It’s getting harder and harder for me to write these sadly, with my ever increasing teaching loads, and broader than ever outreach commitments, I don’t have much time to read as many blog pieces and media coverage as I used to, and a look though a few end-of-year reviews suggests there’s a few discoveries and papers I’d missed which is rather annoying. Still, it is good to at least try and look back over the last year and give a bit of a personal perspective and try and have a bit of fun.
Posts Tagged 'palaeontology'
Tags: Dinosaurs, palaeontology, Pterosaurs
Tags: Dinosaurs, evolution, palaeontology, sexual selection
Those with an interest in dinosaur cranial crests and exaggerated structures (which should really be everyone since they turn up in pretty much every major lineage one way or the other) will probably be aware of the exchanges going on in the literature over these features. Although myself and colleagues have been advocating that sexual selection (and or socio-sexual signaling: the two can be hard to separate) is a likely strong candidate as the prime driver for many of these features, others have been advocating that this is not the case and instead the answer lies in species recognition. The latest to delve into this area is a paper I’ve done with Darren Naish and is the first time we’ve addressed this issue directly. While we have written or contributed to a number of efforts looking at support for sexual selection in dinosaurs, this is the first time we have tackled the other side of the problem.
The paper originally started as a long section that was included in our paper on mutual sexual selection with Innes Cuthill, but as we were later forced to cut down the length of the submission, this was a section that was relatively easy to prune as tangential to the main issue. However, we felt it needed saying and with new data coming out and the discussion ramping up, we revived and revised the work and it is now out. (Well, it has been in press and available for a while but is now properly out).
This is an important area for discussion – after all, the horns, crests, frills, plates, bosses and the rest (not least feathers) are key features and adaptations in various dinosaur lineages and trying to work out how they might have been used and what this means for evolutionary drivers and patterns is going to be a major issue. It’s hard to really understand stegosaurs or ceratopsians say if you can’t say that much with confidence about their ‘bonus’ features. While obviously each clade, or even each genus / species probably needs to be taken on a case-by-case basis when it comes to detailed analyses, some gross patterns can be seen or at least discussed. In the case of species recognition, is it even an actual ‘thing’ when it comes to exaggerated structures, and if it is, how is it supposed to work. The hypothesis has enjoyed some support in the literature for some unusual dinosaur features so it’s well worth examining.
Species recognition (in the context of exaggerated structures) for those who don’t know, is the idea that individuals of a species use these features to help them recognise cospecifics with to ensure they mate with the right species, or to maintain herd coherence. In short, carry round a key feature and you should be able to make it easier to stay in touch with the right animals and avoid the wrong ones. Various lines have been put forward to support this idea (in general and specifically towards dinosaurs) but we feel that none of them actually stack up and some have some serious problems.
First off is a pretty big issue – to our knowledge there is no evidence of any living species using some form of crest or exaggerated structure for species recognition. Individuals of species do recognise each other (not a big shock) but actually things like antlers or casques don’t seem to form part of the pattern that conspsecifics recognise. This may not be a big shock, after all, you can recognise a species by the overall appearance (size, shape, colour), their smell or specific sounds they make, behaviour, and other features. On top of this, some species are very varied in appearance for the big features (antlers of deer look very different as they grow, and are different between males and females and between juveniles and adults etc.) so relying on one feature is a bad idea at best, and a plastic one an especially bad call.
Plus of course, you often get closely related taxa that are sympatric. Is some big set of horns going to help you correctly identify conspecifics if there are half a dozen similarly-looking species also in the area? Look at things like African antelope and gazelle, or more extreme examples like tyrant flycatchers. We have trouble telling them apart sometimes based on their morphology, yet they seem to have no trouble. If this is so critical to dinosaurs, why to the iguanodonts seem relatively free of crests, but the hadrosaurs go nuts with them? And why are they all so similar in general form between species when they are supposed to help separate them out? Surely they should be divergent, not all similar in appearance. And why do we see things like Wuerhosaurus or Spinosaurus running around with all this weight to make sure they don’t mate with the wrong species when there are no other members of their clade to get confused with?
In some cases we see both issues coming together. If we look at the various small protoceratopsians of China / Mongolia, we see disagreement between researchers as to how many species (or genera) there may be. What is notable however, is that the characters being used to separate them out don’t typically involve the frill or bosses of the skull, and where they do, may be things that are not externally visible (e.g. the width of the media bar in the frill). In short – if there are multiple species here, the frills are apparently similar enough that we can’t separate them and so are unlikely to be part of the identity concept of the animals. If however, there is only one species present, then we are back to the paradox of a large frill being carried around but with no other species that could confound any signals.
On top of that, is it really worth it? After all, while you do want to stay in touch and make sure you mate with the right species, bolting on a good few kilos of bone to your head, and then the extra muscle to support it, and then lugging that around for your entire life is a lot of effort. When you can probably already identify conspecifics by their colour, patterns, scent and calls (of simply because nothing else like them at all is on the same continent) surely these would experience strong negative selective pressures if they didn’t have any other support.
Furthermore, how would such features ever evolve? If the populations / species were allopatric then we return to the situation of them not having another group to get confused with and crests are unnecessary for recognition. If they were sympatric though, how would this work? Pretty much the definition of a natural biological population is one that is breeding within itself, but here we’d have to have a population diverging because some don’t recognise each other as conspecifics even though we would expect, pretty much by definition, there not to be too much difference in structure shape between them (e.g. a tiny crest vs no crest). Now some animals might prefer each other, but that’s mate choice, not recognition, and there would have to be enough individuals for this to work – one mutant with a crest when no one else has one is not going to start forming a new species, and if there were a bunch of the with the new crest they’d also have to identify each other as different and avoid mating or hanging around with the others. So how would a large feature that’s for correct recognition allow a population to split in this way? To us at least it appears most unlikely to occur at all, let alone repeatedly.
In addition to this, there is rampant hybridization of closely related species in the natural world (and indeed in captivity). Even extravagantly ornamented species like pheasants with numerous adornments and bright colours and patterns hybridise regularly – clearly no matter how extreme the cue, at least some animals regularly have problems with them or are indiscriminate, but either way they are not that effective.
While some data like the apparent rapid growth of structures late in ontogeny has been used to support the idea that they are characteristics involved in socio-sexual signaling, it’s also a problem for the herd coherency part of the model. After all, lots of juvenile dinosaurs are known from aggregations suggesting they spent a lot of time together, even when the adults did not appear to. If these features were key, we’d expect juveniles to have them, and adult perhaps to shun them when they were no longer needed, but instead the opposite is true. In general the herd coherency argument is a bit odd anyway, again you have lots of ways of identifying and keeping in touch with conspecifics and some are clearly better than visual aids. Scent can have a temporal component, and vocalizations can be interactive beyond line of sight (especially useful in forests, or when things are behind you, or you are foraging and looking down etc.). No matter how big they are, visual structures are not always going to be that useful, even if they are unique.
In the increasingly infamous issue of Torosaurus and Triceratops, if these animals are truly conspecific then for a start we are back to the issue of ‘lone’ taxa (I don’t think Leptoceratops is going to be much of an issue here) and the pointlessness of crests where none are needed. On the other hand, this is also potentially a problem for the mate recognition idea. We know that at least some dinosaurs were sexually mature before they were osteologically mature and this could be the case for these animals too. If so, then the alleged transformation between one morph and the other would create confusion – both the Triceratops morph and the Torosaurus morph (or indeed anything in between) would be viable mates.
In short, we really have no clear evidence for species recognition in any living species, and that alone should make it unlikely to have been a key player across dinosaurs for the whole Mesozoic. Such structures would be costly, and yet not necessarily do the job it is supposed to with other signals being cheaper and just as effective, or more effective in many circumstances. It’s not clear why it should be so important for some clades and not other similar forms (iguanodotids vs hadrosaurs for example) and is clearly either redundant for some taxa, or would not actually reduce confusion. Nor is it clear quite how this would evolve in the first place, or why it would be sustained, and hybridization suggests that crests alone would not even prevent incorrect matings. Put this all together and we feel that there really is no good support for the idea of crests and other structures being primarily used in species recognition. They did of course likely have an effect – it would be odd if Stegosaurus or Corythosaurus didn’t use their respective features as part of how they identified one another. But that does not make them the prime, or only, driving force of all these different features in all these different lineages.
There was a fashion in dinosaur palaeo to write off any odd structure as simply sexual selection and leave it there. This was rightly railed against, but what was often criticised was the fact that sexual selection seemed undiagnosable in the fossil record and so the problem was that it was untestable rather than the fact that such throwaway remarks devoid of context or explanation do little for the subject. Now we are in the odd position where rarely you see very similar comments (in terms of their style) about species recognition popping up in the literature about exaggerated structures despite the lack of support for it, and the now (well, we think), strong cases made for sexual selection, or at least it’s assessment. Although previously the case for sexual selection was pretty weak, it is at least an extremely common phenomenon in living taxa and with obvious powerful effects on anatomy and behaviour. Species recognition has not yet even been shown (in relation to exaggerated structures) in any living clade, and while offhand one-line explanations are not the way to go, it seems odd that one has been replaced with the other.
Tags: evolution, fossils, palaeontology, review, sexual selection
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.
Tags: academia, palaeontology
David E. Fastovsky, University of Rhode Island
Mesozoic, terrestrial vertebrate-bearing paleoenvironments, vertebrate paleontology
1. What first got you interested or involved in your research field?
Roy Chapman Andrews: All About Dinosaurs (1953).
2. What is your favourite piece of research?
Overall, I loved working on fluxes of vertebrate extinctions at the K/T boundary; I also loved working on some very interesting vertebrate-bearing paleoenvironments in NE Mexico; the rocks were crazy; the fossils were weird; it just doesn’t get better than that!
3. What do you think is the most interesting or important discovery in your field in recent years?
Feathered non-avian dinosaurs; the extinctions at the K/T boundary.
4. What do you think is the biggest unanswered question in your field right now?
We’ve begun to move from individual specimens to ecosystems. That kind of work should continue; that’s how to really capture the great rhythms of life through time.
5. What advice would you give to students about research?
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.
Tags: fossils, palaeontology
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.
Tags: Dinosaurs, fossils, palaeontology, theropods, tyrannosaurs
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.
Tags: fossils, palaeoart, palaeontology
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
Tags: arts and crafts, fossils, kids, palaeontology, Pterosaurs
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).
Tags: fish, fossils, palaeontology, Pterosaurs
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.
Images for this post kindly provided by Helmut Tischlinger.
Tags: behaviour, Dinosaurs, ecology, fossils, palaeontology, Pterosaurs, velociraptor
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.
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.
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.
Tags: crocodiles, fossils, Mexico, palaeontology
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.