Monthly Archives: December 2012

Further thoughts on Retallack’s terrestrial lichen hypothesis…

Last night I addressed the claims of Gregory Retallack from a recent publication in Naturesee here for my criticisms. As I was critiquing his claims I did not go into detail on some of the issues which I think it does raise. One is the nature of the Ediacaran biota, the other is the nature of scientific debate as perceived by the public.

On Ediacarans…

The Ediacaran biota really are the most mysterious in the fossil record. Whether you are looking at the frond-like Charnia, or the oval shaped Dickinsonia, or even Spriggina, which at first glance appears to have a head, you’re in for a lot of difficulty working out just what they were. There are so many questions which remain difficult to answer. Are they animals? Or are they “almost” animals? Are they more like fungi or lichens? Are they actually single celled organisms? Can they even fit into a known group or are they some unique evolutionary experiment? All of these have been suggested at some point. Do they all group together as more closely related to each other than to other groups? Or are they from many diverse groups, some of which are familiar to us? Again, the answers remain elusive.

Not only is working out relationships fraught with difficulty, but mode of life can be confusing too. Their ecosystem was very different to anything we have today. We cannot infer modes of life through phylogeny if we cannot discern their relationships. One palaeontologist will see an organism which might have been swimming or crawling around, whilst another sees it as sessile, absorbing nutrients passively. Spriggina is an excellent example, as many see it as some sort of proto-arthropod, yet its “head” has also been interpreted as a hold-fast as though it is a frond.

Spriggina fossil along with two reconstructions, one of which depicts it as a frond. Picture credit: Jack Unruh

Original ideas should definitely be welcomed, they can help us ask all sorts of questions which we might have overlooked, shedding more light on the nature of these fascinating organisms. Retallack did that when he first proposed that they might be lichens, back in 1994, but that is an explanation which has been assessed and found wanting. But this time he brings another novel idea: could the Ediacaran organisms have lived on land?

Terrestrial Ediacarans is an intriguing idea (except that they are not found in terrestrial deposits, contrary to Retallack’s claims). We very well could find something of the same age which is beyond microbial grade and inhabited the land. They could even be well known Ediacaran forms, for who are we to say that they could not have lived on land and in the sea? Modern organisms often tolerate a narrow range of environments, but we cannot claim the same for the past, not least because evolution often functions by an increase in generalists which later become specialists (this happens at all levels, from genes to species). We don’t know where Ediacarans fit onto the tree of life, so we cannot make a phylogenetic case against it. But without any evidence it is merely wild speculation; a nice idea, but not science unless you can back it. Retallack has tried. Retallack has failed.

In coming blog posts I will be exploring some of the weird and wonderful ideas regarding Ediacarans, of which Dickinsonia will be a focus as it seems to have been wedged into nearly every possible group at some point or another. Some of Retallack’s ideas will be presented, but they are not accepted and for good reason. (On a rather random note, check this out.)

Ciavatti 2008 apparently

Even though I think it is nonsense, I do like seeing reconstructions of Dickinsonia swimming and showing off its internal organs.

On Science…

There is, quite naturally, going to be a big response to Retallack. If he had published in a smaller journal as he has done in the past, then there would be less of a response (just the standard criticism), but he has published in what is meant to be one of the biggest journals and it is getting a lot of publicity, which sadly seems to happen often in palaeontology (Chatterjee’s bizarre views about large pterosaurs, for example, see here and here). Martin Brasier is reported to have said that he finds “Retallack’s observations dubious, and his arguments poor. That this was published by Nature is beyond my understanding.”

My biggest worry here is that people will mistakenly think that Retallack has a good case and that any resistance is because you mustn’t challenge scientific dogma. What it really shows is that if you are challenging a view which is supported by a lot of evidence, such as the marine environment of Ediacaran organisms, then you need to make a very compelling case. The response is because he has failed to do that. It also highlights that sometimes a good idea is wrong and that you need to accept it and move on (in rare cases sticking to your guns is a good thing, but not if you ignore contradictory evidence). Retallack’s lichen hypothesis never gained a following for good reasons; it was given a fair hearing and just did not stand up to scrutiny (on a related note, such ancient lichens are known and they do resemble lichens).

The public often sees debate as a bad thing for science. Many will no doubt see this as some form of bullying, as though Retallack is a heroic crusader, fighting a dragon called Dogma, guarded by those black knights of the scientific establishment. But really he is bashing a mop against the walls of a castle in an attempt to lay siege, even though the drawbridge has been lowered, the portcullis raised, and there is even a place at the table for him to eat.

Let’s end with some foliose lichen:

No.

Dickinsonia? Is that you?

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Lichen Controversy in the Land of Ediacara

Imagine that you have been transported back around 550 million years to what is now Australia. The first thing you notice is how cold it is, as the frost on the ground crunches under your feet. The place is eerily silent but for the wind, with no birds in the air, no animals grazing or even wandering, just the sound of your own footsteps echoing around. It is a barren landscape, one which has not been touched by life. But then you start to notice some unusual colours on the ground, small patches which do not blend into the crunchy soil. As you bend down to examine them more closely you start to notice that there are different types of patches, they even look quite familiar. Then you realise: this land is not waiting for life to invade, it already has invaded. Those colourful patches are lichens, and they are wonderfully diverse.

That, at least, is the picture which Gregory Retallack has controversially put forward in a new paper in NatureHe effectively makes three grand claims: he interprets the Ediacaran organisms as lichens; he purports to have shown that the environment of deposition was terrestrial, not marine as previously thought; and that this provides a trigger for the Cambrian Explosion. The implications are that the Ediacaran organisms could not have been animal ancestors and that life was more diverse on land before it became diverse in the sea. I’m all for unusual ideas, particularly with such enigmatic organisms, but does he have the data to support him? Do his claims warrant a paper in a journal which is meant to be one of the best?

*Disclaimer* I currently don’t have access to the paper in question, so I may make claims which Retallack has addressed in his publication. 

[Edit 14/12/12. When I wrote this post I had not seen the Retallack paper, which it turns out is in the Letters section of Nature, nor had I seen the response by Xiao and Knauth. I now have copies of those in my possession, so the article will be tweaked. I’ll try to make sure that it is obvious what I have added.]

Dickinsonia fossils, interpreted by Retallack as lichens.

Are they lichens?

Considering how confusing the Ediacaran fossils can be, recasting them as lichens is an imaginative approach which is worth looking at. Except that it isn’t new, but has been pushed by Retallack since the 90s (Retallack 1994) and dismissed by Ediacaran workers. His original claims focussed mostly on the preservation of the organisms, interpreting the lack of compaction as being due to them having  a chitinous structure, and he expanded on those ideas when he focussed on Dickinsonia, claiming that their growth and decay could also be explained by them being lichens (Retallack 2007). This possible rigid structure was also key in Adolph Seilacher’s interpretations of the Ediacaran organisms as a separate kingdom (or phylum, depending on which papers you read) and later as xenophyophoran protists. Brasier and Antcliffe (2008) noted that contraction zones in Dickinsonia fossils are suggestive that the organisms were elastic and not rigid. Waggoner (1995) pointed out that there are Ediacaran age deposits which contain organic remains and are in the same lithologies as Ediacaran macrofossils, yet they are not found together, unlike with logs preserved in sandstone (which Retallack used to make his case). This would mean that the Ediacaran lichens possessed a rigid biopolymer which resisted compaction but then disappeared without a trace, which of course is problematic. Additionally, Retallack had made the assumption that the sediments above and below the organism were the same, yet the fossiliferous sandstones are often overlying thin clay beds, allowing for an impression of a soft organism to be made.

Retallack claims that Dickinsonia displays indeterminate growth and that this has more in common with lichens and a few other groups than it does with animals. Dickinsonia grew by adding new isomers to the “back” end and by expanding existing isomers, with the prevalence of each process varying with age; through ontogeny the new isomers are added at a slower rate (Sperling and Vinther 2010). How this structure (which Retallack sees as bilateral) fits with lichens is not made clear, let alone the growth pattern. Has he overlooked this? Or have I missed something in his claims?

Image by Aleksey Nagovitsyn, pilfered from Wikipedia.

There is a relatively simple point to make against Retallack’s lichen hypothesis: there is evidence of movement in some Ediacaran organisms. Dickinsonia and similar forms have been found with traces which have been interpreted as showing that they absorbed the microbial mat and then moved (whether they actively or passively moved is irrelevant here, as both would cause problems for a lichen interpretation). Under the lichen interpretation these must be seen as either lichens in different states of decay, or in fairy-ring arrangements, yet many overlap and match the body fossil which accompanies them. Kimberella is also considered by Retallack to be a lichen, despite its much more clear bilateral symmetry, and claims to have an explanation for the trace fossils associated with it. Many specimens of Kimberella are accompanied by Radulichnus trace fossils which show that it fed by rasping at microbial mats. Under Retallack’s idiosyncratic interpretation these are no animal traces, but the moulds of needle ice, thereby showing that the ground sometimes froze [Edit: even though they are arranged in a pattern which cannot be explained by needle ice formation]. I’m really not sure where he gets that idea from, as it just seems a bit desperate.

At least one of the fossils, Charniodiscus, is also found in environmental settings which lichens could not tolerate but we will get to that information shortly. Retallack also claimed that the variability of thickness in Dickinsonia specimens was evidence of decay before burial and that this decay had more in common with the wilting of a leaf, lichen, or mushroom, yet it may also be explained by compaction or of smothering by mats. The majority of Retallack’s claimed evidence for lichen affinities have alternative explanations and he appears to practically ignore some lines of data. As Guy Narbonne said: “Most of us appreciated that Retallack’s lichen hypothesis was innovative thinking and tested his ideas critically, but it quickly became clear that there are simpler explanations for the features Retallack had validly noted, and most of us moved on to more promising explanations.” His lichen claim cannot be supported, but that is only one of his claims…

Were they deposited in a terrestrial environment?

Retallack’s real controversial claim is that these organisms were living on land, long before conventional wisdom would put organisms in terrestrial environments. He has presented several arguments using “state-of-the-art” techniques (according to the press releases) in order to make this particular claim. Yet again it seems that his evidence has other explanations which are consistent with the majority view. This is where I may fall short, as I am not overly familiar with the sedimentology of the sites in question, it was never my strong suit at university, and I can’t yet access his paper, but there are some points which I think are worth making.

The first thing which springs to mind when the environment of deposition is brought up is that there are wave ripples and cross stratification, indicative of a shallow marine environment. Retallack’s response? He invokes floods or lakes to explain these features which have clearly been formed due to water action. What about dessication cracks, where are those? I am wondering if Retallack explains their absence by invoking floods too. [Edited addition: I’m not sure exactly where to stick this in, but I thought it was worth repeating. Xiao’s response mentions that there are organisms with holdfasts which show signs of having been dragged by waves or currents, not possible in a terrestrial environment.]

One of his main supporting arguments is that the rocks are red, indicative of a terrestrial weathering pattern. But this is not a problem for marine deposition, not least because weathering can go on after the rocks have formed. The chemical analyses he used to show that they were palaeosols are apparently easily contaminated by more recent weathering and his claim that the angular, interlocking nature of the sand grains which he claims shows that they were wind-blown does not negate a near-shore origin (sand grains are often transported for miles before eventual deposition). Most of his argument does depend on demonstrating that palaeosols are present, but from what I can tell he does not achieve this. [Edited addition: he notes that the red beds are often underneath beds of different colouration and considers this to be evidence that they were red when deposited. Rocks weather at different rates dependent on their composition, so this is not a surprise.]

In addition to addressing the sedimentology of the Ediacara Hills, there are other localities in which these fossils can be found, and Retallack’s explanations have to account for those too (particularly the White Sea deposits in Russia). Charniodiscus is amongst those labelled as lichens in his study, yet they are also found in the Mistaken Point deposits, which are deep marine, way below the photic zone which lichens require and notably not on land (Retallack thinks that these need re-evaluating).

In Conclusion

When it comes to a period of time so mysterious as the Ediacaran it is good to have some unusual ideas, especially if they can potentially give insight into the Cambrian Explosion (I haven’t properly discussed that here, as it is irrelevant if Retallack’s classifications are wrong). If you are going to make such an unusual claim then you need some compelling evidence, but it seems that Retallack has not managed to provide that, so his publication in a top journal is bizarre to say the least. His claim for lichen affinities in Ediacaran biota has been assessed and found wanting since he first proposed them. His new claim, that the environment of deposition was terrestrial, appears to be based on flimsy interpretations, presenting no data which refute a marine environment. It has been described as ambiguous, and I concur. It seems to me that Retallack has gotten too ahead of himself, as I am sure many of us would if we thought we had cracked two of the biggest mysteries of the fossil record. We’ll continue to scratch our heads over the biological affinities of Ediacaran organisms, we’ll continue to be puzzled by potential causes of the Cambrian diversification, as Retallack has not given us anything to truly connect the dots.

So imagine that you have been transported back around 550 million years. It isn’t as cold, but there are brisk winds as you are near the shore. You look around and see no signs of life, not even lichen or fungi on the floor beneath you. You take off your shoes and go for a paddle in the water, able to feel the ripple marks under your feet, noticing how slimy it all feels. Fortunately you brought a snorkel with you, so you wade out a bit further and dip under the water for a better look. The water is so unusually clear and you notice lots of unfamiliar organisms in the microbial mats below. Some are sticking out of it, extending upwards much like a plant would do, some are embedded in the mats, and some simply appear to be resting on top of them. You don’t notice any movement, except those caused by waves, as you would have to be watching for quite some time to see any motility. You do notice that there are marks on the mats, some scratchess where something has scraped the mats away, some oval shaped marks which look as though something has sucked the life out of the mat below, before moving on for another meal. You could even identify the culprits if you stayed long enough, watching this peaceful underwater world. This isn’t Retallack’s Ediacara, but it appears to be much closer to the right one.

Resources and References

Naturally you might want to read the paper in question if you can access it, which can be followed up with one of the responses, again, if you can access Nature. The journal also gave an article by Brian Switek which gives a decent overview. The press releases contain a decent amount of information, and you can check out ScienceNOW’s article, ScienceDaily, ABC ScienceNPR (where you can listen to people with funny voices talking about it too) and there is the University of Oregon page. Those are just the articles I used and there will be many more out there. When more of the experts start responding I will make sure to share those too.

I also began this blog post using references, but as I started writing this late at night and I have been rather ill the last few days, I gave up being thorough. The ones I did cite are as follows.

Brasier, M.D. and Antcliffe, J.B. 2008. Dickinsonia from Ediacara: A new look at morphology and body construction. Palaeogeography, Palaeoclimatology, Palaeoecology. 270, 311-323.

Retallack, G.J. 1994. Were the Ediacaran fossils lichens? Paleobiology. 20, 523-544.

Retallack, G.J. 2007. Growth, decay and burial compaction of Dickinsonia, an iconic Ediacaran fossil. Alcheringa: An Australian Journal of Palaeontology. 31(3), 215-240.

Sperling, E.A. and Vinther, J. 2010. A placozoan affinity for Dickinsonia and the evolution of late Proterozoic metazoan feeding modes. Evolution & Development. 12(2), 201-209.

Waggoner, B.M. 1995. Ediacaran Lichens: A Critique. Paleobiology. 21(3). 393-397.

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Metro + Piltdown = Head-desk

The Metro newspaper, which is available free to commuters in the UK, recently ran a piece on the Piltdown hoax. I recently had a rant about some of the science reporting in said newspaper, but this one was a lot better. I could quibble about some small details in the post, but those pale in comparison to some of the responses which were published in the “talk” section today. The gist of the article was that Piltdown is being desperately used as an example of scientific misconduct, as though it tarnishes the reputation of the whole field, when in reality it does nothing of the sort. I didn’t get to read the newspaper itself, but thankfully a friend of mine has sent me a photo of the ridiculous responses, which I will share below. It is notable that many of the claims being made in those responses completely ignore what has been said in the article, but some raise issues which were either not properly addressed in the article or are rather irrelevant (I hope that it is readable).

Metro responses

We can start by looking at Paul from Bristol’s diatribe. He makes the claim that Piltdown Man was forged to support evolutionary theory, but he has clearly not engaged with either the article or any of the historical data. Firstly, the article gives reasons why the Piltdown hoax may have been believed for so long and gives us part of the answer: Piltdown Man was British. National pride was key in its acceptance, but so too was the fact that very few were allowed to see the find and scrutinise it. The Bristolian critic makes the bizarre claim that nobody declared that it was a joke, so therefore it must have been perpetrated to establish evolution. It does not take much searching at all to find out that the main suspect, Charles Dawson, died decades before it was exposed as a hoax. With that little bit of searching, dear Paul would have found that Dawson had carried out many hoaxes in his time. Many of his hoaxes had nothing to do with evolution and went along with a rather simple notion: if you give people what they want to see they are less likely to question it; it is called confirmation bias. He didn’t care about establishing evolution, but he could easily trick people who were interested in providing fossil evidence, particularly if it was from the United Kingdom.

As the article notes, many did question Piltdown from the beginning, especially as it clashed with legitimate finds (which the majority of these responses ignore). When it was finally exposed as a fraud it was by the same scientific community which creationists seem to think were involved in a conspiracy. Frauds being exposed are a sign of the corrective nature of science. Perhaps Mr Fulcher should check out some of the creationist hoaxes which have been trotted out from time to time (they have a fondness for man and dinosaurs as contemporaries).

The creationist argument about “kinds” is hardly worth addressing, partly because they cannot define it consistently without having to invoke some large scale evolution (which gets brushed under the table). Fulcher has clearly never had a look into the fossil history of those groups he mentions, otherwise he would find that they blur together a fair bit, as a testament to evolution. When we trace his dog and cat families back, for example, we end up looking at miacids, which were rather primitive carnivorans, roughly the size of a weasel, which look nothing like the modern groups yet have the key features. Where do they fit into these supposed kinds?

So cute, yet there’s no “kind” for him.

But really all we need to do is help people to understand how evolution works. Paul rejects the notion of “one type of creature… turning into a completely different creature” and so do I. What evolution produces is groups within groups, with each new group remaining in its original grouping, but being sufficiently different to other members of that group to warrant its own group (do a shot every time I say “group” or “kind” if you are getting bored). The result is what is known as a nested hierarchy, something which has been recognised in nature for centuries and was the foundation of Linnaean systematics. If we arbitrarily label these groupings “kinds” then we find that evolution does not show one kind becoming another, but “kinds” become more derived and form those groups within groups. We can look at our own species, Homo sapiens, and note that we never stopped being the hominin kind, which is a group within the hominids and we still fit there, which in turn is a group within Hominoidea and we have all the defining features for that group, and you can keep going through Catarrhini, Simiiformes, Haplorhini, Primata, Primatomorpha, Euarchonta, Euarchontoglires, Boroeutheria, Epitheria, and we still fit into those groups. The next larger grouping is Eutheria, which contains all of the placental mammals; we never stopped being the placental mammal kind. Ask any creationist if we are mammals and they will be revealing that we fit into nested hierarchies if they say yes. Creationist “baraminology” ends up producing nested hierarchies (because evolution is true) but they arbitrarily draw a line and declare that it cannot be crossed, contrary to what the fossil record shows.

So anyway, onto the next response…

The second letter, which appears to be from John Clease at first glance, talks about gappiness in the fossil record. Of course the fossil record is incredibly patchy, but that does not mean that it does not support evolution. What it shows is not just consistent with evolution, but utterly inconsistent with even the most optimistic creationist ideas. The next comment along, from an S. Barber, makes some claims along similar lines, so I will address them together.

What does the fossil record show? Well, if Barber is right, then it should show a big jumble (unless they are an old earth creationist, in which case it appears that God created things to look as though they evolved, following an evolutionary logic). What we actually see is what I like to label “a gradual increase in the spread of complexity over time”. If you start from the oldest rocks containing life you find the conspicuous absence of, well, anything with a nucleus. We find only bacteria and their colonial structures for the first 2,000,000,000 years or so of Earth’s history, which then leads into very simply eukaryotes. It is not until around 600,000,000 years ago that we start seeing multicellular grades of organisation, a step up in complexity from the aforementioned early eukaryotes, which are more complex than the earlier bacteria (it should be noted that these do not appear in a strict stepwise manner, but simpler forms often persist alongside the more complex forms, comfortable exploring niches of different scales). We don’t start seeing simple mineralised parts until just before the Cambrian period (which started 542 million years ago) and those gradually become more complex. I’m sure you all know the anthropocentric story from there onwards, with fishy organisms making their début in the Cambrian, developing jaws later along the line, leading eventually into primitive tetrapods during the Devonian, going through the whole amphibian to reptile to mammals and birds sequence (can you tell that I am more interested in the earlier stuff?). At this large scale we clearly find something which practically screams evolution, showing a nested hierarchy pattern and that increase in the spread of complexity. But what if we look closer?

It is when we start looking closer that creationists like to claim that gaps exist, and some really do (we find transitional bat forms, but not for their origins). But gaps are constantly being filled and not all grab the headlines. People want to see gaps between major groups, they want to see human ancestral forms, they want to see whale transitions, fish giving rise to tetrapods, dinosaurs giving rise to birds, and we have examples for all of those. Many of these forms have been found relatively recently too, but some are as old as Darwin’s seminal work. Creationist like to criticise Archaeopteryx yet they have to ignore that all of the supposedly bird features have now been found in dinosaurs (not least feathers) or that working out where these things fit on their family tree is difficult precisely because of their transitional nature; it comes out either nestling with the more familiar birds or being more closely related to dinosaurs such as Velociraptor. (I intend to do a detailed post on all of this relatively soon, so I must apologise for any brevity.) So we find that when we zoom in a bit we end up finding transitional forms, though we still have many more to find. But what if we look closer?

These must not exist…

Looking even closer is difficult, not least because it requires a lot of effort to collect samples and study them for hours on end, taking lots of measurements etc. But this sort of work has been done for decades, with palaeontologists going into a lot of detail, particularly with microfossils, and elucidating different modes of evolution. What this requires is a deposit which covers a large stretch of unbroken geological time and is chock full of fossils. Naturally such deposits are rare, so the fossil record can only show us so much. What we do see is that evolution, over geological time, follows a number of patterns. Amongst these is the gradualism which anti-evolutionists like to claim is absent, but the main pattern appears to be a jerky one, where species often change little, then change rather rapidly (on a geological time scale, and when these “rapid” changes can be found in the fossil record they tend to last tens to hundreds of thousands of years, which is practically nothing to a geologist). Darwin actually did predict such patterns of evolution, so it can hardly be claimed as evidence against his ideas. (Again, expect more on this in the near future.) Clease mentioned Dawkins explaining away gaps in the fossil record as migrationary events, yet it is this very fine-scale evolution where this can be applied. Species migrate, this is undeniable, yet the fossil sequences we require for this sort of study have to be from the same locality. What will migration look like in the fossil record? Well, if you cannot trace the migration through other localities then it will look like an abrupt appearance or disappearance.

So what we see, at all scales, is consistent with evolution. Patchiness is no excuse to ignore the fossils, as what we do have is highly informative. Barber goes on to mention that evolution cannot explain abiogenesis, but that is not what evolution is meant to explain. It applies only to life which already exists and they are separate fields of study. The appearance of design is precisely one of the things which evolution does explain, that’s part of what made Darwin’s ideas so brilliant (although I surmise that they would baulk at my choice of authors, they could do with reading Dawkins’ The Blind Watchmaker).

Finally onto the last one. I could have lumped Jeremy Craxford’s claims in with the last two, but he raises a couple of other issues. He makes the statement that “Tens of millions of fossils have been dug up and still there is not a single clear, undisputed case of a ‘missing link’ between species.” Well, I have already briefly touched on there being transitional forms at multiple levels, but there are two points I want to make. First is that the term “missing link” is a pointless tautology which really should never be used; a missing link is, by definition, missing, so when it is found it simply creates a couple more gaps which need links. We instead tend to refer to transitional forms, of which many are known and are undisputed (note that any disputes come from those who a priori deny evolution).

The second point I want to make is that we currently know of around 8.7 million species of living eukaryotes. The fossil record for eukaryotes shows that they have existed for roughly two billion years, yet the last estimate I saw of known fossil diversity was around 250,000 identified species. That’s close to 3% of the diversity we see around us, spread out over two billion years. If we conservatively start at the first unequivocal bilaterians in the Cambrian period, then we have 542 million years that these fossil species are spread out over. If we calculated it so that each species was, for its duration, the only species on the planet, they would each have 2,168 years alone. I mention that just to give insight into how little we do have. Naturally species tend to last millions of years and it is difficult to estimate how many there are due to difficulties with classification. When each of these species was living there were likely millions more which we will never get to see, particularly those which have soft bodies, or live in environments which are not conducive to preservation. Anyone who thinks we should have a fossil record which perfectly shows evolutionary history is talking out of ignorance. What we do have shows, rather clearly, that evolution is the name of the game and has been for nearly four billion years.

This was a bit of an off the cuff rant (blame Dean Lomax if you found it tedious, or the Metro for publishing those inane ramblings). It saddens me that the public seriously does not understand what the fossil record shows. Someone needs to buy them each a copy of Donald Prothero’s Evolution: What the Fossils Say and Why it Matters. I will be expanding on many of these points in detail in the future, so if I left you unsatisfied you can always come back for more, I promise it will be better.

 

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From Cocoon to Lagerstatte?

There’s a recent bit of palaeo-news which really piqued my interest recently, yet I failed to blog about it when it was announced. So here it is…

The fossil is on the left, a vorticellid in the centre, and a leech cocoon on the right. Image credit: Hans Kerp et al / Muenster University

From deposits in Antarctica a fossilised cocoon, like those produced by the modern medicinal leech Hirudo medicinalis, has been found containing an exceptionally preserved microfossil. A cocoon would, in most cases, be a type of trace fossil, a remnant of ancient animal behaviour, but this one has become much more. Due to its mucous content it trapped a microorganism which had attached itself to the cocoon, becoming preserved along with it when the cocoon fossilised.

This is not the first example of such preservation, though few are known as they have not really been explored thus far. What makes this particular find grab the attention is that it easily fits into a modern group, one which has no fossil record due to its soft-bodied microscopic nature. It is what is nicknamed a “bell animal”, a member of the Vorticella family – single celled protozoa which use cilia for mobility.

What we have here is an ichnofossil (fancy word for trace fossil) which can function like a mini lagerstatte (another fancy term, for a site of exceptional preservation) though the term conservation trap is probably more appropriate (but less grand). Its preservational qualities are much like amber, but with a fossil record which extends further back than amber deposits, and are an untapped source. Similar finds in the future might expand our knowledge of ancient microbes, filling in gaps in the fossil record which we previously thought could not be filled. I personally find that exciting.

For more on the story, you can find press releases here, here and here, and the paper itself is here.

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Separate new blog: Shorts and Socks

I’ve decided to start a new blog specifically for any creative writing which I have done. Every so often I write a short story and seem to be very good at losing track of them, so I am storing them all on one blog. On my old Palaeobabbler blog I used to post short stories alongside all the other stuff, but I decided that this one would be more focussed, so I need another place to vent my more creative side. The stories go back several years and vary in quality and theme, check them out if you are interested in the fiction spewed forth from my mind. So far I have also posted a picture I drew, as it has a little story to it, and I posted some nonsensical pretentious poetry. I am considering also sharing some of the cartoons (to use the term loosely) which I have drawn, as they sometimes have narrative, and maybe even song lyrics (including my old spoof death metal band Womb Wounder). Anyway, if you are interested the blog can be found here. I have organised them into categories, which can be found at the bottom, so if you want something specific it should be found easily.

Or if you want to skip to my own favourites, try looking for Harvester of Sorrow, Ghosts in Space, Mathilde, and Mike’s Final Frontier.

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Thelodonts wore hats.

Thelodonts wore hats.

Due to some comments on a friend’s Facebook status, I ended up drawing a picture of thelodonts wearing hats.

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December 6, 2012 · 12:09 am

“First” Dinosaur and Dodgy Reporting

Today, like many others, I heard the news about the potential dinosaur which has just been described and may be the oldest yet known. Nyasasaurus parringtoni lived around 15 million years before the previous oldest dinosaur, Eoraptor, though N. parringtoni may not be a dinosaur, but even if it isn’t it is clearly very closely related. But that’s not exactly what I want to talk about, so if you want more details, some of the press releases can be seen here, here and here. The paper itself is free to read, which can be found here.

I encountered this information in the Metro newspaper, which had this article on page 19. I love seeing palaeontology in the news, so when the reporting is a bit naff it really bugs me (Science Daily often causes me to rant, so expect many more posts like this in the future). I don’t go looking for errors, they are to be expected, for example the dinosaur’s name should have been in italics, but to complain about that from a free newspaper would just be pedantic.

The first thing to note is not a scientific complaint, but just look at the image below, which is found on every press release, and tell me who the artist is. Yep, it is some guy called An artist. Many newspapers just take images without paying the artist, and sometimes they don’t even bother to credit them. Palaeoartists don’t make a lot of money off of their work, so to not even credit them is rather disgusting. Thankfully the website does correct the error by crediting Mark Witton (a friend of mine) and if you want to know more about how the image was produced, see his blog about it here, as it adds an extra dimension to the picture.

Nyasasaurus parringtoni, with Stenaulorhynchus in the background. Image pilfered from Mark Witton (got to make sure I’m not a hypocrite).

But anyway, the short article manages to make a rather silly claim. The second paragraph states that the discovery of Nyasasaurus “may force us to rip up the scientific textbooks”. But why? Very few textbooks mention early dinosaurs, and those which do will simply need some slight revision for any future editions. It simply extends our knowledge of dinosaur origins, whether it is a dinosaur or a dinosauriform. No paradigm shift is needed, no textbooks need to be ripped up, but some reporters need a slap on the wrist. It is needless sensationalism which just paints a poor picture of science. The public often have this strange view that scientists completely throw out entire theories for new ones, but such an occurrence is rare. On a smaller scale old ideas give way to the new, but this is part of the refining nature of science. This article makes it sound like everything we knew about dinosaurs and their evolution was utterly wrong, which is pure nonsense.

The textbook claim was my major quibble, but the title bugs me too (even the grammar). We have an interesting fondness for “firsts”, often talking about the first person to achieve an amazing feat, and palaeontology is no stranger to this. But in evolution it does not really make sense to talk of something as being the first, except perhaps as the first known. The title asks if Nyasasaurus was the first dinosaur to roam the Earth, but evolution occurs gradually in populations, so there is no single first dinosaur, and from a population perspective it makes no sense to talk of a first dinosaur population when it would have been barely distinguishable from the ancestral population. Just a slight change in words can have huge implications, so journalists reporting on science need to be careful.

It really is an interesting bit of news, filling in the gaps in our knowledge of early dinosaur evolution and how they fit into the Triassic alongside many other cool beasts (the crurotarsans are worth looking at). Most of the press coverage seems to be good, but the Metro has let us down with this one.

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