Important New Ordovician Beasties

I'm a bit late in mentioning this particular discovery, but it is worth mentioning nonetheless. Palaeontologists in Morocco have discovered some assemblages of exceptional preservation from the early Ordovician period which are filling in the gaps in our knowledge of early metazoan evolution (I'm using early quite broadly there). Many Cambrian forms seem to come to an abrupt halt leaving no descendants in the Ordovician, giving rise to the view that the Cambrian was a time of evolutionary experimentation resulting in many dead ends and potentially quite a substantial extinction. The new soft body faunas of Morocco have thrown this view out of the window as they demonstrate that the change seen in the fossil record was due to absence in preservation; the organisms were there but not soft-bodies were found preserved, until now.

Halkieriids are among the forms now found to have lived in the Ordovician. Not only were Cambrian forms found to have continued until at least the Ordovician, but many groups have also had their earliest appearances pushed back. Horseshoe crabs are now known to be at least 30 million years older in the fossil record and cheloniellids (distant relatives of crustaceans and insects) make their first appearance in the Moroccan localities.

The above image, taken from the paper found here, shows some of the spectacularly preserved fossils. a) and b) are demosponges, c) is an annelid worm, d) shows similarity to halkieriids, e) is possibly an armoured lobopod (I do rather like those...) f) is a Thelxiope like arthropod, g) is a marrelomorph arthropod, h) a skaniid arthropod, and i) is a spinose arthropod.

This haul of fossils also highlights the usefulness of amateur palaeontologists and fossil collectors to palaeontology. Locals with interest in fossils are a great source of information as they often know the area better than anyone. Without the help of a local collector these Moroccan fossils may never have been found.

Morocco is quite an interesting place for fossil collectors. Entire fossiliferous areas are off limits, unless you enjoy getting shot at. Yet it is also one of the sources of fossils found in fossil shops worldwide. Be careful if you collect a Moroccan fossil though, it is also known for producing a large amount of fake fossils, I've seen a fake trilobite from there before and they are quite good at crafting fraudulent fossils. If in doubt, just take a freshly lit match (extinguished off course) and poke your fossil with it. If it melts then obviously you have got your hands on a lovely fake fossil probably made of resin. If your fossil is legit then your little experiment will do no harm to the fossil and you can sit happily knowing you have a genuine piece of Moroccan history.

Interesting Breakthrough in Vertebrate Palaeontology

A team at Caltech (California Institute of Technology) have developed a new technique for determining the body temperatures of extinct vertebrates. The technique analyses rare isotopes in bones, teeth and egg shells, which clump in different ways dependent on temperature; higher temperatures result in less clumping. The process has an accuracy of just one or two degrees. They first tested this with living mammals, finding the temperature given came as 37 degrees, before testing it on mammoth teeth to find the same results. They then tested it on 12 million year old rhinoceros and crocodile fossils and found that it matched the results of living organisms.

This breakthrough can potentially have a big impact on palaeontology, giving more insight into palaeoclimates and investigations into both the physiology of extinct organisms and the evolution of warm blood, perhaps even illuminating what drove the change. Of course, one of the biggest questions it may finally provide an answer for (or at least strong evidence) is the classic question were dinosaurs warm or cold blooded? For the record I do not have a strong view on this and it is a while since I looked into it, so I could not formulate any sort of backing for my position without doing more research (which could potentially alter my view). At the moment I see the answer being a big mix. I believe some dinosaurs are likely to have been cold blooded, particularly the larger ones and possibly all of the ornithischians; I think many of the theropods, particularly the large ones, were possibly midway between being warm and cold blooded, but that they may have appeared to be warm blooded due to the warmer climates "turbo-charging" them; I also think that the smaller, feathered theropods were likely warm blooded and that birds inherited their warm blood from their dino ancestors.

Hopefully they will test a variety of dinosaurs when they come to answer this question. This test could potentially be misleading if not used carefully and on a wide range of specimens as it provides data only for a specific time (when the tooth grew for example).

For more information, the ScienceDaily article is here and the journal paper can be viewed here. 

Microevolution & Macroevolution

This is not the most thorough description of the differences as I thought I would share some of the "off-the-cuff" answers I gave on a Facebook discussion recently. After the typical creationist claim of "I accept microevolution but not macroevolution" someone stated that there is no difference between microevolution and macroevolution, so I decided to clear things up, here was my response:

On micro and macro evolution there is a distinction within the scientific community, but not the way creationists would like. One embraced by all evolutionists is that micro and macro both employ different techniques in order to study them; micro uses observable experimentation, whereas macro generally uses the fossil record and genomic comparison for example, though there is overlap occasionally between the two studies. 

The other distinction is the debated one. Many evolutionists believe that macro is simply micro added up (the difference is quantitative), whereas some believe other processes are at work during macroevolution and that there is a qualitative difference (extrapolation is therefore not justified). Processes in the latter include species selection, though this view is the minority. Both sides affirm that macroevolution can and does occur, they merely disagree on how.

I was then asked which distinction of macroevolution (referring to my second paragraph) seems to be evidently accurate, to which I responded: 

A bit of both in my opinion. Species selection is plausible but difficult to demonstrate. The argument centres around speciation really and whether or not it is the locus of major evolutionary change. I take the view that micro adds up to macro but that at times speciation locks in change (this fits into the first of the two views I gave) though I also think that there may be circumstances where species selection plays a part and prevents simple extrapolation. For all intents and purposes, and for a shorter answer, I believe extrapolation of micro to macro is valid in most cases. 

I later decided to expand even further, just in case:

To expand on my point about the differences between micro and macro evolution, just in case someone misunderstands it and thinks I am saying that we do not understand how micro can add up to macro, I think it is worth mentioning that the issue comes from our understanding of natural selection. If natural selection works only on the level of genes and individuals (and modules perhaps...oooh....controversial) then micro extrapolates up to macro no problem. However, if it works on other levels, not necessarily group selection, but certainly species selection (and dare I mention clade selection?) then the extrapolation is unjustified. Considering the levels/units of selection is an abstract concept, it is no surprise that there is disagreement about it. Demonstrating which occurs is not always easy and often requires mathematical arguments to back any experimental evidence and vice versa.

I could expand on this enormously to be honest as a lot of the content needs more development and clarification; put this on the list for the future maybe? If you are interested in more on this subject, I recently wrote a piece which discussed levels of selection in brief, titled A New Type of Selection? And quite a while ago I wrote a piece about punctuated equlibrium, a topic which overlaps with this one to a significant degree. It was called Punctuated Equilibria Explained (or PEE if you like...).

A New Type of Selection?

Another interesting article I found on PhysOrg.com was titled A new type of genetic variation could strengthen natural selection.  This article immediately attracted my attention and provides interesting support for a concept which does not get much attention and is even considered controversial.

The study shows that not only are individual genes and whole organisms selected for, but also gene networks. The study looked at the genomes of variations of yeast within the same species and found that gene networks had been preserved even though the genes are inactive in one variant. Balancing selection allows two variants of the same gene to exist in a population and has normally been observed with individual genes; it has now been found to work on gene networks. It is not yet known whether this is a rare case or whether selection on networks is common.

The concept which comes to mind from reading about this study is modular selection, a controversial view about the level of selection. At which level(s) selection acts often attracts heated debates and the two extremes tend to be gene selection and hierarchical selection (where natural selection occurs on many levels). Current views tend to hold that gene selection and individual selection both occur, but which is more dominant is still often the key issue (other levels are getting a resurgence in popularity, such as group selection). As genes are selected for indirectly (they are not interactors) the idea of gene complexes is used to explain how genes can be selected for in groups. The main argument in favour of gene selection is that a gene is reliably transmitted from generation to generation and so selection has time to act on it. Phenotypes are broken down at the genotype level by recombination with each new generation and so it is argued that the phenotype is not selected for (though it should be kept in mind that phenotypic variation from generation to generation is often so small that natural selection will not "ignore" subtle changes).

Modular selection bridges the gap between these two levels. Selection on a gene complex cannot explain why the gene network has been selected for in the yeast example. It would be wrong to label this modular selection for semantic reasons which should not be ignored (modular selection applies to complex multicellular organisms which form in a modular fashion; gene networks cover modular selection but are not exclusive to it).

In Lu et al (2009) modules are described as "tightly integrated complexes of characters with discrete, semi-independent and temporally persistent histories" and that these "were the principle focus of natural selection and played a leading role in evolutionary transitions".  This places modular selection midway between gene selection and selection on the individual. Modules are both interactors (unlike genes) and have potential phylogenetic longevity (more so than phenotype) which circumvents the issues with each other type of selection. Schlosser (2002) states that "modules tend to be more important in delimiting actual units of selection than either organisms or genes, because they are less easily disrupted by recombination than organisms, while having less context sensitive fitness values than genes".

West-Eberhart (2003) described modular selection as a subunit of evolution. She states "[the] notion of the phenotype as a nested hierarchy of modular subunits implies both semi-independence and connectedness among subunits." This is what is found in this study using yeast, supporting the idea that modular selection is not only valid but to be found in more than just pterosaurs and other vertebrates.

This to me is exciting news and will influence our understanding of how natural selection works, particularly on which level. Sadly PhysOrg.com do not provide a link to the papers they discuss or even a reference, so I struggled to track down the paper.

References:

Hittinger, C.T. Goncalves, P. Sampaio, J.P. Dover, J. Johnston, M. and Rokas, A. 2010. Remarkably ancient balanced polymorphisms in a multi-locus gene network. Nature. 464, 54-58.

Lu, J. Unwin, D.M. Jin, X. Liu, Y. and Ji, Q. 2009. Evidence for modular evolution in a long-tailed pterosaur with a pterodactyloid skull. Proceedings of the Royal Society B. 


Schlosser, G. 2002. Modularity and the units of evolution. Theory in Biosciences. 121: 1-80.

West-Eberhard, M. J. 2003. Developmental Plasticity and Evolution. Oxford University Press, Inc. New York, pp. 56.

Breakthroughs in Evolution are Old News

I was browsing PhysOrg.com earlier, looking for news I have missed over the last few months. I found an interesting article titled Evolution Impacts Environment, Challenging Traditionally Held View, Study Finds. My first thoughts upon seeing this title was that this is obvious, the evolution of life has had enormous impacts on the environment and not just through the evolution of humans. The most striking example is the transformation of the atmosphere (much more than a local environment) by cyanobacteria which resulted in our oxygen rich atmosphere. The evolution of photosynthesis affected the entire planet and continues to do so. This seems like old news to me.

The article states that the traditional view is that ecology shapes evolution; organisms evolve to fit the environment through natural selection. The new insights gained from these studies observing guppies are that evolutionary processes influence ecology too. To someone accustomed to longer time scales this seems to be obvious, but apparently ecologists ignore evolution because ecological interactions occur on a short time scale which evolution is too slow to affect. So what is the real insight from this study?

It seems that what we gain from it is that ecologists become aware that evolution affects their studies too and must be taken into account (they do not ignore evolution, only its effects in the short term). It also backs the growing body of evidence showing that evolution can occur very rapidly and has effects even in the short term. What I often notice with views in evolution is that the middle ground is often the best. Evolution and ecology have a reciprocal relationship, something which just sounds like common sense. Coupling rapid evolutionary change with the understanding brought through the concept of the extended phenotype makes it surprising that ecologists are only just catching up with common sense. More unity in biology is a good thing, thankfully we have evolution.

I must admit though, as I am not an ecologist I might be missing something subtle.

Plans for Summer

So, summer is almost upon us. In just a few weeks I will be venturing back from uni to my home in Conisbrough having finished the first year of my palaeobiology degree. After I go to Download festival I will be spending some time (all going well) at the local museum in Doncaster. I'm looking forward to it as I only recently found out that they have fossil collections. I will apparently be given a little project which will look good on my CV, provide good experience and will be of personal interest. I can't wait.

If you live in the area and have not visited the museum I recommend popping in. It is free and has a range of displays, including a small fossil display as you go in (I will update when changes occur in the future). You never know, if you go over summer you may bump into me.

The work at the museum is the main reason for this post. I will also be celebrating my birthday, going to Taizé again, and have a field trip to Spain at the start of September. 

Attack of the Mysterious Soft-bodied Ediacaran Trilobite

This morning, just before leaving to go to breakfast, I had a quick flick through a couple of pages of Invertebrate Palaeontology and Evolution 4th Ed. by E.N.K. Clarkson, a textbook I recommend for anyone interested in invertebrate palaeontology. As expected there are a few pages on the Ediacaran fauna, including a picture with familiar organisms such as Spriggina and Dickinsonia. Also on the picture was an organism labelled "soft-bodied trilobite". This stuck in my head a little bit through the day (to the point where I mentioned it to someone). Later on I was round at a friend's house and looked in the book Invertebrates 2nd Ed. by Brusca and Brusca where I found the same soft-bodied trilobite image (one I sadly cannot find online). Well, I had to know more.

I was sure that there were no trilobite fossils in the Ediacaran, so I have had another look through Clarkson and found both a reference to a paper and the mention that several fossils had been found resembling trilobites and with several stages of growth. Thankfully Clarkson states that further evidence is needed to assess whether it is a trilobite ancestor. I am a bit busy so I cannot research it into much depth, but what I have found suggests that these fossils are unnamed and simply labelled "soft-bodied trilobite" wherever mentioned. I cannot find a link to the paper mentioned in Clarkson online, but here is the reference:

Jenkins, R.J.F. (1992) Functional and ecological aspects of Ediacaran assemblages, in Origin and Early Evolution of the Metazoa (eds J.H. Lipps and P.W. Signor). Plenum Press, New York and London, pp. 131-176.

The "soft-bodied trilobite" is thought to resemble the Redlichiida (a group of early trilobites) yet has affinities with other Ediacaran forms such as Archaeaspinus (left), Dickinsonia and Vendia which are not thought to be connected to the arthropods.

Claims of putative Ediacaran arthropods are not uncommon, though scrutiny tends to find that either that interpretation meets some difficulties or that there is not enough evidence available. They are almost always connected with the trilobites when claimed as protoarthropods. Among them is Spriggina (right), though its symmetry is not strictly bilateral like that of arthropods as the two sides are offset. I have previously discussed Bomakellia. Others include Marywadea and Parvancorina. The latter is a very interesting one as it may indeed be connected to the arthropods.

Parvancorina  is perhaps too primitive in body plan to be considered arthropodan. There are fine lines on some specimens which have been interpreted by some researchers as paired limbs, but without this data a connection is tentative at best. The biggest issue with identifying an ancestor is the lack of leg preservation (this does not mean they lacked jointed legs, as trilobite fossils rarely have them too). Parvancorina  is thought to resemble the Cambrian arthropod Primicaris, which in turn is thought to resemble a Cambrian trilobite protaspid (the early stage of trilobite growth in which there are no segments) suggesting that heterochrony (changes in developmental timing) may have played a large part in early arthropod evolution (though it should be noted that the growth of Parvancorina is different to that of arthropods).

The earliest known trilobites are Eofallotaspis (left) and Protofallotaspis. Both are fully formed trilobites, though there are Cambrian arthropods such as Skania  and the aforementioned Primicaris  which may even be intermediate forms. Below is an image showing a potential evolutionary sequence from Parvancorina through to an early trilobite:

 On the left is Parvancorina, unsegmented and showing simple metamorphosis (each branch is demonstrating ontogeny). Next is Primicaris showing incipient cephalisation. Naraoia comes next, with complete cephalisation and a still unsegmented body. Then we see Kuamaia  (a helmetid) which shows a clear division between cephalon, thorax and pygidium. Finally there is Redlichia  which has additional trilobite features. This image is not a case of simply lining up fossils and hoping they fit together in a sequence; it is based off of trilobite ontogeny and makes a strong case for Parvancorinomorphs being a basal clade of the arthropods. 

What was intended to be a bit of a rant about Precambrian soft-bodied trilobites instead taught me a fair bit about the origins of arthropods, which is a good way to end the day I think.

Progression in America?

This is not a usual topic for me, but I could not help myself. America has its first Arab-American Miss USA in the beautiful form of Rima Fakih, she also happens to have a Muslim background. 

You can read all about it here. Interestingly she also entered a pole dancing competition three years ago. 

More Evidence for CD Theory

I would expect that everyone has heard about the new species found in Indonesia. What you may not have realised is that the "Pinocchio-nosed frog" is sufficiently hilarious to provide yet more evidence for CD Theory, which I presented in my second ever blog.

The Evolution of Form and Function - The Testing of a Hypothesis

I've been a fan of Sean Carroll's work for a while now and thoroughly recommend his book Endless Forms Most Beautiful  to anyone who wants to understand the evolution of form (something I am very interested in). In it he elucidates the science of evo-devo and how form such as limbs and patterns can evolve. It is not surprising that the evolution of morphology attracts the interest of palaeontologists, of which I recommend the work of Neil Shubin. Carroll's second book The Making of the Fittest is also a great read (easier than the first) though it is the evolution of form that I am discussing now.

In 2005 Sean Carroll hypothesised that changes in morphology (outward appearance) were due to changes in gene regulation, whereas physiological changes (the inner workings) were due to changes in protein structure and function. This hypothesis was initially controversial and was recently investigated by a team from the University of Michigan. The genetic analyses strongly support Carroll's hypothesis. They identified 900 "morphogenes" which affected only morphology and around 900 "physiogenes" affecting physiology. Morphogenes were found to carry instructions for transcription, whereas physiogenes were often blueprints for enzymes, receptors, transporters and ion channels. When these genes were analysed to determine evolutionary rates. Physiogenes were found to evolve quicker at the protein sequence level, whereas morphogenes evolved quicker with respect to changes in expression.

This is great insight both for evolutionary biology and for the study of genetic processes in human disease. For more info: http://www.physorg.com/news189697308.html

Creationists Proving Evolution?

I found this article on the Panda's Thumb blog and found it incredibly amusing and ironic. Creationists have their own system for categorising organisms into Biblical "kinds" (a term which is essentially meaningless) called Baraminology. What has amused me is that creationists are disagreeing over how to classify many of the hominin fossils we have. They have even divided up the australopithecines into a separate group and into the Homo  group. That they cannot put these species into easily divided categories is testament to evolution. Check out the blog article.

Evolving Passions

I've been told that doing a course in palaeontology means I will end up changing my mind several times about what I would like to study. This is a brief run through the different things I have wanted to study within palaeontology over the years.

When I was young it was unsurprisingly dinosaurs which got me interested in palaeontology. I was an absolute dino-nut. I wouldn't even pay attention to pterosaurs, plesiosaurs, ichthyosaurs and mosasaurs because they weren't dinosaurs and used to cringe when people called things like Dimetrodon  a dinosaur. Even the gigantic mammals of the Cenozoic did not do it for me. I think dinosaurs had something exotic about them; they were unusual creatures, but not too unfamiliar. As far as I remember, I had three favourite dinosaurs. On the left is Deinonychus which I possibly discovered properly just after being scared by the Velociraptor  scene in Jurassic Park. That kitchen scene is still one of my favourites. I fell in love with all dromaeosaurs and probably would have been very happy studying those.

Another favourite among the theropods was Allosaurus. I was never a big fan of T-rex, possibly just because every kid knows what T-rex was. I probably wanted to be different and not just favour it, yet I was also drawn in by the large theropods. Thankfully this is no longer my passion. I still absolutely adore these creatures, but dinosaur palaeontology is a very competitive field, even more so when you look at the popular theropods.

 The third of my favourites was a stegosaur. I don't remember the exact reasons I fell in love with this one, but it is Tuojiangosaurus (try saying that when you are drunk). Again, I have no desire to study these beasts any more, despite the fact that I fell in love with palaeontology because of them.

Over the last few years I have been learning about the theory of evolution, which reignited my passion for palaeontology. I knew that I wanted to study evolution in organisms I liked. My favourite transitions included fish to amphibians and dinosaurs to birds. I would have loved to study things like Tiktaalik  or take a look at the famous Archaeopteryx  specimens (I still would, but don't mind if it is not for academic reasons). My favourite though is the early evolution of mammals, possibly the most beautiful transition I can think of.

So, I started my course wanting to study evolution and it was the vertebrates which really drew me in. I probably couldn't foresee any change to this even though I knew it would be a difficult area to break into. At one point I was asked by my tutor what my favourite invertebrate fossils were and I quickly answered "trilobites" without giving it much thought (the one on the right is Ctenopyge). I then started wondering if I would enjoy studying something other than vertebrates, with trilobites being the favourite of course. The answer seemed to be yes. I had gone from dinosaurs, to vertebrate evolution, to trilobites. Fortunately trilobites did evolve and are excellent for studying evolution (though all palaeontology is concerned with evolution anyway).

Since then it has taken yet another twist. I have become fascinated with organisms which came before chordates arrived on the scene (at least from what we see in the fossils) and before even trilobites (though occasionally people think they have found proto-arthropods and compare them to the trilobites). Early metazoan evolution is what is currently fascinating meaning that I have started liking the enigmatic Ediacaran fossils along with the small shelly fossils (SSFs). I like the Cambrian explosion too, but it is what came before that which fascinates me. I remember the first time I saw the Ediacaran fauna and the SSFs; I thought the former were interesting to know about but boring to study and the latter looked rather dull.


I am at the end of the first year now, I have had all of my lectures until September. I wonder what else I will become fascinated with. There are aspects of palaeontology that I find dull, but I know that can change (I recently said gastropods were boring and taphonomy has never thrilled me). I've gone from dinosaurs to vertebrate evolution, to trilobites, to early metazoa, where next?  I know I will always be drawn to evolution, for which I can study almost any group of organisms in the fossil record (invertebrates being the best). I've also been getting interested in the palaeoecology of the Zechstein sea, though that is likely just a personal thing on the side. Where next? We shall see....

Geological History of Britain

At the moment this is one of my favourite subjects. I started to find it fascinating when I discovered that I lived near rocks of the Zechstein basin and wanted to know more about the history of my area. At uni we have also recently been studying this coincidentally (I have a test in it this afternoon). For revision I am listening to this excellent radio programme:

http://www.bbc.co.uk/iplayer/episode/b00n8t48/In_Our_Time_The_Geological_Formation_of_Britain/

I recommend it so far. My favourite quote has been "Britain is like a geological Dr Who".

Ammonites versus Trilobites: Icons of Palaeontology

It sounds like I am pitching a dodgy "monster" movie, though I feel such a film would not be too interesting for anyone but palaeontologists and marine biologists. Instead, I was thinking about which fossil group best symbolises palaeontology. Obviously dinosaurs are a popular choice, but really they make up a tiny but popular part of palaeontology. Both ammonites and trilobites are excellent choices as icons of palaeontology.

Ammonites are a superb choice as they are instantly recognisable and perhaps some of the easiest to draw as well. If I said "curly-wurly fossils" it is likely that most would know what I meant. They are also extremely useful in palaeontology, being used as zone fossils in biostratigraphy and helping us reconstruct what the Earth was like in the past. For more, see here. They are often used as the symbol for palaeontological and geological groups and societies. The Earth Soc at uni hand out a golden ammonite trophy for the winner of occasional events, the losing team gets a golden coprolite.

Trilobites are just as iconic and recognisable, but not as easy to draw. Many of their uses are the same as ammonites and for a full overview I recommend Trilobite  by Richard Fortey.

A brief search of "palaeontology" on google shows how iconic these two groups are. The Palaeontological Society uses both of them, with an ammonite at the top on the tab, though the main logo has a beautiful trilobite:

The Palaeobiology and Biodiversity Research Group from Bristol university seems to make use of both ammonites and dinosaurs on their web page: http://palaeo.gly.bris.ac.uk/

The Paleontology Portal makes excellent use of the
ammonite shell. The Paleontology Society have a variety of things in their logo, but note that a trilobite is most prominent:

I honestly can't decide which is a better icon, both are worthy competitors.

Pterosaur Sex

I recently was shown some porn in which a woman was having sex with three pterodactyls. As pterodactyls are extinct, they were of course men in costumes. They even flapped. This post is not about that, sorry to get your hopes up. Today I attended a guest lecture by David Unwin, one of the world's premier pterosaur experts, from Leicester University. I would love to give a run through of everything he talked about, but I do not have his knowledge and did not take any notes; everything I write here is from memory and will be a brief summation (with chunks potentially missing).

Until recently not much was known about sex in pterosaurs, or their ontogeny. Everything was speculation, a lot still is, and many of their habits were simply taken from birds. The media tended to portray pterosaurs as having nests which they return to and feed assorted live food to the young. A lot has changed since then.

Pterosaurs have been found to be sexually dimorphic, meaning the male and female have different appearances. This is very common, particularly among birds, but demonstrating it is not always easy. A variety of crest forms are found on pterosaurs, even among the same species, which supports the idea of sexual dimorphism. They were also used for display, which is suggested by the fact that there are a range of crest morphologies; natural selection would lead to more consistency. The clincher for sexual dimorphism came with the analysis of the pelvis, as the female had a larger opening for the egg to come out of, unsurprisingly they had shorter crests.

Until 2004 it was not actually known whether pterosaurs laid eggs or whether they were viviparous. In that year 3 embryo fossils were found. They were all contained in eggs, confirming oviparity for pterosaurs, but what is most interesting is their structure. Pterosaur eggs had soft shells, not the hard shells we are more familiar with from birds and dinosaurs. They also appear to have had some hard parts, but not many. This suggests that they did not incubate their young but instead buried them in the ground where they could absorb water. This is a useful trade off, as pterosaurs needed to be very light in order to fly.

The embryos also showed that pterosaurs emerge almost as fully formed pterosaurs, albeit smaller and not sexually mature. The ratios of their wingspan to other body parts fall in the range of fully grown pterosaurs and suggest that they could fly soon after they hatched. Analyses of pterosaurs at various stages of development also show that they grew slowly and possibly never stopped growing, though it did slow down in later life.

Well, that is all I remember. It was a good guest lecture and it seems I absorbed a decent amount of it.

Today's Critter: Dielasma

Today my tutor lent me the book Zechstein Reef Fossils and Their Palaeoecology  by Hollingworth and Pettigrew, so expect more post about the Zechstein in future. Sadly it only covers an area way up near Middlesbrough, but it does give a lot of insight into my own locality (Ashfield brick-clay pit). I'm going to see if I can order it online as it is a useful and potentially cheap resource. It contains some decent information on the different fossils, so I thought I would start with the easiest I identified from Conisbrough and add the info from the book. Here is Dielasma elongatum, a Permian brachiopod which was abundant in the Zechstein:

The brachiopods pictured are bigger than most of the ones I found, which can be seen below:

Many which I found appear to be juveniles or smaller individuals, perhaps suggesting a high infant mortality rate. It may also suggest that the substrate was not firm or that there was crowding and therefore increased competition. The Dielasma specimen in the book is five times bigger than my smallest and around twice the size of my largest. Although I haven't compared yet, this seems to be true of the bivalves I have as well. This would seem to support the idea that there was crowding, though perhaps this did also affect infant mortality.

I won't list the taxonomic details from the book, as those change often and the book was published in the late 80s. For any interested, the description given is:

Shell is oval in outline, pedicle and brachial valves convex, pedicle valve with broad shallow sulcus and brachial valve with corresponding broad fold. Ornament of fine growth lamellae.

Dielasma  was an epifaunal suspension feeder, meaning that it lived on the sea floor (as opposed to within it) and sifted out its food from the water (using an appendage known as a lophophore). They are the ultimate couch potatoes of the sea. They had a thick, fully functional pedicle, which is the bit which attaches to the substrate so that the brachiopod stays put (also indicating that it is epifaunal; without it would suggest it was part of the infauna). The pedicle may have divided into rootlets to give an even stronger hold. Dielasma are often found as nests and with a wide range in size. 

It would be interesting to find Dielasma attached to other organisms, such as a bryozoan reef, as this sort of thing often happened. Many fossils have little brachiopods attached to them, particularly sponges, even way back in the Cambrian. 

How to spot a palaeontologist.

Realistically you can't most of the time. Palaeontologists come from many walks of life. Out in the field is a different story though. Overall there are some stereotypes and some consistencies as they all use similar techniques and equipment. There are also sort of two types of palaeontologist. There is the typical field palaeontologist type who is constantly out digging up fossils and there is the armchair palaeontologist who prefers the research and academia side of things. In reality nobody really fits either of these fully as all professional field palaeontologists get involved with academia and all academic palaeontologists do field work from time to time.

This passage comes from Phil Manning's book Grave Secrets of Dinosaurs:

I saw a tall figure, with a rucksack and the signature paleontologist field hat, walking toward the Society buildings down Water Place. As the figure drew nearer, I knew he had to be Tyler. Dozens of people had passed in the last half hour, and none looked like they belonged in the field. As he entered the building, I instinctively walked over to greet him. As Tyler and I shook hands, he asked how I knew it was him, and I said it was obvious. "You look like a field paleontologist!"

Bob Bakker is a stereotypical palaeontologist in many ways, even wearing the sort of hat that would be expected, but the majority of palaeontology does not take place in areas like the Badlands of America. The most common head-wear for palaeontologists is probably the standard hard hat. Rock exposures are obviously where fossils are most likely to be found and this often involves going to cliff faces and quarries. A hard hat is essential, especially if trying to rescue a fossil in situ. 

I like to think Bakker's beard is another part of the typical palaeontologist, but sadly that isn't true. I've recently grown a beard and like to claim that it is "the palaeontologist look" but really there is no palaeontologist look (and the majority on my course are actually girls ). 

One thing that we are constantly told on my course is that palaeontologists will always have a hand lens close by. Over on the right is actually a picture of yours truly, sporting my hard hat. Round my neck I have the obligatory hand lens dangling. There are a few pieces of equipment we carry on field trips. The geological hammer is the most satisfying, though many will also carry chisels and even picks. Note pads and clipboards may not sound like the stuff of rugged outdoors-men, but they are essential. This also means carrying colouring pencils a lot, despite the fact that we like to claim that all geographers do is colouring in (we do extreme colouring in). Among other bits of useful equipment includes a compass clinometer, GPS devices, plastic bags for specimens, safety specs, tape measure, pen knife, camera and more. 

Clothing is not always predictable except that it must suit the weather. I have actually noticed that palaeontologists do have a habit of wearing palaeontology themed t-shirts (even trainers if you are some kind of awesome). Jeans are not recommended in the field, but not everyone follows that. The only thing I can really state would be worn are proper boots with steel toe caps. 

So apart from the rare stereotypical field palaeontologist with his hat and beard, it seems they are just like you and me (me especially). There may be behavioural clues though. If a person is carrying fossils around that might be a give away, or try talking loudly about dinosaurs and see if they offer their opinion; I'm shy and even I struggle to resist that. If outdoors you might see them staring intently at the rocks, though they may just be your average geologist (you know, the sort you see all the time...). If they look at the floor a lot then they may be after fossils, it is much easier to pick them up off the ground than to chisel them out of the rock face. I'll end with a picture of someone staring at the rocks, me again:

Well, this was quite a random post.

Cake!

I must say, I am a little jealous of this birthday cake that one of my teachers from last year has got:

Mapping at Lulworth Cove

I've just had two tiring days in Dorset doing a mapping exercise with university, for which I will say very little. Instead I will share the few pictures I managed to take today. After seeing the beautiful views yesterday I decided it would be worthwhile to take along a camera, only to find that my batteries ran out very soon into the trip. Others took pictures, so hopefully I will be able to get some off of them.

Above is part of stair hole where the Purbeck beds can clearly be seen on the left, showing a large amount of folding. Within the Cretaceous Purbeck beds were rocks known as the Cinder beds which are often used to mark the boundary between the Jurassic and Cretaceous, though in actuality the boundary is a little lower.

Above, though you may need to zoom, can be seen Lulworth Cove as seen from Stair Hole. Not much of the bedding can be seen from this view, though over on the right the bedding of the Purbeck beds is again quite obvious.

This is the view looking over to Durdle Door, which also continues the Purbeck beds and rocks of the Portland group (Jurassic). In the foreground are a mixture of first year geology students with palaeobiology students. The weather wasn't brilliant at the start of the day, with some slight rain, though in all it was pleasant. From here the extent of the chalk can almost be seen over on the right.

I really like this picture, showing a friend of mine caught eating, not looking very flattering. If I remember correctly these rocks are part of the Wealden group and the interesting looking yellow stuff is jaresite which has leached out of the rocks. Rain will easily wash this away from time to time.

This is my tutor sitting halfway up the Portland group beds. He is gesturing towards a very large ammonite in situ. This particular ammonite is Titanites  and is used as an index fossil for the Tithonian during the Jurassic. Specimens of Titanites can be rather large and very impressive. See below for a picture of another in situ.

Today's Critter: Bomakellia

Today I spent most of my time looking at Cretaceous rocks, so it would not be surprising if I said this critter was Cretaceous. It wasn't. Not even close. Bomakellia kelleri is another fascinating fossil of the Ediacaran fauna, dated to 555 million years old. It is known only from this 9cm long specimen:

It was originally classified as a potential arthropod, possibly even a primitive trilobite or anomalocarid. If it had arthropod affinities then it was certainly primitive. The possible semicircular cephalon and tri-lobed appearance may link it to trilobites, though it does not have segmented limbs or antennae (which may be due to its primitive nature or due to preservation as these parts often do not fossilise in trilobites). Trilobites also have gills on the body, which Bomakellia may be sporting, though this has been a possible connection with the anomalocarids. Below is a reconstruction which fits with the arthropod interpretation:

More recently, as with many of the Ediacaran fauna, it has been interpreted as a possible rangeomorph. The most famous rangeomorph is perhaps Charnia. Rangeomorphs have a frond like structure and were possibly colonial animals, attaching themselves to the sea floor by a hold-fast (interpreted as the head when classed as a proto-arthropod). Spriggina is another Ediacaran organism which has been seen as both a possible arthropod with trilobite affinities and a rangeomorph. Below is Bomakellia reconstructed as a rangeomorph:

Abiogenesis and Eve

For scientists studying the origin of life (abiogenesis) one of the biggest mysteries involves something called chirality. Amino acids have both a left and right handed form (enantiomers) yet the amino acids used in organisms are all left handed. Most mixtures are racemic, meaning they contain even number of left and right handed amino acids; something in the ancient Earth caused the mixtures of amino acids to be non-racemic, leaving its signature on all life since. A recent study into the effects of temperature and other conditions on the formation of amino acid crystals has demonstrated that possible early Earth conditions could easily produce left handed crystals in high numbers. The aspartic acid used has been dubbed the "ancestral Eve crystal" as it may have been the trigger for all other amino acids being left handed: http://www.sciencedaily.com/releases/2010/04/100421121501.htm

Allopatric Speciation Unimportant?

For quite some time it was believed that geographical isolation was the key to speciation, even when other models were gaining ground it was still considered to be the most prevalent occurrence. A recent study set out to test the importance of geographical isolation in an ideal situation. In Martinique scientists have genetically tested lizards separated by around 8 Ma of isolation to find that they have not evolved into separate species. The study also provided the opportunity to compare populations which are not separated geographically but inhabit separate ecological conditions. There was more genetic isolation between the ecologically separate lizards than the geographically separated lizards.

This is being claimed as a blow against allopatric speciation, however, it seems more to be a blow against the role of genetic drift in speciation. With geographical isolation selection pressures may differ or may remain the same. If the habitat is similar and doesn't change then only drift may drive speciation, which it seems does not occur. The study shows clearly that ecological factors are the most effective, which is what is found when natural selection drives speciation. Mere geographical isolation alone is not enough, but when it means a change in habitat it seems as though speciation is almost inevitable.

http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1000929

New End-Ediacaran Species From 2009

This is Cloudina carinata which has been discovered in Spain and is an important fossil for understanding the evolution of skeletons. Unusually for such old fossils they have retained their three dimensional structure. They show evidence of asexual reproduction and are one of the oldest examples of reproduction in animals in the fossil record. It is still not known what Cloudina is and it has been compared to cnidarians and annelids.

Cloudinids are quite fascinating small shelly fossils. They are most often found near stromatolites, suggesting that they inhabited shallow waters and are never found in the same layers as the soft bodied Ediacaran fossils, even though there are deposits where they alternate, suggesting that they inhabited separate ecosystems. Seilacher suggested that they lived in microbial mats and that they built up their tubes in response to sedimentation, needing to grow in order to stay above. Their shells often show signs of predation and there are signs of budding, suggesting a colonial existence. They remain some of the most mysterious yet important fossils found.

The article can be found here:
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VBP-4XMD5PG-1&_user=10&_coverDate=01/31/2010&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=938a1343dd293215c55044478440d617

Fossil Feathers - Similicaudipteryx

I'm going to claim this as my critter for today even though it has been gaining attention for other reasons. This is Similicaudipteryx which is roughly 125 Ma old and was found, predictably for a feathered dinosaur, in China. Although it is a theropod it appears to be a herbivore, with robust jaws and buck teeth. The two fossils found are of a juvenile and an older specimen, allowing the ontogeny to be compared. 

What is surprising is that the feathers differ markedly between the two. This is not too unusual, considering birds go through two stages of change in feather type, from downy feathers in youth to adult plumage. The juvenile displays ribbon-like feathers mixed with down, whereas the older dinosaur displays longer quills and down. It is thought that feathered dinosaurs start with only down for insulation, meaning these dinosaurs may have gone through three stages. 

The ribbon feathers of the juvenile are even more perplexing as they superficially resemble display feathers, such as those found in birds of paradise. They would have provided no benefit for insulation, and ornamental features normally appear during sexual maturity. What use is display in a sexually immature juvenile? The authors of the paper appear to overlook the possibility of it being used as a visual deterrent to larger predators, though why they are not retained in adulthood would be baffling.

These unique feathers have been lost in time, they only superficially resemble display feathers. It seems that the dinosaurs had a greater diversity of feathers than modern birds. Perhaps there was more flexibility in the development of early feathers allowing for a greater diversity which was later cut down and channelled. 

The paper can be found here: http://www.nature.com/nature/journal/v464/n7293/full/nature08965.html

One of the best tattoos I may have ever seen....

Even if you don't like dinosaurs, you have to admit, this tattoo is awesome. If you do happen to like dinosaurs, especially raptors, then you may even want this on your own arm:

The Natural History Museum

Today, for the first time since my childhood, I visited the Natural History Museum in London with the Earth Soc. I won't say much about it, if you want to know more then visit it, you will not regret it. I also recommend the book Dry Store Room No. 1 by Richard Fortey and the recent BBC series Museum of Life. I want to live there. The architecture is phenomenal, resembling a cathedral in many ways, Richard Owen likely did see it as a place to worship the work of the Creator after all. I understand why Darwin takes centre stage, but it is a shame that Richard Owen is tucked away, hidden from the main hall, considering his role in the museum's history.

I need to go back again as I did not have the time to see it all. I went on the behind the scenes tour of the spirit collection which was fascinating. I visited the mammal section where there seemed to be a model of a whale with Down's syndrome. I wasn't too impressed with the cocoon, it seemed like an attempt to be really hi-tech. We spent quite a lot of time in the dinosaur section, admiring the gorgeous dromaeosaurs, the allosaur skeleton, and even an old favourite of mine Tuojiangosaurus (toe-wang-uh-saw-us). For some odd reason we decided to search for the Archaeopteryx lithographica specimen, despite knowing that it was a cast and that the university has casts of it which we see every day. We dawdled in the mineralogy section (which sent us a bit nerdy). Then we rushed through many galleries, attempting to admire Mesozoic marine reptiles whilst practically running, pausing to quickly ogle trilobites and pose next to a big chunk of haematite, until eventually we looked at the cast for about 10 seconds then left for the gift shop. Some day I shall return and dawdle around these sections.

This has been a bit of a ramble, I don't intend to describe my entire visit, everyone should have their own experience of the place. Go! Now!