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Anurognathid pterosaurs ate insects at night

Yes, it’s very early in the year but before 2023 had even hit, this paper managed to squeeze out actually appearing online on New Year’s Eve when I, and indeed most of the world, were not keeping tabs on journals so it rather passed everyone by and I’m now rushing to catch up! The good news is that it’s more anurognathid pterosaurs (arguably the best pterosaurs and certainly the cutest). These odd little animals have had a lot of attention in recent years with a bunch of new finds (some of which include new taxa like Cascocauda) and are just generally an increasingly well-studied clade given how many seem to preserve soft tissues which is rather nice.

For as long as I think anyone remembers, the anurognathids have been considered to be aerial insectivores, flying around at night and trying to catch insects on the wing. I don’t think there are any papers that have seriously challenged this hypothesis, and it’s been the default for decades given that their basic body plan and head shape means they have a massive gape, huge eyes, small teeth and wings well suited to this kind of flight. But it’s also an idea that hasn’t really been tested in any real way, relying on some basic (but perfectly reasonably) comparisons to things like whip-poor-wills and other similar birds.

So the central point of this paper was to try and do some more formal comparisons and see just how the anurognathids fare in comparison. I must confess I didn’t contribute massively to this paper, the lead author Alex Clark, who is based in Cincinnati, contacted me last year with the idea for the paper and really needed help with the pterosaur bit. He’s wrapping up his Masters on bird ecology and thought that it would be a good idea to do some formal comparisons on head shape in various insect-catching birds and those that operate in low light to the anurognathids to see how they overlapped. We also put in some comparisons to some insectivorous bats in terms of their canine shape and the similarly shaped teeth in the pterosaurs.

The details are of course in the paper but the really short version is this. Anurognathid heads shapes in terms of their gape is really similar to that of other birds that catch insects on the wing (like swallows and nightjars) and not like that of other pterosaurs. Their eyes are huge and again are like those of nocturnal, or low-light operating birds (in fact they are generally proportionally even larger). In short, this really strongly supports the conventional interpretations of anurognathid ecology. The tooth comparisons to bats were rather less helpful and the data is very scattered, and it’s at least not contradictory to the general idea.

No, on the one hand, no real surprises here. Our fundamental ideas were solid and the previous comparisons were reasonable, meaningful and turned out to be well-supported. Still, it’s really nice that this does back things up and that our basic inferences about anurognathids were correct and it means that those almost infinite drawings of the spiraling around after insects in the dark are not out of date. On that note, the paper does include some lovely new art of that very action with a new piece by Rudolf Himawan shown here.

I’d like to add a final quick thanks to Chris Bennett for generously letting us reuse some of his drawings to make our own figures clearer and to Manabu Sakamoto who gave us some useful pointers on some of the analyses. Mostly though, I need to thank Alex for inviting me to work with him on this project in the first place and seeing this paper through to the end.

Clark, A.D., and Hone, D.W.E. 2023. Evolutionary pressures of aerial insectivory reflected in anurognathid pterosaurs. Journal of Anatomy.

Microraptor ate mammals!

Ok, if we are being totally reductionist, one Microraptor ate part of one mammal once. But that’s certainly indicative of a pattern and that’s quite exciting. As you might guess, I have a new paper out today describing a Chinese specimen that shows this, though those with excellent memories and niche dinosaur knowledge might already know about this because it’s been announced before and way back in 2010!

Yes, this paper has been on the cards for a very long while. Back in 2010 Hans Larsson was over in the IVPP with his then PhD student Alex Dececchi and looking at various theropods. I was based there at the time working alongside my fellow Postdoc Corwin Sullivan under Professor Xu Xing. While looking over some flattened Yixian specimens, Hans spotted something that really people should have seen before (including me!). Clear as day in the holotype of Microraptor zhaoianus was the foot of a small mammal. Under the ribs.  Yeah, one of the most important and studied early feathered theropod finds had an obvious and very interesting set of stomach contents that had been completely missed.

Hans rather generously asked us all to collaborate on this find and we put in an abstract to SVP that year and so if you have the right knowledge you may have spotted this (or even seen his talk in Pittsburgh). In that regard this isn’t exactly news, and so it might come as a surprise that we ever got this out and so much later. Well, I’ll blame the others for that, (OK, mostly Hans!) but the fact remains it is now out and properly described, documented and put into some context and it’s the first, to my knowledge, example of a dinosaur eating a mammal, so that alone is nice and novel.

We don’t, annoyingly, know what the mammal actually is, despite having a much of things to compare it to, but we do know it’s small (mouse sizes) and doesn’t appear to have much in the way of climbing adaptations so would have been pretty terrestrial. That contrasts with interpretations of Microraptor as some kind of arboreal adapted flier that’s spending a lot of time in the trees. Still, we can’t say if this was predation or scavenging – though either way, it was likely this was picked up on the ground so it’s an interesting nugget of info on Microraptor diet.

On that note, this is now the fourth reported set of stomach contents for this genus with fish, lizards and birds also on the menu. Rather oddly, both fish and birds have been suggested to be something that Microraptor was specialised for, despite showing a) a diverse diet and b) no particularly obvious anatomical specialisations for either of these. Indeed, there’s a greater diversity of things eaten known for this animal now than any other dinosaur and that rather points to a generalist diet of any small thing going down the hatch. This of course comes with a few caveats here, there’s multiple specimens of Microraptor at play from more than one putative species and it’s at least possible that 1 species preferred things like lizards and mammals say, while another took birds etc. or these varied over time and space. Still, if there was any kind of specialistion we would expect to see multiple examples of single clades being taken, and I think that a generalist diet is likely.

That also fits with what we see in other small theropods as there are several with stomach contents or pellets featuring multiple taxa (e.g., Scipionyx) and suggesting they tended to eat a variety of things and specifically those that were rather smaller than them. This is in fact a bit of a pattern in general and while mammals aren’t always the best analogies, there is lots of data for them, and this is a trend seen there so it might well be that small theropod (be they small taxa or juveniles of big ones) tended to be more generalist. We do need to be careful here of course as we also then have preservation biases – Microraptor might, for example, have predated primarily on things like invertebrates and we know there were loads of beetles, spiders and the like around in the Jehol. But those don’t tend to fossilise well (especially not if crunched up and partially digested) compared to small bones, so perhaps these are just missing.

So one other thing we worked in here was to look at the jaw shape of dromaeosaurs in general and how this might fit with biting mechanics and so diet. While generally having incomplete skulls, Microraptor has a rather short head and lies in contrast to animals like Velociraptor with a longer and more slender skull, pointing to a proportionally harder but lest quick bite in the former (for its size) b. That also points to them not being especially adapted for things like insects where a hard bite wouldn’t be too necessary to kill or process them, but a quick bite would be an advantage. So while Micrioraptor might well have taken invertebrates as part of its diet, it doesn’t appear to be especially well suited to the task and biting small vertebrates looks like it was something more normal.

So there we have it, dinosaurs – perhaps unsurprisingly – ate mammals (and at least got their own back for Rapenomammus) at least on occasion. And more than that, Microraptor was (probably) a generalist predator of small vertebrate prey, though we can’t rule out scavenging or indeed other things like insects or even fruit as occasional parts of the diet. This might well be something common to many small theropods, though the general lack of data inhibits us from saying too much, the overall pattern of what information we have would tend to confirm this. It has taken us far too long to get this information out into the world but it’s finally made it and adds a nice note on theropod ecology and behaviour.

Finally, a quick thanks to my coauthors for sticking through all of this but also especially Ralph Attanasia III who kindly provided the illustration that went out with the press release and is shown above.

Hone, D.W.E., Dececchi, T.A., Sullivan, C., Xu, X., and Larsson, H.C.E. 2023. Generalist diet of Microraptor zhaoianus included mammals. Journal of Vertebrate Paleontology.

Larsson, H.C.E., Hone, D.W.E., Dececchi, T.A., Sullivan, C. & Xu, X. 2010. The winged non-avian dinosaur Microraptor fed on mammals: implications for the Jehol Biota ecosystems. Society of Vertebrate Paleontology (SVP), Pittsburgh, U.S.A.

Fifteen years of Musings

The Musings has been very quiet the last few years. I’ve obviously been busy at work and a lot of my outreach has shifted with the podcast (now more than 50 episodes done), various books (2 out, another nearly ready to got to the publisher), having the Guardian column for a few years, and being based in the UK again, I’m able to go and do more things in person, and then there’s Twitter of course which is so much better for dropping in a photo and comment than WordPress ever was.

Inevitably therefore, my output here has dropped and while it has typically been only a few posts a year and usually based around new papers. It still works very well for this, I can go into far more detail than on Twitter or similar platforms, cover all the ground I want to, link back to things, show photos or figures, and have control over it all (unlike media coverage). In short, I still like the format of blogs and I think they still have a place and I’m loathe to give up this one even if it has moved to being much more infrequent and most of the time is now only really about my research. So, it is likely to trundle on for now and fans and readers (assuming they still exist) can expect a few more posts to come and I’ve no immediate plans to wind this up.

That said, while it might be on a long and slow decline, I can take some solace in that it’s still going for now and by my count it’s now some 15 years of blogging (the vast majority on here and then a brief forerunner in a previous and now I think lost website). Compared to the palaeo-centric blogs out there (for example my hopelessly out of date and not at all curated list in the sidebar) I think this means that I’m one of the very longest out there and certainly one of fairly few survivors of the great burst of new palaeo blogs from the 2005-2010 era. I’d like to think that’s in part because this has remained a useful resource and while the posts and comments are less frequent than they used to be, plenty of old posts are still getting plenty of hits daily with some occasional big spikes when new stories break (the Fighting Dinosaurs post is going to be racking up hits forever).

So, Happy Anniversary to the Musings (even if that’s coming from its author) and I do hope there will be at least a few more years of posts to come.

The Future of Dinosaurs

After numerous substantial delays, my next popular science book is out now with Hodder. Called by the slightly cryptic title of ‘The Future of Dinosaurs’ the subtitle rather better explains what it’s really about ‘What we don’t know, what we can, and what we’ll never know’. Yes, this is all about the gaps in our knowledge and trying to spot some things that we probably can solve in the future with further application of our new techniques and new finds, but also look for areas which might essentially be unsolvable.

So this is a bit of futurism and crystal ball gazing, but hopefully something that’s interesting and based on a real understanding of current palaeontology. It’s not all just guesswork and gaps though, clearly to set the scene of what we *don’t* know, I have to start with what we do. What’s the state of play for various different aspects of dinosaur biology (there’s chapters on origins, physiology, appearance, behaviour, extinction and more) and what is certain or uncertain.

From there, it’s other what we don’t know. To give an example, we have recently started to piece together the colours and patterns of some dinosaurs which is something that I think many researchers thought would be effectively impossible. Its potential is enormous for understanding dinosaur biology, but it’s also something that we’ve clearly not yet exploited. Working out the (rough) colour of one black, white and orange Anchiornis is great, but we don’t know if that individual was an exceptional animal – maybe it was leucistic or melanistic and others were less black or less white in places, maybe it was a male in breeding plumage and the females were a different colour, maybe they went white in winter, maybe they were different colours in different regions or this changed over time? All of these are possible, perhaps even likely, and with the huge numbers of well-preserved specimens that have been discovered already and the likelihood of even more being found in the future, then this is something that I think we will inevitably begin to tackle in the coming years (OK, maybe decades). It really should be possible and while it would take a ton of time and research effort, there’s no obvious barrier to eventually being able to work this out and is something we will build on and understand better soon.

On the other hand, there are things we’ll perhaps never know about their feathers and colours. We can only work out some aspects of colour and patterns and things that rely on e.g. the orientation of the melanosomes that we use to work out colour are almost always going to be disrupted and other pigments for whatever reason don’t leave any kind of trace in the fossil record and can never be detected. It is also going to be nearly impossible to work out what displays they might have done, how they might have paired up or had different mating systems and so on, and so the colours will only get us so far.

While lots of people have talked at various times about where various branches of science are going next and what discoveries remain to be made, I don’t think there’s ever been a book like this trying to tackle lots of different aspects of our understanding (or lack thereof) and what shape our knowledge of dinosaurs might look like in the future. How successful I am, either in predicting what’s going to happen, or in suggesting why it might be the case, or for that matter in interesting my audience of course remains to be seen, but the book is out there now so let’s see.

If you do want to buy it, it’s available now as a physical book and ebook in the UK at least, and there is an audiobook version coming soon. This is also going to be released in North America soon through Princeton University Press under a different title (and different cover) as ‘How Fast did T. rex Run?’ but the content is identical.

Cascocauda – a new anurognathid pterosaur

Back when I was working on my big review of all anurognathid pterosaur specimens and their taxonomy, I realised that at least a couple of then unnamed specimens were probably distinctive and warranted naming.

One of them was a rather small, and not especially well preserved skeleton, that despite being nearly complete and with rather poor conditions to the bones, had extensive soft tissues. The preservation of these (both wings and filaments) had been the basis of some work on the specimen and not knowing what else might be going on, I dropped some of the authors a line to ask if they had any interest in the taxonomy of the thing and what they might be planning to do about it.

Cascocauda. Taken from Yang et al., 2022

As it happened, Zixiao Yang was indeed looking further into this as part of his PhD and was putting together a dataset on anurognathids to look at their growth. Having also been looking at this area in pterosaurs too they were kind enough to invite me to join them, and this work is now out.

The first thing to note is that we find that the specimen in question is indeed a new taxon and is named Cascocauda rong roughly translating as the fluffy ancient tail. For an anurognathid at least it has a rather long tail and hence that was chosen to be a key part of its new name. In terms of its relationships, we find it to be with the recently named Sinomacrops and Batrachognathus with all the other anurognathids forming a clade as the sister taxon to this group. We actually got this result using two different versions of the phylogenetic codings of which more in a second.

In addition to this more ‘basic’ work, the main part of the paper looks at the ontogeny of anuroganthids as a whole. While work that I’ve done (and plenty of others) have noted that a lot of pterosaur traits seems to be isometric and basically unchanging with growth, a) we don’t know how true that is of all taxa and b) if it’s not that’s potentially a big problem given how many taxonomic and phylogenetic traits we use for pterosaurs based on things like the ratios of the wing and leg bones.

So this is something we looked at here with the anurognathids, though with the rather odd caveat that we basically took the group as a whole rather than looking at the ontogeny of a single species (since that’s basically impossible). But if the anurognathids are as conservative morphologically as we think that they are then this is a reasonable approach to take and is certainly worth a look.

We do find that various bits of anuroganthids vary with size in some interesting ways though perhaps the most interesting is the length, and especially width, of the skull. They are called frog-mouths for a reason and that big gape is a key feature yet larger anuroganthids have a proportionally smaller skull. That points to both adults and juveniles having surprisingly similar head sizes and suggests that they are feeding on relatively similar sized prey even as they themselves get rather bigger.

Some other traits also appear to change during growth and could well be throwing off analyses that have used these characters when trying to piece together their phylogeny so these were removed or recoded in the analysis. As it happens this didn’t actually make a real difference to our results, but it’s nice to know that this isn’t apparel screwing up the relationships of the anurognathids at least, though it’s going to be something to keep an eye on in future when looking at pterosaur phylogenies given the number of taxa represented by only juvenile animals.

I’ll leave things there and won’t go into more detail since the paper is easily accessible and that will be the place to go for more details.

Yang, Z., Benton, M.J., Hone, D.W.E., Xu, X., McNamara, M.E., and Jiang, B. 2022. Allometric analysis sheds light on the systematics and ontogeny of the anurognathid pterosaurs. Journal of Vertebrate Paleontology.

Welcome Dearc, a giant rhamphorhynchine

Today sees the publication of a new and very cool British pterosaur – Dearc sgiathanach and as I got to see the paper a while back as a referee I thought I’d used that privileged advanced knowledge to write a post about it as it’s a really neat animal and British (and specifically Scottish) pterosaurs do not come around every day.

Photo of the skull and part of the body of Dearc, taken from Natalia Jagielska’s Twitter feed

First off, the basics on the name. It’s full name basically means ‘wing reptile from Skye’ and following s recent trend of using local languages for scientific names rather than Latin or ancient Greek, this is actually based on Gaelic. That’s really rather neat and I can’t think of any other Mesozoic animal so named in the UK and I hope it is not the last. Oh, and the authors (Natalia Jagielska and company) were also good enough to include a phonetic pronunciation in the paper (link below) as ‘jark ski-an-ach’ so hopefully people will be using that properly.

For a Middle Jurassic pterosaur, it has got a lot of good material and not only is it preserved in 3D (and there’s some great CT scan data of it) with most of the skull and wings, and a good amount of the vertebrae column etc. as well. You’d always want more of course, but it’s really a lot and in good condition too. The paper covers a lot of the anatomy in depth but I’m also sure there will be more to come on this in the future.

It’s clearly a non-monofenestratan pterosaur and actually one that is very close to Rhamphorhynchus, enough in fact to be found to be a member of the Rhamphorhynchinae in the phylogenetic analysis that they did. It actually comes out with the odd Chinese pterosaur Angustinaripterus which is known from a single large skull with exceptionally long teeth. In short, you’d expect this animal to be one of the larger and later version of these non-monofenestratans and a shoreline or even oceangoing predator of fish.

What’s really interesting about this animal is its size. The largest good specimen of any non-pterodactyloid pterosaur that we have is a really large Rhamphorhynchus that is held in the Natural History Museum in London and is right around 1.8 m in wingspan or perhaps is a touch more. That is already much larger than any other specimen (the next biggest is about 1.4 m) and while there are some odd large bones out there (like the Angustinaripterus skull) that has long been thought to be about as big as they get. On top of that, Rhamphorhynchus is from near the end of the Late Jurassic and so (anurognathids aside) is among the very last of the non-pterodactyloid pterosaurs. 

Although incomplete and impossible to measure or estimate perfectly accurately, Dearc is complete and robust enough to give it an estimate of over 2.5 m in wingspan. So that’s massively bigger than we have for even the largest Rhamphorhynchus (out of 150 specimens!) and being Middle Jurassic, it’s much older too. Add to that, it probably had more growing to do too.

So that pretty much blows out of the water two classic ideas about the size of non-pterodactyloids. They could get above 2 m in wingspan and indeed much bigger, and it didn’t take them till the very end of the Jurassic to even get up to 2 m in wingspan. That’s really quite an interesting shift in our perceptions of their evolution and in particular means they were getting into some biomechanical realms that we didn’t think they could achieve without a pterodactyloid bauplan. In short, this is a really cool find and it promises much more in the future for our understanding of the evolution and flight of these pterosaurs.

Jagielska, N., et al., 2022. An exquisite skeleton from the Middle Jurassic of Scotland illuminates an earlier origin of large pterosaurs. Current Biology.

Ceratosuchops and Riparovenator: two new British Baryonychines

Today sees the publication of my most recent paper and it’s inevitably exciting as it describes two (yes two, count them) new, large theropods from the UK. Both join the burgeoning ranks of the spinosaurs, which have been increasing in lumber a lot of late and more specifically these are baryonychines.

While Spinosaurus tends to get all the attention, it and its kin, the especially large and sail-backed spinosaurines are known from extremely fragmentary remains and the smaller and less spiny baryonychines include Suchomimus and Baryonyx that are known from much more material.

In the case of the latter, this has been absolutely central to work on the spinosaurs as a whole as being the most complete and by far the best described specimen out there. The foundational monograph by Alan Charig and Angela Milner (who sadly passed away recently) being a cornerstone of spinosaur research. It’s also inevitably rather central to our work here since with two new baryonychines then we going to have to compare them to Baryonyx.

As usual, I don’t want to get into the minutia here since if you really want to look through the details of the diagnoses and traits and stratigraphy that’s all covered in the paper and this post is better placed to give some context to what we have done and why. The first thing of course is the names and their meanings. First off we have Ceratosuchops inferodios or the horned crocodile face hell-heron, the generic name referring to its appearance and species referring to the putative ecology of spinosaurs as a whole. After that is Riparovenator milnerae or Milner’s riverside hunter, in tribute to Angela’s work on these animals and again the ecology of these animals.

The second obvious thing to look at is what actually is there for the remains. Sadly, (if rather predictably) not that much though we do have nice snouts and parts of the skull roof and braincase for both, and in the case of Riparovenator, there’s also a nice section of tail. While pretty incomplete therefore, we do have more than some other spinosaurids and crucially we have the same parts of the skulls of both of these as we do for Baryonyx and Suchomimus. That’s obviously a huge bonus when it comes to the taxonomy work of sorting these animals out and we can make direct comparisons to these parts of the skulls that hold a lot of important traits.

Still, an obvious question about these British animals would be the vexed issue of ontogeny and if one (or both) were juveniles of each other. Happily, all three of the British ones are all extremely similar in size (within about 105 of each other) so it would be pretty hard to argue that they were very different ages and so the differences in anatomy are going to be ‘real’ and not part of their growth patterns. (And if they were very different ages but still the same size that would also suggest they have very different growth patterns and are therefore likely different taxa anyway). While we’re on the subject of the quality of the data here, it’s also worth noting that the specimens are generally really well preserved and not distorted so again, it’s a pretty safe bet to take the available features at face value as being genuine.

A major part of this paper is a new phylogenetic analysis done at the specimen level, with loads of odd bits and scraps of spinosaur material included for the first time in a comprehensive study (though some more things have appeared since we finished so it’s not 100% coverage). There’s not too many real surprises in there, but it should be a great start for resolving some other taxonomic issues for spinosaurs going forwards. One key thing though is the very clear signal that all of the earliest spinosaur material is European in origin and it looks to be a very strong case that this is a European group that then migrated out from here on multiple occasions.

Finally, there is the issue of the ecology of these animals. We don’t actually know if the two were contemporaneous with each either and either or both could be with Baryonyx and so while I’m sure some people will read this as ‘there were three together?!!’ we don’t actually say that. It’s perfectly possible from the data we have that all were somewhat separate in time and in space and of course niche partitioning is absolutely a thing too. I wrote this post on these issues a while back with this paper in mind to make the point about these kinds of situations and how it is easy to misinterpret them or assume that multiple species of large carnivores being together is somehow unusual or wrong. In the case of spinosaurs in particular, I’ve suggested that they are rather off in that they are except when they are common when they are suddenly very common (

) and this perhaps another example of that and hence the plethora of finds in the South of the UK.

I’ll finish up here, but obviously I want to thank Chris Barker and Neil Gostling for inviting me into this project and all my co-authors for their contributions to this publication. The paper is fully open access and available here: Barker, C.T., Hone, D.W.E., Naish, D., Cau, A., Lockwood, J.A.F., Foster, B., Clarkin, C.E., Schneider, P., and Gostling, N.J. 2021. New spinosaurids from the Wessex Formation (Early Cretaceous, UK) and the European Origins of Spinosauridae. Scientific reports.

There’s lots more about these finds online with a Terrible Lizards podcast here with Chris Barker and Darren Naish, and both Darren and Andrea Cau have blogposts out on this too.

Niche separation in the fossil record

There is a slow but steady publication papers that describe new fossil taxa that state or imply that the presence of some new species is evidence for niche partitioning in the animal’s ecosystem. This is basically redundant and is akin to the classic ‘this new species adds to the known diversity’ as if it could do anything else. One of the fundamental ideas of niche theory is that two species will not occupy the exact same niche. If they do, one will go extinct (or be forced out) or will adapt. In other words, for two species to live alongside each other there will be, by definition, niche separation, so pointing it out as some revelation or important insight or gained knowledge from two species being present is really not the case.

Worse, it might be wrong. Most of the time with new finds we don’t have very much to go on, so we don’t actually know that it truly did occupy a unique niche. Perhaps it was a transient species and so could survive briefly in full competition with another species as it passed through or had only just invaded and in the fullness of time would outcompete (or be outcompeted) by another species. So a statement about two (or more) species with similar biology (perhaps they are close relatives) being evidence for niche partitioning is most likely either redundant or wrong. Either way, as currently reported, it’s really not needed as commentary on a lot of papers about palaeoecology.

As a related point, there is an idea floating around (online and in discussions rather than I think in the scientific literature) that large predators can’t coexist normally, especially if they are closely related. There’s an expectation that ecosystems with say three large theropods in (or even three large tyrannosaurs) would be really weird and somehow not normal or possible. I’m not sure why this idea is out there but I think it’s a misunderstanding of the above point about niche separation and is somehow a conflation of the idea that species somehow doing the same thing or eating the same prey means one will inevitably come out on top, but again this isn’t really correct.

First off, species can be catching prey in very different ways, but still competing with each other. You only need to see videos of a baitball and any combination of sharks, dolphins, whales, sealions, large fish, diving birds and others all going after the same small fish. Each has its own technique and feeds and processes food very differently, but they are in direct competition for that same resource. So just because birds are flying and have no teeth, doesn’t mean they don’t compete with the dolphins and there is at least some niche overlap between them. Even very similar and near identical species can still partition successfully depending on quite what they are eating and when. They may be separated by seasonal or daylight cycles, or be targeting different prey species even if they are hunting it in the same manner, they will be likely shifting their niches as they grow, and there could be all kinds of local differences in habitat that are hard enough to spot in living species let alone in the fossil record.

Back in my paper describing Zhuchengtyrannus I made this point and the idea that multiple similar species in ecosystems is not actually that strange. However, some ongoing work on a related issue with theropods has made me look again at this and pull out a couple of relevant examples from modern / recent ecosystems. A quick look at the distribution maps on Wikipedia (hardly the last word in science I know, but sufficient to make the point) shows that the estuarine crocodile C. prorosus overlaps with C. johnstoni in part of Australia, C. mindorensis in the Philippines and C. novaeguinea in New Guinea. C. siamensis and Tomistoma both overlap with it and each other in parts of Indonesia, and there is a similar 3-way overlap with both C. palustris and Gavialis in India. Similarly, in South America, Caiman crocodilus, Melanosuchus and two species of Paleosuchus all overlap with each other. Now, at a very local level in a given pond or a short stretch of river there might be only one or perhaps two species present, and in some cases there are some dramatic differences in skull shape and gross feeding ecology, but these overlaps and the inevitable occasional migrations or transport of individuals means they must be truly sympatric at times and probably under some competition.

For a more terrestrial example, the 2019 paper by Schnitzler and Hermann looking at fairly recent (historical) overlaps of large mammals in Asia (especially lions and tigers) has this wonderful quote [that I have modified a little for clarity] about carnivores in part of Western Asia. “The Western Asian area of the Palearctic Biogeographic Realm includes part of the continental interior of the Near East (the northeastern part of Anatolia in Turkey, and Transcaucasia – Georgia, Armenia, Azerbaijan), part of the Caspian lowlands and western part of Pakistan. [It] had an impressive assemblage of large mammalian carnivores (Asiatic lion, Caspian tiger, Asiatic cheetah, Anatolian leopard, lynx, brown bear, grey wolf, jackal, and striped hyena).”

That’s really quite a set of animals and while jackals were probably not much competing with lions for food, there’s a huge amount of overlap here. Even modern India has striped hyena, jackal, dhole, wolves, leopard, lion, tiger and sloth bears in various parts and until recently cheetah too (plus, of course, three large crocodylians) and while their ranges are now much restricted there would have been much greater overlap in the past. In short, while obviously dinosaurs are very different to mammals and crocs, the idea that a Mesozoic ecosystem couldn’t support two or three large theropod genera looks like a poor hypothesis against the kind of overlaps we see even in modern depauperate and stressed ecosystems. Multiple large carnivores, even including closely very related species from the game genus, that are known to hunt similar prey in similar ways, are commonly sympatric and there’s no clear reason to assume ancient systems were that different.

Schnitzler, A. and Hermann, L., 2019. Chronological distribution of the tiger Panthera tigris and the Asiatic lion Panthera leo persica in their common range in Asia. Mammal Review49(4), pp.340-353.

Dinosaur tails redux

Getting on for ten years ago, I published a paper looking at the lengths of the tails of dinosaurs. The short version of that is that total length of tails in dinosaurs varies massively both between clades and even within groups (or within species!) which mean that a lot of the ‘total length X’ estimates for various dinosaurs are probably way out. Still, it wasn’t the biggest dataset and there’s not a lot of nuance to looking at total length vs body length, plus being restricted to only complete tails really cuts down on the number of specimens you can use.

Still, not too long after the paper was published, I set about trying to get a better dataset together as more dinosaur tails were coming out of the woodwork. That led to this appeal on here which helped reel in a few more specimens. Still, I wanted to do something more detailed and that led me to roping in my friend and colleague Steve LeComber.

At the Cheltenham Science Festival (L-R, Me, Steve Le Comber, Chris Faulkes, Jane Hallam)

Steve will be all but unknown to readers on the Musings as he never worked on dinosaurs before, though as a great science communicator he helped me out at a number of my events, especially when we went to the Cheltenham Science Festival together a few years ago.  Sadly, this will also be one of his last papers as he passed away at the end of 2019. Steve was one of my closest friends and colleagues, and was one of the most popular and friendly people I have ever met. He had an entire career as a journalist and writer before switching to science and was a superb statistician as well as a great biologist and a wonderful educator.It’s a testament to his work that papers are still coming out of his lab and his work on geographic profiling will have an important and lasting legacy in biology. He will be forever missed. (A scientific obituary was published for Steve here in the Journal of Zoology, where he was an editor for many years).

I had turned to Steve because he was tremendously creative with analyses and I had no idea how to approach the next problem I wanted to tackle – what was happening with individual vertebrae in the tails of dinosaurs? Very little has ever been written about this, and what there is implies or even states that as you go down the tail, each vertebra is shorter than the last. But you only have to look at a couple of specimens to see that this really isn’t the case. It’s true for big chunks of the tail, but the part closest to the hips often has short vertebrae but after that they tend to get longer, and in very long tails like those of sauropods you can find multiple sets of vertebrae that are lengthening. But how to capture this information? If groups of vertebrae are letting longer or shorter, and if this changes slowly or dramatically, or is just an oddity, can we capture it? Happily, he had some ideas.

As I was by now established at Queen Mary, I really lacked the time and opportunities to revisit collections and measure individual vertebrae so we then roped in Scott Persons, who has his own interest in dinosaur tails and had measurements we could use, or was able to get into some of the Canadian collections to procure more data. Various issues delayed the paper on numerous occasions but it is now out so here’s some quick take-home results (the full paper is in PeerJ and open access so you can see all the figs and data there).

First off, with more and better data, we did revisit the issue of overall dinosaur tail length and it is still very variable and unpredictable. Total length estimates without most of the tail present could easily be very wrong, and even some tails that you might think are pretty complete could easily truncate suddenly or go on much longer than you might think. There’s still a place for these of course (especially for engaging the public) but the standard ‘my theropod is longer than yours’ battles really need to stop. Total length isn’t a great indicator of size (mass is) and tail lengths, and by extension total lengths, are very hard to estimate without a near complete tail.

Obviously we do now have a much better Spinosaurus tail, but this old image by Scott Hartman demonstrates just how wildly different tail lengths (and so total lengths) of an animal could be for the same body size.

On to patterns within tails. First off we do find that individual vertebrae within tails simply don’t tend to get shorter as you go along them. There’s some interesting and cool patterns going on and I don’t want to cover all of them here (for example Coeplohysis is all over the place, and Juravenator seems really weird) but here’s a few of the more interesting ones. We use broken-stick regressions where we can have multiple different trajectories of sections of the tail lengthening, staying the same length or shortening. It’s a great tool to see what is happening and is visually nice and easy to follow, without getting mired down in the odd vertebra that’s rather out of place with the others.

First off, that means that it’s good for spotting changes in patterns of vertebrae lengths and also deal with (bits of) missing data quite well. This is also really useful for predicting the lengths of missing vertebrae and this is likely to be useful for things like working out total lengths of animals and the sizes of individual verts when reconstructing fossils. It’s also absolutely ideal for putting together skeletals and even mounted skeletons in the future.

Second, many dinosaurs have a pattern of a set of short vertebrae, then longer ones, and then the rest of the tail does indeed taper off. The second switch (were the long ones stop and it starts to taper) coincides with the ‘transition point’ in the tail, where the main leg muscles terminate, suggesting an important link between the two and from this we hypothesis that this short-longer- tapering pattern is a functional one linked to tail flexibility and muscle power. This clearly needs more work, but it’s a very interesting starting point.

Next, some exceptions. Plenty of dinosaurs don’t fit this pattern for various reasons (some it’s probably just missing data or it’s a subtlety like the tapering happens in two different phases), including some that do just generally taper. There’s some huge intraspecific variation in some but others are very consistent. All three specimens of Archaeopteryx we included show a weird humped distribution which is also very similar to Microraptor, and also different to other dromaeosaurs. That rather implies that this is flight related and that this is an important convergence, though again quite what and how is well beyond what we cover in the paper, it’s an area that hopefully others will pick up on. And aside from Microraptor, the dromaeosaurs appear to be highly variable which we attribute to their ‘sheath’ of elongated supporting rods for most of the tail length which would dominate any other functional issues and might leave the lengths of individual vertebrae to be fairly free of constraints.

I’ll leave it there since the paper is freely accessible and there’s lots that can be extracted from it, but I think this covers some of the more interesting points. The methods in particular should work well for any repeating units and while we have focused on dinosaur tails here, they should apply equally to any vertebral series or things like ribs, arthropod segments, and so on. I’d really hope that people will immediately see the use of this for describing things like sauropod or plesiosaur necks, pterosaur tails, or the lengths of neural spines or size teeth in a series. Of course I also need to say thanks to Scott and Steve and various referees and editors for helping get this published, and especially thanks to all those who contributed data to get this moving.

Hone, D.W.E., Persons, W.S.C. & LeComber, S.C. 2021. New data on tail lengths and variation along the caudal series in non-avialan dinosaurs. PeerJ. 9:e10721.

Protoceratops socio-sexual signalling again

It’s Protoceratops time again (hooray!). I have now published half a dozen papers about (or at least with a healthy dose of) Protoceratops andrewsi and a large part of that is because of the high number of really well-preserved specimens which make it one of the best dinosaurs to work on. There’s young juveniles through to large adults, large numbers of skulls and even skeletons, and all from a very narrow time and space that make it near enough (in palaeontological terms) a single population.

Among other things, I’ve used this to look at the growth and development of the frill and the implications for this major bit of dinosaurian anatomy being linked to sexual selection and dominance signals. (Here’s a recent round-up I did of all this work). The new paper out today is led by my former PhD student Andy Knapp and takes this previous simple work that only examined a few simple linear measurements and turns it up to 11.

Andy got to see almost every good Protoceratops skull going, including trips to New York, Warsaw and Mongolia to see material. Taking numerous photos of each allowed him to build 3D photogrammetry models of them and then get going with some quality morphometrics and analyses to look at how the skull changes in shape as the animals grow. It also shows that the skull can be divided up into distinct units and that these are somewhat independent of each other in their changes to size and shape and suggests evolution could act on each separately. The frill, rather inevitably, turned out to be a single unit and one that changed the most and one that is the most variable.

This fits very nicely with the prediction that the frill is used as a socio-sexual signal and if it’s true for Protoceratops then it’s probably true of other ceratopsians as well. I’d also suggest that this is good as we get very similar results from this very intensive and complicated methodology as we did from taking a few simple measurements of the skull and that gives some confidence that for future studies, the much quicker and easier methods may be more than sufficient to determine what kind of growth patterns are at play. There’s inevitably some more nuance and detail in the paper but happily this is another fully Open Access one, so click on this link here to be transported to a magical world of colourful ceratopsian skull bits in 3D.

I’ll finish here, but obviously huge congratulations to Andy on his great work on this long and complicated project and on getting an important paper out of it. I should also thank the Jurassic Foundation who gave Andy a grant to help with his travel and work on this project.

Knapp, A., Knell, & Hone, D.W.E.2021. Three-dimensional geometric morphometric analysis of the skull of Protoceratops andrewsi supports a socio-sexual signalling role for the ceratopsian frill. Proceedings of the Royal Society, Series B.

Depictions of Spinosaurus

New ideas (or at least new papers reviving ideas) on the appearance, behaviour and ecology of dinosaurs are often accompanied by a wealth of new palaeoart as people get invigorated and inspired by potential ideas and want to create them. The flipside of this is that there is a tendency for the previous ideas to be immediately written off as being wrong or out of date. Given the huge volume of images of Spinosaurus that have been produced in the last few years off the back of the swimming hypothesis, I think this is therefore probably worth addressing.

Spinosaurus by Bob Nicholls of Palaeocreations

As we say clearly in the paper (and I said in an earlier post), there’s no reason at all to think Spinosaurus did not swim (pretty much all tetrapods can) and it was hanging around, and in, water really quite a lot. I don’t think it was swimming that much though, and diving would have been strenuous and difficult, but probably not impossible. Even animals we don’t think of as swimmers can at least get in and around water – I once saw a large grey heron in Japan dive into the water from a high river bank, get completely submerged and come up a few seconds later. That doesn’t mean that’s normal for that individual let alone the species, but depicting a heron underwater grabbing a fish would not be wrong.

In short, the vast majority of sketches, drawings, paintings and even videos of Spinosaurus underwater are not now suddenly wrong, inaccurate, or dated. Still, if you think that the wading model is something worth illustrating or if you have seen other ideas and hypotheses in the paper and want to use that on the next round of Spinosaurus (or indeed other spinosaur) illustrations, here’s a few key points and details and suggestions. As above, none of these are inherently correct at this point, but these all come up and would be relevant if you were trying to do an animal according to our ideas in the paper.

We suggest that the tail ‘fin’ may have been a display structure (in addition to the dorsal sail and the head crest) and as such could have been brightly coloured or patterned with strong contrasting colours. We also noted that crocodylians do a head-and-tail-up display posture in water which would be a potential option for a spinosaur.

Based on work done on Irritator, the head may have been typically held at 45 degrees (though there’s lots of variation seen in these value as per the excellent recent bovid study on head posture). This could well be close to a natural posture when foraging with the snout underwater (and we reference this specifically in one of our figures).

This is one that seems to get missed. We don’t have a single good full Spinosaurus skull but we do have a good idea of the nostril position and it’s a long way from the top of the snout. There is a question about how far forwards it is, but it’s very much not near the front or top of the snout. If foraging with the snout underwater, the nostril is usually going to be kept clear of the water.

And on that note, we propose that the snout would likely be below the surface normally, either when waiting for fish to come past that can be attacked, or possibly even shovelling around the bottom. (Come to think of it, we don’t really explicitly state this in quite these words, but we do talk about stork and heron-like behaviours, and show a stork foraging stirring up mud and reference searching for benthic things, so I think we cover both of these possibilities in what we have written).

If the animal is foraging while standing in water would not be too deep so that it wouldn’t float. This would probably be anything up to the belly (or of course much less).

We did also suggest that it may have made crocodile like thrusts into water to grab things, using the legs and tail and probably generating a lot of splash.

It doesn’t have to be in or even near water. There’s good evidence that some were spending considerable periods on land as ‘normal’ theropods.

A lot of things were probably on the menu apart from fish. We know from isotopic data that some individuals were eating herbivorous dinosaurs and the like with little or no aquatic prey in the diet and the tooth and skull structure point to Spinosaurus at least having the capacity to eat things like turtles and crustaceans, while we know other spinosaurs took dinosaurs and pterosaurs, and it probably scavenged too.

In short, there’s lots of opportunities to expand the range of things Spinosaurus is shown doing (OK, so those opportunities were already there, but here’s some specifics with reasons) and hopefully this will help give some hints and tips. I’ve already seen lots of new artwork popping up, in addition of course to the wonderful rendition that Bob Nicholls did for us (shown at the top) that has already been plastered round the web. Coupled with the (revised? alternate?) skeletals that are out there by Scott Hartman and Get Away Trike (which we used in our paper), this should be a productive time for drawing this and other spinosaurs outside of them being deep underwater. Pencils and tablets at the ready!

Testable hypotheses for Spinosaurus

I tried to emphasise in the last post that there is still more to come here. I’m sure other people are writing more about Spinosaurus and its behaviour, ecology and functional biology right now and there will inevitably be further discoveries and data coming out in future. While I am confident in the wading / heron-like idea, further work could easily provide major modifications to that or overturn it. Such is the way of science: things are not settled. Below, I thought I would put together a few ideas of hypotheses or aspects of the model that could be tested or assessed further to show how much more there is to come and move away from the ‘this is settled’ idea that I’m sure at least a few people will have articulated. Some of these are much easier than others to tackle (measuring toes is way easier than working out drag) but all are, I think, something we as a scientific community can tackle in the coming years based on the techniques we have and the available fossils.

What does naris and orbit position look like in an even wider range of reptiles and in birds?

What is the overall density and distribution of mass? In particular, how buoyant would it be?

What was the exact arrangement of the neck muscles?

How flexible is the neck?

How stiff is the dorsal series?

What is the exact arrangement of the dorsal sail?

How much drag would the sail / legs produce when swimming?

How much wave drag would there be at different depths?

How spread were the toes? Is this more than other theropods?

What swimming form would it use? (Whole body or just the tail)?

Would leg thrusts help in propulsion or add more drag than thrust?

How flexible is the tail?

How strong are the caudal neural spines?

How much muscle did it have in the tail and where?

Would increased flexibility help it provide propulsion?

Would a leg and tail driven thrust in water be effective, even for a single thrust?

How efficient would it be walking?

What would the efficiency calculations for the tail look like with a more accurate model with variable flexibility and different degrees of submergence?

Are there more general common features of various aquatic and semi-aquatic reptile lineages and can we quantify things like leg reduction, tail musculature, drag reduction etc. to look at this as more of a continuum than a binary state?

Is ungual curvature driven in part by size / evolutionary relationships / habitats?

What are the isotopic signatures like for teeth that are in situ in jaws?

How many different habitats and environments did Spinosaurus occupy? And what were these like?

I think that all shows that we can push this forwards considerably. The new paper covers all kinds of different bits of anatomy, ecology, mechanics and possible behaviours and some considerations of the environments too, but this is still all just starting points. This of course is all based on existing fossils and any future discoveries (an arm would be nice, or a complete skull for that matter) is only going to provide most data (or fuel to the fire, take your pick). Still, this hopefully provides a few ideas for people to be getting on with.

If you want even more discussion on Spinosaurus (and why wouldn’t you) then the first episode of the new series of my Terrible Lizards podcast is now up and it’s a whole hour of wading hell-herons (copyright Andrea Cau).

@Dave_Hone on Twitter


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