One of the most remarkable fossil sites in the world is located in Chengjiang in China, where exquisitely-preserved fossils record the early diversification of animal life. The 525 million year old mudstone deposits in the hills and lakes of Yunnan Province, South China are so fine that they have preserved not only the shells and carapaces of Cambrian animals, but also the detail of their soft tissue. In recognition, the site was added to the World Heritage list by UNESCO in 2012.
Professor Derek Siveter, a senior research fellow at the Museum, has been studying this material for a number of years, authoring a book – The fossils of Chengjiang, China: The flowering of early animal life – in 2004. But the rate of discovery of new fossils over the last decade has led to a wealth of new material to be documented.
So Derek recently headed back to the University of Yunnan for a two-week visit, where he began work on a revised edition of the book. Much of the documentation of these important fossils is currently in Chinese, so the new edition will bring the material to English-speaking researchers and fossils enthusiasts too. It introduces both the professional and the amateur palaeontologist – and all those fascinated by evolutionary biology – to the aesthetic and scientific quality of the Chengjiang fossils, many of which represent the origins of animal groups that have sustained global biodiversity to the present day.
An intriguing new fossil has been donated to the Museum. It’s a large straight-shelled nautiloid with a colourful history.
Nautiloids are marine cephalopods related to modern-day octopus, cuttlefish and squid. They have an external shell and horny jaws but the soft parts of nautiloids are rarely preserved as fossils. Comparison with the living Nautilus suggests that this animal also had a ring of tentacles surrounding the mouth.
This particular specimen was handed down through five generations of one family, before finally being donated to the Museum by Mrs Jan O’Leary via her children, Tim O’Leary and Kate Whittingham.
Accompanying the nautiloid was a lithograph of the specimen, labelled:
ACTINOCERAS. (MOUNTAIN LIMESTONE.) Newbury Marble Works – The Peak, Derbyshire. SECTION IN THE MUSEUM, OSMASTON MANOR
“Mountain Limestone” is an old-fashioned term for Carboniferous Limestone, which means the fossil was from the Lower Carboniferous Period, around 350 million years ago. Osmaston Manor was the historic home of the donor family until its demolition in 1965.
On the far right hand side of the donated lithograph is a reconstruction of what the nautiloid may have looked like in life (shown at the top of this post). This is very unlike modern reconstructions of nautiloids, and looks rather more like the reconstruction of a squid-like belemnoid (complete with ink sac) in William Buckland’s Geology and Mineralogy (1836). So did nautiloids have ink sacs like belemnoids and modern cephalopods? What was known at the time the reconstruction was drawn, and what do we know today?
Looking at dates of construction and demolition of Osmaston Manor, as well as the operation dates for the company credited with producing the lithograph, we can assume that it was created sometime between 1867 and 1888. So what information on fossil cephalopods would have been available at that time? Buckland provided proof that belemnoids had ink sacs, but, information on nautiloid soft parts at that time was practically non-existant. We can only suppose that the reconstruction is an extrapolation from the belemnoid evidence. Given that this specimen was living in the Carboniferous Period (359 – 299 million years ago), and the belemnoids described were from the Jurassic Period (199 – 146 million years ago), this is quite a leap of faith.
And the state of knowledge today? Phylogenetic studies suggest that ammonoids and coleoids (belemnoids and their living relatives) split from from the nautiloids in the Silurian Period (443 – 416 million years ago), then coleoids split from ammonoids in the Devonian Period (416 – 359 million years ago). But where on this branching tree did ink sacs arise?
A paper by Doguzhaeva and colleagues (2003) described an ink sac in the Upper Carboniferous coleoid Donovaniconus, which means that ink sacs had indeed evolved as far back as the Carboniferous. But, despite intriguing historical reconstructions and beautiful fossils, we are yet to find any evidence that nautiloids really did have ink sacs at all.
Beautiful gemstones are always popular with the public when they’re brought out for Spotlight Specimens. Monica Price talks about some she’s been showing off recently at our daily drop-in sessions.
Now here’s a mineral that most people recognise straight away when I bring it out for Spotlight specimens. It is amethyst, and it is the most popular of all purple gem minerals. By a happy coincidence it is very common too, so jewellery made with amethyst need not be very expensive.
But that wasn’t always the case. In the past, fine, large, transparent crystals of amethyst could only be found in Germany, Russia and a few other places in the world. In Europe, the colour purple is traditionally associated with royalty and wealth, and so rare amethyst gems would feature in crowns and jewellery worn by heads of state and religious leaders.
Amethyst is actually a variety of one of the Earth’s most common minerals, quartz. Quartz is composed of silicon dioxide and helps form many different kinds of rock…. it even makes up most beach sands! Amethyst is the kind of quartz that contains a little bit of iron to turn it purple.
So how did amethyst suddenly become so common? During the 18th century, huge flows of volcanic lava were found by explorers in Brazil and Uruguay. Some had air bubbles which were lined with superb purple crystals of amethyst. Soon, these crystal-filled cavities were being sent to Europe, and today, they are sold all over the world. The biggest bubbles were a metre or more in size – huge! Nowadays, nearly all the amethyst you see for sale comes from those 135 million year-old South American lava flows.
My spotlight specimens include an amethyst gemstone and some lovely examples of those gas bubble cavities lined with crystals. One rather curious thing is that the crystals are rarely purple all the way through. The colour typically concentrates towards the tips of the six-sided crystals. If you come when I next show my ‘gas bubble gems’, you will see exactly what I mean!
Next up to share his favourite five specimens from the Museum’s collection is Philip Hadland. Phil joined us a few months ago as an Earth Collections assistant and has already discovered some fascinating fossils in the stores.
5 – Fossil crab from Folkestone
These Cretaceous crabs are interesting because of their similarity to modern Bubbler Crabs. As you can see from the photo at the top of this post, Bubbler Crabs feed during low tides on microscopic creatures living between grains of sand, processing it into ‘sand balls’.
In some cases, trace fossils very similar to the modern sand balls can also be found. Natural casts resembling ostrich footprints have been found alongside the ‘sand ball’ fossils.
Maybe the crabs were a food source for the mysterious animals that left the footprints?
4 – TV rock
Ulexite (NaCaB5O6(OH)6•5(H2O)) (hydrated sodium calcium borate hydroxide), is a mineral with natural fibre optic properties. The fibres transmit light through internal reflection, which is the same way that fibre optics work. If a crystal of ulexite is cut correctly and placed on an image, that image will be projected to the other surface. For this reason it is also known as TV rock.
3 – Heteromorphic ammonites
Heteromorphic ammonites are extinct cephalopods, related to squid and cuttlefish. They are different from other ammonites with flat spirals; they coil in unusual ways. Some are shaped like paperclips and some resemble tower shells. They are a fascinating enigma and we can probably only guess how they lived. I suspect that at least some were mimicking other animals. Mimicry is often used by living animals to catch food or to avoid becoming prey themselves, so perhaps they sat motionless on the sea bed waiting to devour unsuspecting crustaceans, a popular prey of living cephalopods.
2 – Challenger Shark Tooth
A fossil shark’s tooth collected on the Challenger expedition (1872-1876), dredged from the Pacific ocean, at a depth of 2350 fathoms, over 4 kilometers. The naturalist Henry Moseley (1844-1891) published notes on the expedition, describing numerous encounters with living sharks. The largest they encountered was Carcharodon rondelettii known today as as Carcharodon carcharias, the great white shark. In the notes he also states “The Challenger dredged in the Pacific Ocean in deep water numerous teeth of what must be an immensely large species of this genus”. In fact these were fossil teeth of the extinct giant shark Carcharocles megalodon. Awesome!
1 – Kirkdale Cave Mammal Fossils
In 1821 labourers in a quarry at Kirkdale, Yorkshire, found a cave full of animal bones. Professor William Buckland of Oxford University visited the cave and recognised over 20 kinds of animal, including Elephant, Hippopotamus and Hyaena. These fossils were 120,000 years old! He thought that it was once a Hyaena den, as there were many hyaena bones in the cave. To prove his idea he gave an Ox bone to a Hyaena, which was travelling through Oxford in Mr Wombwell’s menagerie. The Hyaena produced gnaw marks identical to those on a comparable Bison shin bone from the cave. I think this was really clever. It may be the earliest example of experimental palaeontology.
Like most museums, the Leeds Museum Service has far more specimens than they can possibly show in their public displays. Much of their huge collection is carefully stored in their Discovery Centre, waiting to be used. Trouble is, if you don’t have an expert on the team, how do you know which specimens are particularly rare or precious, which ones are important for researchers, which ones are ideal for people to handle..? Indeed which ones are really no use to anyone anymore?! The Leeds curatorial team decided to carry out a ‘Geoblitz’, inviting specialists in all the different branches of geology to go through storage trays specimen by specimen, telling them about the highlights (and occasionally the lowlights) in the collection. The project has been generously funded by the John Ellerman Foundation, and will also include a programme of activities and exhibitions to start making use of the best specimens. You can follow their progress on their blog.
I was delighted to be invited to be a visiting expert, looking at the mineral collection, and I’ve just come back from three days working through literally thousands of specimens. It was great to see how many had information about the places where they were found, some even saying which level or vein they came from in the mine or quarry. Nearly all those mines and quarries are now closed, and most are flooded or inaccessible. This means the mineral samples collected from them are irreplaceable and particularly useful for research.
The instructions were that I’d read out the tray number and specimen number, and then explain why I thought the sample was so interesting or special. Project officer Neil Owen was busy taking lots of notes. There were some incredibly beautiful display specimens (like the beautiful wavelite sample at the top of this post), some excellent examples of very rare minerals, and many samples ideal for people to both see and touch. Trouble was, each time he took the tray lid off to reveal something exciting inside, I’d always start by saying ‘wow!!’ and only think to tell him that all-important specimen number last of all!
It was fascinating to see another good museum collection, and I’ll be reminding researchers that Leeds has lots for them to explore. But most of all, I’m especially looking forward to seeing some of the specimens I picked out go on public display. Very best of luck to Neil and all the Leeds team, as they continue the Geoblitz!
Five hundred million years ago, in the Cambrian period, the oceans teemed with strange and unusual creatures that are now preserved as fossils. This period in Earth’s history is important because almost all known groups of animals appear very suddenly in the fossil record at this time. Many of them look just like their modern day counterparts, but several are much more weird and wonderful, with a very different appearance from anything alive today.
I was recently awarded the Whittington Award from the Palaeontological Association which includes a small research grant that will allow me to study one of these weird fossils. The creature in question is known as the “muscle worm”, or Myoscolex, and is particularly interesting because almost the whole fossil is made up of very well-preserved muscle fibres. It’s the oldest record of muscle tissue in the fossil record.
The material comes from the Emu Bay Shale fossil site, located on Kangaroo Island in South Australia. The original collection of fossils is nearly 35 years old now. These original fossils showed the muscle tissue of Myoscolex very clearly, but unfortunately we don’t know much about the rest of its body and scientists can’t even agree on what type of animal it is! Some people believe it is an annelid worm – a segmented creature – while others think it could be an early ancestor of either the arthropods, which includes animals like crabs, shrimp, spiders, centipedes, and insects, or the chordates, a group which includes any animal with a backbone, including ourselves.
Fortunately, many new fossils have been collected in the last few decades that will help us solve the mystery of the Cambrian muscle worm. Active collecting by the South Australian Museum and the University of New England has revealed hundreds of new specimens that show us more details about the anatomy of Myoscolex, including the head, legs, skeleton, and even its digestive system.
I have been working with researchers in Australia on Emu Bay Shale fossils for several years now, both on the fossil collections in the museum and in the field. The Whittington Award will allow me to travel to Australia to study the new muscle worm fossils. The research will involve taking photos, making drawings, and analyzing the nicest specimens under scanning electron microscopes. I will then come back to the Museum in Oxford and compare the fossil information with modern animals found in our collections here. All of this work should allow us to finally figure out what the Cambrian muscle worm really is.