Theropod sociality

My recent paper on sexual selection touches on quite a few areas of dinosaur and pterosaur ecology and possible behaviours. Most notably (or rather, of most likely interest to people who like dinosaurs) is what we have to say about the possibilities for degrees of sociality in theropods. The idea that some theropods (and yeah, inevitably, especially dromaeosaurs and tyrannosaurs) may have lived in groups seems to be the subject of more debate, disagreement and hyperbole on the web than any other subject (and I bet there’s more coming in the comments), and yet there is remarkable little actually written about this in the literature. There is now a little bit more though.

Space limited what we could say but there are two points that we did get in and are worth elaborating on just a little here. First off, for those theropods rocking crests, these are more likely to be taxa regularly engaging in social interactions. That’s not to say they were necessarily living in groups, they might still have been solitary. However, they might well have encountered each other often in territory disputes, or even engaged in activities like lekking. Basically a big and honest signal can be a good advert of your fitness (or overall health) and thus you can avoid serious combat with another theropod that covered in claws and teeth that you’ know you’d lose to. Thins like the evidence for craniofacial biting already shows this kind of thing may have been going on, but this is taking it from another, if related, angle.

Secondly there was a paper not too long ago by Roach & Brinkman on the evidence for sociality in Deinonychus. In general they made some very good points and noted that much of the evidence purported to support this idea was questionable at best. However, they also argued that there were no cooperatively hunting extant archosaurs and thus this could be ruled out from an extant phylogenetic bracket point of view. Now one needs to be careful about quite how ‘sociality’ or ‘groups’ or ‘cooperation’ are defined, but as we note in the paper there are a variety of birds which hunt together, even cooperatively, and in the case of some hornbills – on the ground. By any measure that would seem to be a great analogy for small theropods and show that it’s not unknown in birds. There’s even evidence for degrees of cooperation in caimen and yes, going further out from archosaurs, komodo dragons. Coupled with the inherent strong plasticity of behaviour, I don’t think there’s any good reason to rule this out.

Now there’s noting there that definitively rules it in either, but I do think it likely that at least some species of theropods were at least highly tolerant of each other as individuals, and might well have formed socially structured, functioning groups. We have all but the flimsiest of evidence for that right now, but that’s no surprise really given how hard it is to get evidence of this kind of thing. However, there’s certainly no reason to say it was impossible and analysing the available evidence and searching for more is pretty far from a fruitless task.

41 Responses to “Theropod sociality”


  1. 1 Maija Karala 05/01/2012 at 10:08 am

    Very interesting post, thanks. I haven’t had time to read through your new paper yet, but did you have a reference for cooperation in crocodilians? I have been looking for one, but haven’t found more than a couple anecdotes.

    I remember reading from somewhere (well, that’s a credible source) that there is no fossil evidence of pack hunting in wolves either. Recent animals as they are, they have a good fossil record compared to any individual dinosaur taxa – and they mostly hunt in packs. Still, if wolves were extinct, we would know nothing about it.

    So, I’d be very careful stating that some behaviour probably didn’t take place if we don’t have evidence either way. Especially since we’re talking about a hugely diverse, long-lived group of animals we only know a fraction of anyway.

    I asked about this once in Andrea Cau’s blog, and he, at least then, was in the opinion that non-avian theropods had too small brains for “complex behaviour”. I think that animals with surprisingly small brains are capable of very complex-seeming things, like pack-hunting in catfish or social grooming in eusocial flies. What do you think about the brain size thing?

    • 2 Andrea Cau 05/01/2012 at 10:15 am

      My comment below was written before reading this.
      I’m not against behaviours seen in catfishes with small brain: these behaviours could be genetically determined (as in ants). I’m against small-brained theropods behaving like big-brained lions.

    • 4 David Hone 05/01/2012 at 10:23 am

      Here’s one: Yamashita, C. 1991: Social fishing behavior in Paraguayan caiman. CSG Newsletter 10, 13.

      We originally had others but cut them for space reasons. As notes this is probably closer to mutual exploitation that sociality, that is, they tend to line up across rivers when spawning fish are migrating. Each patrols an area and they don’t interfere with each other, and they mutually benefit. Still, it’s not a ‘simple’ behaviour and its definitely not asocial.

  2. 6 Andrea Cau 05/01/2012 at 10:13 am

    The hornbills and other birds showing some kind of social behaviour are all derived neoavians. I don’t think they are a good analogue for more basal forms (non-avian theropods). Is the development of the brain relevant in these behaviours? I suspect, yes: derived birds show much larger brains than every known mesozoic theropod, so I’m skeptical on inferences based on extant neoavian behaviours. The mere ecological similarity between ground birds and small theropods could not be relevant, given that even varanids live in similar ecological conditions (and nobody suggests they behave as hornbills). Modern non-avian reptiles show gregarious behaviour and even some rough kind of cooperation (as discussed by the paper you mentioned), and that level of sociality is the most plausible for non-avian dinosaurs, based on known evidence.
    I’m not a priori against sociality in theropods, but I see that often too much speculation has been involved.
    Someone could comment that absence of evidence is not evidence of absence: in the last decades I’ve seen too much myths flourishing from absence of evidence (puck hunting dromaeosaurs and tyrannosaurids, allosaurids feeding their young and so on).

    • 7 David Hone 05/01/2012 at 10:28 am

      Well I guess my main point would be that incredibly complex behaviours are possible with tiny brains (look at ants). You sure as hell don’t need to be a genius to cooperate at a very low level – say a group of animals all run in the same direction at the same time will probably get more prey than one on it’s own, no need to invoke complex theory on mind and ambushes and beaters etc. If that level of sociality any more complex a behaviour than building a nest, signalling to mates, fighting to mate, laying eggs, feeding hatchlings etc,?

      I’d argue it isn’t and there’s good evidence for all those things in dinosaurs and it’s present in crocs. Now I freely admit it’s very hard to assess those against each other, but again we see this in crocs and even lizards and certainly *some* dinosaurs seem more than capable of quite complex behaviours, including living together in groups (which inherent involves dominance, an understanding of social ranking etc., recognition of other group and non-group members) so I really don’t see that a very simple level of cooperation should be beyond them.

      • 8 Andrea Cau 05/01/2012 at 10:41 am

        These are good arguments for a sociality in dinosaurs (a reptilian way to socialism), better than citing mammals (the main target of my critiques in my blog).
        It should be noted that assuming that most theropods killed juvenile prey (as discussed by you and Rauhut in a paper that I consider relevant as Roach and Brinkman’s one in this discussion), then hunt cooperation between adults in these situations seems useless: a single predator can kill a small prey. Ichnosites and bonebeds seem to indicate that juveniles lived together and not with the adults: this kind of aggregation could be a plausible adaptation from the predation cited above, and could eventually evolve in some kind of cooperation between the brothers.

      • 9 David Hone 05/01/2012 at 10:50 am

        Well I don’t rule out mammals as analogues simply because they are the only big, diverse, terrestrial predators we have to work from, but I’d agree it’s far from ideal.

        I don’t necessarily see that the idea of juvenile predation has to conflict with sociality. If nothing else, I’m sure not *every* theropod tended to juveniles and if you want to hit bigger stuff, you need a group (interestingly and perhaps pertinently, the only extant example of any predator that doesn’t favour juveniles but takes them and adults equally is lions). But as usual, it’s about trade offs (sure a shred juvy doesn’t go far between 5 adults, but if you catch them at twice the rate hunting in a group it makes sense, again, hornbills are a good model here) and of course almost inevitably there are some conflicting signals in the data if you consider all theropods simultaneously.

  3. 10 Darren Naish 05/01/2012 at 11:20 am

    I’m with Andrea. Social behaviour of various sorts was likely in Mesozoic dinosaurs, but we need to move as far as possible from the idea of always thinking about wolves and lions. But that’s fine – as we say in the MSS paper (Hone et al. 2011), and as I’ve always tried to emphasise on Tet Zoo – modern lizards, crocodilians and other reptiles get up to social behaviour plenty ‘sophisticated’ (ugh) enough to keep dinosaur specialists happy. I’m not saying these things were necessarily present in Mesozoic dinosaurs, but such aspects of social behaviour as co-operative hunting, provisioning of juveniles, extended monogamy, long-term bonds between juveniles and adults, play behaviour etc. etc. are all consistent with a more appropriate ‘herpocentric’ view of Mesozoic dinosaurs.

    • 11 David Hone 05/01/2012 at 11:27 am

      Oh yeah, there’s too much has been written that’s not based on evidence and while it is sparse, there is some stuff there. And as I was saying here based on the bit of our paper, we also shouldn’t rule things out for the wrong reasons either.

    • 12 Jaime A. Headden 06/01/2012 at 1:52 am

      I’m actually curious about this point. Has anyone ever assessed the frequency of “complex” or “sophisticated” behaviors, or qualified these “mammalian” aspects of their behavior before? Note that this question comes from wondering: How often during a day or whatever period a given behavior may be performed alongside “less complex” or “less sophisticated” behaviors?

      While I think the statements above (Darren’s) to be relatively true, and analysts/observers drastically undervalue the complexity of behavior in lizards, crocs, and so forth, frequency matters too: Adaptability and flexibility in tool use functions and social group dynamics (whichever groupings separate “snake balls” from meerkat colonies or wolf packs) tend to appear in higher frequency in more avian and mammalian groups, while no nonavian reptile seems to use tools. The flexibility of the brain seems to have quite a bit to do with this, including how often an ability might be employed.

      • 13 David Hone 06/01/2012 at 9:24 am

        I’m not sure anyone has looked into it seriously, mostly because it’s obviously incredibly hard to quantify and compare. As usual the neontologists don’t have to worry much about this stuff as they can just study the living animals or infer from very close relatives. As such when we come to do things like this we often have to sort out the neontological stuff first and then try and do the actual palaeo.

  4. 14 Ben 05/01/2012 at 1:01 pm

    Interesting stuff Dave, I’ve always pictured dromaeosaurids hanging around together. Nonexpert question:

    It seems to be pretty widely accepted that dealing with complex social setups was one of the key selection pressures for ballooning brain size amongst apes. Does this have any bearing on what we reckon dinosaurs got up to? I know we’re one of a kind in animal history but if a certain complexity of society suggests bigger brains to cope and do better in that environment, does that place any sort of upper bound on the complexity of, say, a pack of deinonychus, who were hanging around together a lot longer than it took early hominids to start, y’know, making stuff?

    Or are you just anticipating here that they just about managed to put up with one another and never approached the level of cooperation we see in, say, big mammals?

    • 15 David Hone 05/01/2012 at 9:51 pm

      Short version, primates are rather more complex, not least with their parental care. There does seem to be some evidence (and for me quite convincing) that sociality goes hand in hand with development of intelligence and you can see how they could feedback into each other. That said I don’t see why you can’t have quite complex behaviours without it. More specifically, I think we need to separate out ‘pack hunting’ (i.e. simply a group of animals predating together without necessarily invoking complex ambushes etc. no one argues hunting dogs aren’t pack hunters, but they more or less jsut chase stuff till it keels over) and complex socio-sexual behaviours and heirarchies.

  5. 16 Maija Karala 05/01/2012 at 1:01 pm

    Sorry to bring the wolves back to conversation, but what to make of this study?
    http://www.sciencedirect.com/science/article/pii/S0376635711001884

    “These two simple rules are enough to reproduce the wolf-pack hunting ethogram. No communicative skills and no hierarchy are needed to complete the hunt properly.”

    • 17 David Hone 05/01/2012 at 9:52 pm

      Sorry, don’t have time to read that right now, but my answer above it probably what you’re after. I don’t think to be a ‘pack’ you need be smart or do anything clever. There’s different issues at play.

  6. 18 Henrique Niza 05/01/2012 at 5:36 pm

    Doesn’t exist a correlation between large brained neornithes and their ability to powered flight, more so than their highly intelligence compared to non-avian reptiles? Mind you I’m not arguing that non-avian theropods are equally intelligent as avian theropods.

  7. 19 Zhen 05/01/2012 at 5:47 pm

    We were just arguing about this on the JPlegacy forums. I’ll be sure to point them to this articlde.

  8. 20 Manuel Sosa 05/01/2012 at 6:15 pm

    Theropods as a whole represent a long lived lineage of animals in constant developement of hunting strategies for better results and sucessfull survival.
    Such great part of the mesozoic biota find responses of theese strategies on the diversification of defensive-ofensive anatomy of other dinosaurs and other potential preys (just like today), some of them represent a great deal to confront alone (see social behaviour on sauropods, ornithopods, ceratopsians ; heavy armoured ankilosaurs and stegosaurs, etc )
    So why not expect social “tolerance” (a very appropiate word) and cooperative work between theropods? Having evidence of young breeding (and feeding? I remember a work of Bakker in Como Bluff…) and whith the most closely related extant bracket behaviour´s almost unknown?
    I think that we can´t recognize any known dinosaur alive, even if it stands over our heads! jej

  9. 21 Anonymous 05/01/2012 at 9:20 pm

    Ah, finally! It’s so good to see a post discussing possible social behavior in theropods that doesn’t flock to Brinkman and Roach 2007 and claim it is impossible for theropods to even stand being in the same room as one another based on phylogenetic bracketing. Admittedly, many theropod species probably were solitary, even amongst mammals many predatory (or omnivorous) species such as leopards, tigers, and bears live alone for most of their lives, and many presentations of theropod social behavior are a bit ridiculous, but dismissing the idea of theropod sociality a priori is getting a bit annoying.

    “I don’t necessarily see that the idea of juvenile predation has to conflict with sociality. If nothing else, I’m sure not *every* theropod tended to juveniles and if you want to hit bigger stuff, you need a group (interestingly and perhaps pertinently, the only extant example of any predator that doesn’t favour juveniles but takes them and adults equally is lions). But as usual, it’s about trade offs (sure a shred juvy doesn’t go far between 5 adults, but if you catch them at twice the rate hunting in a group it makes sense, again, hornbills are a good model here) and of course almost inevitably there are some conflicting signals in the data if you consider all theropods simultaneously.”

    And if you even want to take on a juvenile or sub-adult sauropod, having one or two other members of your species to back you up doesn’t help. Juvies or not, those things are still plenty big.

    The hornbill example is especially interesting, given that these animals tend to take prey that is somewhat smaller than them anyway. A lot of bird species (not necessarily carnivorous ones, but still) form “foraging groups”, don’t they?

    “I’m with Andrea. Social behaviour of various sorts was likely in Mesozoic dinosaurs, but we need to move as far as possible from the idea of always thinking about wolves and lions.”

    I agree to a point on this. Wolves and lions aren’t really the best example of a modern analogue for theropods, both anatomically and evolutionarily. However, crocs and birds aren’t really the best examples either. Crocodilians are specialized for piscivory or ambush predation in the water, and all extant birds are either large herbivores or relatively fragile fliers with highly modified bodies. In short, neither group are good analogues for theropods, but they’re the only one’s we’ve got. Carnivorans work better in an ecological since, but in terms of anatomy crocodilians and birds are a lot closer. Too bad the phorusrhacids still aren’t around.

    “Very interesting post, thanks. I haven’t had time to read through your new paper yet, but did you have a reference for cooperation in crocodilians? I have been looking for one, but haven’t found more than a couple anecdotes.”

    Same here. I have heard anecdotes of rather complex cooperative behavior in Cuban crocodiles (at least, relative to other crocodilians), but no references to back it up. Unusually, I have also heard Cuban crocs are the most terrestrial of living croc species.

    By the way, is there any news on how the argument presented in Brinkman and Roach 2007 is affected by the new theropod fossils coming out of the Cloverly? Brinkman and Roach claimed that the large number of Deinonychus fossils found at the Cloverly localities was simply due to Deinonychus being the only predatory theropod species present in the formation. However, there’s a paper out describing basal tyrannosauroid teeth from the formation, and this year’s SVP reported the first Acrocanthosaurus bones in the Cloverly.

    • 22 Maija Karala 06/01/2012 at 8:54 pm

      “Same here. I have heard anecdotes of rather complex cooperative behavior in Cuban crocodiles (at least, relative to other crocodilians), but no references to back it up.”

      I found this:
      http://www.thefreelibrary.com/_/print/PrintArticle.aspx?id=141091822

      Apparently, at least one source of claims about pack-hunting in Cuban crocodiles is a tooth found stuck in a giant ground sloth bone found by the fossil hunter Barnum Brown. The reasoning is that the croc couldn’t have taken that big prey alone and must have attacked in groups. I find this doubtful at best. It would be interesting to know is anyone has attempted to rule out scavenging.

      Not that I think simple “guys, let’s all bite the same sloth instead of attacking one each” kind of pack hunting would be necessarily outside the boundaries of crocodilian intelligence.

      Later parts of the article describe the commands and tricks that can be taught to captive Cuban crocodiles. They do seem surprisingly intelligent.

    • 23 Maija Karala 06/01/2012 at 8:58 pm

      “Unusually, I have also heard Cuban crocs are the most terrestrial of living croc species.”

      At least they do have long legs for a crocodile. This is one of the couple living in Skansen Akvariet in Stockholm:

      http://planeetanihmeet.files.wordpress.com/2011/12/img_1738.jpg

      Seeing a crocodile in its own element was rather scary, actually.

  10. 24 LeeB 05/01/2012 at 9:32 pm

    There is video of saltwater crocodiles engaging in cooperative behaviour while fishing here:
    http://news.bbc.co.uk/2/hi/7268805.stm

    As interesting as the cooperation may be the fact that they gather from long distances to engage in this behaviour when the tide levels are right.

    LeeB.

  11. 25 Tayo Bethel 05/01/2012 at 11:12 pm

    Is it possible that parental care is primitive for archosaurs? All living archosaurs exhibit some degree of parental care even when the young are capable of looking after themselves.

    Many birds form foraging groups, but i was under the impression that the main function of these groups was predator detection. Large theropods would be unlikely to form groups for such a purpose, and it may have even have been to their benifit to hunt solo–no need to share. Still, social interactions were probably inevitable, and even the supposedly asocial great white shark interacts socially. The brains of crocodilians have been described as small but highly complex, and the social tendencies of crocs are pretty well known. So, the solitary but not asocial theropod is more than likely. As for pack-hunting theropods … pack hunting isnt common among predators, but those who engage in it generally exhibit higher social tolerance and (possibly) greater intelligence. So while pack hunting shouldnt necessarily require the need for complex hunting strategies, whichever stheropod did hunt in packs probably employed some the same complex-seeming hunting stragies with lesss apparent brainpower.

    • 26 David Hone 06/01/2012 at 9:26 am

      I would call (limited) parental care primitive for archosaurs. It’s there in birds, crocs and lots of dinosaurs at least.

      As for the rest of your comment, yes all pertinent stuff. But I don’t want to say much about it as a lot of this is covered in an ongoing manuscript of mine! ;)

      • 27 Tayo Bethel 06/01/2012 at 10:53 am

        Will you be covering possible dinosaur vocal behavior as well? The image of a herd of hissiing sauropods just doesnt seem right (intuition talking. This is just an educated lay person LOL)

        Could you send me a PDF of your mutual sexual selection paper please?

      • 28 David Hone 06/01/2012 at 11:59 am

        Hello, PDF on it’s way. Nope, nothing on vocalisation becuase there is basically nothing to say. We have an exceptionally limited understanding of dinosaur hearing and no idea at all about vocalisations. I’m sure they made noises and communicated, beyond that I’m basically out.

  12. 29 peteykins 05/01/2012 at 11:31 pm

    “they might still have been solitary”

    Well, hah, yeah, but only up to a point, right? After all, mating has to happen somehow! Unless, of course, somebody discovers evidence of parthenogenesis in dinosaurs (at first I meant that as a joke, but it’s been demonstrated in some reptiles and even birds, hasn’t it?).

    • 30 David Hone 06/01/2012 at 9:22 am

      Yes of course. I doubt there were parthanogenic dinosaurs. But animals can be solitary or even anti-social except for brief periods. Apart from mating I don’t think adult puma for example ever get into contact with each other (apart form border disputes etc), they actively avoid one another.

  13. 31 Herman Diaz 06/01/2012 at 3:56 pm

    “I remember reading from somewhere (well, that’s a credible source) that there is no fossil evidence of pack hunting in wolves either.”

    Actually, there is fossil evidence for pack hunting in wolves ( http://171.66.127.192/content/5/1/81.short ). Whoever said otherwise didn’t do his/her research (Shame on him/her).

    “Sorry to bring the wolves back to conversation, but what to make of this study?
    http://www.sciencedirect.com/science/article/pii/S0376635711001884

    As Bekoff has shown ( http://www.newscientist.com/article/mg21228380.500-wolf-smarts.html ), Coppinger’s model doesn’t apply to wolves.

    • 32 Maija Karala 06/01/2012 at 8:46 pm

      Thanks for the links and corrections.

      I’m pretty sure I read that stuff about wolf fossil record before 2009, so it might just be outdated now, not when it was written. :) And, well, it’s not strictly about the modern wolf.

      Social sabertooths? I have heard it suggested before, but didn’t know about this evidence. Cool.

      Good to know the pack-hunting model study has been criticised (though I can’t access the article, so I don’t really know why). Could it be, anyway, that it might apply to predators other than wolves?

      • 33 Herman Diaz 07/01/2012 at 1:34 am

        “Good to know the pack-hunting model study has been criticised (though I can’t access the article, so I don’t really know why). Could it be, anyway, that it might apply to predators other than wolves?”

        As Bekoff pointed out, Coppinger’s model is based on the faulty assumption that wolves don’t communicate while hunting (among others). As indicated by the Stevens quote, pack hunters in general communicate while hunting.

        Quoting Stevens ( http://www.nytimes.com/1993/01/19/sc…ted=all&src=pm ): “As used by Dr. Ellis and his colleagues, the term requires that the foraging pair or group be a stable social unit; that some members, in a division of labor, sacrifice their own prospects for a direct kill in deference to the group interest; and that group members share in the spoils.In the most complex forms, raptors exchange signals to coordinate the hunt and cooperate in hunting outside the breeding season.”

  14. 34 Herman Diaz 06/01/2012 at 4:32 pm

    “I’m with Andrea. Social behaviour of various sorts was likely in Mesozoic dinosaurs, but we need to move as far as possible from the idea of always thinking about wolves and lions.”

    W/all due respect, why? Based on what I’ve read (E.g. http://www.nytimes.com/1993/01/19/science/rabbits-beware-some-birds-of-prey-hunt-in-packs.html?pagewanted=all&src=pm ), pack hunting in birds is comparable to pack hunting in wolves.

    “The idea that some theropods (and yeah, inevitably, especially dromaeosaurs and tyrannosaurs) may have lived in groups seems to be the subject of more debate, disagreement and hyperbole on the web than any other subject (and I bet there’s more coming in the comments), and yet there is remarkable little actually written about this in the literature.”

    In reference to tyrannosaurs, my opinion is this: As Witmer has shown (See 19:10-20:10: http://www.videozer.com/video/9Y177Zn ), large theropods probably had the intelligence for pseudo-cooperative (I.e. Communal) hunting, but not true cooperative (I.e. Pack) hunting.

    In reference to dromaeosaurs, my opinion is this: As indicated by the adult-only clump (E.g. Ostrom 1969), multiple shed tooth (E.g. Maxwell & Ostrom 1995) & trackway (E.g. Li et al. 2007) evidences, Eudromaeosaurs were probably social predators (be it communal or pack hunters); As indicated by the brain evidence (E.g. Walsh & Milner 2011), Eudromaeosaurs probably had the intelligence for pack hunting; AFAWK, there are no large terrestrial hypercarnivorous endotherms that are social predators w/the intelligence for pack hunting, yet don’t hunt in packs; Therefore, combining said evidences makes pack hunting Eudromaeosaurs probable.

    • 35 David Hone 06/01/2012 at 4:41 pm

      My comment was about the hyperbole and discussion, not the actual scientific evidence. There’s less than dozen papers that seriously deal with sociality in theropods at any length or in any detail and that is very little, there are however huge tracts of discussions online by people at to which taxa were or were not pack hunting and why, generally with no reference at all to the evidence because (mostly) of Jurassic Park and related stuff.

      • 36 Herman Diaz 06/01/2012 at 5:15 pm

        No worries. I understood what you were saying. It’s just that you mentioned tyrannosaurs & dromaeosaurs in particular, so I thought I’d give my (evidence-based) opinions on the matter as it concerns them.

      • 37 David Hone 06/01/2012 at 5:23 pm

        Well that’s becuase those are the two groups that get talked about most of all because those are the ones that have been mentioned specifically (Currie & Ostrom esp).

  15. 38 Lucy 30/01/2012 at 12:57 am

    “No extant archosaur practices cooperative hunting?”

    Apart from the obvious stuff about hornbills etc, the medium-sized hawk /Parabuteo unicinctus/ lives in extended family groups and regularly hunts cooperatively for prey larger than itself, with several individuals attacking the same rabbit or hare. We’re talking about wolf-level cooperation here.

    Now, it’s not the world’s greatest model for dromaeosaurs or tyrannosaurs – it’s tiny and fragile, it’s highly specialised for flight, it’s not that closely related, and I’m pretty sure it has a much bigger brain/body ratio – but why is it never on the list of possible models?


  1. 1 More on dromaeosaurs vs azhdarchids « Dave Hone's Archosaur Musings Trackback on 05/03/2012 at 8:40 am
  2. 2 The giant, feathered tyrannosaur Yutyrannus huali « Dave Hone's Archosaur Musings Trackback on 04/04/2012 at 6:02 pm

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