Research – Page 23 – More Than A Dodo

Last Friday afternoon at around 5.30pm, just as I was about to go home after a busy week, the phone rang. It was BBC Radio Oxford asking if I would appear on the breakfast show at 7.50am the following Monday morning. They wanted me to talk about a new study published this week about the extinction of the dinosaurs…

The research, led by Dr Steve Brusatte from the University of Edinburgh, suggests that perhaps dinosaurs were rather unlucky not to have survived a meteorite impact 66 million years ago. The paper, which is published in Biological Reviews, suggests that a number of other factors were already weakening the dinosaurs’ survival chances, presenting a perfect storm of bad luck.

Commenting on this research on the BBC Oxford show, I explained to presenter Phil Gayle that the dinosaurs died out at the end of the Cretaceous period when an asteroid hit what is now the coast of Mexico (apart from the earliest birds, which had already evolved from dinosaurs and mostly survived).

Hilary at the BBC Oxford radio studio in Summertown, talking to Mike Reid on BBC Radio Berkshire, later the same day.

But even before their extinction, the end of the Cretaceous was a time of great change. The climate became cooler than it ever had been during the 160 million years of dinosaur reign, and sea levels were changing quite dramatically, although this was not so out of the ordinary. More unusually, there was a massive amount of volcanic activity going on in India, forming one of the largest volcanic features on Earth – the Deccan Traps. This caused acid rain and cooling of the atmosphere in the short-term.

On top of this there was the enormous impact, thought to have been an asteroid around 6 miles in diameter. It left a crater over 100 miles wide and 10 miles deep near Chicxulub in Mexico. The impact would have caused massive earthquakes and tsunamis, acid rain, and a temporary removal of the ozone layer. A thick cloud of dust thrown up by the impact would have darkened the Earth and cooled the planet by several to a few tens of degrees.

This shaded relief image of Mexico's Yucatan Peninsula show a subtle, but unmistakable, indication of the Chicxulub impact crater. Most scientists now agree that this impact was the cause of the Cretatious-Tertiary Extinction, the event 65 million years ago that marked the sudden extinction of the dinosaurs as well as the majority of life then on Earth. Image: NASA/JPL-Caltech, modified by David Fuchs at en.wikipedia [Public domain], via Wikimedia Commons. — The Chicxulub impact crater in Mexico.
Image: NASA/JPL-Caltech, modified by David Fuchs at en.wikipedia [Public domain], via Wikimedia Commons.

Unfortunately, due to the coarseness of the fossil record scientists have found it difficult to reach a consensus on which environmental change, if any, caused the dinosaurs’ demise. Was it solely due to the massive asteroid impact? Was it just temperature change? Was it a combination of all four factors, or even none at all?

The new study uses the most up to date information on the fossil record, and combines this with new and powerful statistical techniques to try and shed more light on these questions. The researchers found that the extinction of the dinosaurs was abrupt, coinciding almost exactly with the asteroid strike, although there was no evidence to suggest that dinosaurs around the world were already dying out before then, as some people have claimed.

However, they did find a decrease in the diversity of plant-eating dinosaurs in North America shortly before the impact; this might have disrupted the food chain and made the dinosaurs more susceptible to extinction. The decrease in diversity could have been caused by climate change, sea-level change or the volcanic activity, but without more data it’s still not possible to pin the reason down.

The findings led Dr Brusatte to suggest that if the asteroid hit at any other time in the dinosaurs’ history, they might well have survived. They were essentially just very unlucky, he claims. This is an interesting idea, but unfortunately there’s no way we can test it in a scientific way. A 6-mile wide asteroid hitting the Earth is an experiment you can only really run once, and it’s one I personally don’t want to see repeated!

It’s amazing that these incredible creatures, including the largest carnivore that ever lived on land, T. rex, could have become extinct in such a short space of time. They ruled the earth for nearly 160 million years and seemed invincible. The end of the Age of Reptiles seems somewhat poetic. And it makes me wonder, what might give rise to the end of the Age of Mammals?

Hilary Ketchum, Earth Collections manager

29 July 20141 August 2014

More than a Dodo1 Comment

A splash of prehistoric colour

Ina 2 — Azurite (formerly called chessylite) and malachite are two copper minerals that were used as pigments 9,000 years ago.

Last week, Ina St George visited to photograph and sample some of our most colourful minerals. As part of research for her DPhil at the Archaeology Department in the University of Oxford, she is studying the pigments used at an archaeological site in Turkey.

Our Museum’s collections include samples of the kinds of minerals used for colouring in paintings, artefacts, and body decoration, obtained from countries all around the world. Ina tells us:

“My project is looking at paintings and pigments from a Neolithic, 9,000 year old site in Turkey called Çatalhöyük. Part of the project is to characterise these pigments using techniques for mineralogical and chemical analysis. The palette of colours at my case study site has both pigments often used in prehistoric times such as iron oxides and carbonaceous blacks, and much rarer ones such as the minerals cinnabar, azurite, and malachite.

Monica Price (l) and Ina St George (r) are removing tiny samples from the mineral specimens, ready to analyse

“Historically, pigment analysis, referred to as ‘technical art history’, focuses on the actual material that gives the colour, such as hematite or cinnabar. This is more appropriate for historical or modern pigments where preparation techniques and tools were more refined, allowing the artist to use grains of pure colourant.

“In prehistoric times, tools for the preparation of pigments were cruder, and so archaeological samples of pigment tend to have more of other minerals contaminating them. For instance, we see a higher proportion of quartz in a cinnabar sample, or iron minerals in an azurite or malachite sample. In my project, I will be able to see this using a microscope, looking at particles at high magnifications, and analyse the minerals using techniques such as X-ray diffraction or scanning electron microscopy.

“Seeing the minerals in the Museum of Natural History’s collection is an opportunity to better train my eye to see the source minerals for pigments, and to photograph mineralogical samples with a confirmed provenance for my D.Phil thesis.”

You can find out more about Ina’s work in her blog: www.inastgeorge.com

Monica Price, Head of Earth Collections

14 July 201418 July 2014

More than a Dodo1 Comment

Experience gained

Over the past few days the ranks of the Museum have been swelled by the arrival of a host of summer interns from the University of Oxford Internship Programme and the EPA Cephalosporin Fund scheme. Overall, twelve internships are being run at the Museum, and the new faces have been squirreled away into the various departments and collections throughout the building.

We’ve got people working on a wide variety of activities, from audience research for Oxford ASPIRE, to the curation of longhorn beetles (Cerambycidae) in the Life Collections, to work on the archive of 19th-century entomologist James Charles Dale.

One of the interns, Grace Manley, is pictured above peering into a microscope. Grace is working with Dr Tracy Aze, a research fellow at the Museum who is studying planktonic foraminifera – fossils of single-celled organisms found in deep-sea sediments – to investigate marine extinctions. Tracy explains how Grace is contributing to the work during her internship:

Grace is helping me to test some methodological practices that will feed into how I conduct my future research. She has been involved in all the stages of micropalaeontological processing, from washing down core sediments and microfossil identification, through to imaging specimens on the scanning electron microscope.

The project gives her the opportunity to learn many of the common practices that micropalaeontologists use in a lab today and is excellent experience should she decide to continue to work in this field, or other areas of palaeontology.

Caption — Grace Manley working on the planktonic foraminifera as part of her internship with Research Fellow Dr Tracy Aze

For Grace, the internship provides ‘a practical experience of scientific research in the field of environmental change and extinction’. At the same time, she is enjoying ‘the chance to learn about the hugely diverse range of collections in the Museum and how they are actively used for scientific research today.’

We hope that all the interns across the Museum are finding a similarly rich and rewarding experience and we’ll feature some of the highlights of their work on this blog over the coming weeks.

In the meantime, a big welcome to Naomi Saunders, Stephanie Faulkner, Grace Manley, Emily Giles, and Samuel Peacock on the University of Oxford programme; and to Branwen Snelling, Keyron Hickman-Lewis, Ellen Foley-Williams, Max Brown, James Evry, Cecilia Karlsson, and Emily Tibly on the EPA Cephalosporin Fund scheme.

Scott Billings – Public engagement officer

6 June 20147 June 2014

More than a Dodo2 Comments

A question of size

Ever heard of the Bone Wars? Probably not, but this was the name given to a period of intense academic rivalry between American anatomist and palaeontologist Edward Drinker Cope and his erstwhile academic partner Othniel Charles Marsh. This 20-year fued at the end of the 19th century saw each man trying to out-compete the other by naming as many new Paleocene vertebrate species from North America as possible. And it was during this intense period of fossil collecting that Cope noticed something remarkable…

Observing many specimens and publishing an astonishing number of academic papers (over 1,300 in his lifetime, still the highest number by a single individual), Cope uncovered what appeared to be a tendency towards larger body size in a population’s lineage over evolutionary time. This was, he suggested, because new groups are commonly founded at smaller sizes, but it was generally advantageous to be larger. This became known as Cope’s rule.

A classic example of a group of organisms that conforms to the rule is that of horses, or the Equidae lineage. Early ancestors of modern horses were no bigger than dogs during the Eocene period (56-37 million years ago), as illustrated below.

Late Eocene: 37-33.7 million years ago; Middle Miocene: 16 – 11.5 million years ago; Late Miocene: 11.5 – 5.3 million years ago. Image: H. Zell

Cope’s rule now has an extensive history of research, with some studies supporting a trend of size increase and others countering it. The notable palaeontologist Stephen J. Gould proposed that the best way to test Cope’s rule would be to study all lines of ancestry within large groups with excellent data over substantial geological time. Not so easy – much of the fossil record is just too poor to support this approach.

That’s where the little fellas you can see in the picture at the top of the post come in. At the Museum I am investigating the validity of Cope’s rule by using the fossil record of something called planktonic foraminifera. These are single-celled organisms that make a hard shell no bigger than a grain of sand. But when viewed under a microscope these shells display a wide variety of shapes, as you can see in the photograph, making it possible to identify different species.

They live in our modern oceans, but have existed for over 100 million years and can be found from the poles to the equator. Crucially, they have the best-documented species-level fossil record of any group for the last 65 million years and a well-constrained family tree (phylogeny).

This means we can drill deep-sea cores and collect countless planktonic foraminifera specimens from all the world’s oceans. These specimens can then be sorted into different species and measured. And that’s what I am doing. With over 30,000 specimens measured, the project I’m running at the Museum will be the largest and most robust test for Cope’s rule anyone has ever attempted. Hopefully it will shed some light on this fascinating phenomenon.

Tracy Aze – Research fellow

26 May 201428 May 2014

More than a Dodo1 Comment

Lost & Found

One of the tasks of a University museum – and indeed all museums – is to communicate often complex and detailed academic knowledge to a non-specialist audience. There are lots of creative ways for us to go about this, from capturing children’s interest in nature and natural history through well-structured schools and family sessions, to the careful interpretation of specimens and subjects in exhibition displays. Another route is to collaborate with artists who can respond to and present the collections in a different manner.

We’ve been running a collaboration like this in our Life Collections since 2011, working with local artist Jane King. Jane has more recently teamed up with another Oxford-based artist, Neil Mabbs, and together they have formed Pale Blue Dot, a not-for-profit arts-science partnership that aims to raise public awareness about environmental and social concerns through exhibitions, publications and events.

Jane picks out a great yellow bumblebee (*Bombus distinguendus*)

The first of these events is a multimedia installation called Lost & Found, running at the North Wall Arts Centre in Oxford from 28 May – 13 June. For this project Jane and Neil have worked with head of Life Collections Darren Mann and Amoret Spooner in the Museum, along with Professor Dave Goulson at the University of Sussex.

The Lost & Found exhibition asks whether consumerism is causing the extinction of millions of the planet’s species and the ecosystem services they provide. It uses a variety of material, including mixed media prints, photography, film and projection, 3D display, live planting, textiles, and artists’ books.

Artwork is supported by ‘Evidence Tables’ containing specimens from the Museum’s collections, as well as the results of the latest scientific research in the area. It is part of an effort by Pale Blue Dot to communicate complex scientific messages to a wider public audience.

Amoret explains the idea behind the project:

It focuses on the pollinators and decomposers that provide humans with some of the most tangible benefits in terms of ecosystem services.

The pollinators are a group of almost 500 species of UK bees, hoverflies, butterflies and moths. Specimens from the collection are being displayed in cases to represent many of the species, as well as being utilised as source material for the artwork.

Pale Blue Dot’s Lost & Found aims to raise awareness of some of the research carried out by scientists here at the Museum that visitors wouldn’t normally hear about.

Jane and Amoret researching bee specimens

Darren’s photographs of dung beetles and his research papers on the role of dung beetles in the environment are featured. Dung beetles’ daily task of dung recycling helps increase crop yields by speeding up the release of nutrients into the soil, as well as reducing the spread of farm animal parasites and infections caused by biting insects. One of the pieces made by Jane is an artist’s book – Beetle Book – which highlights this vital ecosystem service that beetles provide to humans.

Many of our beetle, bee, moth and butterfly specimens will be on display in the Lost & Found exhibition at the North Wall, so head over there from 28 May to check it all out.

9 May 201416 May 2014

More than a DodoLeave a comment

Saint Helena shrimps

Over the last few months, a number of parcels containing marine decapod crustaceans – yep, ten-footed sea beasts – have arrived at the Museum from the small island of Saint Helena in the South-central Atlantic. Saint Helena is perhaps best known as the place of exile and death of Napoleon Bonaparte, but far less well known are the marine fauna of the island, especially the decapod crustaceans.

The specimens that have been arriving for our Invertebrate Collections were collected by Dr Judith Brown of the Environment and Natural Resources Directorate in Saint Helena and Professor Peter Wirtz of Universidade do Algarve, Portugal. Until now only 36 species were known from the island, and the majority of these were collected between 1958 and 1964; only a single additional species has been recorded since, a specimen collected in 1977, but only reported on in 2007!

The present collection is being studied in collaboration with Dr Paul Clark at the Natural History Museum in London and has so far yielded upwards of ten additional species found on the island, as well as four completely new species.

The snapping shrimp Alpheus cedrici, pictured right, is one of the new records for the island. The species was previously only known from two specimens collected in 2008 from Ascension Island, 1,300 km further north, during this Museum’s Ascension expedition; it was formally described in 2012.

Gnathophylleptum tellei, pictured at the top of the post, is not a new record for St Helena but it is a very rare species of shrimp, currently only known from three specimens in museum collections worldwide (and now one of them is here!). The species was only sighted for the first time in 2001 in Gran Canaria and is otherwise only known from Saint Helena.

The four new species will now be described in the scientific literature, after which a new check-list of the decapod fauna of Saint Helena will be produced. It’s also clear that there’s plenty more to learn about the decapod crustaceans of the island so plans for a more focused collecting trip are now underway.

Photographs: P. Wirtz

Sammy De Grave – Life Collections

Category: Research

Dino demise

A splash of prehistoric colour

Experience gained

A question of size

Lost & Found

Saint Helena shrimps