Archive for the 'Dinosaurs' Category

Testing for sexual selection

I had a new paper out a few weeks ago but it was at the very height of my busy start to teaching and so barely even got a tweet out about it and completely failed to do anything on here. That’s a shame as this is a paper that has some serious and major implications for trying to detect sexually selected structures in extinct animals (and indeed looking at some odd structures in living ones too). I’ve written a huge amount about dinosaur dimorphism and sexual selection and with numerous papers covering different aspects of the evolution and behviour of dinosaurs (and pterosaus) when it comes to signals and sexually selected things like crests, spines and horns.

The short version is that these are of course hard to look at becuase we can’t directly observe behaviour in extinct animals and coupled with small sample sizes, taxonomic uncertainty of specimens and then issues like extended growth periods and cryptic dimorphism and this is a frustratingly tricky subject to tackle. One standard, if imperfect, measure has been to look at the growth trajectory of the anatomical feature in question and to see if it grows more rapidly than the rest of the naimal, especially iof this happens relatively late in ontogeny. In short, animals don’t need sexaul display structures when they are not sexually mature but when they are this is important so things like horns tend to be small for a long time and then grow very quickly.

This paper led by Devin O’Brien and featuring a host of sexaul selection theroists and biologists posits that things may be more complex still. Features that directly rate to body size will be postively allometric (this can include things like horns and crests in dinosaurs) but those that are not (like say a moths’ antenna), will not. The former are accurate representations of the animals they are attached to and so act as a proxy for their size and quality, but other traits that can still be variable and under sexual selection are not acting in this way and so wouldn’t follow this pattern. There may even be some allometry in these latter traits (non-reproducing animals will not likely invest in such features until the can mate) but the allometry will be much greater, and the correlation with body size present in visual signals.

To help resolve this, we also reccommend in the paper that allometry be tested not jsut again body size but also some other reference trait that is likely to (or been shown to) grow close to isometry. So for example, don’t just measure your dinosaur horn as it related to overall skull size, but also compre it to something like tooth size or humerus lenght. That will help keep things clear when there are other traits around that can grow rapidly or are large but that don’t function as signals. One wonderful example of this we inlcude is a comparisons of the horns on the head of a chameleon with the lenght of the tongue. We used foot size as a reference trait andf show that while both tongues and horns do show allometry, the tongue is little more than isometric but the horns (used in combat and an obvious visual siganl to reflect that) have a much greater allometric slope and show greater variability which is likely to reflect differing quality.

We include a whole raft of such measures of various animals from insects up to mammals and covering both signal and non-signal traits. Two extinct animals were included based on dataset I’ve been working on for a while and may be of interest. One was the frills of Protoceratops which I and colleagues did some time ago but now updated with some extra specimens that we did now have before. These produced a simialr result to our analysis which is no big surprise but nice to see the previous results verified. The second one though was to look at the growth of the tail vane in Rhamphorhynchus.

The standard interpretation of basal pterosaur tail vanes has been that these functioned in steering in flight and acted as something of rudder. That works out quite well since many of the shapes adopted are surprisingly close to the rudders actually made for various aircraft and putting a small vane at the end of the tail would make mechanical sense to increase the effects. However, it is notable that the vanes for Rhamphorhynchus (the only pterosaur where we have a decent sample size) seem to change quite dramatically in shape as they grow and this is rather at odds with the idea that this is purely mechanical. Similarly, there is some serious variation between various basal pterosaurs in vane shape which suggests that the tail is unlikely o be (purely) mechanical in function and the fact that the pterodactloids gfot rid of theirs implies it is hardly critical for flight. Some people have suggested that these vanes were therefor acting as some form of signal and our analysis bears this out. The height of the vane grown very considerably and shows strong positive allometry as the vane changes from a narrow leaf shape in juveniles to a triangle in adults. The vane could of course be multi-functional and it could well be that it has been co-opted from something initially mechanical to function in signaling.

The fundamentals of the methods and theory described here have been around for some time, but the nuance is important to try and distinctuish between traits that are sexually selected and those which are also likely used in some form of display and even combat. It should make for a more reliable way of assessing these kinds of traits and that should be of real benefit to palaeontologists who have an interest in these things. I hope it is not long until more animals are formally assessed for their growth trajectories and what that might mean for understanding their behaviour.

The paper is open access and is freely avaiable here:

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.

Yet more on bite marks

Yes, I have a new paper out and it is another paper describing bite marks on bones. I have done a number of these now and it can easily seem that they are incremental publications with limited application, but this is important stuff. As has been shown across various papers and descriptions, piecing together the taphomonic history of a specimen and the environmental conditions around it, as well as the nature of the bites, is crucial to showing if bites were likely inflicted by feeding predators or scavengers as well as what species/ clades may have left these traces. If palaeontologists are going to be able to amke effective statements about what bites can tell us then it will help enormously if we have numerous detailed datapoints where we are confident about what information they provide.

So, enter a small and beaten up piece of ceratopsian frill. I was shown this a few years ago by Darren Tanke and Caleb Brown after it was found during a dig in Dinosaur Provincial Park in Alberta, Canada. It was unusual in that it was from a fairly young animal and the bite marks were quite small. It is also unusual that these are bites on a frill, it’s not the kind of place an animal would usually feed on becuase there’s bascially no meat there, just a bit of skin and bone which rather points towards these being scavenging traces from an animal that got to a very decayed carcass rather late.

The bites are hard to interpret with lots of cracks and breaks not helping things. There are two clear bites and they fit the classic morphology of theropod traces and we can rule out things like crocodiles, champsosaurs or mammals having been responsible, despite the small size. One looks more like a tyrannosaur bite (though it would have to be from a very small one) and a second looking more like it was from kind of deinonychosaur. It is certainly possible that more than one animal bit this same bit of bone, but equally bite can be variable and identifying them accurately can be very difficult or even impossible to accurately work out who the biting animal was. So despite the apparent possible different candidates it’s hard to say quite what happened here. That’s obviously disappointing, but it’s important to try and evaluate each bite on it’s merits if possible and this does a least provide evidence that even smaller centrosaurs were being bitten by the local theropods and these were not beyond trying to make a snack of a damaged squamosal.

The whole paper is freely available and open access and is online here if you want to see more:

Hone, D.W.E., Tanke, D.H., & Brown, C.M. 2018. Bite marks on the frill of a juvenile Centrosaurus from the Late Cretaceous Dinosaur Provincial Park Formation, Alberta, Canada. Peer J.

 

Non-tyrannosaurs biting like tyrannosaurs

The internet has obviously revolutionised communications between people but it throws up new connections and opportunities that I think few would have seen coming. A couple of years ago, Dan Chure put up a photo on Facebook of a small sauropod femur with some very obvious theropod bites on it. This was from the Dinosaur National Monument site where Dan worked (he’s now retired)  which made it unusual since non-tyrannosaur faunas tend to have far fewer bites in them than do those where the tyrants are present. At first glance though, this looked like a tyrannosaur-type bite with a long set of bite-and-drag marks where the cortex had been really ripped through so this was really unusual. With my extensive background of research on theropod bites, this was something I was very interested in and I didn’t recognise it. I’d assumed something this unusual and interesting would have been described before but not only had it not been (as far as I know it’s not in the literature at all) but no one was even planning to work on it.

So Dan and I got to work on this and inevitably ran into some issues. Identifying what is effectively an isolated and damaged femur from a young animal is tricky. There are a lot of sauropods knocking around in the Morisson and femora are not one of the more diagnostic elements, but we were able to show that it was from a diplodocoid. The femur s under 60 cm long and while that’s obviously a sizeable animal, it is really small for a sauropod and means this was likely a pretty young individual.

The marks on the bone are concentrated on the dorsolateral side of the bone and consist of a series of grooves across the face of the bone that are especially deep at the upper end. At their deepest, these go through the cortex and indeed a fair bit of bone seems to have basically been snapped off, perhaps coming apart as a result of the amount of damage to the element.

This could also have happened at least in part through transport too. Taphonomically the bone has an odd history, apparently isolated, it is actually very close to a second and near identical femur which suggests that both were from a single animal, but there are not other obvious comparable bones nearby and this suggests a very disarticualted carcass. Not only does the other femur lack any bite traces but these are essentially absent in the quarry as a whole. Of the huge number of bones present, only this small saurpod has any bites on it. That’s obviously really rather odd – if loads of carcasses were around, you might expect either tons of bites from theropods getting stuck into the wealth of food or almost none because feeding carnivores avoided biting bones when there was lost of muscle, or they simply couldn’t get to the bodies (if they were say underwater). But one bone badly bitten when even it’s companion wasn’t and then nothing else, is clearly an oddity. It suggests some odd circumstance where this one bone was, perhaps temporarily, accessible to a feeding theropod though the exact details of what may have happened are irrelevant, it does add a level of intrigue to this case.

The bites themselves are reminiscent of those made by tyrannosaurs – long and deep scores made by a bird-like pull back of the head. That action was common among larger theropods but the specialised premaxillary teeth of tyrannosaurs made them well suited to doing this when the teeth were in contact with the bone. Non-tyrannosaurs did not have the inclination to do this when feeding as with their thinner teeth, these would be at risk of breaking. Other fossils show they had the power to bite deep into bones but generally didn’t, rather than couldn’t, making this case a rare example of this behaviour. While it may have been an exception, it does at least show the capacity of non-tyrannosaurs to feed in this way.

Exactly which theropod this may have been though is a still harder question to answer. One of the nice things about bites left by large tyrannosaurs is that they are the only credible candidates for the trace maker in a given environment and you are generally only picking between a couple of pretty closely related species. You may struggle to say if a bite was from Albertosaurus or Daspletosaurus say, but it was still a large tyrannosaur with fundamentally simialr anatomical specialisations and behaviours and therefore general interpretations are going to be pretty solid either way. In the Morrison though you have large allosaurs and ceratosaurs and some unstable / uncertain taxonomy too (like Saurophaganax) meaning the options are much more open.

Various researchers (inlcuding me) have commented on the possibilities of using the spaces between teeth as an indicator of which animal might have left a given mark. However, as Dan and I cover here while in theory that could be useful, in practice we can’t account for the variables of things like ontogeny and missing or offset teeth and the angle at which an animal might drag the head could all dramatically affect the spacing between traces left by the teeth. In short, where there are mutliple credible trace makers it it going to be very hard to pick between them without soemthing diagnostic like shed teeth.

Still, wit no large tyrannosaurs around in the Morrison, whatever did this was not one so we can at least say confidently that at least one large theropod was engaging in tyrannosaur-style feeding, even if it was rare. Perhaps of course the style of feeding was common but merely tooth-bone contact was limited and this fits with waht we do know about that pull feeding action. Even so, this is something of a frustrating project between the quirky history of the bone and its bites and the uncertain identities of the bone and the trace maker. Hopefully more traces like this will turn up or be described from Jurassic beds and we may begin to piece together the feeding styles of large theropods. This one might be a partial mystery for now, but it hopefully provides some useful data fitting into what we know about the behaviour of some of the big theropods other than tyrannosaurs, even if this leads to the idea that they may have been more simialr to each other in this regards than we previously realised.

 

Hone, D.W.E., & Chure, D.J. 2018. Difficulties in assigning trace makers from theropodan bite marks: an example from a young diplodocoid sauropod. Lethaia.

Ceratopsian horns and frills – what drove their evolution?

So I have another new paper out on sexual selection and what this means for dinosaurs. This one has been led by my PhD student Andy Knapp (follow him on Twitter here) and he agreed to write about it here:

Ceratopsians are among the most instantly recognisable dinosaurs thanks to their enormous, elaborately-adorned skulls. The frills and horns of ceratopsians have been the subject or ongoing debate in palaeontological circles since the discovery of Triceratops in the late 19th century. Triceratops is known to everyone, specialists and non-specialists alike, and remains the classic example of ceratopsian skull morphology, with three large forward-pointing horns and a thick, shield-like frill extending back from the rear of the skull. It seemed obvious to early palaeontologists that these features had evolved for protection. The trouble is that Triceratops is almost alone in possessing this precise combination of features. Many of the larger ceratopsians that we know of didn’t have such large horns, and most had large, weight-saving fenestrae in their frills which would offer little protective value in life. In recent years the large number of known ceratopsian species has increased with a steady stream of new discoveries, each with its own characteristic horn and frill morphologies. These discoveries have posed a whole load of new questions as to what their purpose was.

Large, elaborate features with no obvious use – such as the frills and horns seen in ceratopsians – are expensive to grow and maintain, and obvious parallels in living creatures involve sexually selected features. The most extravagant examples of sexually selected features, as realised by Darwin in his book The Descent of Man, involve extreme sexually dimorphism in traits and/or overall size; peacock tails, elephant seals, etc. In contrast, there is no convincing evidence of sexual dimorphism in any ceratopsian taxa. This has led some researchers to reject the hypothesis of sexual selection as an explanation for exaggerated features in ceratopsians and other dinosaurs, and suggest that instead these features have evolved for species recognition.

Species recognition is the idea that being able to differentiate members of your own species is vital in herding, protection and mating. Basic examples of ‘species recognition’ are everywhere in nature; zebras don’t have trouble telling lions apart from other zebras! The more specific idea that physical traits evolve as a mechanism to allow differentiation is controversial. There are a few known examples of divergence of traits in closely-related taxa where hybridisation could be detrimental to fitness, a process known as reproductive character displacement. This is distinct from ecological character displacement, where sympatric taxa that fill similar ecological niches diverge in traits associated with resource acquisition. The rock nuthatches Sitta neumayer and S. tephronota exist across central Asia in partially overlapping ranges. Where they are sympatric, the distinctive dark eye stripe, ubiquitous across the rest of the two species’ ranges, fades in intensity in the population of S. neumayer. This has been interpreted as an adaptation to prevent hybridisation between the two species. Crucially, other known examples of reproductive character displacement involve minor modifications to pre-existing, often sexually selected features.

Reproductive character displacement is not expected to operate where a taxon exists in isolation, because there is no evolutionary pressure for traits to diverge. This prediction allows us to test the hypothesis of species recognition as an explanation for the presence of distinctive traits in extinct taxa for which we have good geographical information. Ceratopsians fit these criteria well. They were widespread across North America and Asia, speciose, and many species are known from relatively complete remains. We compiled and assessed a list of 350 cladistic character traits for a 46 well-known ceratopsian species and compared how the traits generally considered ornamental, and thus contenders to be species recognition traits, varied between sympatric and non-sympatric species. We also examined at other traits; those that were internal and therefore not visible during the animal’s life, and those that were external but not considered to function as a display trait. We then conducted a pairwise comparison of each possible species pair for three distinct character classes; internal, display, and external non-display.

We then compared the results for species pairs known to be sympatric and, therefore, likely to encounter one another in life, with non-sympatric species pairs. For each category we found increasing character divergence with increasing phylogenetic distance as expected, but, crucially, found no difference between the disparity of the display characters of sympatric species and those of non-sympatric species. This suggests that interaction between species has no effect on the evolution of ornaments in ceratopsians, and that species recognition is not a contributing factor to ornament evolution. Of course, it is entirely plausible that ceratopsians were able to identify conspecifics by their ornamentation, but this would have been a byproduct of ornamentation, not a cause.

The ruling out of species recognition as a driver of ornament evolution, at least in ceratopsians, shortens the list of possible explanations. Avoiding hybridisation would benefit both parties and so the evolution of distinguishing features should tend towards a zero-cost exercise. In contrast, ceratopsian skulls are the largest of any terrestrial vertebrate and impose certain limitations on their bearers. Computer models of ceratopsians have shown their massive skulls shifted their centre of mass further forwards than other quadrupedal dinosaurs. Compared with the hadrosaurs that they shared the ancient river deltas of what is now Canada’s Dinosaur Provincial Park, this made them poor swimmers and liable to drown when crossing bodies of water. This obvious handicap, along with the sheer cost of growing and maintaining such a large component of overall body mass that has no obvious mechanical or ecological function, points to an explanation that favours investment in high-cost structures.

An additional result of our analysis was that at the lowest phylogenetic distances, ornamental traits were around ten times more diverse than internal traits and three times more diverse than non-ornamental external characters. This suggests a general trend for rapid evolution of ornamental traits. Rapid evolution and high-cost are both hallmarks of sexually selected features. If the frills and horns of ceratopsians are sexually selected, as has been previously suggested, they are distinct from extant taxa in being both highly exaggerated and sexually monomorphic. This combination suggests strong sexual selection that applies more-or-less equally to both sexes. Some evidence for ceratopsian ornamentation being sexually selected has been demonstrated previously, and this study both adds to this evidence and rejects a competing hypothesis. Ultimately, our findings open up further avenues for exploring the life history and ecology of these fascinating and enigmatic creatures.

 

Knapp A, Knell RJ, Farke AA, Loewen MA and Hone DWE (2018). Patterns of divergence in the morphology of ceratopsian dinosaurs: sympatry is not a driver of ornament evolution. Proc. R. Soc. B. 20180312. http://dx.doi.org/10.1098/rspb.2018.0312

 

References

Brown WL and Wilson EO (1956) Character displacement. Systematic Zoology. 5: 49-64

Darwin, C. (1871). The Descent of Man and Selection in Relation to Sex. London, John Murray

Henderson DM (2014). Duck Soup: The floating fates of hadrosaurs and ceratopsians at Dinosaur Provincial Park, in Eberth D and Evans D (eds). Hadrosaurs. Bloomington: Indiana University Press. pp. 459-466

Hone, D.W.E., Wood, D., and Knell, R.J. (2016). Positive allometry for exaggerated structures in the ceratopsian dinosaur Protoceratops andrewsi supports socio-sexual signalling. Palaeontologica Electronica. 19.1.5A: 1-13

Knell RJ, Naish D, Tompkins JL, and Hone DWE (2012). Sexual selection in prehistoric animals: detection and implications. Trends in Ecology and Evolution. 28; 38 – 47

Maidment SCR, Henderson DM, and Barret PM (2014). What drove reversions to quadrupedality in ornithischian dinosaurs? Testing hypotheses using centre of mass modelling. Naturwissenschaften. 101: 989 – 1001

Padian, K. and Horner, J.R. (2010). The evolution of ‘bizarre structures’ in dinosaurs: biomechanics, sexual selection, social selection or species recognition? Journal of Zoology. 283; 3 – 17

Spinosaurs in review (sort of)

So I have a new paper out written with Tom Holtz and looking at the spinosaurs. It covers a number of issues and should have something for everyone working on this group be it taxonomy, behaviour, ecology or anatomy. This is an odd paper for a number of reasons and while I think it came out just fine, it might be worth looking at the background.

It was originally penned to be part of a special volume of papers which then never happened and this lead to major delays between submission and publication and thus while the title harks back to the original description of Spinosaurus, it is now a little dated. It is also odd because it was conceived originally as something close to a chapter from The Dinosauria (2nd ed) but obviously focused on a much smaller group. That means it’s something of a review of both the history and state of the art of spinosaur research, but was then an opportunity to clear up a few issues and introduced some ideas and corrections and thus while it is a review generally, it also has novel material and corrections. That means it rather awkwardly straddles the boundary between ‘review’ and ‘original paper’ and while it leans more to the former than the latter, it’s certainly got elements of both.

The spinosaurs have had a real renaissance of attention in recent years. Leaving aside the huge interest (positive and negative) surrounding the new Spinosaurus material there have been a bunch of new taxa named recently (Ostafrikasaurus, Oxalaia Ichthyovenator) as well as revisions of others (Sigilmassasaurus) and plenty of new finds like sets of teeth and cranial remains of even well-known taxa. In short, we’ve never had more material to work from but in many ways we’re hampered. Major taxa still await decent descriptions and many taxa, while valid, are based on limited material. That makes comparisons difficult and hampers research.

One area where we hope we have made a real contribution was in tweaking various taxonomic definitions. Baryonyx is a real case in point as its definition has not really been revised for some time and numerous characters that were once considered unique to the genus are now known to be present in many other spinosaurs and thus are not diagnostic to this animal. That really means little more than a bit of housekeeping in terms of sorting out some character states but it needs doing and (hopefully) we have now cleared up a few issues with the various diagnoses.

The other area we take a look at in more detail is some of the hypotheses about the behavioural ecology of the group. There have been lots of hypotheses about how these animals lived, and especially the function of the jaws, claws and sail. Many of these are mutually contradictory and the supporting evidence and arguments greatly limited or frankly non-existent. We try to critically appraise a few of them and put things on a firmer footing, but we do also note that spinosaurs may have been decent diggers.

There are whole suites of characteristics seen on animals that are good at digging and these are seen in some dinosaurs not least the alvarezsaurs. The spinosaurs and not anything like this specialised but do show at least a couple of these traits (the large claws and robust humerus for example) suggesting this is a hypothesis worth of some consideration in the future.

I’ll leave it there as obviously the real place to read all of this is in the paper which is online here. Good reading!

Hone, D.W.E., & Holtz, T.R. 2017. A century of spinosaurs – a review and revision of the Spinosauridae with comments on their ecology. Acta Geological Sinica.

Buried Treasure – Matt Wedel

I’m not quite sure whether I’m supposed to be talking about my favorite paper out of my little flock, or the one that I wish had gotten more attention. But it’s okay, because the answer in both cases is the same: my 2012 paper on long nerves in sauropod dinosaurs. It’s freely online through Acta Palaeontologica Polonica.
This one is my favorite for several reasons. I think it’s the most personal of my papers, in that there was no obvious need for it, and probably no-one else was ever going to write it. Whereas with pneumaticity I just got in at the right time – that work was going to be done by someone, and probably sooner rather than later. I also like the long nerve paper because all it required was thinking. I didn’t discover anything, and I didn’t do any real work. In fact, at the outset I was basically thinking of it as sort of a stunt paper. If it had any broader meaning at first, it was merely, “Ha ha, I thought of this before anyone else did.”
But that’s the great thing about science – if you pick up any given thread and follow it, you may soon find yourself in a labyrinth of possibilities, like Theseus and Ariadne in reverse. That happened with the sauropod nerve project, which has spun off in a couple of new directions for me. One is thinking more about the peripheral nervous systems of extinct animals, which has attracted almost zero attention so far. It’s pretty esoteric – nerves leave even less of a trace on the skeleton than air sacs – but there are some interesting and useful inferences that we can draw (to find out what those are, wait for the paper!). The second spin-off is that writing the 2012 paper fired my interest in the physiology of neurons, and in fact kicked off some conversations and potential collaborations with neuroscientists. That is a career wrinkle I never anticipated.
Still, I have to admit that it is a paper without a lot of obvious applications. It hasn’t been cited much – about half as many times as other papers of mine from around that time – but I have been happy to see it cited in a variety of fields, including neuroscience, computer science, and linguistics. That’s satisfying because I cited works from a variety fields in writing the paper in the first place. In part that was because cell biology in giant dinosaurs is an inherently cross-disciplinary problem, and in part because the example of the recurrent laryngeal nerve in the giraffe has become widely known and referenced across so many fields.
My goal now is to build on the 2012 paper with at least a couple of follow-ups to show paleontologists that, yes, there is some actual science to be done here, beyond the gee-whiz aspects. That was the subject of my talk at SVPCA last year. And as I said at the end of that talk, if you’re interested in the interplay of evolutionary novelty and developmental constraint across multiple levels of biological organization, thinking about the cell physiology and comparative anatomy of large animals is a fertile playground.

The Tyrannosaur Chronicles is here!

Well it’s been coming of course but today sees the publication of my first book. I’ve always wanted to write one and now it’s done and I can (sort of) relax. There’s lots of PR stuff ahead and the official book launch tomorrow, but there’s not much to do now except let it go free and hope that most people enjoy it.

I’ve been writing about dinosaurs and palaeo one way or another for nearly 10 years now between various blogs and ventures as well as the odd review paper and book chapter that are for more of a general audience than a typical paper, but this is obviously a much bigger and rather different undertaking. It’s also rather different in that I was writing for something of a different audience (certainly compared to here where I generally assume readers know at least a little anatomy, what a phylogeny is, what the main time periods were etc.) and over a long book you want to introduce quite a few topics and aspects of not just tyrannosaurs, but also their contemporaries and major issues like behaviour, anatomy, local environments, extinction and more. It turned out to be a lot to cover and while trying to keep it interesting for the reader.

Hopefully, I’ve managed that but it is nervy letting this out into the wider world with little control over it. That may sound odd given how much I’ve written online, but with a blog (either here, on Pterosaur.net or on the Guardian) you have a fair idea of who your audience is likely to be, and people will soon leave if they don’t like it. Getting someone to pick up and be immediately drawn to, and then stick with, a whole tome is rather different so obviously I am nervous and curious as to how it goes from here.

The book is very much in the popular science mould and so while I would hope even some academics and researchers would get something from it and enjoy it, really it is aimed squarely at the general public and those with little or no knowledge of dinosaurs or paleontology and even biology in general. As a result, despite the fact that the book is around 85 000 words long, it really doesn’t delve into the tiny details of but tries to cover a broad spectrum of tyrannosaur origins, evolution and their biology. Given my interests there’s quite a lot on ecology and behaviour and there’s a few bits of informed speculation or suggestions that I hope are novel and interesting, but also clearly flagged as such.

It was a huge effort to write all of this while keeping up with a full time academic job and try and keep my other blogs ticking over, and it was also important to try and update things. The last few years have seen a near endless stream of new tyrannosaurs being named and some parts of the book I changed a half dozen times to reflect the addition of new species, and with the book going to print in February, it’s inevitably already out of date thanks to the most recent addition to the ranks of this clade, despite my efforts. Still, I have tried to make this a modern take on tyrannosaurs and I hope I have managed to overcome a few of the more persistent anachronisms and misconceptions about these animals. Anyway, enough of the (brilliant) text and its (brilliant) author, and time to talk about some other aspects of the book and to give a minimal amount of credit to other people.

The book is illustrated by Scott Hartman and there’s around a dozen figures of his scattered through the book, with lots of skeletals (especially of tyrannosaurs, but also various other dinosaurs too) and other little bits, a number of which were done especially for the book, but will be popping up on his website if they haven’t already. I’m obviously especially grateful to Scott for finding the time to do these and putting so much time and effort into them, the book benefits enormously from it.

There is also a colour section in the middle with numerous photos of various specimens and some reconstructions. Plenty of these have been in print in various places before but there are some novel shots and views of various things and I’ve been blessed with the generous assistance of numerous colleagues and friends who have sent in pictures and allowed me to use them. While I’m on the subject therefore I must thank Peter Falkingham, Jordan Mallon, Larry Witmer, Xu Xing, Lu Junchang and Phil Currie for providing various images and also the Royal Tyrrell, LACM, IVPP, Hayashibara, Mongolia Palaeontological, Royal Sasketchewan, Carnegie and New Mexico Museums, and also Don Brinkman, Mark Loewen and Matt Lamanna for helping me negotiate to get a couple of the images. Finally I must also thank Darren Tanke and Chisaka Sakata for the photos of me that are on the covers of the paper- and hardbacks respectively.

Finally with regard to the text I had a series of editors and assistants at Bloomsbury though most especially I want to thank Jim Martin for commissioning the damned thing in the first place and also in particular for supporting my campaign for the colour scheme of the cover. Several friends of mine including Marc Vincent (yes, that one) read through an early draft for me and provided useful feedback and special mention goes to Tom Holtz for reading through it looking for errors (and mercifully he found only one, so I’m happy to blame him for any others that slipped through). A whole host of other friends, collaborators, coauthors and colleagues are thanked in the acknowledgements for sharing their knowledge of tyrannosaurs with me over the years and I hope this book helps do justice to these amazing animals.

Well, the book is out now (actually I’ve had reports of it being on sale since Monday) and while I’ve always wanted to say it’s available in all good bookshops actually I have no idea. It is available online (including direct from the publishers Bloomsbury) and it’s in at least a few physical places. I know it’s available in hardback (paperback coming next year) and e-book versions and there’s an audio version coming via Audible, and hopefully a few translations too. The US have to wait till early June, but not long for you to wait and in the meantime you can enjoy me talking about the book here. Hopefully many people will find it one way or another (such as in charity shops for £2 in a few weeks) but more importantly I do hope people enjoy it. Happy reading.

The Tyrannosaur Chronicles actually exists!

So the official publication date is drawing near (21st of April) of my first book and I actually have a physical copy in my hands! Oooh! It’s got nice pictures and photos and words and everything!

Obviously I’m very pleased but I am also rather nervous about the whole thing – people will be paying actual real money and I really don’t want to let them down. I know you can’t please everyone and even the greatest books will not appeal to every person that picks up and reads even a few pages but despite the years of blogging and outreach stuff this is a new style and form and it’s rather more global in spread than even online media. So, lots of nerves my end.

However, anyone who does buy it and hurls it across the room a few hours later in frustration may at least be mollified by having paid 30% below the cover price thanks to a discount being offered by the publishers. If you order direct from the publishers Bloomsbury before May 31st and enter the promo code ‘DINOSAUR’ at the checkout, it should be reduced. (This has only just been set-up, so do leave a comment if this doesn’t work, or indeed if it does to let me know it’s working!).

Finally, if you are in and around London there is a small formal book launch on the 22nd of April. Tickets are free (but you need to reserve them here in advance). It won’t be long or special, I’ll talk about the book for a bit, answer some questions and sign any copies going (available for sale there, and also at a hefty discount).

Hope to see some regulars there and I do hope you enjoy the book.

 

 

 

What is an adult dinosaur?

Back in early 2015 I took a trip to LA, primarily to catch up with Mike Habib and look at some pterosaur and tyrannosaur material there, but I also took some time to see Andy Farke and Matt Wedel up in Claremont. We chatted about various ideas for things we could collaborate on and threw around a few ideas. Andy suggested something on ontogeny and this soon led to the issue of diagnosing life stages for dinosaurs – something that had been an issue for our Protoceratops paper – and within a few weeks I’d actually had an invitation to submit a review to Biology Letters, and so a plan was hatched.

That paper is now out and in it we look at the vexed issues of what are adult / subadult / juvenile / hatchling etc. dinosaurs. This is of course really quite fundamental to huge amounts of research, if it’s not clear how old an animal is, then issues like taxonomy, systematics and their position in an ecosystem are going to be hard to sort out. Comparing across specimens or species will also have their issues. None of this is a major surprise and yet looking though the literature it’s clear that although people recognise this, they don’t necessarily actually define the nature of the animals they are working on. Things are called ‘adult’ or ‘subadult’ without a definition, specific diagnosis or reference to papers or alternatively they do provide some kind of definition and reason for the assignment but it’s different from all the others out there. It doesn’t take long to find a bewildering and ever changing list of definitions, none of which can be aligned or compared easily between specimens or species.

There’s clearly nothing wrong in principal with diagnosing an animal by different means but not all specimens can be accessed in the same way or preserve things you want to look at. So something that can help bring them into alignment should help everyone. This is a key part of the paper as we try to come up with something close to a universal definition that should apply as widely as possible. We make it very clear that this should be only a starting point and that whatever works for people is fine, but that hopefully it helps, and even if people utterly ignore these definitions, in general we need to be much more careful about actually putting definitions into papers, even for things that are ‘obviously’ adults or juveniles.

Although short, we do cover a lot of ground in the paper and I hope there’s things in there that will resonate and be familiar and useful to many people (and of course lots of the points apply to other extinct clades too). There’s obviously a lot more to come here and more nuance and details than we could easily include but it’s one of he most contentious and important issues around at the moment and I really hope we have contributed meaningfully to it.

The paper currently seems to be available freely online and can be downloaded here.

Edit: here’s a bonus – Mat Wedel’s sauropod-centered take on the paper

Hone, D.W.E., Farke, A.A., & Wedel, M.J. 2016. Ontogeny and the fossil record: what if anything is an adult dinosaur? Biology Letters

 

The Tyrannosaur Chronicles

Chronicles cover

So I’ve been keep this quiet for a while, but for the last year or so I’ve been writing what will become my first (and hopefully not only) book. It’s a popular science book with Bloomsbury Press and their new Sigma range of titles, all of which are science / natural history and it’s due out in early 2016. Obviously it’s a dinosaur effort and this is focused squarely on the tyrannosaurs. It tries to cover everything from their origin to extinction and that means evolution, taxonomy, anatomy, physiology and mechanics, and in particular my areas of special interest in ecology and behaviour. It’s not quite wall-to-wall dinosaurs since there’s the context of their environments, competing carnivores and potential prey and that means some other things do at least get a look it.

As will be obvious from the cover, Scott Hartman has been involved and in addition to the skeletals adorning it, there’s a bunch of his renditions inside too. (Those who read his blog might have spotted the recent plethora of tyrannosaurs and this book is part of the reason for his push on them). So that means at least some bits of the book will be accurate and in a desperate attempt to make sure the text isn’t too littered with errors, Tom Holtz has been good enough to plow through the entire thing for me (so I’ll blame any remaining mistakes on him going too fast). More seriously, I really can’t thank them both enough.

Right, that’s enough shameless self-promotion for now, so I’ll return to editing the thing and watching the Mexican standoff between my geckos. Thanks for reading the blog, and hope you might read the book.

 

Edit: it’s available for preorder at Bloomsbury here, assuming anyone is desperate / foolish enough to order it sight unseen. 🙂

Combat and cannibalism in tyrannosaurs

skull lat7_nIn recent years, it has become clear that at least some large theropods (and notably tyrannosaurs) engaged in some form of intraspecific conflict that can be identified by the numerous injuries inflicted on various skulls. Unlike predation attempts which would expect to strike to areas like the hindlimbs and tail, these are very localised to the face and imply animals stood head-to-head or side-by-side while doing this. Furthermore, at least a couple of records suggest cannibalism of conspecifics and this too has been seen in tyrannosaurs. Wading in myself, I have new paper out with Darren Tanke which describes a series of injuries to what is a fairly battered Daspeltosaurus skull that gives support to both of these areas, since it has both pre- and post-mortem bites on it from other tyrannosaurs.

First off, I must thank a number of people for getting this research to happen at all. The project started while I was unemployed and obviously short of research funding. My trip to Canada to examine the material was supported by a crowd-sourced campaign run through Experiment.com. Numerous people at Experiment and huge numbers of friends and colleagues contributed (and I’m sure, plenty of regular Musings readers) and they need my thanks. First among equals was the palaeoart community with Julius Csotonyi, Luis Rey and especially Brett Booth donating artwork or sales to support the work, but many people are gratefully acknowledged. Don Henderson put me up while I was in Canada, and Darren Tanke obviously invited me to write up the specimen. While naturally a lot of work has gone into this paper, the essentials of the marks and interpretations were things Darren himself had identified years ago so much credit needs to go his way there too.

IMG_3317

Right, onto the paper. It’s freely available through PeerJ and with 17 figures, so there should be more than enough info there for those who want to delve into the details, and thus I’ll try to keep things relatively brief here. The specimen is of something close to a sub-adult animal and there were plenty of the bones in the quarry (importantly these are in superb condition and there’s basically no evidence of transport or wear). There are numerous injuries across the skull (though absent elsewhere) and these consist primarily of healed injuries on the cranium. Not all of these can be directly attributed to bites, and some could have come from a number of sources.

However, a few healed marks can be interpreted as bites. There are some circular marks and punctures on various locations (including on the snout) and damage to bones that appear to represent some heavy impacts (deviated bones, pieces that have broken off and then fused back to the bone slightly out of position) and the like. Quite incredibly, both sides of the occipital region show some serious damage. On the left a piece appears to have been entirely removed (there’s healing round the remaining edge) and on the right, there’s a healed but circular puncture through the bone. In short, at least one and probably two separate bites came in to the back of the skull and snapped through the bones, though the animal survived and the injuries healed.

occiThis animal, despite not even having reached adulthood, clearly got into at least one big dustup and I would imagine, probably several, to have got so many hits to the head. Although there are a number of theropods showing injuries to the head that are interpreted as coming from other conspecifics, this is more extensive and serious than I’ve seen before. As to assigning it to a conspecific, this is tricky as there are other large tyrannosaurs in the formation (Gorgosaurus) and though these animals might well have come into conflict with one another, one can expect that conspecifics would likely come into contact more often (competition for similar niches, living in more similar habitats or direct interactions from being in groups perhaps). Thus it’s reasonable to infer this was a more likely source of such injuries.

Even so, the post-mortem damage is perhaps more interesting still. There’s one series of score marks along the inside and rear of the right dentary that well match similar bite marks from large theropods. A piece of bone has also broken off between two alveoli and been jammed down in between them and the score marks are coincident with some damage to other parts of the posterior mandible, so it looks a lot like there was a big bite here that took apart the back of the jaw. Given the position of this and the lack of healing, it’s reasonable to infer this as being post-mortem, but things get more interesting when you look at the taphonomy.

surang

When discovered, the dentary was more anterior than would be expected if the specimen had decayed in situ (the skull was lying with the palate uppermost). However, a number of dentary teeth (including those that must have come from the missing right dentary) were lying in the palate below where they should have been if the dentaries were in a natural position. Given the lack of evidence for fluvial action generally, this implies that the jaws were originally in place, decayed sufficiently to shed their teeth, and then the dentaries were moved. One has vanished and the other is in a more anterior position than if the specimen had simply decayed in situ (and the teeth have been dragged along somehow). It’s hard to imagine the tooth ligaments coming apart within hours of death, and the lack of bites to other parts of the specimen that would have been a more obvious target for feeding suggest this was probably scavenging.

This may or may not have been cannibalistic as it is not possible to tell apart Gorgosaurus from Daspletosaurus based on the bite marks alone. Still, it is very much a record of a scavenging interaction between two large tyrannosaurs and that is a nice addition to the available information on interactions between large theropods. Getting an idea of how these kinds of things worked in past environments really is a case of building up data from the rare occasions when such interactions are preserved, so while interesting in its own right, this really does help produce a more rounded picture of interactions between large carnivores both before and after their deaths.

 

Hone, D.W.E., & Tanke, D.H. 2015. Pre- and postmortem tyrannosaurid bite marks on the remains of Daspletosaurus (Tyrannosaurinae: Theropoda) from Dinosaur Provincial Park, Alberta, Canada. PeerJ, 3 e885.

 

Finally, while I’m talking about crowdfunding stuff, do check out David Orr’s appeal for his kids book on palaeontology. David designed the snazzy logo that I used for this project as modeled by myself and Darren above, so you can see how good his stuff is. Oh yes, and here’s an interview with myself and Darren Tanke on the new paper.

Discovering dinosaurs in the field

I’ve already written a bit about the fieldtrip to Alberta from this Autumn that I led from Queen Mary with a team of colleagues and undergraduates where we had a great time and found some great stuff. My friend and colleague Rob Knell was with us as pseudo-official photographer and he also had video capacity with his cameras so took plenty of footage and has now edited this together to make a brief video to show off what we did. This has been put together in order to  promote the course and show future students what the trip is likely to involve, but it should be of general interest to those who have not seen Dinosaur Provincial Park firsthand and what a better idea about hunting dinosaurs.

 

 

 

 

 


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