Archive for August, 2012

Interview with Julius Csotonyi

The first single-fingered dinosaur, Linhenykus, commissioned to publicize the discovery (2010).

Today I’m delighted to bring you an art interview with Julius Csotonyi. I first came across his art relatively recently after he ended up doing a lovely life reconstruction of Linhenykus and this sent me to discovering his work. I recently got in touch to ask to borrow a bit of that piece for my new blog banner and casually suggested he might like to join the ever-growing list of artists on here and he was most keen. So keen in fact I’m rather buried in his artworks, so enjoy! As usual this art is Julius’ and should not be reproduced etc. without his permission as he retains the copyright. Continue reading ‘Interview with Julius Csotonyi’

Dinosaur tail length bonus data

Happily for me I have been contacted by several colleagues in the wake of my last post pointing me to the specimens and papers that I’d either missed or have come out too recently for me to have included in the tails paper. More happily still a couple of them are really interesting and so worth sticking up here. Remember that I’d been scaling the length of the tail against the femur as a proxy for body size with most values being around 3-4 (i.e. the tail was 3 or 4 times the length of the femur) with the very shortest clocking in at just 1.2 or 1.3 and the highest at 8.8.

First off, Jordan Mallon pointed me to a paper of his describing a chasmosaurine with a complete tail that clocks in at just 1.9. The next lowest value I had for any ceratopsid was 2.8 so this is a quite a big drop and this is the same as Nomingia which I think is fair to call a very short-tailed oviraptorosaur. So there’s at least one more shorty out there.

I’ve also been mailed by Matthew Herne who’s working on Leaellynasaura and given me permission to publish this nugget of data here before his full description makes it into the literature. Now Leaellynasaura did get a mention in the paper as being a possible outlier with a long tail based on an SVP abstract by Matthew, but obviously without the actual data I had no idea just how low this might be. Well, as I say, he’s mailed in the result and it’s a truly whopping 12.4! It’s tail was more than 12 times the length of it’s femur. Wow.

Variation of tail length in dinosaurs

So I have a new paper out and inevitably I’m going to talk a bit about it on the Musings. While I’ve had a few abstracts and the odd short paper out as sole author, this is pretty much my first proper effort in a major journal where I’m the only author. Not that I didn’t have help of course (which is what the acknowledgements are for) and I do especially want to take the opportunity up front to thank various people for their contributions and help, but most especially Susie Maidment for her help in data collection.

Right, onto the actual paper. Way back in 2010 I was looking at pterosaur tails in connection to an anuroganthid that turned up with (for one of them) an unusually long tail. This got me thinking about dinosaur tails and it struck me that while we obviously had some taxa with short tails (like Caudipteryx) and some looked pretty long (like Diplodocus) that no one seemed to have looked at just what kind of variation there was. Moreover, the more I thought about it, and the more I looked through papers and collections (and then later on asked various colleagues) the more often I came across ‘complete’ specimens that were nothing but when it came to the distal caudals. And so began my investigation into the tail lengths of the non-avian dinosaurs (though admittedly Archeopteryx sneaks into the paper as do the scansoriopterigids). Obviously the paper is there to be read, but hopefully this will serve as a quick summary and discussion of the basic points for those who can’t get it or don’t want to read it.

The first thing to note is that actually we really do have very few dinosaur fossils with complete tails. Despite a good hunt through the literature, a couple of collections, and exchanges with a number of colleagues I was able to track down very few specimens where every caudal was known. Even in things from localities like the Jehol and Solnhofen where skeletons are preserved in beautiful condition and soft tissues are common, there are actually very few specimens with every caudal vertebra preserved. Sure the sauropods might expect to do badly given how incomplete they always seem to be, and we’ve got more than a few dinosaurs known from only fragmentary remains. However, on the other hand we now have thousands of dinosaur fossils, and some species are known from dozens or even hundreds of good specimens and many of these are from sites of excellent preservation. But for all my searching and asking, I found less than 20 dinosaur specimens in total that have every caudal preserved. That’s really very low. Even things like ankylosaurs and dromaeosaurs with those lovely reinforced tails don’t seem to do any better either, complete tails are really, really rare.

Now there are a good number that are probably close to being complete with only a few distal ones missing, but obviously quite how true this may be is hard to determine. Sure there tends to be a general tapering of the size of the caudals which can give you a reasonable guess as to where it likely ends, especially if they are very small when they stop, but things like Diplodocus with it’s near endless rod-like caudals or the sudden stop in Nomingia means you could easily be wrong. In short, while a specimen like Sue we can probably have a pretty good guess how long the tail was and quite how much was missing, for plenty of other species it’s not going to be so easy. And things get worse from here.

Not only are there few dinosaurs with complete tails, but in one wonderfully illustrative case we have some major intraspecific variation. Two specimens of Leptoceratops are preserved side by side and so we can be confident that these aren’t just the same species, but are even from the same population. The problem is, one has 10 more caudals than the other, and their tails are proportionally rather different in length too. There’s quite a bit of intraspecific variation there, and indeed a look across other amniotes suggests that this is quite common – caudal counts and caudal lengths can vary a lot in tetrapod species. Tail length is sexually dimorphic in some snakes for example, and can vary a lot even in mammals.

Interspecific variation can be high too, which means it may not be safe to reconstruct missing tails from even close relatives. The wonderful little Epidexipteryx has the joint shortest tail known for any dinosaur that I found, but it’s sister taxon, Epidendrosaurus, has one of the longest tail known (and that one is incomplete and would have been longer still). While this might be an unusual case, there’s a decent bit of variation seen in a couple of other clades too.

All of this means that we need to be a fair bit more careful when talking about dinosaur tails and especially when it comes to recounting their size in terms of length. The length of a dinosaur is absolutely ubiquitous in the media as a measure of size and it turns up in a few papers too. However while some taxa are of course known absolutely in terms of their length, and many are probably about right despite being not entirely complete, others would seem to be little more than a best guess – and a best guess based on not very much to be honest. The data for sauropods in particular seems to be incredibly sparse and accounting for the inter- and intraspecific variation seen, I don’t think I’d be confident in reconstructing the tail of something like Argentinosaurs to within even a 50% error – it could be really long or very short and there’s no way of picking one over the other. Even ignoring some of the outliers, there’s a fair bit of variation there and can have quite an effect on the appearance of an animal.

Scott Hartman has been good enough to make this for me – a Spinosaurus with a short, ‘normal’ and long tail. All of these kinds of lengths can be seen in various theropods and to my mind are all plausible – indeed, we’ve been quite conservative here and could easily have copped off another hatful of caudals or plugged on a good few more and the results would still be quite plausible and within the bounds seen by other theropods. Of course note that while the length of that tail in each varies enormously, and as such, so too does the total length of the animal, the mass would not change that much. A 16 m long Spinosaurus sounds massive compared to a 12 m one, but if the only difference is in tail length, then in terms of mass there might not be much in it, just a few tens of kilos in a multi-ton animal.

So, estimating the length of a dinosaur without a mostly complete tail could give you a rather inaccurate number. There does seem to have been a fair bit of inaccurate information out there in the literature in the past with people giving ranges of caudal counts for groups when individuals were known with much higher values, and clades being described as having ‘long’ tails when they didn’t (or there was no real way to tell). However, there is a little more to this, I also did an analysis where (as far as possible, which admittedly wasn’t that far) the variation in tail length was compared to snout-vent length.

When examining living species, most biologists use snout-vent length as a proxy for how large animals are. After all, the tail length can vary a lot as we’ve seen, and even weight isn’t a great measure for a lot of living animals as it can fluctuate a lot on an annual basis, and of course isn’t available for specimens in museums. So a measure from the tip of the snout to the vent / anus is a common measure of size but we don’t seem to use it much in palaeontology (and certainly not for dinosaurs). In short therefore, we’re using a measure which not only includes a lot of variation in the tail that might screw up the results (and that most of the time we don’t know for sure anyway), but it’s not compatible with other datasets on extant taxa. The question is though, would the equivalent be any better for dinosaurs?

My simple analysis suggests so – that from the available data, tails are rather more variable in dinosaurs than the body. As for the vent, well, that we obviously don’t know exactly as a decidedly soft tissue structure so I plumped for the last sacral being a point that would be close to the vent and an unambiguous point on the skeleton that would be easily identified and would likely be preserved. This measure (snout-sacrum) is one I suggest we should start using when we want to talk about dinosaurs sizes in terms of length.

So there you have it. We don’t seem to have too many dinosaur tails, those we have suggest much inter- and intraspecific variation and so estimates of total length or using total length may not be very reliable. Snout-sacrum length is probably more reliable and in any case would bring the data in line with that used by most biologists. My final note though is an appeal – despite the work I did trying to uncover dinosaurs with complete tails, I’m sure I’ve missed some. Perhaps they’ve simply not been described, or are squirreled away in obscure journals, or are only listed as paratypes etc. I have seen a couple of things published since this work was finalised that look like the tail is complete but where the paper doesn’t actually say and it’s not entirely clear from the figures. I can’t believe that some of those massed ranks of undescribed Psittacosaurus, Protoceratops and various massed ranks of hadrosaurs and iguanodontians don’t have a few more complete ones lying around that can be measured. So if you do know of any specimens out there with complete tails (and better yet, totally complete specimens in terms of the skull and vertebral column) do please let me know. I’ve exhausted all the easily available avenues to date, but I’d love to do the analysis again with much more data. One day.

Hone, D.W.E. 2012.Variation in the tail length of non-avian dinosaurs.Journal of Vertebrate Paleontology, 32: 1082-1089.

A new pterosaur appears

This is a bit of an odd post, but one I had to share. I got an e-mail from Helmut Tischlinger late last night saying that press release was going out in Germany featuring a new pterosaur. It’s from Wattendorf, is being worked on for a description at the moment and it apparently going on display today at the Bamberg museum. That’s all I know. I’m assuming it’s from the Solnhofen proper and it’s clearly a pterodactyloid and most likely a ctenochasmatid based on those fantastic jaws.

However, it looks superb and Helmut was good enough to share this photo (on which he retains the copyright, do not reproduce etc. without permission) with me which he gave me permission to put up here. So here it is, enjoy.

New pterosaur. Image copyright Helmut Tischlinger.

One million and counting

In all the excitement of starting the Lost Worlds (remember to update your blogrolls folks!), the Musings has still been ticking over and yesterday rolled over one million hits. It’s taken a fair while, but it’s got there. Of course the ‘real’ total for the Musings should be rather higher since the old Version 1 of this blog has still been accruing hits over the years and has tens of thousands of recorded visitors, but it’s still nice to see the counter tick over on here too.

Not that it’s a bad score at all, but it’s taken years (literally) or writing to build up this audience and it’s almost a shame that I’ve managed to eclipse myself so quickly. My all time top day on here is just over 4000 reads, and the all-time record for a post is a massive 33 000 (though obviously accumulated over a good period of time). Now naturally I’m writing for a broader audience on the Guardian and it’s a big site with a lot of traffic, but in the half dozen posts I’ve put up, I’ve already got several posts with tens of thousands of hits. In short, I’ve eclipsed over 5 years of blogging achievements in just a few weeks. Wow.

Still, as promised the Musings isn’t shutting down and I do have some more posts in the works on here including more art interviews and covering a paper of mine due out next week. Even so, it’s hard not to feel that despite the record here, I’ve rather moved onwards and upwards. But I’m proud of this and I hope this will continue to grow, if slowly and more Musings are coming.

Dinosaur Art book review

I’m sure a good number of readers will be well aware that there is a new book on it’s way to the shelves for mid September on palaeoart and more specifically, dinosaur art. I’ve been lucky enough to get an advanced copy in exchange for doing a review, but I’d have been happy to do so anyway. First things first though, I know almost every artist featured (and am friends with several) and even the editor Steve White and indeed have interviewed them myself on the Musings. Obviously I’ll try to be a neutral as possible, but while this review is gushingly positive, it’d be unfair not to point out my obvious connections to many of those involved.

Doug Henderson asteroid piece

Anyway, onto the book. Quite simply it’s superb, and really doubles as covering two very different things in a single volume. Most naturally it’s a book crammed with high quality artworks from a great number of superb artists and features numerous images that will delight. Even with my familiarity with a great deal of palaeoart and having had the chance to browse the collections of my friends, there were plenty of images here I’d not seen before.

A Sinornithosaurus by Todd Marshall

The paper quality and print quality is superb (which is important) and there are even a few fold-outs to give maximum exposure which is significant given that already it’s quite a large format book. This is a seriously nice piece and I can image there will be a good number of sales to people with no great interest or love of dinosaurs because it just looks fantastic. It’s a real coffee table book in that sense (and I mean that as a compliment).

Julius Csotonyi Cretaceous scene.

However, aside from just looking gorgeous, this book also provides some real commentary on pretty much every aspect of palaeoart. Each series of images (grouped by artist) is accompanied by a dialogue / interview between the editor and artist. This covers the artists origins in palaeoart and obvious little questions about their interests and favourite species, but also delves into the creation process, the style and techniques of the artist and the state of play with modern developments and especially the rise of digital media. As part of this we do see drafts and sketches for pieces showing how the artist changed aspects of the work or developed pieces which is truly fascinating. Each section also has a featured taxon with a series of images by that artist on the relevant species and some accompanying text about the animal in particular, giving a bit more depth and study to each of these compared to a lot of the bigger works which are presented largely without comment.

John Sibbick Scleidosaurus sketch and completed work.

If there are any quibbles it’s that I would have liked to have seen more text. What is said is really interesting and while I’m sure the hefty tome wasn’t cheap to produce with all those pages of full colour artworks, I can’t see that a half dozen extra pages of just text would have made much of a difference. My other minor issue would be that there’s really quite a lot of non-dinosaur stuff in here. Now that’s not me being against non-dinosaur palaeoart in any way shape or form, but the book *is* called Dinosaur Art and at least a few readers might be disappointed that there are a few places where a good number of pages can be turned before finding a dinosaur. While the dinos do dominate, it does just seem a little between-two-stools – it’s not 99% dinosaurs (or even Mesozoic reptiles) as one might expect from the title, but then nor is it mix of all kinds of palaeoart (even if that would likely feature more reptiles than anything else). As I say, both very minor things and ones that I doubt will put off anyone who really likes their art, and indeed nor should it.

Mauricio Anton South American mammal assemblage

Overall then this is a real must-have. I can’t recall another book like it either in terms of the volume of art, the production values or the interviews / sketches that add a new level of detail. While I rarely do go out and get volumes like this (and of course was lucky enough to get mine gratis) this is something I’d have gone out of my way to get my hands on and you should too.

Raul Martin Citipati

Oh and finally I should add that all the images here were provided by the publishers who allowed me to use them to promote the work. They and / or the artists retain the copyright on these images.

John Conway’s Tarbosaurus chasing Gallimimus.

The Complete Dinosaur, 2nd edition – a brief review

The original ‘Complete Dinosaur’ book was one of those I never quite got around to getting my hands on. I only really became involved in dinosaur research sometime after it had come out (way back in 1999) and it was (obviously through no fault of it’s own) starting to date by then. It was quite clearly a great and compact synthesis and review of a huge amount of data and in the days before wikipedia represented and excellent and authoritative volume and the kind of thing too rarely produced for scientific disciplines.

So here we are, a good decade on and a new edition is out. In fact it shipped a while ago but authors outside of the U.S. have been slow to get their copies. Mine turned up at the weekend and so obviously the following review is naturally brief and based on little more than a flick through and a skim of various chapters and concerted reading of only a few choice bits and bobs. It’s a mammoth 1100+ pages so I doubt anyone will be coming with a full review anytime soon, but the basics are rather obvious and that’s what will form the basis of my thoughts here.

First off, to get it out of the way, the bad. Naturally any subject like dinosaur biology is going to have some controversy in it and no one is an expert on everything, and of course you have multiple editors and authors to satisfy which is going to cause conflict. In short, there are some bits presented as ‘correct’ that I think many, if not most, researchers would disagree with as being incorrect, out of date or just off (the short section on pterosaurs buried in one of the chapters is, well, not good to say the least). That’s a bit unhelpful for something billed as up-to-date and new and aimed at a broad general audience. The layout of the chapters is a bit odd too in places – there’s a chapter each of stegosaurs and ankylosaurs, but all non-avian theropods are lumped into a single block. While I’ve not read them yet, there’s three whole chapters devoted to dinosaur physiology (in addition to a chapter on growth and one on heterochrony) which seems excessive. Some of the figures don’t print too crisply (though this might be more to do with the paper or of course just my copy, but I don’t think so) which is a shame, but no real information is lost. The one thing I really dislike is the huge waste of space. The margins of each page a fully a third of the width, and while figures are spread across the page and some headings appear in the margins, there are dozens and dozens of pages where only 2/3rd of the space is used. It’s a horrible waste of paper and of course this is only exaggerated in a volume that over a thousand pages long, and of course rather egregious when it’s a scientific volume and scientists if anyone should appreciate and understand the concern in wasting resources.

Now to the good and there is much of it. What the book tries and succeeds in doing is bridging the gap between ‘typical’ dinosaur / palaeo books and the scientific literature. There’s a liberal use of scientific terms and citing of research, but all of the terms are explained in the text and the citations aid, and don’t dominate, the statements made. Someone with a real interest and enthusiasm who has gobbled up all manner of books like Tom Holtz’s or Darren Niash’s would still probably really struggle if you plopped them down with a copy of The Dinosauria or a handful of published papers. This book will get them to a point where they could probably appreciate these works, and that’s some achievement.

That this is possible is down in good part to the layout of the book. It’s not an encyclopedia as such or just a procession of chapters on various clades etc. but a series of long essays each tacking a subject of dinosaur research. While birds, sauropodomorphs and marginocephalians are tackled in chapters for example, we get sections on footprints, how fossils are mounted in museums, the basics of biogeography, excavating fossils, taxonomy, context from historical discoveries, basic osteology and myology and so on and so on. While it might be a slog for the non-expert to get through 50 pages on physiology say, the writing is aimed at a non-expert audience and with a style that helps to try and elevate the reader and put everything in context with clear examples and illustrations and laying out the basics of the problems, evidence and solutions.

There’s nice coverage of issues rarely looked at in research papers as well. A chapter on reconstructing dinosaurs and art by Dough Henderson is a particular joy as he dissects his piece on Coelophysis which is a personal favourite of mine to boot. Things like excavations are covered too which do tend to be learned ‘on the job’ when it comes to palaeo training with no obvious paper or manual that I’ve seen in the technical literature, but again here there’s a great short section that would give any novice an idea of what can and should be done when prospecting and digging up material.

This is also a work that will benefit and be used by professionals. Some areas of research and anatomy do lack good, solid reviews and can be hard for PhD students or even seasoned researchers to get to grips with. I’ve never really had to do much with braincases (for which I am grateful) and each time I have even a passing dealing with them I have to crack open a raft of papers and try to get back to speed and cross reference various bits and pieces. Here though is a chapter on dinosaur neurology with various endocasts shown, labels for all the classic cranial nerves and their typical positions and each section of the brain labelled and discussed. It’ll be the first thing I reach for the next time I need to check something or as a simple reference that reviews the basic information if I want to make mention of the subject in a paper.

In short, while I obviously have at least a slight hand in this as the coauthor of a chapter and friend and colleague to many of the authors and editors involved, it’s hard not to give this a hearty recommendation on balance. As I said above, I really have only look at this superficially and read barely a few dozen pages from various chapters, and there is a vast amount to catch up on, but it looks great and will provide much information and detail for huge numbers of researchers, students and general enthusiasts alike. I look forwards to digging into it more fully, but for now I’m very happy with it and I think a great many readers will be too.

Chunk of this are visible with Google Books for those who want to take a look. Bonus Musings points are available for anyone who spots me in there, I did sneak into one photo oddly enough.

@Dave_Hone on Twitter

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