Bias in the fossil record

Despite what people might think, fossils are not evenly distributed on the Earth’s surface. That might make intuitive sense – surely not everywhere can produce dinosaurs, mammals, fish, ammonites and trees, but even where fossils are found the numbers can be strongly skewed towards some kinds and away from others, and not necessarily in the way one might imagine. This is intended as only the sketchiest review of the major factors that affect the frequency with which some animals are fossilised and some are found (the two not necessarily being correlated) but is well worth knowing about.

These biases do exist, but of course they are incredibly hard to quantify – how do you tell how much more of some species you should have, or if there is probably a large predator missing from the fossil record? Even if you have a comparable extant fauna, there may be some aspect you have missed that drastically changes the fauna and makes the comparison far more subjective than you realise. Thus these tend to be only relative, there IS a bias towards fish in the fossil record, but how much of one, nobody knows. None the less these must be kept in mind when examining fossil faunas and looking at palaeoecology and biogoegraphy as it is all too easy to think that the fossil record accurately represents the fauna that it sampled when clearly this is likley to be far from the case.

Since this is the archosaur musings, I’ll try and stick to archosaurian examples and effects, though of course these points are largely applicable to any fossil organism and a few are applicable to the fossil record as a whole rather than individual beds or formations.

Travelling without moving

Due to the entertaining complexities of internet access in China, I can only actually access and update the Musings from one computer, the laptop of my long-suffering colleague Corwin Sullivan. He is off to SVP in the US this week and then taking a tour of some of North America’s finest natural history museums, leaving me Musingsless. However, have no fear as a nice collection of posts have already been written and uploaded onto WordPress and I can still drop them into the internet at semi-regular intervals. So while you won’t be starved of archosaurian based goodness, I won’t be able to answer (or approve) comments, correct any of my inevitable spelling mistakes or anything else for a few weeks.

It’ll all be back to normal soon enough and perhaps you might then get deluged. One of the things I did manage to do in Mexico was get some writing done, and I came back with notes enough to write about 50 posts, plus odd ones based around single images etc. and the 15 or 20 I had already started before had I even left. All told that should keep me going for about a year on here! Now I just need to write them up, get the references, check the data, sort out the images….

Don’t waste your time or mine Pt. 2

It’s very easy to criticise people, so I will. Same as before, don’t know who is responsible, and don’t want to waste time on what’s wrong. I will say however that to be fair, this is from a small non-natural history museum which did not have a huge budget, had to fit the thing in a small space which obviously constrained how it was built, and actually did not too a terrible job. The weird thing was they got some relatively minor details right while screwing up the obvious ones which makes me thing the former was more luck than judgement.

While the last one was pretty obviously supposed to be a T. rex, it is probably worth pointing out to the non-pterosaur aficionados that this is supposed to be Quetzalcoatlus.

Edit: Not sure what’s up with the font, I’ll try and fix it.

The Great Pterosaur Exhibition of 2007

While I have at least mentioned the Wellnhofer pterosaur meeting of Munich a few times here (for full coverage go here on Tetrapod Zoology) there were wider events going on in Munich at the time in which I was naturally involved. The Bavarian State Collection for Palaeontology and Geology where I was working at the time is a very small place – the main hall is perhaps 10m by 15m and based around a balcony but still manages to cram in a huge amount of material. Each autumn they prepare a small exhibit on a specialised topic and with the Flugsaurier meeting already planned for October, the obvious choice was for a display on pterosaurs. Now this is a year old, and no longer on display it seemed like a good time for me to have a little retrospective and for you to sit through it.

Don’t waste your time or mine

I do want to show this picture because I thought it would amuse. But please don’t bother pointing out the flaws in the damn thing, it’ll take forever. And don’t ask me who made it (I don’t know) or where I found the picture (I don’t want to say). Still, there is something familiar about it….

How to spot a palaeontologist

Stereotypes are a double-edged sword. On the one hand they can be useful shortcuts to extrapolate a whole bunch of correct information based on very little. On the other hand they can be deeply flawed shortcuts to extrapolate a whole bunch of incorrect information based on very little. The typical stereotype of a scientist or indded a palaeontologist as presented to the world at large by the media is not exaclty flattering and full of deep inaccuracies and, well, stereotypes. However, there is always a reason for the stereotype and here is one of them…

How do you spot a palaeontologist? Allow me to be your guide:

Language issues

Despite my best (and sometimes not so best) efforts, I remain pretty much a monoglot. My French is not too bad, my Spanish is barely passable, my German is limited to a few words and my Chinese barely that. However, right now my head is a complete mess.

I have just come back from a month in Mexico where I have been working with both locals and German colleagues and trying to resseurect my shaky grasp of two languages while mostly just speaking English. Of course I started in Chinese, but that vanished quickly. Like many people, when stuck with a word I don’t know in another language I tend to default into another foreign one, rather than English. This means I produce lots of sentences that are primarily Spanish or German with a bit of French thrown in when I get stuck.

However, I have left that behing and then after just a few hours in the UK I have come back to Beijing and in addition to the CHinese, I have several French colleagues here who I try to practice with. (Typically I ask them a question in French and then they reply in English – not answer you understand, they ask me what I said). It’s probably not hard to guess that I have spent most of today talking in a mixture of Spanish and German to the bemused Chinese populace of the city and when realising that I am using the wrong language, promptly switching to English or worse, French. I hope it will clear up in a few days if not the local shopkeeps are just going to have to work out that ‘gracias’ means thanks.

The BSPG Triceratops

It is often a surprise that some fossils end up where they do. One might expect that any scientifically important fossil found in a country would end up either in the nearest museum or university, or at least the major central repository of that country (i.e. a national museum). However, plenty get spread far and wide – in the olden days, fossils were often traded or sold between institutes (or occasionally given as gifts) and this practice still occurs, though generally only things of minor importance (i.e. duplicates of specimens – there are only so many Lycoptera that are worth keeping) and certainly nothing that is a type, or is especially important through completeness, or soft tissue preservation etc. Nevertheless, some fossils do still move legally between institutes (both legally and sadly illegally on occasion) and it can be frustrating sometimes when you discover that the specimen you *really* want to see is not where you expect it to be.

A case in point is the Yale Rhamphorhynchus (pictured, copyright Yale Peabody Museum) – one of the best preserved specimens with exceptional wing preservation (or so I’m told). Very few Solnhofen pterosaurs ever left Germany (of course a few are in Austria and Switzerland, but they are hardly difficult to see) so it is a surprise that something this nice made it to the US. Actually the BSPG (my old institute in Munich) got a pretty good deal out of sending the Rhamphorhynchus (and some other pterosaur bits) over in 1964 – they got this in exchange:

Museo de las Aves

I have not really gone in for ‘reviews’ on this blog (of books, papers, abstracts or anything else) with just the odd one slipping in. However, my travels in Mexico have thrown up a couple of things that are worthy of further discussion for various reasons, and the above museum is well worth it. For the few of you whose Spanish is less accomplished than mine, it is the “Museum of Birds”.