Sexual selection in dinosaurs, the story so far…

I have a major new paper coming tomorrow on sexual selection in dinosaurs. This is an area in which I have been extremely heavily involved in the last decade and have published numerous papers on this subject with various colleagues, writing about the underlying theory of sexual selection and how it might appear in the fossil record, providing evidence for it and actively testing hypotheses. This has also led into my working on related issues of ontogeny and social behaviour in dinosaurs which feed back into these areas to try and deal with certain aspects that came up as a result of these analyses.

Suffice to say I’m not going to go back over the whole history of my work in the field, or that of plenty of other researchers which is both relevant and important. But a little bit of context is important with respect to the coming paper because it’s something that I’ve had in my mind to do for about as long as I’ve been working on this subject but I didn’t think I’d be able to do because the dataset didn’t exist.

All of the work I have done really tried to get into answer the questions of which features of which dinosaurs may have been operating under sexual selection and can we tell. (More properly, I should say socio-sexual selection since teasing out social dominance signals from sexually selected signals is probably impossible though mostly the two are more or less synonymous in various ways so it’s not a major issue conceptually). The short answer is that really quite a lot of features probably are under some form of sexual selection. We can see this by the fact that we can rule out functional explanations for things like ceratopsian crests as being anchors for muscles attachments, radiators, or for defence because they are highly variable and / or fundamentally don’t work (Elgin et al., 2008; Hone et al., 2012). They are costly traits to grow and lug around (be they stegosaur plates or hadrosaur crests) and so clearly have a fitness cost, ruling out species recognition as a signal (Knell et al., 2012; Hone & Naish, 2013). Similarly, there is no clear pattern of differentiation among sympatric species as would be critical for a recognition trait (Knapp et al. 2018). They are highly variable both within and between species, another hallmark of sexually selected traits (Hone & Naish, 2013; O’Brien et al., 2018) and finally they grow rapidly as animals reach sexual maturity which is absolutely characteristic of sexual selection (Hone et al., 2016; O’Brien et al., 2018).

The one issue that has remained elusive in all of this is the vexed issue of dimorphism. This has proven very hard to detect for a variety of reasons, but most notably the generally small sample sizes we have for dinosaurs and the tendency for males and females to overlap in size and morphology over much of their lifespan (Hone & Mallon, 2017). To top it off, mutual sexual selection can reduce or even eliminate dimorphism making it harder still to detect and meaning even an apparent absence of it, does not mean sexual selection is not in operation (Hone et al., 2012).

It would be nice to be able to explore the issue of dimorphism in particular in more detail with an extant analogue. Plenty of comparisons have been made to various living taxa in terms of dimorphism (be it body size or major features like a crest or sail) but they run into various issues. Mammals are nice and big and often have things like horns that differ between males and females (either in shape or presence / absence), but they’re phylogenetically very distinct and have the problem of growing quickly to adult size and staying there. Lizards offer something interesting with some dimorphic species with various signal structures (like some chameleons) but then while they are reptiles, most are small and the biggest varanids have no sexually selected structures. Birds are obviously literally dinosaurs but have a mammalian-like growth and are not very big. While there’s plenty of size dimorphism in them, there are few that have obviously dimorphic traits that would show up in the skeleton (like horns).

That leaves the crocodylians, which are off to a good start. Some are very large and take a long time to grown to adult size, all are egg layers, they are sexually mature long before full size meaning they would likely express sexually selected traits while still quite small (like dinosaurs and unlike birds or mammals), and a number are also sexually dimorphic in body size. The only thing missing is some kind of sexually selected bony feature, or at least one with a clear osteological correlate.

And so to the gharials, the wonderfully weird crocodylians of the Indian subcontinent which tick every single one of these boxes right down to the growth on the snout of males, the ghara, that is absent in the females. This has long been obviously the one taxon that ticks pretty much every possible box and would provide an excellent living model to analyse and see how easy (or not) dimorphism is to detect when you have a known dataset to work from. The obvious limit to this plan is that these animals are extremely rare and most museums have few, if any, specimens. The one species that was pretty much perfect for my plans immediately fell out of contention because I couldn’t see how I could get a dataset together that would be sufficient for analysis, so the idea was shelved. Until recently…

Obviously, to be continued.

 

Papers on sexual selection, dimoprhism, socio-sexual signaling, social behaviours and related subjects in fossil reptiles:

O’Brien, D.M., Allen, C.E., Van Kleeck, M.J., Hone, D.W.E., Knell, R.J., Knapp, A., Christiansen, S., & Emlen, D.J. 2018. On the evolution of extreme structures: static scaling and the function of sexually selected signals. Animal Behaviour.

Knapp, A., Knell, R.J., Farke, A.A., Loewen, M.A., & Hone, D.W.E. 2018. Patterns of divergence in the morphology of ceratopsian dinosaurs: sympatry is not a driver of ornament evolution. Proceedings of the Royal Society, Series B.

Hone, D.W.E., & Mallon, J.C. 2017. Protracted growth impedes the detection of sexual dimorphism in non-avian dinosaurs. Palaeontology, 60: 535-545.

Hone, D.W.E., Wood, D., & Knell, R.J. 2016. Positive allometry for exaggerated structures in the ceratopsian dinosaur Protoceratops andrewsi supports socio-sexual signaling. Palaeontologia Electronica, 19.1.5A.

Hone, D.W.E. & Faulkes, C.J. 2014. A proposed framework for establishing and evaluating hypotheses about the behaviour of extinct organisms. Journal of Zoology, 292: 260-267.

Hone, D.W.E., & Naish, D. 2013. The ‘species recognition hypothesis’ does not explain the presence and evolution of exaggerated structures in non-avialan dinosaurs. Journal of Zoology, 290: 172-180.

Knell, R., Naish, D., Tompkins, J.L. & Hone, D.W.E. 2013. Is sexual selection defined by dimorphism alone? A reply to Padian & Horner. Trends in Ecology & Evolution, 28: 250-251.

Knell, R., Naish, D., Tompkins, J.L. & Hone, D.W.E. 2013. Sexual selection in prehistoric animals: detection and implications. Trends in Ecology and Evolution, 28: 38-47.

Hone, D.W.E., Naish, D. & Cuthill, I.C. 2012. Does mutual sexual selection explain the evolution of head crests in pterosaurs and dinosaurs? Lethaia, 45: 139-156.

Taylor, M.T., Hone, D.W.E., Wedel, M.J. & Naish, D. 2011. The long necks of sauropods did not evolve primarily through sexual selection. Journal of Zoology, 285: 150-161.

Elgin, R.A., Grau, C., Palmer, C., Hone, D.W.E., Greenwell, D. & Benton, M.J. 2008. Aerodynamic characters of the cranial crest in Pteranodon. Zitteliana B, 28: 169-176.

 

 

Noripterus returns – sorting out some pterosaur taxonomy

New reconstruction of Noripterus by Rebecca Gelerenter. This is a composite based on all the material we have from various specimens (known material is in white).

Immediately after the Munich pterosaur meeting ended in 2007, I moved to Beijing to take up a postdoctoral position at the IVPP. Perhaps the first bit of mail I has there was from the now late Wann Langston thanking me for setting up the Munich Flugsaurier (which he had attended) and sending me a photocopy of his notes and some old photographs he’d taken on a trip to China back in the 80s. This was of a superbly preserved pterosaur hindlimb, and one he wanted to know more about but which had since not been seen by any researcher he knew, or been in the literature.

This was a specimen of Noripterus, a small dsungaripterid from China found by, and then named by, C.C. Young back in 1973. The original description of this was both a bit sparsely described, and in Chinese which is a shame as Young mentions a number of specimens, and illustrates or measures only part of some of them. I asked around the curators at the IVPP but no one knew the location of the material and it was suggested to have been borrowed and not returned.

Fast forward a couple of years and while Paul Barrett was visiting the IVPP he had been directed by a colleague to a little used set of cabinets in the collection, where apparently some mislaid dinosaur material was residing. I happened to be looking over a specimen in the collections at the time so inevitably was keen to see what might turn up. On opening the case, Paul found his specimens, but one thing I spotted was immediately recognisable from Wann’s photos – the lost Noripterus foot. Accompanying it was quite a lot of other pterosaur specimens with similar specimen numbers – Noripterus was back.

Since then I’ve been working on and off on a number of projects on these specimens (hampered by my no longer being in China) and the first is finally out as part of the volume from the back of the 2015 Flugsaurier meeting in Portsmouth. A more full description is in the work but this is the first and important step because the taxonomy of the Asian dsungaripterids has been an issue that’s been problematic for quite a while, and much of it hinges on Noripterus.

Things have been difficult to resolve because as noted, the original description doesn’t give that much information on the material (and less if you don’t speak Chinese – I am indebted to my collaborators here as you may imagine). If you want to sort out how various other species and genera relate to it (or not) you really need to know what it actually is anatomically and taxonomically, and so having the specimens available means we can make some significant updates to Young’s identification and how other more recent discoveries might relate to it.

First off the bad news – what was originally designated as the holotype is mostly still missing. Only a fragment of the jaws remain and they are not in great condition. Still, they are diagnostic which helps us to define Noripterus better. On the good news side of things, there is a lot of nice associated material as Young collected multiple specimens from just a few sites and despite the lack of overlap in some areas, there’s some good reasons to think they are all the same thing. Noripterus is known from several superbly preserved specimens including a near complete set of limbs and girdles preserved in 3D. There will be more on this in the future, but obviously it’s very useful material to have.

A superb set of limbs from one specimen of Noripterus

Working out quite which specimen was which however actually took quite some time and detective work. The field numbers on the bones and the specimen numbers on the boxes they were in, did not always line up with the identities given in Young’s paper (either illustrations or the few measurements).  Eventually though we got this sorted out and so one part of the paper gives some new specimen numbers and sorts out the various specimens into their (hopefully) correct sets.

The main issue though is the taxonomy itself of these animals. Noripterus was only the second dsungaripterid identified (you may not be shocked to learn Dsungaripterus was the first) and so it might not be a surprise that it’s considered a valid taxon. It is rather smaller than it’s more famous relative, and has straight rather than curved jaws, as well as rather more narrow teeth. That’s the easy bit.

Then we have ‘Phobetor’ from Mongolia, named from some very fragmentary material that has never been described in detail. More recently there’s more Mongolian stuff from 2009 called the ‘Tatal pterosaur’ that was used to link together that material, ‘Phobetor’ and Noripterus all under the latter name. On top of that we have the Chinese genus Longchognathosaurus known from little more than a few bits. Clearly lining these up and working out if there were one, two or three genera was going to prove difficult while 2 of these 4 sets of specimens were fragmentary and most had never been described or illustrated properly. In this context, getting to see Noripterus was clearly very useful in terms of making some meaningful comparisons of key characters.

So, what did we find? Well, actually the Tatal material and the original ‘Phobetor’ are very similar based on the limited descriptions of each suggesting they are the same taxon. However, they have some consistent differences with the Noripterus material which suggests they represent a valid and separate genus and should not be synonymised with it. That also means that ‘Phobetor’ is still lacking a name (it’s preoccupied by a fish). Finally, Longchognathosaurus has at least a couple of the supposedly diagnostic characters present in the holotype of Noripterus and while it’s not necessarily the same thing, it is hard to justify it being unique at this point.

Clearly all of this is provisional, and lacking a good skull for Noripterus (or at least the rest of the holotype) would really help firm all of this up, not least when the Tatal specimens include a good skull and Longchognathosaurus is based mostly from cranial material. In fact given how much good Noripterus material there is, it is an oddity that there’s so little of the head, but hopefully more will turn up. In the meantime, this should help move things forwards and provide a better basis for sorting out these taxa and some curiosities about their relationships to other pterosaurs (in particular Germanodactylus which may or may not be an early dsungaripterid). Now we just need some more detailed descriptions of all the other Asian dsungaripterids (and yes, more on Noripterus too) but this is a start.

 

TLDR: We have a good amount of Noripterus back. ‘Phobetor’ is probably separate and valid and the same thing as the ‘Tatal pterosaur’ material. Longchognathosaurus is probably not valid.

 

Sciurumimus again

Last week I took a very brief trip to Germany to do a round of several museums and collect some data for various projects I am working on. As well as catching up with some old friends (human and fossil) I got to see some new ones (human and fossil). I’ve been filling in the pterosaurs over on Pterosaur.net (including this guy which is an absolute must-see) but here I thought it would be best to bring back Sciurumimus. This little theropod did make an appearance on here when first described, but now I have a couple of pictures of my own (the specimen is currently on display in the Solnhofen Museum) it seemed time to bring it back. So here’s a couple of additional images of this outstanding little theropod.

Science communication and fossil preparation

As part of my travel to Canada for the Project Daspletosaurus work, I attended the Fossil Collections and Preparation Symposium hosted at the Tyrrell. Obviously I’m not much of a preparator, but after getting through the mammoth Gorgosaurus prep stuff with Darren Tanke, there was obvious scope to talk about sci comms in general and what we’d done with the field of preparation specifically and how me might go about improving that. All of the talks were recorded and have now gone up on line. There’s some cool stuff like removing old consolidants  or microvertebrate screening, so hunt around on the Tyrrell’s YouTube channel, so it’s well worth having a look around, there were a ton of talks.

Sexual selection in the fossil record

Regular readers will know that for the last few years I’ve been slowly building a research profile concentrating on the behaviour and ecology of dinosaurs and pterosaurs. While the various papers on feeding behaviour, stomach contents, predation and niche partitioning in theropods has been the more high profile, I think the work on sexual selection is arguably more important as it potentially has profound implications for how we interpret all manner of fossils and how they may (or may not) relate to one another. After all, there’s a major ecological and taxonomic difference between identifying two species of a clade, and one species that exhibits major sexual dimorphism.

My colleagues and I have already looked at the idea that sauropod necks were driven by sexual selection, and after much strife, finally got a paper published discussing mutual sexual selection and the implications that has for diagnosing taxa in the fossil record and what it might mean for parental care and other aspects of behaviour. There’s more to come in these areas as I have further work planned and am involved in some other areas linked to this, so the area is growing rapidly and, I hope, ripe for a general revisit in the literature. However, while these papers have in large part being about drawing out some false assumptions in the literature and providing new hypotheses about sexual selection that could be looked at in the fossil record, they were a bit short on how this could be done, and were if anything, narrow in focus (not that Ornithodira is a small group, but its got nothing on Animalia).

So then to a paper in TREE that came out yesterday online. Led by entomologist Rob Knell, it also includes  Darren Naish and myself and attempts to provide a review of the entire question of sexual selection in the fossil record. We look at ways in which this could be diagnosed, some false dichotomies and assumptions that have been put forwards in the past, try to identify some key features that may help diagnose sexual selection and look at some of the more convincing cases for this that have been put together to date. Clearly there’s a limit to what we can get into under 10 pages for what is supposed to be a review, but I think there’s some nice synthesis in there and a bit more “we can try doing this”-type stuff, that just covering what has been said before. Anyway it’s out and available (though behind a paywall, sorry) so go take a look.

Knell, R., Naish, D., Tompkins, J.L. & Hone, D.W.E. Sexual selection in prehistoric animals: detection and implications. Trends in Ecology and Evolution, in press.

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.

Another link round-up

Just a little post with some links that have come up recently, that I hope you’ll find interesting. This is a really good set, so do dive in.

First off, a massive collection of palaeoart by the legendary Zedenek Burian. And it really is massive, over 600 images, for me at least, there were hundreds I’d not seen before, as well as some great classics.

If you think you can get up to Burian’s standards but don’t want to get bogged down in all that tedious painting and drawing stuff, why not enter the 2012 Dinosaur Diorama contest at the Dinosaur Toy Blog. All in good fun and some nice prizes available.

Next there’s a lovely set of photos of Mesozoic bird specimens with commentary on them bu Luis Chiappe.

Then there’s Matt Wedel’s long and detailed posts (parts 1 parts 2 and now part 3) about the birfurcation of sauropod vertebral neural spines. Part 2 is especially nice as it contains a little guide and discussion on how to tell if a sauropod is an adult.

Mike Habib has also been looking at the interesting area of water launch in pterosaurs, an area that intersects with what I have been experimenting on.

And finally, one of the most recent Google doodles was dedicated to the father of moving pictures, Edwaerd Muybridge and his running horses.

Sinornithosaurus details

There’s no great purpose to this post, but it will become a little more relevant tomorrow with the follow-up so I thought it sensible to stick this in now. I have covered Sinornithosaurus a couple of times on here before since, well, it’s a great fossil (search the archives for various posts that mention it including a few photos). I do have these close-ups of the manus (above) and pes (below) so it seemed a waste not to use them in context.

While obviously the preservation of material like this means the bones are rather flat, it’s worth remembering that not all flat fossils are the same. You can get nice looking, but basically crushed specimens like the Microraptor gui holotype, of those where the bones split between slabs making a real mess like the second Anchiornis, or things like this which while compressed are not in 2D but have a lot of the shape of the bones retained as well as preserving soft tissues. No it’s not 3D, but there’s rather more detail in there than might be expected and it’s not the mess you might initially expect.

This will become more relevant shortly, stay tuned.

Fossil collecting – a delicate balance act

Outside of buying a token ammonite from a museum gift shop or a seaside fossil shop one might not think there was a huge amount of trade in the buying and selling of the remains of ancient animals. In fact it is a big business and people can, and do, buy specimens worth millions of you denomination of choice. This has all manner of mixed implications for researchers trying to study a dwindling resource.

While obviously animals like pandas and blue whales are critically engendered and may become extinct, with careful protection and good husbandry and a bit of time, you can get (theoretically at least) an infinite number of them – they will breed. On the other hand, the number of Tyrannosaurus specimens that there have been or will ever be is fixed. Only fossils remain and every one that is lost through erosion, built over by a road, destroyed by mistake or whisked off into a private collection will never be seen again. In theory at least those in a private collection may come back one day but often without the critical data of exactly where it was collected from.

Scientists make a policy of only studying specimens held in public (generally state owned and run) museums. There are some exceptions, but in general if it’s not there, you can’t work on it, or at least journals won’t let you publish on it. That naturally gives us a lot to work with, but good, even great, specimens are in private collections and private museums. True, these do sometimes hand over their material to other museums (which is nice) but as there’s no guarantee they ever will, so we stick to what we have and what we can get for ourselves.

And therein lies the problem. Digging up fossils is both expensive and time consuming. Researchers can only ever do so much, and with willing buyers out there, and many more dealers and collectors looking for fossils than the researchers then we tend not to find the best stuff, and we can’t afford to (and in many cases morally shouldn’t) buy them. In short, research is losing out massively to collectors.

The problem though is a very complex one. Good fossil dealers (and they are out there) are quite happy to hand over, or sell at a discount, or at least give first refusal to museums for good and important specimens. Generous owners do donate their collections or individuals specimens to museums. Many people will develop an interest in palaeontology and fossils they might not have had otherwise from the purchase or gift of some small trilobite or sharks’ tooth and I don’t think any palaeontologist would begrudge them it. The problem lies in where this kind of dealing should stop.

Selling on an ammonite of a species represented by thousands or even millions of specimens? Sure, go for it. How about some new and incredible species of dinosaur, preserved with a dead mammal in it’s stomach, a set of eggs in it’s body and preserved with skin and feathers? Absolutely not. What about a dinosaur foot though? Or half a skull? Or a single caudal? Or a broken tooth? Every specimen can add some information, even if it’s just to pool data and build a bigger database, but there is understandably a huge grey area in the middle, and one that is only compounded by confusing laws and regulations that vary between countires and even regions of countries.

It can be legal to collect and own fossils, and to give them to people, but not trade or sell them or export them. It may be legal to collect fossils only in certain places but then legal to export or sell them. It may be illegal to import fossils, but once in the country legal to sell them. It may be illegal to buy, sell or own fossils of ‘scientific importance’ without approval (though try defining that). Fossils may be dealt with as historical artefacts, or as art, or as zoological specimens, or even geological ones. Laws might be different for research as for private ownership. Given the international dealing of material (in the UK I have seen material from Morocco, Egypt, Germany, Brazil, the U.S.A, Mongolia and China for sale and we are hardly a big hub for this kind of thing) that makes for a big and complex mess.

Moreover, I have been to places where as a professional academic my group was required to obtain half a dozen different permits to dig and excavate material and had to pass all manner of spot checks and legal hoops to jump through to dig in an areas renowned for the levels of local illegal excavations. We get checked on as approved researchers, employed by said country to excavate, while over the hill people are walking off with rare and important specimens worth a fortune. Fossil dealers are common in some countries even when it’s expressly forbidden (I’ve been told of one famous dealership that sits on the street opposite the ministry who banned fossil trading). In short, even when the law is in place, it’s rarely or improperly enforced. Indeed it may not be possible to enforce as proving the provenance of a fossil can be very hard. Even when it can be narrowed down, geological formations do not follow national boundaries and it may be impossible to prove that a given specimen came from the U.S.A. and not Canada or Mongolia but not China and so on.

In short, it’s a nightmare. The laws vary from state to state, and often unclear or not enforced. Even when they are, it can be impossible to enforce or require huge amounts of expert time and effort to work out what something is or where it may have come from. Many countries most at risk obviously have more pressing concerns for their budgets and what they do have might well go towards tying to stop trade in more emotive problems like cultural artefacts or protected living species rather than what can be seen as chunks of rock. You certainly don’t want a blanket ban – people should be allowed to own fossils and that entails collectors and dealers, but at the same time important sites and specimens do need protection.

Where does this leave us? In a mess frankly, but one thing is for certain, the lack of clear national and international regulations and the lack of enforcement means that valuable specimens are being lost to science. And if gone, very few will ever come back.

Pterosaurs of the AMNH pt 1 – Solnhofen

Recently I talked about the slow diffusion of Solnhofen specimens that have made their way to institutions around the world. I’ve had a few good leads and comments already which is nice, and reader Steve Cohen was kind enough to send in some photos of the various specimens and mounts at the legendary AMNH. While this material is well known, most of the images I’ve seen date back to the 70’s and photocopies of scanned black and white photos are quite simply pretty low resolution.

My thanks to Steve for these and there’s more, non-Solnhofen stuff coming tomorrow. For the non-pterosaur taxonomists reading this, that’s a rather nice Rhamphrhynchus at the top. Below we have small Ctenochasma and then a really nice and complete Pterodactylus with a near-perfect counterplate.

Extra final bonus Gorgosaurus preparation post

Well, it has been a while since the last post where we finally rounded up and summarised Darren’s massive series of posts on preparing a Gorgosaurus specimen. Here Darren summarises the prep work done since and provides new photos of the skull now seen from the others side.

After a long hiatus, I update the Gorgosaurus preparation series, with this, the final installment. Since the last posting, the entire specimen, and select parts thereof were moulded in a high-quality silicone rubber compound so detailed casts of the specimen can be made in the future. After the moulds were removed, the entire specimen was covered in a separating layer of wet tissue paper, and then plastered over and flipped over.

The side now facing up is that which faced up in the field. As this is the upward-facing side, and there was only low rock overburden in the field, this side of the skeleton was more exposed to the effects of rain, frost, rock fracturing and rock expansion/contraction from summer heat (up to +40C) and cold winter temperatures (down to – 40C). Because of this, this side of the specimen is less well preserved, in fact I’d say in many places it is poorly preserved- in some areas the bone is like the consistency compressed hot chocolate powder. Bones are also badly crushed in many places. If I can remove the equivalent of a sugar-cube sized piece of rock per day, that is pretty good going as I super detail the many bones preserved. The skull, being better ossified, was in better shape, but the bone quite splintery in places. This means the work has proceeded very, very slowly. The tools and techniques were much the same as in earlier postings, though much of the work is being done with a head-mounted magnifying lens and later, probably microscope work. Also the work has to go much slowly. It can be seen that the posterior right side of the face is missing. This is because as the carcass rotted, the side of the head, exposed to water currents, was disarticulated and piece by piece the bones were washed away. We have a couple of them, but are missing 6-7 to make a full skull. However, we get a beautiful side view of the braincase which is important for researchers. We had the whole skull CT scanned recently and really nice images resulted for study by one of the Royal Tyrrell Museum scientists.

Preparation work on this side has also revealed some anatomical details that are important to future scientific study and eventual publication(s) that cannot be shared here or at this time and therefore, this series must end with this posting. I have been happy to share the preparation of this gorgeous little specimen with you all and hope you learned something about the intricacies of fossil preparation.

Best, Darren Tanke, Senior Technician II, Royal Tyrrell Museum, Drumheller, Alberta, Canada.

As usual all images are copyright to Darren / the Tyrrell Museum.

A little more on making Fedexia

Back at the end of last year, buried in the huge mass of posts based on my superb trip to the Carnegie in Pittsburgh, I covered this lovely little display about the creation of palaeoart, based on an animal named Fedexia. The artist responsible, Mark Klingler, was kind enough, not only to supply me with the means to get hold of his DIY Quetzalcoatlus, but also provided me with some of his files on his reconstruction to show the process rather more clearly. My thanks to him for these.

Key to the above collection:
A 1–3. Fossil skull: Dorsal View, Diagram, Lateral view

B. Reconstructed skeleton as it may have looked

C 1–11. Reconstruction process to create the look of Fedexia
C1. original pencil drawing with #2 mechanical pencil on Bristol board
C2. color overlay with color pencil on vellum
C3. scanned in pencil, contrasted in Photoshop
C4. overlay C3 over C2 in Photoshop
C5. scanned in pattern outline, original in pen & ink on vellum, and filled pattern dots in Photoshop
C6. knocked out areas outside pattern dots
C7. addition of purple form midtones
C8. addition of sky blue highlights on bumps of skin
C9. shadow overlay added to Fedexia
C10. highlight overlay added to Fedexia, later lightened in transparency
C11. final Fedexia striegeli reconstruction

D 1–6. Reconstructed environment for Fedexia; 2H pencil, mechanical pencil on vellum
D1. Thumbnail sketch layout
D2. Place Fedexia in for size
D3. Final pencil Pennsylvanian time period, some 300 m.y.a., plants include:
• Calamites carinatus (after Hirmer 1927)
• Psaronius (tree ferns from Stidd 1971)
• Fallen lepidodendron trunks
• Walchia (conifer, after Moret)
• Asterophillites equisetiformis
D4. Color overlay, color pencil on vellum
D5. Assembled pencil background contrasted in Photoshop with Fedexia reconstruction
D6. Assembled colored background with Fedexia reconstruction