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.

Buried Treasure – Dave Hone

I could hardly expect everyone else to write about their own papers without taking a turn myself at some point. In may case it’s a fairly recent paper that I’d like to cover, my paper in the Journal of Zoology on sorting out hypotheses for behaviour when dealing with fossil species. OK, so it’s only a few years old and things take time to accrue citations, but it does seem to have had very little impact given the raft of papers I have seen that (I think) would really benefit from taking a look at what I and my coauthor Chris Faulkes proposed.

Over the last few years I’ve become increasingly invested in looking at definitions and how they are used. When you are trying to look at multiple species and compare them, or get a sense of something of the state of play for an issue like the ratio of different life stages of animals, it’s enormously helpful if everyone is using the same definitions. Unfortunately the opposite is true, people use different words to mean broadly the same thing (without ever clarifying it), or the same word to mean very different things depending on context (again, without ever providing an explicit definition) and the whole situation becomes a bit of a mess. My paper on defining juveniles and adults for dinosaurs is a case in point and similarly, there’s lots of unhelpful use of the term ‘social’ with out reference to other works (especially on living taxa) as covered in my paper on Protoceratops and what it means to be ‘social’.

In short, we need to be careful about how things are defined because that’s important for making data comparable, but it’s also an issue for testing hypotheses. If it’s not clear what you mean by ‘juvenile’ then it’s very hard to say whether or not this is the correct assignment, or using it to assess a growth pattern etc. The other side of this, is whether or not a hypothesis is really credible in the first place. I think with palaeontology we are so used to dealing with incomplete specimens and limited data generally that hypotheses based on little evidence is the norm, but it does seem that when it comes to behaviour (and / or ecology) these can get erected based on almost nothing at all, and really only add to a long list of vague statements that don’t really add anything to our understanding of how animals lived. I won’t pick on any specific examples, but it’s not hard to find hypotheses like ‘this animal may have been a piscivore / scavenger / hunted in packs / migrated long distances’ and so on based on the flimsiest of lines of evidence. Statements about the sociality of whole clades of taxa based on a set of footprints of two individuals together is not something that should be taken seriously, but too often it’s not only published but then picked up and carried forwards.

So my paper on establishing hypotheses was designed to be something that could help provide guidance towards making hypotheses stronger. What lines of evidence would likely be useful to support a case, which would be weaker, how can that evidence be best integrated with available data or our understanding of the behaviour of living animals? Taken together, is an idea even supported by enough data to make it worth evoking as a formal hypothesis and if so, how can this best be formalised to the species or specimen in hand in a way that is supported by the evidence and is most amenable to further support or even formal testing later on?

I think this is really important. We as a field have become so much better at being rigorous when it comes to assessing ideas about descent, relationships, ages, functional morphology, evolutionary patterns and many more, but I do think that behaviour really lags here. Too many vague and unsupported hypotheses are not just in the literature, but are entering the literature and I do hope that the ideas in this paper will help slow up some of this and get people (authors, referees and editors) to take a more critical look at terms and how they are used, and in particular the support for hypotheses about behaviour.

Hone, D.W.E. & Faulkes, C.J. 2014. A proposed framework for establishing and evaluating hypotheses about the behaviour of extinct organism. Journal of Zoology.

Buried Treasure – Andy Farke

Sometimes, even research that gets a fair bit of press can get overlooked–particularly for little tidbits in the paper that might get obscured by the “big picture” stuff.

One of the coolest fossils I’ve ever worked on is a “baby” Parasaurolophus from southern Utah. The fossil–the smallest, youngest, and most complete of this kind of duck-billed dinosaur (hadrosaur) ever discovered–was found in 2009 by one of my high school students. The resulting 2013 paper received international press and has racked up a decent number of citations since. The fossil was even invited to travel to Japan as part of the 2016 Dinosaur Expo, where it was viewed by nearly a million people!

I am incredibly proud of the work, a collaborative effort with high school students, myself, and bone expert Sarah Werning, and consider it one of the best pieces of research I have ever published. Yet, there is one tiny angle that seems to get overlooked by a lot of people: the beak.

The skull on our baby Parasaurolophus is accompanied by an impression of the horny beak that lined the front bones of the upper jaw. Notably, it shows that the skull was not a terribly accurate representation of life appearance–the beak itself extended far beyond the bony anatomy.

Importantly, the baby Parasaurolophus was not the first hadrosaur to show this, either. Fossils of Edmontosaurus, reported as far back as the 1920s, revealed a similar structure, and strongly indicate that an elongated horny beak was pretty typical across “duck-bills”. In fact, they weren’t really duck-bills at all, but more like “shovel-beaks” (Brian Switek has a great post on this topic). The beak extension created a big scoop that was perfect for mowing off vegetation!

Long-beaked sauropod by Panzarin

Long-beaked hadrosaur by Lukas Panzarin

Despite a long history of knowledge about the beaks in these animals, very few artists include the structure in their reconstructions. I’m not sure why this is, but even very recent reconstructions by many talented artists simply follow the bony outline of the jaws. It is just a tiny blow to my ego that this tidbit from our Parasaurolophus paper (and work by others) gets overlooked!

Hadrosaurs looked quite a bit different than usually pictured. So, if you are an artist, or advising artists, give hadrosaur beaks an extra little bit of love!

Postscript

If I have to pick an underappreciated historical paper, I would say it has to be the classic monograph on the anatomy of Protoceratops by Barnum Brown and Eric Schlaikjer. It’s got a ton of careful anatomical description and some really brilliant thoughts on ontogeny (changes during growth). There is unfortunately a bit of a misconception arising that long-ago paleontologists didn’t think about ontogeny in any serious way–Brown and Schlaikjer show this isn’t true. Peter Dodson’s 1975 paper on ontogeny in hadrosaurs is another great one–he was one of the first people to show that what had been split into multiple species of duckbilled dinosaurs were in fact young and old individuals of a single species. This work by Brown, Schlaikjer, Dodson, and others paved the way for ongoing investigations of ontogeny today, many of which are using methods like histology to add another layer of data to the questions.

Citations

Brown, B., and E. M. Schlaikjer. 1940. The structure and relationships of Protoceratops. Annals of the New York Academy of Sciences 40:133–266.

Dodson, P. 1975. Taxonomic implications of relative growth in lambeosaurine hadrosaurs. Systematic Zoology 24:37–54.

Farke, A. A., D. J. Chok, A. Herrero, B. Scolieri, and S. Werning. 2013. Ontogeny in the tube-crested dinosaur Parasaurolophus (Hadrosauridae) and heterochrony in hadrosaurids. PeerJ 1:e182.

Morris, W. J. 1970. Hadrosaurian dinosaurs bills–morphology and function. Los Angeles County Museum Contributions in Science 193:1–14.

Versluys, J. 1923. Der Schädel des Skelettes von Trachodon annectens im Senckenberg-Museum. Abhandlungen Der Senckenbergischen Naturforschenden Gesellschaft 38:1–19.

A cornucopia of pterosaur papers

I’ve already covered here at some length my paper on the taxonomy of some of the Asian dsungaripterids as related to the rediscovery of some missing material of Noripterus. That paper is my entry to a volume that I have edited with Mark Witton and Dave Martill* and is the collected works that comes off the back of the 2015 Flugsaurier meeting in Portsmouth. This is being published by the Geological Society of London, an august institute to host this, and a nice hark back to the truly seminal 2003 volume they produced from the back of the Toulouse pterosaur meeting. It will be very hard to meet the standards of that collection (not least as it contained some absolutely fundamental papers on systematics and critical specimens) but I hope not to stand too much in that particular shadow.

Unlike many previous volumes this has the advantage of papers being published online as they come in and so we do not need to wait for the final paper to be sorted before the volume becomes available. That means that a number of papers are already available to read, even though not all of them are yet back from edits by authors and approval by the editorial team. We do hope to have the paper version out by the end of the year, but in the meantime there’s a pile of papers to enjoy.

There’s a diversity of subjects covered here with papers describing new specimens, revisions of existing taxa, new genera being named (or resurrected), a major new phylogenetic analysis, studies on muscles, jaws, and wings as well as various other bits and bobs. I won’t go through them one by one, you can see the list here (and it will continue to update as papers come in). The volume is, sadly, not OA but the production of PDFs means that authors have copies that can be readily disseminated so as with many papers, an e-mail should secure you a copy (and people like to know their work is being read). There should be something in here for everyone (provided of course you like pterosaurs) but here’s a select group of personal highlights so far (and some other important and interesting papers are coming).

First off would be Mark Witton’s excellent review of pterosaurs in food chains – both things they ate and that ate them. This deals exclusively with direct evidence of diet (stomach contents and the like) of which there is a fair bit, rather than so much work which is understandably often built on inferences about these relationships. It’s an excellent foundation for this area which is growing quite rapidly.

Next would be Chris Bennett’s paper with Paul Penkalski on a bizarre Pteranodon that has a striped skull. This isn’t (sadly) colour patterning or soft tissues but remarkably seems to be a pattern of the bone itself. It’s really quite strange and shows that even pterosaurs we know well can pop up with some big surprises.

Finally there’s Colin Palmer’s paper on the properties of pterosaur wing membranes. Although not the first to tackle this subject, since the last major review and set of hypotheses on their performance, we have learned a lot about the structure of the soft tissues, the layers that go into it, and the size and shape and extent of the main wing as well as the orientations in which it likely functions. That makes a synthesis like this very useful as both a review of where we are and what we might expect as well as giving us ideas to test.

I’ll leave that here for now and let readers explore the volume as it firms up. It only remains for me to thank my co-editors and the various referees as well as of course the authors themselves and the people at the Geological Society for their help with producing this volume and  look forwards to seeing the final printed version.

 

 

  • For the record as this kind of thing has caused consternation among some before, I did not have anything to do as editor with my own authored paper. It was handled entirely independently by the other editors and I had no access or input to the process (and nor did they to their own papers). In a small field like pterosaur research it’s hard if not impossible to find referees and editors who are truly independent, and it’s a bit odd to exclude people who have the knowledge to edit a volume from contributing to it, so this is the best solution. This really is common in lots of specialist volumes, but it’s worth noting that it was done as transparently and ethically as possible.

 

Buried Treasure – Jordan Mallon

What is my least appreciated paper? That’s an easy one:

Mallon, J. C., and Evans, D. C. 2014. Taphonomy and habitat preference of North American pachycephalosaurids (Dinosauria, Ornithischia). Lethaia 47:567–578.

This is a paper that I co-wrote with my good friend and colleague, Dave Evans. It’s been published for nearly three years now, and has garnered only two citations—both of which are from Dave and me! Despite this, the paper effectively debunks a widely held meme that North American pachycephalosaurs were mountain dwellers, à la big-horned sheep. This is an idea that gets a lot of play in both the popular media and textbooks (including some that have come out even after our paper was published).

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See what I mean? The belief that North American pachycephalosaurs lived in the mountains is all over the place!

 The idea for the project came to mind shortly after I started my postdoc at the Canadian Museum of Nature in 2013. I was reading some papers by my predecessor here, Charlie Sternberg, and repeatedly came across this notion of his that North American pachycephalosaur skull domes tend to be well worn, “as if they had been rolled down a stream” (C. M. Sternberg. 1970. Comments on dinosaurian preservation in the Cretaceous of Alberta and Wyoming. National Museums of Canada Publications in Palaeontology 4:1–9). For Charlie, the implication was that these pachycephalosaurs must have lifted in upland—even intermontaine—environments, and not in the ancient coastal plain environments where their skull domes are typically found. Others have run with the idea since then.

But was Charlie right? Are these pachycephalosaur domes typically water-worn? No one had done the hard work of looking over the original fossil material to find out. Fortunately, most of the domes that Charlie collected were available for examination at the Canadian Museum of Nature. Dave and I further supplemented our dataset with domes from the Royal Ontario Museum and the Royal Tyrrell Museum of Palaeontology. In all, we had a respectable dataset of 187 domes, which is nothing to sneeze at (particularly if you’re a dinosaur palaeontologist). Without going into the nitty gritty of how we assessed dome wear (you can read the paper for that), suffice it to say that we found that domes were not typically worn. We also found that dome wear does not correlate with distance from their presumed origin in the Rocky Mountains, nor are pachycephalosaur remains relatively more abundant in intermontaine deposits, which we could expect if the critters lived there.

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North American pachycephalosaurs almost certainly lived in the ancient coastal flood plains where we find their skull domes today. Image credit: Brett Booth.

Dave and I took this to mean that pachycephalosaurs must’ve been living where we find their remains: in the low-lying coastal floodplains, alongside the more common hadrosaurids and ceratopsids. It’s an important first step in understanding things like dinosaur community ecology and beta diversity. It’s also a good reminder that taphonomic processes like erosion can actually inform our understanding of the habits of fossil organisms, and are not simply information-destroying by nature.

If anyone wants a copy of the paper (which is behind a paywall), please fire me off an email at jmallon AT mus-nature.ca.

 

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.

Noripterus returns – sorting out some pterosaur taxonomy

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

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

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

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

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

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

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

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

A superb set of limbs from one specimen of Noripterus

A superb set of limbs from one specimen of Noripterus

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

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

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

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

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

 

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

 

Buried Treasure – Tom Holtz

I consider my 2008 paper “A critical re-appraisal of the obligate scavenging hypothesis for Tyrannosaurus rex and other tyrant dinosaurs” to have the highest “underappreciated:applicability” index. (The fact that it took 10 years for the paper to actually come out doesn’t help my appreciation for its unappreciatedness, too…)

It isn’t that other theropod workers ignore it; they do cite it. But since the topic of tyrannosaurid predation is studied by a larger spectrum of workers, many of whom do not have particular expertise in dinosaur morphology or even paleontology, many papers where it SHOULD have been cited do not do so. This is particularly frustrating because it is not a hard reference to find on a scholar.google search, and more importantly because it was specifically written to be accessible to a non-specialist audience. Of course I don’t think that they had to agree with every point in it, but I did collect and address all the major arguments for obligate scavenging in tyrannosaurs proposed up to that point, so it should at least be discussed.

Furthermore, when (often younger) paleontologists respond to the newer (and sometimes non-paleontologically-informed) studies on tyrannosaur predation, they wind up “re-inventing the wheel” (not being aware of my paper from so long ago…)

Holtz, T.R., Jr. 2008. A critical re-appraisal of the obligate scavenging hypothesis for Tyrannosaurus rex and other tyrant dinosaurs. Pp. 370-396, in P. Larson and K. Carpenter (eds.), Tyrannosaurus rex: The Tyrant King. Indiana University Press.

—-

In my opinion, one of the least appreciated papers in dinosaur paleontology is

Janis & Carrano’s 1991 work comparing reproductive turnover in dinosaurs and mammals. The implications for this paper reach into nearly every aspect of dinosaurian ecology (size; evolutionary turnover rates; ontogenetic niche shifts; number of species per fauna; extinction sensitivity; etc.) in comparison to placental mammal ecology. And yet it seems (at least to me) to be underreported relative to its applicability.

Janis, C.M. & M. Carrano. Scaling of reproductive turnover in archosaurs and mammals: why are large terrestrial mammals so rare? Annales Zoologici Fennici 28: 201-216.

Buried Treasure – Mike Taylor

So kicking off the first in the series of favourite / underappreciated papers is Mike Taylor of SV-POW. Here’s his thoughts on one of his own works:

The paper I look on most fondly is Taylor and Wedel (2013) on “Why sauropods had long necks; and why giraffes have short necks”. I like the snarky title, of course — when I give talks about this subject, I just use the second half — and the subject matter is dear to my heart. But it’s how this paper came together that makes me love it the most.

It started out on a car journey in 2008. All three Wedels were staying with us that summer, as Vicki had a leprosy conference in Bradford. Matt and I visited several museums while they were around. I think it was as we were driving back from Oxford that we started listing the ways that sauropod necks didn’t make mechanical sense to us. Since I was the one driving, Matt took out his notepad and started making lists. “What the hell is going on?”, we asked — and so the embryonic project was dubbed WTH, for “what the hell”.

More than any of our other papers, this one went through really significant revisions. The earliest “complete” version was rather formless: it contained a lot of good stuff, but there was no structure to it. We revised it into an unconventional form with three main sections: “Facts”, “Interpretation” and “Speculation”. At this point, the title was still “What the hell is wrong with you? Mechanical design flaws in the necks of sauropod dinosaurs”.

This was also the basic shape of the version we finally submitted to a journal, though by then it had the more sober (and boring) title “Vertebral morphology and the evolution of long necks in sauropod dinosaurs”. We had a very bad review experience at that journal, which I won’t go over here; but suffice to say that the result was that, having thoroughly reworked it into a form resembling the one we know today, we sent it to a different journal rather than back to the first one. We were bullish about this submission, and pleased to think we were giving a good paper to a journal that could probably use it. So we were rather shocked to find it rejected with reviews that we couldn’t sympathise with — especially one that said “The manuscript reads as a long “story” instead of a scientific manuscript”, which we feel is praise though it was intended as criticism.

We made some revisions in response to those reviews, but by the time we’d done that PeerJ was on the horizon so we sent it there — and after very quick and genuinely helpful reviews, it was published as part of that journal’s first batch: https://peerj.com/articles/36/

We’re really happy with the “story-like” final form of the paper. Our goal was to make something that was not only informative but also fun to read. I hope the progression of the argument makes sense — Introduction, Long Necks in Different Taxa (finishing with sauropods), Factors Enabling Long Necks, Architecture of Sauropod Necks — and that readers always have a solid sense of where they are in the progressing argument. We’re also really happy with the illustrations in this paper: PeerJ, being an online-only open-access journal, imposes no limits, so this is a lavishly illustrated paper with some comparative illustrations (Figs 1, 3 and 7 particularly) that we’re really proud of: https://peerj.com/articles/36/#fig-3

Finally, I won’t deny it’s satisfying that a paper which was (wrongly, we feel) rejected by two palaeo journals has gone on to be viewed 23,000 times by 17,000 different visitors, and has been downloaded 3,000 times. We very much hoped that that paper would reach a non-specialist audience as well as other researchers, and those numbers suggest that’s happening.

 

Finally, Mike has a pick for an underappreciated paper by someone else is:

Hokkanen, J. E. I. 1986. The size of the largest land animal. Journal of Theoretical Biology 188: 491-499.


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