’re studying from the Isle of Skye in Scotland. These mouse-like animals lived in the Middle Jurassic (166 million years ago), and tell us about the evolution of mammals in the time of dinosaurs.

The two fossils belong to Borealestes serendipitous and Borealestes cuillinensis. B. serendipitous was the first Jurassic mammal ever found in Scotland, known originally from pieces of fossil jaw found on Skye in 1971. In our new paper, we describe the skull of a partial skeleton of this species, found in 1972 by the original discoverer of the site, Dr Michael Waldman and his colleague Prof Robert Savage. But this exceptional fossil lay unstudied for over 40 years. Only now is it giving up its secrets thanks to powerful synchrotron X-ray scans, which reveal the anatomy in incredible detail.

The other fossil skeleton was found in 2018 by my colleague Prof Richard Butler. After taking it back to the lab and CT-scanning it, we realised it was a new species. We named it Borealestes cuillinensis in honour of the Cuillin mountain range on Skye (Gaelic: An Cuiltheann), a stunningly jagged set of peaks that overlooks where the discovery was made.

The fossil jaw of new species, Borealestes cuillinensis, moments after its discovery. By Elsa Panciroli

Most ancient mammals are only known from a few teeth and jaws, so these skeletons are exceptionally rare. They are currently the most complete Jurassic mammals described from the UK.

The Middle Jurassic is an important time in animal evolution, because it marks an increase in the diversity of lots of different groups. Just afterwards, in the Late Jurassic, there are many new species of mammals, amphibians, small reptiles and dinosaurs, which flourish into the Cretaceous period. All of this diversity began in the Middle Jurassic, but fossils from that time are rare, making it difficult to unpick the causes of these changes. This means that any material from that time period is extremely important to our understanding of the course of evolution, and the drivers of animal diversity.

Fieldwork team on the Isle of Skye: (L to R) Roger Benson (University of Oxford), Richard Butler (University of Birmingham), Elsa Panciroli (OUMNH and National Museums Scotland), Stig Walsh (National Museums Scotland).

Our team have been carrying out fieldwork and research on Skye for the last decade. It includes researchers from National Museums Scotland and the universities of Oxford and Birmingham. We are working on many more exciting fossils from the island, so keep an eye out for the next discovery!

Read the paper ‘New species of mammaliaform and the cranium of Borealestes (Mammaliformes: Docodonta) from the Middle Jurassic of the British Isles’ published today in the Zoological Journal of the Linnean Society.

Top image: Digital reconstruction of two Jurassic mammal skulls. (c) Matt Humpage

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Celebrate science in a cemetery

By Nina Morgan, Gravestone Geology

Cemeteries not only provide a peaceful place to commemorate the dead, and observe and enjoy nature; they are also wonderful repositories for the study of local history and art. But that’s not all. Cemeteries also offer an easy introduction to science that anyone can enjoy.

A visit to a cemetery presents a wonderful way to learn about geology and the other sciences, such as chemistry, physics and engineering, that underpin it. For geologists – whether amateur, student or professional – almost any urban cemetery provides a valuable opportunity to carry out scientific fieldwork at leisure, right on the doorstep, and at no cost.

Headington Municipal Cemetery, Oxford

Geology on show

Because gravestones are made from a wide variety of rock types formed in a range of geological settings, cemeteries can be geological treasure-troves. Many headstones are made of polished stone, so reveal details – such as minerals and crystal features – that are not easy to see elsewhere. Some demonstrate the textures and mineral composition of igneous rocks – rocks formed when molten magma cooled and solidified. Others are happy hunting grounds for lovers of fossils. Some gravestones reveal sedimentary structures that show how the rock was originally deposited. Others provide clues to earth movements and environments that occurred hundreds of millions of years ago.

For those interested in engineering, examination of gravestones can also provide useful information about topics ranging from weathering of stone to atmospheric chemistry, effects of pollution, stability and settling in soils and land drainage. 

St Andrews Church in Headington, Oxford

Cemeteries in Oxford include ancient churchyards, such as St Andrews Headington, as well as Victorian cemeteries like Holywell (pictured top) and St Sepulchres, and more modern burial grounds, such as Headington Municipal cemetery. Together they exhibit the main features and stone types that can be seen in cemeteries all around Britain.

St Sepulchres Cemetery, Oxford

In the short video below, filmed in the churchyard of St Mary and John in Oxford’s Cowley Road, Philip Powell and I introduce the basics and show you how to get started in exploring these geological gems. If you want to learn more, visit www.gravestonegeology.uk. But be warned – gravestone geology can be addictive. Once you’ve got your eye in, you’ll never look at cemeteries in the same way again!

All images and video by Mike Tomlinson.

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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.