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Curator of Micropalaeontology's blog

6 Posts tagged with the conodonts tag
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This week I 'claim an assist' at the start of the football season, visit the lab where David Attenborough once dropped his camera into a vat of acid, move a microfossil tree across the Museum, am reminded how difficult it is to place a monetary value on microfossils and manage to retrieve an important file in preparation for a talk to a local society.

 

Monday

 

In footballing terms you'd call this 'claiming an assist'. In 1995 I wrote an article in the Palaeontological Association Newsletter advertising the Former BP Microfossil Collection that I was curating at the time. This alerted Prof. Paul Pearson to our collections, he arranged a visit and found some exceptionally preserved material.

 

His subsequent drilling projects at the same sites in Tanzania have provided some amazing material, both foraminiferal and nannofossil that have made a major contribution to the science of micropalaeontology and have been the basis for the careers of several young researchers making their way in academia.

 

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The holotype specimen of Hantkenina singanoae. Coxall & Pearson, 2006.

 

Today I am registering some type material Prof. Pearson donated us from his Tanzania work. These type specimens have been published in three key papers in 2004, 2006 and 2014 but the material is currently part of our backlog for computer registration. Most journals require published material to be deposited in museum collections and this remains one of our key methods for collections development.

 

News of a backlog should not put off potential donors to our collection though. Pretty much every museum has a backlog and it is my priority to register this material, particularly if it has been published. I'd argue that it is better to be in this backlog, safely housed in the Museum and available for study than to be hidden in a drawer in a university office.

 

Tuesday

 

This morning I am alerted to a new paper on Research Gate, which is a kind of Facebook-for-academics highlighting the latest work by your peers. This 2014 paper provides new evidence that shows the main conclusion of my 1993 thesis is no longer valid.

 

My job allows me 10 percent of my time to carry out research projects and today this takes me to the acid lab in the basement to dissolve microscopic teeth called conodonts from Permian limestones from Oman. The aim is to provide dates for other studies where new trilobites and other macrofossils have been found.

 

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The acid laboratory at the Museum. My 3kg limestone samples are in the second bay along in small boxes like the one on the floor to the left.

 

The laboratory is designed for preparing large vertebrate specimens by dissolving them in acetic acid (vinegar) and was most famously used by David Attenborough in his programme Life on Earth. During the filming of a time lapse series of pictures showing one of these dissolution experiments, Sir David apparently dropped his camera into the vat of acid.

 

Wednesday

 

Our Zheng Shouyi microfossil tree is to be photographed in the photo unit today so first thing I place the hanging microfossil models in plastic bags to prevent them from bashing into each other as the tree is wheeled through the gallery. It takes 15 minutes to move a short 20m distance through the Bird Gallery because members of staff on their way into work keep stopping me and asking about it.

 

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The Zheng Shouyi microfossil tree, complete with plastic bags to prevent damage during transit (left) on its way through the Bird Gallery and (right) after its photoshoot.

 

When I get to the photo unit, photographer Kevin Webb is surprised because he had been told it was a fossil tree and was expecting some fossil wood! I bump into another member of staff who says they have heard about the tree at a Science Uncovered briefing but didn't realise it wasn't a real tree either, so I send some of Kevin's photographs to them for distribution.

 

Thursday

 

As I can't wheel the tree back through the gallery during opening hours I have to collect it early the next day. It takes even longer to get back through the Bird Gallery as there is a considerable amount of interest in the tree. This bodes well for our desk on the Climate Change Station at the forthcoming Science Uncovered Event on 26th September when I will be joined by my colleagues underneath the cocoon of the new Darwin Centre.

 

More about Science Uncovered 2014

 

The rest of the day is spent dealing with two loan requests, firstly for long term visitor Yukun Shi who has requested some of our larger benthic foraminifera for CT scanning. Another loan involves some specimens I computer-registered in 1994 but requires some thought as we are required to put a valuation on any material we send out on loan. It reminds me how difficult it is to value microfossil specimens when there is little commercial market for them.

 

Friday

 

An email today reminds me that a little over a year ago I agreed to give an evening talk to the Harrow and Hillingdon Geological Society. Over the last few years I've given similar talks at St Albans, Horsham and Hertford. I look for the powerpoint file for the talk that had been prepared for another venue but the folder on my hard drive has corrupted, as has the folder on my back-up hard drive. After a few moments of panic I find another copy of the file on the pen drive that I'd used when I last gave the talk.

 

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An Oxford Geology Group advert for a talk I recently agreed to provide in 2015.

 

My colleague and fellow NaturePlus blogger Dr Erica McAllister is asked to give talks like these all the time. A few months ago I asked her if she ever gets choosy and says no? She said she always says yes if she can, in fact on one day she once gave three! If you have some spare moments then why not check out Erica's blog or read my colleague Mark Graham's guest post where he describes hosting a recent visit from Sir David Attenborough including a trip to the acid lab.

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For obvious reasons I have always wanted to do fieldwork on Pulau Langgun, one of the islands that make up the Langkawi Islands off the far NW coast of the Malaysian Peninsula. In my last post I described the difficulties of interpreting the geology of the Malaysian Peninsula and how we were attempting to use conodont microfossils to answer some of the questions by dating the isolated rock exposures.

 

We travelled to Langkawi Island to sample conodonts from the most complete exposure of rocks in the region as it will act as a reference section for our student Atilia Bashardin and help to interpret the isolated rock exposures on the mainland. The islands are also where the conodont Panderodus langkawiensis was first described and this species was a target for our collecting.

 

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For two days our field vehicle (above) left us on the coastline early in the morning. The unfavourable tides meant that we only had three hours on the section before our boat had to come and pick us up.

 

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The early morning trip to the section was amazingly picturesque as we motored through mangroves and past imposing forested limestone crags. On the first morning we encountered dolphins as we moved out into the open water.

 

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This was our first sight of the study section from the sea. Initially it was difficult to see any rock exposures as they are hidden behind the margins of the forest that encroaches the beach. We landed at the end of the pier that you can see to the right and made our way along the coastline to the left.

 

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This is a typical limestone exposure in the area. Despite the idyllic setting, it is quite hard work to sample here. In my previous post I described how you usually need several kilogrammes of rock to find conodonts. Here the surfaces are very weathered leaving some beds standing proud. Unfortunately it is the recessed, weathered parts of the beds that we needed to collect as these will most easily dissolve in acetic acid (vinegar).

 

Microfossils can be recovered from most sedimentary rocks but it is important to choose the correct part of the rock to sample in order to maximise the yield. This often requires interpretation of the environment in which the rocks were originally deposited. It is not possible to know while sampling if a particular bed will yield conodonts and sometimes even an experienced eye can be wrong.

 

We are sampling here because these beds have previously yielded conodonts according to a paper published in the late 1960s and a recent study by a University of Birmingham undergraduate student.

 

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A scanning electron microscope image of an element from the apparatus of the conodont Panderodus langkawiensis recovered from one of the samples processed by John Lignum, former University of Birmingham undergraduate. The dotted scale bar at the bottom is 0.176mm.

 

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This is a rare blog picture of the 'Curator of Micropalaeontology' looking rather sweaty and muddy after an extended session with the geological hammer. The words on the pier behind say 'Teluk Mempelam' which means Mango Bay. Unfortunately there were no mangos to be seen.

 

In a 2005 paper published by two of my retired colleagues, Robin Cocks and Richard Fortey, the old name for the limestone here the 'Upper Setul Limestone Formation' was changed to the 'Mempelam Limestone Formation'. They studied the distribution of invertebrate fossils of this region, particularly the brachiopods and trilobites, to interpret the geological history of the region. Many of the collections that back up these findings are housed in the Museum.

 

Initial findings from the conodonts have provided more precise datings for some of the newly named geological formations suggested by Cocks and Fortey. It will also be interesting to see if the Mempelan Limestone Formation can be traced to the mainland.

 

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Not all the rocks on this coastal section were easy to swing a hammer at. Here Atilia is looking pleased with herself as she has managed to collect a nice lump of limestone from this rock exposure where previously I had failed! I had told her to give up but her persistence was rewarded.

 

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Here are two of our Mempelam Limestone Formation samples with a view of the section in the background.  These samples were too large to fit in our standard sample bags so we had to label them with indelible marker pen and carry them back to the boat by hand. The surface is pitted from weathering and some of the edges were quite sharp so they were quite difficult to carry.

 

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Dr Aaron Hunter (right) is pictured here with Universiti Teknologie PETRONAS undergradate student Vittaya Boon (left). He joined us on the trip as he is lucky enough to be doing his undergraduate project on Pulau Langgun, Langkawi. The two large cool boxes on the trolley were packed full of the limestone samples we collected.

 

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On the way home we gained a flat tyre and ended up having the valves on all four wheels replaced! Perhaps the extra loading from a heavy box of rocks caused this mishap? Emma and Aaron are seen here surveying the damage. A big thank you is due to Emma who drove us throughout the fieldtrip with an enormous amount of skill, concentration and patience.

 

The title of this blog was designed to make you want to read on and not meant to imply any slackness on our part . Hopefully over the last two blogs I have shown how conodonts can play a major role in Palaeozoic (roughly 500-200 million year old) geology by providing palaeotemperatures, palaeoenvironments and most importantly datings for rock successions. This fieldwork has also been an excellent example of the Museum developing links with international universities, providing teaching while expanding our collections from this geologically important region of the world.

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You may have noticed that I haven't posted regularly to my blog over the last couple of months and that's because I've been in Malaysia visiting my Masters student Atilia Bashardin at the Universiti Teknologie, PETRONAS, where I have just been appointed a visiting lecturer. This and the next two posts will be an annotated series of pictures covering my visit to Malaysia, fieldwork, the university and even a few pictures showing what a lucky geologist eats while they are in the field!

 

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Peninsular Malaysia does not, at first sight, look very promising for geologists as it is mainly flat, covered with palm oil plantations and paddy fields like this one above. Every now and again, amazing, imposing limestone hills rise from the flat landscape, while granites form a mountain backbone to the peninsular. As the granites formed beneath the surface of the earth, the heat given off metamorphosed the limestones, often turning them to marble. This gave them the hardness and resistance to erosion that causes them to stand out as we see them today.

 

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Because the limestone hills are geographically isolated from each other and heated to varying temperatures depending on proximity to the granites, it is difficult to work out if they relate to the same rock formations based soley on descriptions of the rocks exposed.

 

Knowing the relative ages of the hills and the distribution of rock formations present is vital for reconstructing the geological history of the area. The area surrounding the Malaysian peninsular has a complex geological history and now consists of roughly north-south trending major crustal units or terraines that docked together at various stages through geological time.

 

Studying conodonts from these limestones can help to date the rock formations, give an idea of the environments in which they were deposited and even suggest the maximum temperature to which they have been heated.

 

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It's important to be well fed while you are carrying out fieldwork. This curry lunch banquet above was served on a granite table lined with a bed of banana leaves. The food in this region is a delightful mix of Thai, Malay, Indian and Chinese, often combining these various tastes.

 

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PhD student Haylay Tsegab (right) is pictured above with his supervisor Dr Aaron Hunter (left), who was my host for the duration of the trip. Aaron has volunteered at the Museum and previously held a short term curatorial position in our Palaeontology Department (now part of Earth Sciences at the Museum). He is also co-supervisor of our Masters student Atilia Bashardin. Haylay is studying the carbonate sedimentology of some of the limestone hills in the Kinta Valley where the city of Ipoh is situated.

 

During our first day in the field we visited one of Haylay's study sites at Sungai Siput. Here they are going to drill a borehole through a section of relatively unmetamorphosed limestone. The digger behind them was used to clear the path to an old quarry so that the drilling equipment could be transported to the site.


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In the picture above, the hammer marks the approximate site where the borehole was due to be drilled a few days later. I took a sample for conodonts just to the left of the hammer in an attempt to date this succession of rocks that are believed to be Silurian age (approximately 415-440 million years old). I carried the 2kg sample home in my suitcase and it is now dissolving slowly in acetic acid (vinegar) in a lab down in the depths of the Palaeontology Building.

 

As well as dating the rock, it is hoped that the conodonts will be able to tell us the maximum temperature to which the rock has been heated: as conodonts are heated, they change from a pristine amber to black, grey and eventually white and these colour changes can be calibrated to show a maximum palaeo-temperature reading for the rock formation they came from. This is important as oil, gas and other minerals form under various temperature conditions.

 

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The limestone above has a large number of calcite veins running through it. The quarry was originally set up to provide ornamental stones like this one. Usually for a field picture like this, I would include a lens cap, coin or finger for scale. However, I didn't want to spoil this image so you will have to believe me that the field of view is approximately 20cm across.

 

The sample selected during field work contained as few calcite veins as possible because conodonts from these types of samples are likely to be fragmented due to the stresses and strains that the rocks have been subjected to. This section is important as it is relatively unmetamorphosed and early indications suggest that the limestone is black because of its high organic content. This, as well as its accessibility, is why this site has been chosen for drilling as part of Haylay's studies.

 

One of the questions remaining to be answered is whether these organic-rich-rocks are a potential source for hydrocarbons? The colour of any conodonts found should be able to tell us the answer to this. Malaysia's oil has been obtained from much younger rocks offshore to the east of peninsular Malaysia and North Borneo, not from the region we are studying. 

 

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The 'path' shown above is a typical limestone exposure reached after a drive north to Kg Ujung Bukit, Perlis. Here we took a sample for Atilia's M.Sc. project to study conodonts from Silurian rocks of the mainland and Langkawi Island. The rocks here have been given the same formation name as those exposed on Langkawi Island to the west. The fact that two different names have traditionally been given to this formation, the Setul Limestone Formation and the Mampelan Limestone Formation, shows some of the issues with interpreting the geology of the region.

 

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This is Aaron and Atilia after we had taken a sample of limestone that filled half of Atilia's rucksack. Usually conodont workers would take samples of at least a kilogramme in size and some have been known to take 50kg samples! Here we took about 5kg but didn't hang around for long after this picture was taken as we heard a snake in the undergrowth. We had probably disturbed it with our hammering!

 

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We followed up various reports of small quarries and rock exposures which led us to a small, shallow, disused quarry at the back of a house. The owners and their children were very interested to see why Atilia appeared to be trying to put piece of rock from their back garden into a plastic bag! While I was writing this blog post, I heard from Atilia that this sample has yielded some conodonts. Sometimes it can take weeks or months for samples to dissolve in weak acids, in this case, acetic acid. The tiny conodont elements then have to be picked out individually from under a microscope with a fine paint brush in the lab.

 

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Here we presumed that Atilia was trying to find out from the house owner if there are any more exposures of the limestone in the local area. Shortly after this, he led us to a quarry on his motorbike but sadly there was no limestone there. It may have already been quarried out. We did see some of the same rock lining a drainage ditch by the side of this road but resisted all temptation to sample it! It wouldn't have helped us as it was not part of an in-situ rock exposure so could have come from anywhere.

 

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Atilia demonstrating how to remain well covered up during mid-day fieldwork while carrying another limestone sample.

 

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It's important to remain hydrated while doing fieldwork in the humid conditions of South-East Asia. On most days there would be a large thunderstorm that cleared the air and, fortunately, we were never in the field during one of these. Most of these drinks shown above are iced water but usually we combined it with some lovely fruit juices and an occasional iced coffee. 

 

I have attempted to set the scene for some of the geological problems that we are hoping to solve using conodonts. My next post will detail our trip to Langkawi Island in search of yet more conodonts and hopefully more answers to our questions.

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Conodonts are extinct phosphatic microfossils that 'look like' teeth and are used extensively for dating rocks roughly 500-205 million years old. Ever since they were first described as fish teeth by C. H. Pander in 1856 they have caused arguments over how they should be classified and, nearly 150 years later, continue to do so. Read on to find out if they really are teeth, why they are so difficult to classify, give names to and even decide which way up they should be!

 

 

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Images of platform, blade-like and coniform conodonts from the Museum collection. Note the presence of white matter inside and beneath the denticles of some of the specimens, a feature unique to conodonts.

 

For consistency, I shall refer to these individual phosphatic elements as conodonts and the creature that produced them as the conodont animal. Some consider this incorrect; you wouldn't refer to the 'cat animal' or the 'lion animal' for example. Often the individual specimens are referred to as conodont 'elements'.

 

  • What do they look like?

 

Conodonts are generally between 0.1mm to 2mm long, although some examples from a single deposit in South Africa measure up to 20mm. They take a variety of different forms including complex platforms, blade-like structures, simple cones and elongate bars with denticles (i.e. small teeth or tooth-like structures). Each specimen has a basal cavity and depending on preservation and species, white matter can be seen inside.

 

  • How do you find them?

 

Usually they are found in marine rocks (limestones or shales) and are released by dissolving them in acetic acid (the acid constituent of vinegar); a process that can take many weeks and sometimes months. The resulting residues are sieved and concentrated into a heavy fraction containing the conodonts by using a heavy liquid such as sodium polytungstate. The majority of collections consist of disarticulated remains and this is the main issue facing scientists studying their distribution.

 

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A scanning electron microscope image of conodonts from the Silurian of Gotland, Sweden (photograph Dr Paul Taylor, NHM). Although many different shapes can be seen here, the specimens illustrated probably belong to only two species.

 

  • What is a species?

 

Early conodont workers described each shape encountered under a different species name as nothing was known about the animal that produced them, or even if it was an animal. Despite the later discovery of bedding plane assemblages of individual conodonts arranged in biological position, many workers continued to give separate names to each form.

 

In the latter stages of the 20th Century, arguments raged over whether to use multielement taxonomy, where different shaped but biologically related elements were grouped together under one species name. Some scientists preferred to continue to name each element separately and as a result, older published literature can be confusing.

 

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A bedding plane assemblage of Idiognathodus from the Carboniferous of Bailey Falls, Illinois, USA. Fused clusters of conodonts and bedding plane assemblages like these are preserved in the fossil record only in exceptional circumstances. They give direct evidence of the biological grouping and positioning of the various elements in the conodont animal. Left: an SEM image. Right: the same specimen photographed under a light microscope. The black scale bar in the middle is about 0.5mm.

 

  • Are they teeth?

 

Although conodonts look like teeth, it has also been suggested that they could have functioned as sieve structures to filter fine particles. One of my favourite early interpretations of the conodont animal was published by Maurits Lindstrom in 1974. You can imagine these elongate conodonts with upper denticulated surfaces acting very much like a filter if arranged like this.

 

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An interpretation of the conodont animal as published by Lindstrom in 1974. I like to call this the 'loo roll' reconstruction!

 

Polygonal patterns on the upper surfaces of some conodonts show the impressions of cells and suggest that - at least at some stage - parts of some conodonts were fully enclosed in soft tissue. Wear patterns on the surfaces of conodonts and growth studies based on bedding plane assemblages suggest that for some conodonts, the elongate denticulated conodonts were used in a rasping action to capture food and pass it backwards to more blade and platform shaped cutting and grinding teeth. However, this is not universally accepted with some scientists suggesting that conodonts could not have functioned in a cutting action. 

 

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Polygonal microsculpture representing the impressions of cells on the platform surface of the Devonian conodont Ancyrodella.

 

  • What produced them?

 

The conodont animal was discovered by chance in a Scottish museum in the early 1980s by some scientists looking for shrimp fossils in the Carboniferous Granton Shrimp Bed. This story is often quoted by curators trying to justify the upkeep of large collections as it is an excellent example of a major discovery resulting from an old uncatalogued collection. The discovery ended one of the longest running sagas in palaeontology; what produced the conodonts?

 

IMG_2817_conodont_animal_blog.jpgThis is one of 10 specimens from the Granton Shrimp Bed of Edinburgh where details of the body of the conodont animal are preserved. The Museum purchased this specimen in the 1980s at around the time that the first paper on the conodont animal was published. The scale bar shows millimetres so the preserved part of the body is just over 1.5cm long.


Details from the 10 specimens available were amalgamated to produce a reconstruction of the conodont animal showing that it had an elongate body with chevron shaped muscle blocks, a caudal fin, a notochord running along its body and paired eyes. There are now other examples of soft body preservation of conodont animals including the giant conodont Promissum pulchrum from the Ordovician of South Africa. This has a very similar body plan to the Granton animals.

 

  • How should they be classified?

 

Although many early conodont workers were only interested in studying the stratigraphical distribution of conodonts for biostratigraphy (relative dating of rocks on the basis of their biological content), between 1876 and 1975 there were 46 different conodont affinities published. Some concluded that they were related to worms, snails, arthropods, chordates and even plants. Others considered them so different from anything else that they should represent a separate phylum, the Conodonta.

 

The precise interpretation of the preserved soft tissues of the conodont animal and histological sections through conodont hard tissues continues to divide the scientific community. Interpretations of conodont hard tissues as representing enamel, cellular bone and globular calcified cartilage have led many to classify them as early vertebrates placing them as more derived than the living lampreys and hagfish and precursors to the early fishes.

 

Not all scientists accept this because some vertebrate workers consider the tissues, particularly the conodont white matter, to be unique to conodonts and unrelated to the dentine and bone present in early fishes. This, allied to differing interpretations of the conodont soft tissues has led to suggestions that they are Chordates but unrelated to the Vertebrates.

 

 

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The conodont feeding apparatus and its position within the conodont animal (boxed area) based on Idiognathodus and Clydagnathus respectively. Image courtesy and copyright of Prof. Mark Purnell, University of Leicester. See the text for an explanation of the labels.

 

  • What way up should conodonts be?

 

Before the discovery of the conodont animal and detailed studies of bedding plane assemblages, the exact biological positioning of conodonts within the mouth part of the conodont animal was conjectural. Various conventions used to describe anterior/posterior, upper/lower and inner/outer have subsequently proven to be incorrect. For example, in old terminology the 'anterior blade' of the P1 element is shown above to be a ventral blade.

 

P (Primo) elements were considered to be at the front of the mouth and S (Secundo) elements further back. Discovery of the conodont animal has shown that the reverse is true. Element terminology using the terms P, S and M is ingrained in the literature and will never be changed. However, many continue to use outdated terminology to describe anterior/posterior, upper/lower and inner/outer or use similarity of shape to infer similarity of biological positioning within the conodont animal.

 

  • Summary

 

I have given a very simplistic guide to conodonts here, showing some of the reasons why there have been and still are so many arguments over naming them, working out their function, classifying them and even orientating them. This post is not intended to champion the research of any particular academic or to give strong views on any of the arguments mentioned but if you are interested to receive further details of scientific literature discussing these issues then why not comment below or contact me directly.

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The Erasmus Programme is European Union funded and enables higher education students in 31 European countries to study for part of their degree in another country. This is exactly what Italian Geology student Angelo Mossoni is doing here at the Museum this summer as part of his masters degree at Cagliari University.

 

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Angelo working in the Micropalaeontology Laboratory

 

Angelo contacted me in early 2011 asking if I had any projects that I needed doing on conodont microfossils. Conodonts are the teeth of an extinct worm-like organism that are used widely for investigating the age of rocks between 200-500 million years old. This sort of information is very useful for oil or mineral exploration companies as well as for revealing the geological history of rock formations.

 

Finding conodonts can be a long process. The first stage is to dissolve in vinegar, limestones or other rocks that were deposited in shallow to deep seas. This produces large residues of microscopic fragments less than a millimetre in size that need to be examined under a microscope. I had already dissolved tens of kilogrammes of limestones from Oman so Angelo's first task was to help examine the residues.

 

Angelo has previous experience of this type of work but has not used separating techniques to reduce the size of the residue needing to be examined. He was introduced to a method using a heavy liquid sodium polytungstate that concentrates the heavier fractions of the residues that include the conodont microfossils. This means that less time is needed to examine the results under a microscope, a process that can sometimes take weeks or even months.

 

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Adding residues to the heavy liquid sodium polytungstate

 

The heavy fraction then needs to be examined under the microscope and a fine paint brush used to transfer the conodonts into a separate cavity slide for further examination. Angelo and I then worked together to choose which specimens should be illustrated. Angelo was then taught to use the Axiocam Imaging System to take good publication quality colour images of the best specimens that he found (see below).

 

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One of the conodont specimens found by Angelo. It is just over a millimetre in length.

 

The very best specimens were also illustrated using a scanning electron microscope so that the conodonts we found could be classified and used to provide a geological age for the sample. Precise dating of rocks from Oman is potentially of interest to oil companies in this region. Angelo found many other interesting fragments of fish and microfossils that will be published along with the conodonts in the future.

 

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Studying some microscopic fish remains on the scanning electron microscope

 

Part of the strategic plan for the Museum is to 'provide a unique and personalised experience for learners, through engagement with real science, scientists and specimens'. We have certainly done this by teaching Angelo new techniques in the study of conodonts while he helps with a research project that has significantly enhanced our collections. More importantly we have enabled Angelo to achieve some of the goals of the Erasmus Programme by experiencing study in a laboratory away from is own country and greatly improving his English.

 

Angelo leaves at the end of August but that will not be the end of his association with the Museum. During his stay he has found many interesting new specimens that we will eventually publish together. Hopefully this will also be a great help to him in his future career as a micropalaeontologist. He has certainly done a large amount of very useful work during his time here for which I am very grateful.

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What is micropalaeontology?

Posted by Giles Miller Jun 21, 2011

The answer to this question is the straightforward part of this post: palaeontology is the study of fossils and micropalaeontolgy is the study of microfossils. Alas, that’s the easy bit done… what then, are microfossils?

 

I’ll assume that we all know what a fossil is (if not, I recommend starting here) so a microfossil must be a small fossil, right? Actually, this is a harder question to answer than you might think so here are some thoughts on how large a microfossil is, how old they are and how we manage them at the Museum.


Size

There is no agreed size below which a fossil stops being a large fossil and starts becoming a microfossil. Some people arbitrarily say that if you need to use a microscope to view a fossil then you are looking at a microfossil. However, some fossils we consider microfossils measure more than a couple of centimetres in diameter. The rocks that were used to construct the pyramids in Egypt contain microfossils that can be as large as a ten pence piece!


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Photo of Egyptian pyramid courtesy of Bobbie Molloy.


This size delimiting definition also gets slightly difficult to use when you are studying the microscopic parts of a larger organism, for example the fossilised scales of a fish or a minute example of something that is usually larger like a gastropod (e.g. a snail). Most people studying these topics would consider themselves microvertebrate workers or gastropod workers and not micropalaeontologists. However, many micropalaeontologists, like me also study microscopic remains of larger organisms like fish that they find during laboratory preparations for other microscopic remains.


Biological classification

Some people try to restrict micropalaeontology to particular biological groups that are commonly considered microfossils. This can also be open to personal opinion, for example, palynologists study microscopic organic remains like spores, pollen and oceanic plankton – all microscopic in size – but some of them would consider themselves palynologists rather than micropalaeontologists. The Micropalaeontological Society defines its specialist groups to reflect biological classifications of organisms commonly accepted as microfossil groups.


Age

As with size, there is no agreed age beyond which something stops being recently dead and becomes a fossil. With specimens in this narrow window of age (ie 0-10,000 years old) it is virtually impossible to tell how old a microfossil specimen is without carrying out some sort of destructive chemical analysis on it.


Our collections

At the Museum, we mainly follow the Micropalaeontological Society's definition of a microfossil and in the Palaeontology Department we have collections of Foraminifera, Ostracoda, conodonts, Radiolaria, nannofossils and various palynological groups such as the dinoflagellates and spores. In future posts I will introduce each of these microfossil groups as I highlight projects that are currently happening here at the Museum.


My job is to manage all of these collections which number over 750,000 objects. It would be impossible to count the exact number of specimens because some slides and residues contain hundreds of thousands of specimens.


The lack of clarity over what age makes a microfossil causes problems sometimes with deciding where to store specimens in the Museum collections. In the Palaeontology Department we have all the extant (modern) Foraminifera as well as the fossil specimens, so no problem there. However, ostracods are split between our department and the Zoology Department, with us holding the fossils and Zoology the recent (extant) forms. In practise it is very difficult to draw the line between fossil and recent and we certainly have some ostracods that could be in the Zoology Department and probably vice versa.


The majority of the microfossil collections are Foraminifera, which are unicellular animals with a foramen (i.e. an opening, sometimes multiple) that form small shells of calcium carbonate, silica or organic materials. Examples of Foraminifera are shown below, where the field of view of the slide from the Heron-Allen Collection is about 2cm.


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The Heron-Allen Collection

 

I mentioned that some micropalaeontologists like me also work on microscopic fragments of fish (microvertebrates). At the Museum these are kept with the fish collections so they do not come under my ‘jurisdiction’. However, I still study them and some of my most important discoveries have been on this subject as you will find out in the next post to the blog.



Giles Miller

Giles Miller

Member since: Apr 21, 2010

This is Giles Miller's Curator of Micropalaeontology blog. I make the Museum micropalaeontology collections available to visitors from all over the world, publish articles on the collections, give public talks and occasionally make collections myself.

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