Flugsaurier 2018 Circular

This has been in the works for too long but we do now have a formal first cicular for Flugsaurier 2018. The abstract submission date is but 6 weeks away, but then you should have known about this conference from 3 years out… 🙂

 

Flugsaurier 2018: Los Angeles
The 6th International Symposium on Pterosaurs: First Circular

Welcome to Los Angeles

We invite all individuals working on, or interested in, pterosaur biology or associated geosciences to submit abstracts for the 2018 Flugsaurier meeting in Los Angeles, CA, USA. The meeting will be held August 10-14 at the University of Southern California and the Natural History Museum of Los Angeles County. Please mark your calendars for what we are sure will be an exciting meetinng!

Current  Calendar:

all events at USC, except Welcome Reception/Specimen Viewing and Field Trip

August 10th: Ice Breaker at USC (AM) and aRernoon technical sessions
August 11th: Technical Session; Welcome Recepion and Specimen Viewing at NHMLA
August 12th: Technical Session (AM); Workshops (PM); Paleoart Exhibition
August 13th: Technical Session (AM); Workshops (PM); Conference Dinner (PM)
August 14th: Field Trip (TBD)

Notes: The NHMLA is located adjacent to the main campus of USC. The Conference Dinner loca4on is TBD, but we expect to use a venue either on the USC campus or in nearby Downtown Los Angeles. The Field Trip costs will be included in the registraion. We hope to arrange a trip to the Moreno Forma4on of California.

Abstract Information
Abstracts have a limit of 500 words with up to 3 references (Harvard format) and 1 figure.
For details, or to determine if abstracts meet criteria, please contact Michael Habib:
habibm@usc.edu. Abstracts can be submi]ed here. We will accept mul?ple submissions from authors but only one talk per lead author. Abstracts will be reviewed. We cannot guarantee speaker or poster slots. Abstracts submissions are due by midnight, Pacific Time, on March 26th.

Host Committee:
Host committee will also be the review committee for all abstract submissions Michael Habib (Chair), Brent Breithaupt, Nathan Carroll, David Hone, Lu Junchang, Elizabeth Martin-Silverstone, Taissa Rodrigues.
Special Thanks goes to Luis Chiappe for hosting the NHMLA components of the program.

Travel Information

Accommodations:
The closest hotel is the Radisson Hotel Los Angeles Midtown at USC. Rooms at this hotel
average 178 USD per night: https://www.radisson.com/los-angeles-hotel-ca-90007
Less expensive options can be found in some parts of Downtown Los Angeles. The American Hotel often has rooms for 85 USD per night: http://www.americanhotella.com/. The hotel is walking distance from a light rail sta?on, from which rail travel to USC and the NHMLA is approximately 10-12 minutes.

We are currently working with USC to secure some low-cost housing on campus. We expect this to be limited and available mostly to students. More informa?on about on-campus housing will follow as soon as it is confirmed.

Travel to Los Angeles:
The closest airport to the conference venue is Los Angeles International (LAX). However,
travelers can also fly into Hollywood Burbank Airport (BUR) or Long Beach Airport (LGB). LAX runs regular buses to Union Sta?on, from which light rail can be taken to Downtown Los Angeles and USC.
Note that travel to the United States for a conference typically requires a B Class Visitor Visa, unless the port of origin is part of the Visa Waiver Program. For details on Visitor Visa applications, and to determine if your country of origin is associated with a VWP, please check here: https://travel.state.gov/content/travel/en/us-visas/business.html

Natural Histroy Museums of LA County:
The Natural History Museum of Los Angeles County is the largest natural and historical museum in the western United States. Its collections include nearly 35 million specimens and artifacts and cover 4.5 billion years of history. The NHMLA houses an extensive collection of specimens from the Niobrara Chalk and Pierre Shale, including a sizeable collection of Pteranodon specimens and one of the few partial skeletons of Nyctosaurus. In 2016, the NMHLA hosted Pterosaurs: Flight in the Age of Dinosaurs, from the AMNH.

Other Area Museums:
Alf Museum, Claremont CA: The Raymond M. Alf Museum of Paleontology, located on the
campus of The Webb Schools, houses extensive vertebrate fossil collections, including multiple excellent pterosaur specimens. It is the only nationally accredited museum in the USA on a high school campus. The Alf Museum provides a unique research program for Webb students where they study fossils they find on collec?ng trips and publish the results of their research in collaboration with museum staff, a unique program for secondary school students.
Tar Pits Museum, Los Angeles CA: Part of the LACM system of museums (along with the
NHMLA), the Tar Pits Museum in Los Angeles has one of the largest Pleistocene collections in the world. Active excavation continues throughout the year on the grounds of the museum, which is located in the Miracle Mile district.

 

The official website to keep an eye on is this one: https://flugsaurier2018.wordpress.com/

 

New Perspectives in Pterosaur Palaeobiology

So a new volume of papers in now online that I have edited and now there’s lots of pterosaur goodness to access. This is above titled volume produced by the Geological Society and is volume 455 in the Lyell Collection. The full list of papers and links is here but while most have been available online for some time, there is not this pretty published hardbacked version (cover art and photo by Mark Witton).

This volume is ultimately the product of the  2015 Flugsaurier meeting held in Portsmouth and features a number of papers that were presented there as well as others that have come in. There is a new taxon named (an anuroganthid!) and papers on taxonomy, systematics, anatomy, ecology, ontogeny and biomechanics. There are 17 papers and an introduction and as such I think it’s fair to say that this is a major collection and anyone with a serious interest in pterosaurs is going to need to read this.

Sadly the collection is not OA and these volumes can be expensive, but they are generally available at a reduced rate after a year or so. Unlike earlier editions the individual papers have been produced as high quality PDFs and distributed to authors, so if there’s a particular paper you are desperate for, I’m sure you can enquire. Personally I like dead tree versions of things, and this volume is printed on nice paper and has nice colour figures too which is clearly a bonus.

I should take a moment to thank Mark Witton and Dave Martill my coeditors in this venture and all the referees who took time to work on these papers. Also I’d like to thank the staff of the Geological Society who accepted our pitch and helped guide us through the work necessary to get this volume completed. I’m very pleased with the finla result and it’s nice to see citations already accruing for the papers within. The books are bing printed and shipped so for anyone who has ordered or was an author on a paper, expect these to arrive in the next few weeks.

Enjoy!

 

 

Sexual selection: patterns in the history of life

Longtime reads will know I have a huge interest in sexual selection and what that might mean for the evolution of all kinds of features (horns, crests, colours, feathers) in various archosaurs. In an effort to explore this further and help make new research connections, I have got together with Rob Knell and Doug Emlen to arrange a small meeting on this through the Royal Society. This will take place on the 9th and 10th of May next year jsut outside London.

The speaker list is fantastic and includes palaeontologists, modellers, theorists and people who link between those disciplines and with interests in dinosaurs, birds, insects, mammals and other clades. In short, this should least to a wide ranging discussion and opportunities for people to put some ideas out get and get collaborations and research going in major new directions.

Attendance is free (though there are costs for accommodation and food) but you will need to register and places may be limited. All of the details of the meeting are here including the speaker list. We hope to also run a poster session for non-speakers too.

 

 

Hawkins’ St George and the, errr, ‘dragon’

I was recently introduced to the image below and thought it was something I should share. Given my interest in pterosaurs and palaeoart I was rather surpised by it as I was completely unaware of its existence. That is is by a British artist with a major influence on early depicitons of fossil animals only added to my surpise that it had passed me by. Perhaps it is well known and I’ve simply managed to miss it, but I rather supect it may not be common knowledge at all since it was apparently not created for a palaeontological audience.

The picture in question was made in 1783 by Benjamin Waterhouse Hawkins, he of the Crystal Palace dinosaurs fame. Hawkins designed these, and many other sculptures, and produced all manner of artworks that were used to show off dinosaurs and other ancient beasts. In this case this wasn’t ever a palaeoart pic as such but really an illustration of the legend of St George and the dragon only with the latter having a very prehistoric bent. Those who know the Crystal Palace animals will reconise the pictured ‘pterodactyl’ as being a very close representative of the pterosaurs that sit on a rock above the dinosaurs. This animal is rather larger than these and would be big for a pterosaur known at the time, (and huge for a Pterodactylus) but despite some oddities (the back of the head in particular, and the very long tails) is very clearly pterosaurian.

Given the number of prominent scientists of the age who are at some level creationists (including Richard Owen, Hawkins’ employer on the Crystal Palace sculptures) it is tempting to assume that this was an influence in illustrating such a religious figure with something that’s perhaps less a fictional dragon and more real, if extinct, creature. Is there an attempt here to give credence to the legend by suggesting the dragon was real, if a little out of time? I can’t help suspect so, though I don’t know Hawkins’ intent, perhaps it was simply a case of a nice bit of inspiration for him to be able to use one set of ideas on a second project. Either way, for me it’s a rather interesting piece of early pterosaur illustration and one that deserves to be better known.

 

Write me a review!

Calling all my fellow academics, I am the new Reviews Editor for the Journal of Zoology and as a result I’m on the lookout for review papers that cover any aspect of whole organism biology (behaviour, ecology, taxonomy, evolution, anatomy and many other aspects). The journal has a good track record of covering palaeo topics (including dinosaur combat, display, trilobite diversity) so it’s not all about fluffy mammals.

I think reviews are important to science and provide a great platform for state-of-the-art updates, for people entering new fields (including students) and for steering debates or having new ideas put out there. They are also, I think, often a great paper to write as part of a PhD – they might not be REF-able, but give you a chance to get to grips with a subject and are often highly cited. In short, if you have an idea for a review you are likely to find me a sympathtic ear with a possible opening for you.

In particular I’m keen to reach out beyond the regular readers here, so do please pass on the gist of this message to people far and wide, especially in the biological / invertebrate divisions where I know far fewer people that the dinosaur / vertebrate community.

Tenth Anniversary Post

This blogpost is in fact a bit late since this date passed on the 7th of September, but I have now been blogging for a full decade. The archives here do not quite reach back that far, but very long time readers will know that I first started on the now defunct DinoBase pages (though these are available on some internet archive sites) hence the apparent gap.

I don’t want this post to turn into a long ramble about all of my posts and things I have got done, how I got blogging and so on, (this is after all covered in various places), but this seemed too big a milestone to ignore. I’m really not sure when I started all of this, how long I thought I might keep going for, but I doubt it would have included a guess of anything like ten years.

Back then I was still on my first postdoc with no guarantee of employment in another year or so, let alone an academic career and I was already running Ask A Biologist which was a massive outreach project in its own right. If I’d thought about it, I think I would have considered five years to be a big but achievable target and while I’m hardly going at the rate I once was, to still be going is something I’m rather proud of.

That really is it, just a post to mark the passing of the event. The blog will continue, slowly, as things progress and topics come up that I still want to talk about or are relevant. I doubt that I will still be going in 2027, but that in some ways doesn’t seem too far away or too unlikely. Time will clearly tell but I’m not stopping any time soon.

Flugsaurier 2018 Los Angeles

Well it’s been a while coming but the dates are finally fixed for next year’s pterosaur conference. Keep your diaries free for the 10th-14th of August next year.

As ususal there will be talks, posters, specimens and a fieldtrip (or possibly two) and we hope to be havikng a fairly major palaeoart presence as well. Details will be finalised ASAP but the basics are now all in hand.

Mike Habib is leading this one though his parent institutues of the University of Southern California and the Los Angeles County Museum. Luis Chiappe of the latter has been extremely helpful and the rest of the committee will comprise of Brent Breihaupt, Taissa Rodrigues, Lu Junchang, Liz Martin-Silverstone and myself. Volunteers for additional ssistance are also welcome.

Obviously this is still early days but a number of people have already committed and we are expecting a good turnout. Now that we are out of phase with ICVM, I am hoping that we will capture a bunch of people who are interested in pterosaurs but not been able to come in the past and not simply be solely those with a pterosaur research focus. If you have toyed with these animals or wanted to do more on them, or are a curator with a couple of bits in your collection this might be the conference for you.

Anyway, stay tuned, more will be coming soon and I’ll keep things posted here and e-mails will be going out to the ususal suspects as well as on the DML and Vert Pal lists and I’m sure we will get a Facebook group or simialr up and running soon. Hope to see you there.

In the meantime, almost all the papers from the Portsmouth meeting are now online and the formal book should be printe by the end of the year (or very early 2018), so now is the time to read up on your favourite flying mesozoic archosaurs.

Soft tissues and pterosaur taphonomy, but not as you might expect

In what now seems like a distant and past life, I briefly had a job in University College Dublin teaching in the biology department. Happily, this was on the floor above the earth sciences dept which had a healthy population of palaeontologists including some friends from my previous jobs in both Bristol and Germany. It meant that I had a good time chatting to colleagues on both sides of the ‘divide’ about various research aspects.

One day I was talking to Sue Beardmore (then doing her PhD) and her supervisor Paddy Orr about taphonomy. Through discussion with Paddy, Sue had developed a method of assessing the taphonomy of a vertebrate skeleton in aquatic settings, which could be used to compare environmental conditions among several localities, and infer differences and even changes through time. In theory, if we have the same or very similar species (that will essentially decay in the same way because of their similarities) preserved at two localities, it is possible that their final preserved state will still be different because they were subjected to different external processes. For example, they might have disarticulated to different degrees, suggesting differences in the relative time over which they had decayed before burial by sediments. If their completeness was different, it would suggest a greater number of, or more intense, (biostratinomic) processes. Perhaps one was exposed to stronger currents and less settled waters, which would move away any bits of the body that had separated during decay. In quiet water with few such processes, decay still occurs, resulting in the disarticulation of the skeleton without separated bits moving far from the main part of the carcass. Sue and Paddy have gone on to publish a series of papers exploring this idea, but I realized that it could also be turned around and used from an alternate perspective.

Differences in taphonomy between two related animals in the same environment should reflect differences in anatomy and in particular how well various body parts are secured to each other. In other words, the way in which various bits of the animals have decayed, disarticulated and / or lost allow us to infer something about the soft tissues, even though they are not preserved. This idea inevitably led me to pterosaurs and the huge numbers of Rhamphorhynchus and Pterodactylus specimens that have been recovered from the Solnhofen. They are pretty close relatives and certainly overlap strongly in time and space in these ancient lagoons but we also know that a profound shift in bony anatomy was going on between the two – is this also reflected in their soft tissue? Roping in Emma Lawlor who was then looking for a research project for her undergraduate dissertation, we then had a project to put together.

First off of course we needed to survey pretty much every specimen that we could (and as far as possible in person) leading to examining a whole lot of fossils and supported by photos where necessary. Essentially the animal is divided up into a bunch of segments (head, limbs, tail, body etc.) and are scored for articulation (attached to the right other bit of the body e.g. the wing to the shoulder, fingers to the wrist) and also completeness (so whether or not they are present on the specimen). A fossil could potentially be 100% complete but with 0% articulation, though the two factors are at least partly correlated since anything lost is also by definition disarticulated.

Going through the data there are some simple but fairly stark patterns that emerge. First off, a lot of the specimens are more or less complete and more or less articulated. That’s perhaps no big surprise – the Solnhofen waters are famously fairly anoxic and still, which is why we so often get lots of very well preserved specimens, even including fragile things like pterosaurs as well as soft tissues being retained. Still, it does highlight the general situation at play and that’s also importantly because pterosaurs were generally pretty pneumatic and less dense than many other vertebrates. That would imply that they could potentially float for a long time before sinking which would allow for lots of bits to come off and go missing. That this is generally fairly rare suggests that these effects were pretty limited. When we do see loss of articulation we also see loss of the elements, so decay when it did occur was likely mostly in the floating phase, and that things did not tend to fall apart much once the specimen had settled or we would see lower articulation with higher completeness. In short, there wasn’t much going on at the bottom, likely due to both low currents and limited bioturbation.

Generally, Pterodactylus specimens are less complete than Rhamphorhynchus which may point to them floating for longer (since they are more pneumatic) allowing things to be lost, but could also point to greater transport to sites before sinking and burial. There are also far fewer specimens of Pterodactylus available so this may be a result of the limited data exaggerating the differences a little.

Despite the long and presumably heavy tail of Rhamphorhynchus, this was preserved far more often than the much smaller one of Pterodactylus. This implies that in the former the tail was very strongly attached to the body and was held on with a strong set of muscles and / or ligaments and points to its greater use than in later shorter tailed pterosaurs. Where we see limb loss in Rhamphorhynchus this seems to coincide with the loss of the other limb from the same side – in short if you lose a left arm you also tend to lose a left leg. That points to the idea that the two are attached to each other quite firmly and tallies with the ankle attachment for the main wing membrane.

There’s some other issues at play in these patterns of course (and various other similarities and differences) which I won’t dwell on as that is what the paper is for, but this should give an idea of what we have done and what we can potentially infer with these methods. Sure, the information available is rather limited but it gives a framework for looking at certain anatomical areas in more detail, and it’s likely possible to combine this with other information to delve more deeply into our understanding of pterosaur soft tissues.

Beardmore, S.R., Lawlor, E., & Hone, D.W.E. 2017. The taphonomy of Solnhofen pterosaurs reveals soft-tissue anatomical differences between basal and derived forms. Naturwissenschaften.

 

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.

Some outreach

A couple of months ago I was lucky enough to be invited to give a second talk at the Royal Institution in London. It was, perhaps inevitably, on tyrannosaurs but if you want to hear an hour of me talking about them then the video is now up on YouTube here. As a bonus, they also filmed the Q&A afterwards so there’s an extra 20 mins of me droning on here.

If that’s still not enough of me for you (and it’s hard to imagine that it’s not actually too much for most people), I’m also doing some talks on the 29th of September as part of thy exhibition of Chinese dinosaurs in Nottingham. Keep your eyes peeled for details later. I’m also currently heavily involved in a secret dinosaur project which should be on your screens this Christmas (in the UK at least).

Dinosaur dimorphism, cryptic absence

Yes it’s new paper time and this is one I want to talk about in some detail, so here’s a longer than normal post on this. It’s an issue that has been in my brain for years but has taken time to mature with the right set of circumstances and quirks that make up the profile of a research paper possible. This one is returning again to the much investigated area of sexual selection in the extinct Dinosauria. I think it’s fair to say I’ve been a leading researcher in this field with a string of papers on various issues surrounding sexual selection and dimorphism in dinosaurs (and others), how we might detect sexually selected traits and what they may mean for behaviour, ecology and evolution.

The new paper is written with Jordan Mallon, and in it we tackle the issue of the apparent lack of dimorphism in dinosaurs and why there is still no good case for a dimorphic dinosaur. Despite numerous studies suggesting a split between male and female morphs (or similar robust and gracile ones) revisions have generally found the cases to be lacking and Jordan’s own recent paper in this area is relevant for several reasons. The story though starts quite a few years ago.

My own works on sexual selection mostly kicked off with a paper discussing mutual sexual selection and the idea that both sexes in many populations of dinosaurs may have borne ornaments for social and / or sexual dominance. In short, males had big ornaments (claws, horns, frills, crests etc.) to advertise their general good health and status to females for mating and other males in terms of competition, but females likewise advertised their general quality with the same signal. That meant that in something like a typical ceratopsian both males and females had a big frill and horns and hence an inability for us to identify and separate out the two populations.

This general concept had been completely overlooked in the literature in sexual selection and dimorphism in dinosaurs and it’s worth repeating that this can totally confound some ideas and tests for sexual selection and it needs to be borne in mind when discussing these kinds of traits. While later papers have built on this issue and surrounding ones for the function of crests and the like, in my mind it has always been an unsatisfying explanation for things. Sure, it’s a big issue and to ignore it is incorrect, but while we are finding more and more examples of mutually sexually selected species, it seems unlikely that so many dinosaurs (huge numbers of hadrosaurs and ceratopsians, various theropods and other lineages) all had equal ornaments. Sexual dimorphism, be it in body size or crest size and shape (or of course, presence / absence) surely was present in a few of these lineages?

One issue is of course that for a lot of species we have very few specimens (often only one) and certainly don’t have lots of adults in good condition from a single site for many. As I noted in a paper on social behaviour in dinosaurs, lots of large terrestrial mammals at least show different fundamental patterns in group behaviours between the sexes so even if we do have 50 animals from a mass mortality site, there’s no guarantee it is not a group of 50 males or 50 females. Identifying different sexes is also problematic of course but it would help if in a few cases we *knew* we had both present in a sample size.

Even so, where was the dimorphism? Was it really absent or merely for some reason, hard to detect? After quite some thought I realised that what might be a major factor is the growth patterns of dinosaurs. Where large mammals and birds rather race to adult size and then stick there, dinosaurs (at least the larger ones) took a longer and more reptilian growth pattern with an extended growth phase (even if they were sexually mature during much of this). That means that much of the reproducing population isn’t full size and that even if say males were much bigger than females, you’d struggle to tell apart and old female from a young male which might be comparably sized. Right, now I had a hypothesis and a mechanism to test it by getting a dataset on dimorphic animals with differential growth and see how they looked depending on how things were sampled.

And then I got stuck. Datasets like this, (especially with reptiles and birds) simply didn’t seem to exist in the literature. Over perhaps 5 years I sent out dozens of e-mails and spoke to various people about data, including biologists, palaeontologists, conservation and zoo workers – anyone I thought might have or know of a dataset of mass for lots of individuals of known sex and age. I got nowhere. Even trying to compile sets from lots of individual measurements didn’t get me anywhere and I was resigned to having a good idea I couldn’t test, until Jordan got in touch.

He sent me a draft of his now published paper re-examining analyses that had looked for dimorphism and found them wanting. Reading it through I was annoyed to see that he seemed to be leaning the same way and that the elongate growth might be a decisive factor, but while the paper discussed some issues around detection it didn’t go there. I was relieved that my idea seemed to still be mine to work on, but as Jordan had asked for any comments to help improve things, it also seemed a bit mean to withhold an idea that might provide a nice extra aspect of the paper.

Happily, as these things often do, a quick chat via Skype helped revolve things. Jordan liked the idea but agreed we could try and combine forces, as he thought he had a good lead on some data we could finally use and importantly also knew how to run the analyses. So with new impetus, the idea was resurrected and the final output of this collaboration is now out.

So, what did we find? Well it looks like my thoughts were generally correct but far more so that either of us suspected. We used alligators as the reptile model since they form a part of the dinosaur phylogenetic bracket and have large dimorphism (at full size, males are 30% and up longer than females), with rheas on the other side (also show major dimorphism and are large birds). Doing various subsamples of each it is clear that it’s much easier to detect dimorphism in the birds because you are tending to sample animals that are at full size. You can use a much smaller sample size to detect dimorphism in birds than reptiles. You typically need around 30 animals of *each* sex to get a statistically significant difference in alligators, even though that have one of the highest levels of dimorphism recorded.

Given how few dinosaurs even have a dataset of 60 animals (and then the issues of making sure you can measure them all accurately, and of course the fact that you’ll be lucky if even a few are sexed, and you may have all of one sex, and there is often variations between populations) and then it becomes little surprise we have picked up no good signals for dimorphism in dinosaurs to date. This does become a little better when we sample from larger individuals (as there are several biases against juveniles in the fossil record) but still well below what we can do for almost any dinosaur.

One other aspect that we look at is the range of dimorphism appearing in extant reptiles. There’s a surprising (to me) level of variation in populations with major variations in terms of just how dimorphic one population is versus another and these can also change over time. Some populations of single species even show males being larger with others having larger females. That’s also potentially an issue given our tendency to have to lump together specimens from multiple different sites to get to a decent number of animals to measure and while it might not be common, it’s clearly a potentially confounding signal.

This is of course not the final word on any of this. There are other aspects to both growth and dimorphism and how we measure it in both living and extinct animals. Certainly I think it’s possible to make a good case for dimorphism with only a limited sample (as has been looked at for example with oviraptorosaur tails, or indeed for some pterosaurs) but the apparent lack of dimorphism for dinosaurs in the fossil record is not as alarming as it might seem. Yes we might expect numerous species to have been dimorphic but it appears that our sample sizes are simply too small. Through in the unknown age and sex of most specimens, and the potentially confounding effects of mutual sexual selection and it becomes perfectly possible that many species (even those represented by large numbers of good specimens) were strongly dimorphic but we are simply unable to identify it.

For years I’d been puzzled by the apparent lack of dimorphism, and Jordan’s paper confirmed that we really have yet to show it clearly in any dinosaur. Mutual sexual selection is a major issue but it probably doesn’t explain all the cases we know about, but I think this paper adds a pretty substantial concept to our understanding of dinosaur dimorphism. Or rather, that we don’t understand it that well but that the apparent absence could well be a classic absence of evidence problem. As with a number of issues in behaviour and ecology, I rather suspect we don’t know as much as we think we do, but understanding what we do and don’t know with confidence is a major step forwards to getting to grips with the problem, so this hopefully is progress even if we can’t find much right now.

 

Hone, D.W.E., & Mallon, J. [joint first authors]. In press. Protracted growth impedes the detection of sexual dimorphism in non-avian dinosaurs. Palaeontology.

 

The Tyrannosaur Chronicles – now in paperback

So nearly a year has passed since the book launched and that now means that the paperback is due. I’ve been fielding a few questions about it (and of course I want to promote the new release – due on April 20th) so this seemed like a good opportunity to do a quick blogpost on it.

As you can see the paperback has a switched-up colour scheme from the original purple hardback but that’s one of the biggest changes. The book has really not been updated and while there are some corrected typos (and the annoyingly switched around phylogenies in Chapter 4) these are the only real alterations. There are some more notes in the introduction, but that’s it – I didn’t have the opportunity to revise and update the book as a whole and I’m not sure I’d have taken it if I had, so please don’t invest thinking this is a new version, it is not. The paper quality is good on the paperback and the Hartman figures and drawings do not suffer at all, and the glossy photos are all still there in the middle.

One year on is a decent time to reflect on things and I’ve been amazed at the positive response to the book. I always expected it would go down well with dinosaur aficionados but it has sold in numbers that show it has gone well beyond any fanbase I might have, and even that tyrannosaurs might have, and there’s been loads of responses and reviews from more ‘normal’ people who simply enjoyed it as a book on popular science. Amazon.com is especially good averaging 4.6 from 28 reviews, but Amazon.co.uk is hardly bad (4.0 from 7 reviews) and it’s done well on Goodreads as well (3.93 from 114 ratings with 34 reviews). I’ve yet to see a review below 3/5 (though I’ve hardly been hunting down bad ones!) and that is really nice since it’s impossible to appeal to everyone, but clearly it’s coming across well generally.

That’s it really. I’m obviously delighted with how things have gone and hope it continues to do well. It naturally is already dated (damned new species being named!) but the fundamentals I hope will be relevant for many years to come and continue to be enjoyed by readers.


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