Thursday, 31 May 2012

Return to Minnie's Quarry

A couple of weeks ago I embarked on the latest field trip of the new season. This was a welcome return to Minnie’s Quarry – somewhere I had not been able to get back to for about three years. After that first visit the quarry owners, like so many nowadays, heavily curtailed access and I am unaware of any visitations taking place during the time period after we had visited. And then the quarry itself was closed for a time, apparently on a temporary basis, during the worst of the economic downturn.

Fortunately, this appeared to be fairly short term and the quarry was reopened some months later. But still the same problems persisted and there was no access permitted. There were rumours that the quarry was being poached by illegal collectors and that at least one person had been caught but, whatever the truth may have been, access was still denied.

We were, therefore, pleasantly surprised when the quarry appeared on the list of venues available for a field visit. It had, apparently, taken a lot of coaxing and negotiating to gain access and we were both surprised and delighted at the outcome. I was curious. I knew the site was being considered for major redevelopment and was unsure where we would be allowed  to prospect since the site covers a massive area and small quarries are continually opened to strip away the economically viable glacial sand and gravels. And, of course, below these lies the Oxford Clay and yet more opportunity for finding ammonites and the highly prized reptile remains.

So it was with great eagerness that we drove to the quarry ready for our day in the field. The event was well attended and the conditions looked good. Despite a lot of recent heavy rain, the quarry had been drying out well and the quarry manager confirmed that the trip could take place. We made our way to the quarry and I expected to traverse a field, climb down a ladder and make my way eastwards to the quarry, about a quarter of a mile distant.

Imagine my surprise when, after we had barely entered the field, we turned right and headed westward. On reflection, this should not have been so surprising since, as I mentioned, the site is massive and different quarries were being opened on a fairly regular basis. This time we crossed another field before paralleling a drainage ditch and then heading down toward what was obviously an old exhausted quarry.

This was filled somewhat with water but the old spoil heaps kept the water in check and the site looked interesting – especially as there were obviously large areas of clay to check out. Unfortunately we were told that this quarry was strictly off limits and we were a little disappointed to say the least. As we skirted around the quarry we made our way through a gap in a hedge and then made our way up a ditch and finally reached the quarry we were to be allowed to prospect in.

At first glance, it looked much like any of these glacial quarries do – a series of drainage ditches criss-cross the quarry floor interspersed by spoil heaps and plateaus of the prized sand and gravels. However, the much prized Oxford Clay was conspicuous by its absence and although there were a few small isolated patches of clay that were readily apparent it was obvious that there were no significant exposures of clay to prospect.

Disappointed we asked the quarry manager why this was the case and was told that new directives  dictated that the clay was no longer to be excavated unless it was needed to shore up the sides of the quarry and help with stabilising the drainage ditches. This was hugely disappointing and I felt a little sadness that this particular deposit of the Oxford Clay was unlikely to be exposed at any point in the immediate future.

Undaunted we still had the Pleistocene deposits to prospect and these had proven to be quite productive in the past. However a further restriction placed upon us meant we only had a couple of hours to search for fossils before we had to withdraw – things were a little disappointing to say the least. However, we were finally unleashed and started to prospect in the quarry and I made my way to the clay deposits for a quick search just in case something may have been uncovered. 

I need not have bothered since the clay was only surface deep really and it was obvious that there was nothing to find – not even a belemnite. So it was onto the glacial exposures to see what could be found. The answer was not much really. I found nothing at this point but there were a couple of bits of mammoth tusk found although these were quite rough really and the only bones of note looked to be a bison tibia and a nice rhinoceros toe bone. Apart from that there were only scraps.

No sooner had we gone in then it was time to come out and this, since there was still a lot of the quarry to be searched, compounded my frustration. We took the opportunity for a spot of lunch at which point only seven of us remained at the quarry and the others returned to their vehicles – including the organiser and quarry manager. It was at that point my luck took a turn for the better.

Where we were having lunch was at the top of the quarry on a gravel plateau that had been levelled off some time in the past and since there was lots of vegetation and bushes that were well established it was largely ignored. After I had finished lunch I decided to take a look around and see if anything may have washed out over the previous months (years?).

Mammoth toe bone

I had only walked a few yards when I noticed something protruding from a bank of gravel. I was not sure what it was at first since there was some vegetation obscuring the view but as I pulled the plants out of the way I was rewarded with a strange looking bone that I was, frankly, unsure of its identification (if it’s not dinosaur or other reptile I’m in trouble). Fortunately I had Carl with me and he excitedly exclaimed that I had found a mammoth toe bone! That was a real bonus and I was very pleased.  

There were now four of us prospecting on this plateau and then, within about ten minutes, I found another super specimen completely exposed on the gravel surface. It was lying on its side and as I picked it up I could see that I had found a substantially rooted tooth which, I was reliably informed, was almost certainly from a horse although there was a slight chance it may be from a bison as well. Needless to say I was delighted with the finds and although we spent a little longer picking over the plateau there was nothing more forth coming.   Still I was more than pleased.

Then we got word that, because of our truncated visited into the quarry, we were to be taken into the works itself and be able to root through what is known as the rejects pile. When the gravel is removed from the quarry, it is transported to the works for sorting where it is graded by size and stored accordingly. The reject pile contains any rock or gravel that is 10mm in size and over and, of course, this contains rock that is very much bigger than that which got picked up in the excavation process. And naturally enough this includes some fossil material.

A rooted horse tooth

When we arrived at the works, we were promptly shown the reject heaps and were allowed to get stuck into them straight away without any rules or regulations other than common sense. The heaps did not disappoint and there were some nice specimens recovered including a mammoth tooth and many other odd bones. The find of the day was a beautifully preserved lower jaw complete with several teeth in situ from what was probably a deer. How this managed to get through the excavating and sorting and survive is something of a mystery but it really was an exquisite piece.

For my part I found a few bits which included a distal end off a small metatarsal from something or other and a segment from a hippopotamus tusk which is quite rare by all accounts so I had to be happy with that.  Eventually, I called it a day during the late afternoon sun and started the long journey home. I wonder how long it will be before we can get back into the quarry again this time. I’m really not so sure anymore and all we can do is hope that we are given the opportunity to search in this interesting quarry again at some point in the future.

A section of hippopotamus tusk

Sunday, 27 May 2012

Palaeochat: 1

Over at Archosaur Musings, Dave Hone has been publishing Academics on Archosaurs in which various palaeontologists are asked the same five questions about palaeontological research – past, present and future. One of these featured Jerry Harris and Jerry made a wonderful observation regarding something that has been a continual bane of contention in palaeontology – the use of extant analogies.

When a dinosaur has been discovered, and has gone through the long process of excavation, preparation and description, then the palaeontologist quite often reaches an impasse when it comes to suggesting physiological and anatomical adaptions and especially behavioural patterns. Faced with this degree of uncertainty palaeontologists’ often make inferences based on similarities in animals that they are familiar with today – the extant analogy (EA).

When the EA demonstrates adaptions that the fossil taxon does not then these missing properties in the fossil taxon can then be the object of an inferred analogy. The problem with this, however, is that analogical inferences are often guided by established constraints that allow the palaeontologist to make selected inferences – and herein lays the problem. Just what these constraints are is a matter of conjecture.

This suggests that more palaeontologists are likely to make confident assumptions when they recognise the EA and fossil taxon as similar as they are to disregard them. Of course this is a natural thing to do and we have all done it – we want to see the similarities so that we can envisage our fossil specimens as living breathing animals. This is because common characteristics increase the recognised similarity of two species whereas different traits reduce the recognised similarity. And the more characters shared between the two species, the stronger both our inferences become and similarity appears to be.

Of course, this is not a criticism of, for example, the extant phylogenetic bracket – not by a long way but it does not hurt to be always questioning ourselves when we make perceived assumptions because of similarity. We can hypothesise about various inferences based upon characters found in the EA which are not preserved in the extinct taxon but this must always be quantified by additional phylogenetic, morphological and osteological analysis and, even then, there must be a further rigorous reappraisal of data before drawing any reasonable conclusion. And, even after all this, there will still be a degree of speculation.

Behavioural inferences are speculative in the extreme. Similar physical adaptions and characteristics may appear to suggest a similar lifestyle for an extinct taxon – take the heron-like analogy for Spinosaurus in Planet Dinosaur. But this is completely untestable speculation and, as Jerry Harris stated, non-avian dinosaurs are a totally unique group of animals with no real extant analogues and so the challenge is to concentrate on what made the dinosaurs unique within a much bigger framework that includes everything from the animals themselves to the environment they lived in.

Moving on and Jon Tennant over at Green Tea and Velociraptors recently made a critical appraisal of the very well publicised paper that suggested that methane produced by sauropods could have contributed to a global temperature increase in the Mesozoic. Plenty of other people have made their feelings clear regarding this paper and I’m not about to review it further but Jon made the following observation:

“The amount of times statements are preceded by ‘could have’ ‘suggests’, ‘estimates’, ‘likely’, etc. is an immediate trigger for concern. There’s nothing actually concrete in the paper.”

And yet these words and phrases are universally used in the world of paleontology and with good reason. I suspect that no matter how solid your research may be, how thorough the data analysis is, even how testable a hypothesis may be , it is natural for  authors to quantify any statement they make – especially when it is presented to an ever growing audience that has an insatiable need for more and more knowledge. An ever more critical audience too it has to be said.

As a blogger I have become very aware of this phenomenon. So when I review a paper or discuss a conference I do indeed tend to use the words “suggest”, “hypothesise” or “likely” purely because to state anything as fact is guaranteed to set you up for a grilling from a very discerning audience. I still have the odd lapse but I can rely on my readership to point it out - that’s for sure.

Even when I feel certain that a theory is probably correct, and ascribe to it with confidence, I will still describe it as likely or possible. For me, if some research appears correct in my eyes and I can see how the theory was arrived at, I am very likely to subscribe to the premise of the paper and be confident in its testability. However, if a subsequent theory by another palaeontologist is able to disprove the first paper and I am satisfied with the data analysis presented, then I am happy to ascribe to it from that moment on. This does not mean that the previous paper suddenly becomes insignificant or useless but further research has built on the original findings presented and the new paper often uses this data to formulate a new premise. This is the very crux of good science and long may it continue.

It is also another reason not to use those words which state theory and hypotheses as fact and it makes sense to be neutral and impartial.  I am, on occasion, shocked by the aggression shown by some paleontologists’ to another’s research when it is published. I’m not talking about these odd papers that crop up from time to time that we all know are full of, how shall we say, dubious information but those papers that are from reputable researchers, which have gone through the peer review process and published in entirely legitimate journals. This is unfortunate and, in my eyes, entirely unnecessary. Constructive criticism yes but when it degenerates into a slanging match in the palaeontological public eye then I’m not interested - what’s the point in that?  

Which brings me to my final thought for now and it directly relates to the previous point. I have been asked a couple of times why I do tend to sit on the fence and that I never actually criticise anyone. Well that’s not strictly true and I learnt my lesson a few years back when I opened my mouth a bit too freely on a couple of occasions and was promptly reprimanded by a couple of seasoned palaeontologists – and rightly so (thanks for that guys – you know who you are).

When I took a step back and thought about it I soon realised the truth. Who am I to openly criticise someone’s research that, in all probability, took years to produce? These researchers had endured years of sacrifice, toil and expense to get where they are today and produce the literature that I love to read. Not for me to criticise anything these palaeontologists’ do and more power to them I say, even if I do not necessarily agree with the data presented – they have my utmost respect. I am reminded of the old saying “I do not agree with what you say but I will defend your right to say it”.

However, that does not mean there are those papers which, in my humble opinion, are pretty average and where, again in my opinion, the data provided does not necessarily add up. But this paper is still a valid and peer reviewed contribution to the literature and must be respected as such. There are exceptions and I have no qualms about savaging those so called publications such as the notorious kraken and aquatic dinosaur debacles. But then, in these extreme circumstances, we all do don’t we?

Thursday, 17 May 2012

A Little Sauropod Imagery

Just a brief post this week because of various commitments but I’m pleased to say that the most important of these are palaeo-related. When this post goes live, myself and a few colleagues will be busily engaged in promoting education, conservation, preservation and the need for environmental awareness – all in a palaeontological context . We are certainly doing our bit – let’s put it that way!
In the meantime, here are a few sauropod images from my time in Lisbon – enjoy!

A cast of a specimen from Tendaguru.

An associated string of camarasaurid caudal vertebrae.

Friday, 11 May 2012

The Cretaceous in Flames

Recently I blogged about the complex ecological issues regarding the abundant flora and fauna of Laramidia and how so many large dinosaurs managed to exist in such a relatively small area of land. I postulated that increased levels of CO² created a greenhouse effect that generated the vast amount of vegetation required to sustain large populations of big herbivores. High humidity, warm temperatures and abundant rainfall all increased growth levels.

 I highlighted how the dinosaurs themselves may have driven the plants to diversify and increase in quantity (coevolution) and how this may also have spurred on the rapid evolution of the angiosperms. All these suggestions, in combination with the geographical and physical barriers such as rivers and mountains, may have been enough to create and sustain an ecological explosion in both plants and animals unlike anything else we are familiar with, both today, and in the past.
And now a recent study introduces yet another player into the already complex world of the Cretaceous – wildfire. The paper by Sarah Brown et al was published in Cretaceous Research in February and reveals yet more insights into how fire added a further dimension to the terrestrial ecosystem and how the implications were often significant.
There studies reveal that, although CO² levels were indeed high and that a greenhouse effect was in place, oxygen was also increasing in volume – in fact quite significantly. This does not surprise me at all since the increased the amount of CO² taken in by a rapidly growing and expanding plant flora would have also produced large volumes of oxygen through photosynthesis. What I had not realised, however, was the effect this would have on the control of wildfires that affected the ecosystem.
The authors were able examine the records of wildfires during the Cretaceous by analysing the remains of charcoal that are dispersed in quite often large quantities in deposits throughout the world. Simply put, charcoal represents the remains of plants and trees that were caught up in these fires and when examined, using scanning electron micrographs, reveal a varied community of plants and trees – particularly the angiosperms.
Despite having to be aware of sampling bias (such as a lack of sites in the southern hemisphere), the first evidence of abundant wildfires is during the Valanginian and there appears to be a general increase in the amount of fires from that point on and they become worldwide during the Late Cretaceous. Each charcoal deposit displays unique taxanomic plant diversity and highlights the progression of the angiosperms throughout the period.
The charcoal reveals the effects of fire during high oxygen conditions. What I had not realised is that rainfall is not as effective a controller of fire as in a conventional scenario because the oxygen content enables fire to burn under wetter conditions – even wet plants would combust more readily. The sheer volume of plant fossils in the charcoal and the high oxygen content all suggest extensive wildfires – particularly in the Late Cretaceous.
There are many possible side effects of such fires and principle amongst these was post-fire erosion which has various implications for any ecosystem. Once fire has destroyed vegetation and the litter and scrub covering has been removed, the soil becomes liable to further enhanced erosion and large volume transport of sediment can occur. The lack of coverage enables, thereafter, an increase in surface runoff during rainfall and flooding events and the surface, because it is now exposed, can also be then affected by an increase in temperature which can change the soil profile leading to yet further erosion.  

An exposed charcoal bed at the Bluff
One of the after effects of such a flood event is that both charcoal deposits and dinosaur carcasses can be washed together and deposited in one accumulation. It is a fact that dinosaur remains are often found within charcoal deposits and I have first-hand experience of this at the Bluff which, coincidentally, features in this paper as does the Cuckoo’s Hole Quarry. It has been known for some years that bones and charcoal are found together but this is the first time a mechanism has been suggested to explain the cause.
As already noted, angiosperms began to proliferate during the Late Cretaceous and these wildfires may also have been instrumental in their rise to prominence. Angiosperms were much better equipped to deal with fire due to their ability to take in the increased levels of oxygen which, although enabled the plants to burn at a quicker rate, also allowed them to recover quickly and grow at elevated rates.
The study suggests the possibility that dinosaurs may have been driven to their death by these fires and that, at the very least, there would have been a form of displacement as herbivorous dinosaurs had to move off in search of fresh fodder. Another effect is that the surface runoff would have been flushed into the sea and may have caused an oceanic anoxic event whereby an algal bloom may have occurred and oxygen levels were depleted but this is only suggested and was beyond the scope of this paper. I will say that we often find the charcoal remains of trees in the Oxford Clay so we can certainly confirm that burnt remains of such plants were indeed washed into the sea although this was during the Jurassic.

A charcoal log in the Callovian Oxford Clay

I have to say that this is really a quality paper and I am impressed by the amount of data collected and the attention to detail. There are plenty of quantifications included suggesting the aforementioned sampling biases that may occur and the fact that more study is obviously needed. This study adds a further chapter to the already fascinating world of the complex ecosystems in the Late Cretaceous.  
Brown, S.A.E., et al., Cretaceous wildfires and their impact on the Earth system, Cretaceous Research (2012), doi:10.1016/j.cretres.2012.02.008

Wildfire image courtesy of SERC Media.

Thursday, 3 May 2012

Book Review: Dinosaurs of Eastern Iberia

It is very easy to forget , when you focus so much of your attention on the high profile formations of Asia, Canada and the United States, that there is significant dinosaur bearing strata virtually right on your doorstep. I was always aware of the importance of Eastern Iberia but, until this book was published, had not realised how many and how diverse these locations were. Only a couple of hours flying time away lays one of the most important and astonishingly rich dinosaur grave yards in the world.
Published by Indiana University Press in 2011, Dinosaurs of Eastern Iberia is a fascinating introduction to the past, present and on-going studies into, not only the dinosaurs that inhabited the area, but also the other flora and fauna that shared their environment.  Also considered are the palaeobiogeographical aspects of these studies as well as highlighting evidence of the K-T boundary in the numerous Late Cretaceous sediments. There are a total of twelve chapters that cover the history, geology and palaeontology of Eastern Iberia covering a multitude of different subjects along the way.
The first chapter deals with the history of palaeontological discoveries in the region which began in the 1860’s and developed slowly throughout the twentieth century. However, after the Renaissance, interest in dinosaurs exploded and soon hundreds of sites were located, identified and excavated. The 21st century brought new unparalled riches to the fore and this chapter really sets the tone for the book especially if, like me, you did not realise how rich the various localities are.
There are dinosaur bearing localities from the Late Jurassic, Early Cretaceous and Late Cretaceous and the next two chapters explain some of the geological and climatic aspects of the region. Using diagrams, images and a combination of both enables the reader to appreciate how the so-called Alpine Cycle affected the Iberian Peninsula throughout the Mesozoic (and beyond) and describes the different conditions that formed the fossil-bearing sedimentary rocks of today.
Chapter 4 focusses on the dinosaurs themselves – specifically their history and classification. This was a favourite chapter of mine in the book and describes in some detail what actually constitutes the makeup of a dinosaur. Unusually for a book of this type, the osteology data is supplemented with skeletals and images of individual bones that really help the reader to understand some of the terminology that is frequently used but that may not be necessarily understood.
Chapter five is a straightforward description explaining how diverse the dinosaurs were and introduces the various clades and suborders whilst chapter six describes the various techniques that are employed in describing the various fossils. From prospecting in the field, to collection, preparation and study, this chapter gives a solid introduction to the world of the vertebrate palaeontology. No stone is left unturned as paleoichnology and the study of eggs are included and the very latest bone histology studies, CT imaging and other digital technologies are highlighted.
The next two chapters focus on the saurischian and ornithischian dinosaurs of the Iberian Peninsula and compares them with other dinosaurs from around the world. Explaining the origins and relationship between the various groups the chapters represent current, solid and reliable data backed up by some stunning images and reconstructions.
Chapter nine was another favourite since it describes the animals and plants that shared the dinosaurs’ world in the various Mesozoic ecosystems. This was another chapter brought to life by the images of the fossils and reconstructions of the various life forms. When you imagine these ancient worlds, complete with the flora and the amazing variety of fauna there was, it would have been a truly wondrous sight to behold.
The next chapter describes the effects of continental drift on the region and how this affected, climate, environment and dinosaurian distribution throughout the Mesozoic whilst chapter eleven addresses that perennial favourite - the extinction of the dinosaurs. Describing how the concept of extinction was initially arrived at through to highlighting the five major extinctions that have affected the planet since the Pre-Cambrian, the chapter runs through the various concepts that suggest how the demise of the dinosaurs came about. The focus, however, is on how the Maastrichtian beds of Eastern Iberia reveal a thriving dinosaurian community virtually right up to the  K-T boundary and the authors are very positive that, as more beds are studied, more evidence will be revealed that will help piece together the final days of the dinosaurian dynasty.
The final chapter is written by Oscar Sanisidro, whose magnificent artwork dominates this volume, and looks at how the dinosaurs and their world are reconstructed and brought vividly back to life. He explains that a combination of studying the skeletal remains, working out the muscle and tendon configuration and comparative anatomy helps the scientist and artist restore these long vanished animals. Virtually the same techniques are used to reconstruct the flora that shared the dinosaurs environment – variants on a theme if you will. The combination of all these disciplines can be very dramatic as demonstrated so admirably in this book.
To summarise, this is a very beautiful book that is delightful on the eye and relies heavily on its imagery. That is not to say that there is not a copious amount of data presented because there is but you cannot get away from the visual beauty of this volume. As James Farlow states on the back cover: “I suspect that many will buy the book for the artwork alone!” – And he would be right.
Criticisms? This book is aimed at the general reader but I suspect that this volume is a little more highbrow than that and I feel that the average general reader may struggle on occasion. Part of the reason for this is that sometimes the text appears clunky or even awkward in places but I suspect that this may be due, in part, to some of the literal translation from Spanish to English. Some of the artwork too has come in for minor criticism but I believe that most of these issues are due to limitations of the digital rendering process.
This is great book in which there is a wealth of information provided and is a great introduction to the dinosaurs of Eastern Iberia. If, like me, you only had a limited interest in the dinosaurs of this region then buy this book! I promise that you will regard this important and fascinating region with a new found interest and respect.  
Galobart, A., Suñer, M. and Poza, B. 2011. Dinosaurs of Eastern Iberia: Indiana University Press, Bloomington, Indiana, USA. 321pp. ISBN 978-0-0253-35622-2