Posts Tagged 'palaeontology'



Make your own Quetzalcoatlus!

Back in my stint at the Carnegie, I had a great chat to Mark Klingler about his palaeoart. Mark mentioned that years ago he had created a little ‘build your own pterosaur’ kit where you could print out a Quetzalcoatlus he had designed and stick it together. He was extremely generous in offering this to the Musings to go up for people to do themselves, but he needed to check the copyright issues and find the necessary files.

Mark got back to me the other day to tell me that unbeknown to him, the files were already online and available on the Carnegie’s own website. So problem solved, you can get them whenever you want and make your own (small) giant pterosaur. Just go here and follow the instructions. Mark was cunning enough to make it so that it’s a skeletal view on one side and a life reconstruction on the other!

So get building and enjoy. my great thanks to mark for his original generous offer and for tracking down his files. Sure it’s easy enough to get them where they are, but even he didn’t know, so I’m delighted to bring this to a wider audience and well done to the Carnegie too for making this freely available for kids (and palaeontologists).

Looks like I picked the wrong week to quit writing about pterosaurs being killed…

Surely this can’t be serious? Yeah you wait years for a paper about pterosaurs being munched on by other vertebrates and then two come along at once. A paper? What is it?

In this case it’s an online publication, which is nice (PLOS again so freely available, reference and link below). This time it’s from (very) occasional Pterosaur.net contributors Helmut Tischlinger and Dino Frey. It seems the large Solnhofen fish Aspidorhynchus may have had a thing for pterosaurs.

While other specimens are apparently known of a similar interaction, a new specimen has come to light showing individuals of each species being intimately linked. Nope, it’s not that Rhamphorhynchus had a drinking problem so much as it got grabbed and dragged under by the fish. Too big to eat and with its wing membranes stuck in the teeth of the fish, the two were locked together. Drifting into the anoxic zone of Solnhofen lagoons (little use for loading or unloading there) would have killed them both, still locked together (and is also how you get things like this).

Interestingly, while Aspidorhynchus had tried to have ‘chicken’ for dinner, the flying pterosaur had had fish (incidentally I had lasagna). There’s a fish in the throat of the pterosaur, suggesting it had only just caught one at the surface of the water when it was snagged by the bigger fish below.

Right, I’ve got to go take a call on my white phone to do an interview about Microraptor colours, and it’s not a big pretty white one with a red stripe down the side.

Frey E, Tischlinger H (2012) The Late Jurassic Pterosaur Rhamphorhynchus, a Frequent Victim of the Ganoid Fish Aspidorhynchus? PLoS ONE 7(3): e31945. doi:10.1371/journal.pone.0031945

Images for this post kindly provided by Helmut Tischlinger.

Velociraptor scavenging an azhdarchid pterosaur

Image courtesy of, and copyright to Brett Booth.

So yesterday at short notice I rushed up this teaser post which seemed to do the trick, and now I’ve got a bit more time on my hands, I can start putting down a proper post on the subject. Yep, I have a new paper out and this time featuring dromaeosaurs and pterosaurs. Long time readers will remember that almost exactly 2 years ago I had another paper out on dromaeosaur scavenging featuring shed teeth and bite marks on some Protoceratops material. Coupled with the famous fighting dinosaurs specimen we have pretty good evidence for dromaeosaurs, and specifically Velociraptor for feeding on this dinosaur. The record of dromaeosaur predation and feeding is actually pretty good compared to other theropods groups and there is also an isolated pterosaur wing bone from Canada with shed dromaeosaur teeth and bite marks.

This ‘new’ specimen marks the first record of gut contents for Velociraptor and the first record of a pterosaur bone as gut content in a theropod. (The ‘new’ is becuase this specimen was actually found in the 1990s, but has yet to be described, though I’m told there’s a photo of it in Luis Chiappe’s recent birds book). Thus we do have rather exceptional evidence for a Velociraptor chowing down on an azhdarchid.

Velociraptor specimen with a pterosaur bone as gut content (black arrows). From Hone et al., 2012

And here it is, well part of it. The Velociraptor in question was remarkably well preserved and complete which allowed the preparation of it with the chest cavity as a single articulated piece with the vertebrae, sternum, ribs, gastralia and even uncinate processes all intact and in their original positions. The bones are really well preserved and much of the material has been prepared free of the matrix entirely. One obviously example is the skull which, bizarrely, is on display in Barcelona so at least some reader might have already seen that, though sadly I haven’t and had to rely on some superb photos kindly sent by Fabio Dalla Vecchia. It’s hard to show the bone off properly what with the whole ribcage in the way (which is, incidentally, a broken ribcage, one of the ribs took a huge battering and shows a healed break – white arrow in the above picture). S you’ll be delighted to know there are also some close-ups in the paper like this one (below) and even some CT scans in the supplementary data.

Close up of the bone. From Hone et al., 2012

As you can see the bone is incredibly thin-walled which is the major reason that it’s inferred to be an azhdarcid pterosaur, though their presence in the Late Cretaceous, including a related formation, and the general absence of other pterosaurs in the Late Cretaceous helps support this identity. Given what is around and the thinness of the bones, it’s pretty unambiguous as indeed is the identification of the dromaeosaur as Velociraptor given that we have basically the whole thing. In short, this is about as convincing a case as one could make that a Velociraptor had eaten an azhdarhid. But was it really scavenging? Well that and other issues I’ll be talking about tomorrow, as there’s quite a lot more to say on this. Stay tuned.

Finally, my thanks to Brett Booth for more awesome artwork for me to use, and you can see more of this and my interview with him on his dinosaurs here.

Hone, D.W.E., Tsuhiji, T., Watabe, M. & Tsogbataar, K. Pterosaurs as a food source for small dromaeosaurs. Palaeogeography, Palaeoclimatology, Palaeoecology, in press. Horrible uncorrect proof and behind a paywall, but the abstract, figures and other bits are visible to all.

Deinosuchus on display

Very longtime Musings readers will remember I had a lovely autumnal trip to Mexico back in 2008. While I traveled around a bit, this was based at the Museo del Desierto in Coahulia. I still have friends there, and indeed one before I went – Héctor Rivera-Sylva was doing his MSc in Bristol when I started my PhD and we’ve been in touch ever since. In fact we have just had a paper accepted on some local (to him) dinosaur specimens. More of that soon, but today I’m looking towards Héctor’s most recent project on Deinosuchus.

As big and badass crocs of the Mesozoic go, Deinosuchus seems to play second fiddle to Sarcosuchus. Despite the impressive size of the latter, it’s hard not to look at it and think that the skull is at least superficially gharial-like and really rather narrow for much of it’s length. Deinosuchus on the other hand appears to have both sheer size and a real set of ‘proper’ crocodilian chompers.

Héctor has described some new Deinosuchus material from Coahuila (shown above) and clearly they felt it was time to give this animal it’s dues. So Héctor and the rest of the prep team at the museum set about creating a mount for display and it was unveiled just recently. He’s been sharing his photos online and was kind enough to let me grab a few of them to post up here. As you can see there are in fact two, a whole body one and then a front half that lunges from the water at a rather blasé Tyrannosaurus.

What is perhaps more interesting for some is the construction process of these mounts and not being one to write one post when I can eke two out of it, they will be following tomorrow.

Not a fossil

One occupational hazard of being a palaeontologist is that it’s quite a rare field to be in and yet fossils animals and especially dinosaurs are familiar to the public. Thus odd rocks and cattle bones can, to the untrained eye, look very exciting. With a regular feed on media stories along the lines of “Sam Smith found an odd bone on the beach and it turned out to be a new dinosaur” it’s no great surprise that people are eager to push these to the nearest palaeontologist or geologist, no matter how far fetched the idea or unlikely the interpretation. Pseudofossils cause particular problems, but any old chunk of rock or bone can be prized as a shell, dinosaur bone, mammoth tusk or usual shell.

It’s a common enough problem that people in the past have had to take action. I got hold of this recently from one of the curators at the Natural History Museum in London. It’s rather old (the fact that it has a telegram address is rather a give away, as is the style of the phone number) and shows that even what was (I’d guess) 70 years ago or more, that it was considered an important time saver to have these printed up with the most obvious candidates prelisted and ready to be checked off.

This is true of other fields as well. Archaeology perhaps unsurprisingly suffers from a near identical syndrome (prompting this piece of humour) but others get it too. I recall in Simon Singh’s superb book on Fermat’s Last Theorum that so many mad and bad attempted proofs of the theorum were sent to a university professor who was supposed to assess them that he had thousands of cards printed similar to that above that ran along the lines of “Dear…., the first error in your proof is on page….. line….., thus the proof is flawed”. It’s an ongoing struggle and one we cannot win. But in the meantime it can at least be fun.

The top 5 most important pterosaur specimens

Just an idle bit of fun this, but the thought was running through my head and I thought there was a blog post in there somewhere so decided to have a go at it. All very subjective of course and hard to assess but there are issues of completeness, importance, the scientific information held or conveyed by the material and other things. Anywhere, here’s my effort at least (in no particular order):

1. The Dark Wing Rhamphorhynchus.

Specimens from the Solnhofen are not uniquely flat, but the vast majority are compressed into two dimensions. The sheer number of Rhamphorhynchus specimens means that we do have a great understanding of their anatomy and ontogeny, even if it is 2D and there are lots of specimens with bits of soft tissues or unusual details preserving. This specimen though pretty much has it all. It’s complete, the bones are nearly entirely in 3D and it comes with a magnificently preserved set of wing membranes – easily the best out there. Stick all that together and it’s a hell of a specimen.

 2. Jeholopterus holotype

Sure Sordes is nice and already covered in pycnofibers, but Jeholopterus is much the better preserved with more details of both ptero-fuzz and the wings. As a bonus it’s by far the best preserved anuroganthid specimen (well in total, the juvenile Anuroganthus is magnificent but has no softs), an otherwise badly known but potentially very important group.

3. The Tokyo Anhanguera

Probably the single most complete and 3D specimen I know of. Sure there are a few bits missing, but unlike the dark-wing, every bone is free of the matrix and can be picked up, turned around, examined from every angle and checked. Sadly it’s a juvenile and so some of the features aren’t quite what they would be at adult, but it is one hell of a specimen for the actual gross skeletal anatomy.

4. The Darwinopterus + egg combo

This one is a bit fortuitious since it does rather let me get a two-for-one with both a transitional pterosaur (and just how significant that is for a number of reasons) and gives us a bona fide pterosaur egg. Each tells us so much about pterosaurs and pterosaur evolution, it’s an incredible animal.

5. The big Quetzalcoatlus.

Every specimen can tell you something, and there are surprises everywhere. The new Nyctosaurus and Thalassodromeus revealed how huge crests could get, the series of ‘Tapejara’s told us about the integration of soft tissues, Raeticodactylus served a warning about eudimorphodontid-like teeth for taxonomy. But head and shoulders over all of this is the giant specimen of Quetzalcoatlus (even if it isn’t yet properly described). Size is such a crucial aspect of the biology of any organism, but in this case it is simply so big and in a flying animal too, that it really was almost a gamechanger for our understanding of pterosaurs in their own right. That a flying animal could get this big was a shock (despite some of the wild estimates, 10 m is bloody massive!).

 

And to close out, a few near misses from the list: footprints that showed us how they walked, the Pterodactylus holotype which brought pterosaurs to the world, one of the embryos which proved they did lay eggs and gave us a window into their life history.

 

 

Online resources for palaeontologists

I was chatting to Mike Taylor the other day about Cladestore as I couldn’t find the page I needed and was surprised he didn’t know of it. To be fair it did start off well and then rather sank, but the principle is sound and it seemed relevant enough that he might know of it. It is, in short, an archive for the various files and datasets used for phylogenetic analyses. Obviously these are generally published alongside any paper that they feature in, but typing these out again or taking the raw data and formatting it into a useable manner can be a pain, and it’s not always easy to get things out of the original authors. The idea therefore was to create and archive for these files so they were easily accessible to all. Since this does seem little known, it’s well worth advertising. And I should add that despite it’s slight antiquity, I believe they still take submissions so send ‘em your nexus and tre files.

Coupled with my reference to the Paleobiology Database earlier and it got me thinking. It would be nice if there was a single, simple, one-stop-shop for all manner of palaeo websites and online resources that are useful to researchers and those interested in the field. So I’ll try and create one, as it’ll help me learn and I expect, help my colleagues. So, anything you can think of, do submit it below. I’m thinking general stuff – a database of tyrannosaur specimens, or pterosaur papers is fine but it won’t be of much use to too many people so it’s not really worth putting here. I’m thinking of major resources that cover whole fields or are simply so vast with the data collection that they are must-know-abouts.

Here’s the few I can think of, add yours below and I’ll package them all up. And do spread the word please – blog and tweet this. This could, I think be very useful to a lot of people.

VertNet – online registry of vertebrae specimens (recent and fossil)

iDigBio – index of specimens in museums (often with photos)

Cladestore – archived phylogenetic datasets

Morphobank – more phylogentic datasets

FigTree – creates phylogeny diagrams for publication

Palaeobiology Database – data of fossil specimens, deep and wide set of data

Tree of life – phylogenetic tree of the whole diversity of life

Palaeotology Journals – Jerry Harris’ lists of journals, major and minor, that publish palaeo papers

Rankings of Palaeo Journals – Kenneth de Baets’ list of journals and things like IF, SJR, OA etc.

Polyglot Paleontologist – translations of non-English papers

The Marsh Archive – PDFs of papers by Marsh

Stratigraphy.net – archive of stratigraphic data

Phylogeny programs – list of phylogenetics software

Morphometrics – various resources for morphometric analyses

Morphobank -hmm, link doesn’t load for me…

Digimorph – digital anatomy archive of extant and extinct taxa

Comparative osteology database – mostly mammals and a few birds, but very good

3D skulls – Witmer Lab visualisations and scans of various taxa extant and extinct

Paleoportal – search museum collections for specimens

Data Dryad – data of all kinds from published papers

Figshare – data of all kinds from unpublished studies.

Biomesh – FEA models and properties.

Biodiversity library – huge archive of books and paper.

Microstrat – stratigraphy database

I’ve started adding these as the comments come in so it’s easier for people to see and avoid duplicates rather than have to hunt through the comments to see if they have been suggested or not.

Guest Post: Dysalotosaurus histology

Today Tom Hübner takes us through his recent paper on the bone histology of Dysalotosaurs. This little ornithopod is a close relative of Dryosaurus (pictured here) but unlike the US Dryosaurus, comes from the famous Tendaguru beds of Tanzania. This is a great piece of work to see for me as Tom started this work for this PhD thesis in Munich while I was there and so I know the long hours and hard work Tom put into this and it’s great to see it come to fruition.

Many of you might know it already that I finally got a rather long paper on the bone histology of a small ornithopod dinosaur (Dysalotosaurus) published in PLoS ONE. 29 pages sounds like a lot but I wanted to break with tradition a bit to publish only as brief a paper as possible. This had something to do with the beginnings of my studies on bone histology because most papers at that time restricted the information to the most necessary facts which was quite difficult to follow and reconstruct. Without the personal help of ‘experts’ I never would have understood all that. Another reason for the length of the paper is the enormous variation in the microstructure of the bone. Many times I was struck by a completely different type of tissue and it needed some time to identify them and sort them out. That’s because ‘variation’ is also one of the three main topics of the paper.

Anyway, for everyone interested in bone histology, I think it is worth reading [seconded, it’s a great review as well as providing new information and analyses]. The most important aspect is the usage of a new type of growth cycles for life history reconstructions which might be applicable for other vertebrates as well, especially when they lack lines of arrested growth (LAGs).

From Hubner, 2012. Thin sections of Dysolotosaurs bone in normal and polarised light

Some might wonder why such a small animal delayed sexual maturity until about its 10th year of life because it should suffer many losses by all types of predators. Well, that’s a good question and difficult to answer. One strategy is definitely the precocial breeding strategy, but the predators could also be the reason for delayed sexual maturity. The animals would not start breeding until they were large and strong enough to withstand the additional stress of mating and breeding, and they still had at least 5 years for reproduction because, according to the size-frequency distribution, only after about 15 years of age decreased their abundance within the herd significantly. Large ornithopods, on the other hand, had the opposite strategy (see Cooper et al. 2008) by outgrowing predators in a short time. Most of them also had altricial breeding behavior. This, and other arguments presented in the paper, could be a good non-phylogenetic difference between small and large ornithopods in general, but there is still much do to before this can be a strongly supported theory. As always: “More fossils and more studies …”.

From Hubner, 2012: Comparative growth rates of Dysolotosaurs with other dinosaurs and mammals

Constructive criticism is always welcome, so don’t hesitate to post them. I’m still not at all too old to change my mind. Well, this is science – nobody can learn something new without knowing where the mistakes are.

As this is in PLoS ONE, the paper is freely available here.

Hübner TR (2012) Bone Histology in Dysalotosaurus lettowvorbecki (Ornithischia: Iguanodontia) – Variation, Growth, and Implications. PLoS ONE 7(1): e29958. doi:10.1371/journal.pone.0029958

Mutual sexual selection in dinosaurs and pterosaurs

As of last night my latest paper has come out, coauthored with Darren Naish and Innes Cuthill. Those with access to the journal Lethaia can get it here. Believe it or not I’ve been juggling with the idea as to whether or not to blog about this for quite some time. This is, I think, the most significant paper that I’ve produced and it’s the product of literally years of work (though at least part of that was as a result of very difficult editors and referees at various times, this was started back in 2007!) and I’m really rather proud of it.
Then why not blog it? Well the short answer is that this is a long and complex paper and it ultimately deals with a huge range of difficult issues (and not in the length we’d have liked, it had to be cut down severely to fit the journal and we still incurred page charges). It touches at various times on pterosaurs, sauropod body size, various ornithischian lineages, theropod sociality, the origins of feathers among other themes. All of this means that it’s very hard to blog about and cover the salient points for a non-expert audience without writing thousands upon thousands of words and, well, I did that for the paper.

This is obviously counterintuitive for a blog that is effectively about science communication, but I can’t do everything all the time (I certainly haven’t blogged all of my papers of the last few years). Moreover, in my experience, a paper like this which rather stomps a bit over some much cherished hypotheses of people tends to attract huge number of comments along the lines of “but what about *this* contrived example!” which I can assure you gets very annoying when people won’t let it drop.

None of this means I *won’t* be blogging it at length. But I know it’s likely to be covered a bit elsewhere on the web and thus it’ll look odd that I’m not doing it right away and it seemed sensible to provide an explanation up front. What I will at least talk about it mutual sexual selection – it’s right there in the title and the abstract and is, I suspect, a concept unfamiliar to most, perhaps nearly all, readers. it is after all, something almost entirely absent from the literature on dinosaurs and pterosaurs, Darren and I could only find two other references to it ever and one of those was what we put into the Taylor et al. paper on sauropod necks and the other sprang from Portsmouth. So it’s something that’s only really just coming into the literature.

Sexual selection is probably familiar – the idea that some traits are selected for by the opposite sex and can drive the development of bight colours, crests. displays and all manner of other things. The obvious one that’s endlessly used is the train of a peacock, that makes the male look very different to the drab female. This is typically coupled with sexual dimorphism (again, like the peacock) where the male is bigger than the female and has the extra ornaments etc. and males compete for females, with the best ornaments males advertising their fitness through the size and quality of their fitness (though in some cases like jacanas, this is reversed with bigger females).

So far, so simple. Mutual sexual selection is simply an extension of this into both genders. Both males *and* females are ornamented (or rather, have sexually selected traits) and just as males are competing with other males for the best females, so too the females are competing with each other for the best males. This means that dimorphism is limited or even absent – both genders having such traits. This is in fact, well known for quite a number of bird species and the number of papers on the subject in living species is increasing in leaps and bounds.

In the paper we hypothesis that this may have been common in the ornithodirans. It explains (potentially) quite a lot and solves a couple of previous paradoxes about crests evolution and development. Critically it means that you *don’t need* dimorphism of a feature for it to be sexually selected – both genders can have a crest and it can still be a sexually selected feature. This needs testing, this paper does little more than lay out all the conceptual issues and evolutionary biology and ecology behind the hypothesis, but at the same time, I think we do have some pretty good support for our ideas.

But as ever, what really needs to happen is for you to go and read the paper! And yes, I do have a PDF if you want it.

 

HONE, D. W., NAISH, D. and CUTHILL, I. C. (2011), Does mutual sexual selection explain the evolution of head crests in pterosaurs and dinosaurs?. Lethaia. doi: 10.1111/j.1502-3931.2011.00300.x

Another Allosaurus


So having never covered Allosaurus before on the Musings in what, four years, I’ve now done in twice in the last few months. Last time out it was in Japan, but this is an all-American one that’s sat (to no-one’s surprise) in the Carengie. Well, more running than sat, but you get the point. Here it is alongside an Apatosaurus, though perhaps making its way towards junior.

This being the Carnegie, there’s also an original skull to accompany the mount and let you see real bone alongside the cast. Though as Tom Holtz has pointed out in the comments, it’s Marshosaurus and not Allosaurus.

Western Interior Seaway

Well we’ve been through a whole load of pterosaurs and dinosaurs over the last few weeks, but now it’s an opportunity to cover some of the other bits of the Carnegie. Starting with this superb corner dedicated to the Cretaceous Western Interior Seaway. There’s a mixture of mounts and murals and cases, and what a selection. I’m not normally too moved by the marine side of the Mesozoic but this was superb. Things I’d not seen before (my first icthyorniform bird) or only ever seen as casts (my first Archelon) or just impressive (the massive and incredibly mounted 3D fish skeletons). Great stuff.

Reconstructing Fedexia

Today’s sign is a bit of a different one. It comes from the Carnegie’s superb family gallery that lays out a fun and informative A-Z of museums, what they do, how they work, and why they are important. Here is a lovely display about the reconstruction of a fossil taxon by noted artist Mark Klingler.

While I have seen a number of signs and exhibits about producing like reconstructions of fossil animals, but these tend to focus on fleshing out skeletons and issues of colour patterns, but here it’s devoted more to the art itself. Sure those issues are present here as well, but there’s things about composition and structure. It’s a level of depth I don’t think I have seen before for this subject and it was well presented, especially in a gallery of the museum focused at a younger audience.


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