The ecological implications of Zhuchengtyrannus

OK, I admit there’s not actually too much to say about this, but what little there is, is quite important. Zhuchengtyrannus is really rather big – a little smaller than Tyrannosaurus, about the same size as Tarbosaurus and thus as a theropod perhaps bigger than anything except these two, Spinosaurus, Mapusaurus and Giganotosaurus (and more coming on that tomorrow). It was certainly a serious customer.

More boringly, in a way, Zhuchengtyrannus is really quite a normal large tyrannosaurine –the anatomical differences are sufficient for taxonomic purposes but would probably make no real difference to the overall appearance of the animal – that is, as far as we can tell it would look in life very much like Tarbosaurus and Tyrannosaurus. While there isn’t that much of it, what we have is quite normal and it’s reasonable to infer that this animal was occupying a similar niche to the other giant tyrannosaurines (and that means predation and scavenging).

That is in itself a bit of a novelty. As I’ve noted before when discussing spinosaurs, it’s actually quite common to find multiple, similarly-sized large theropods in the better-known dinosaurian faunas. We find Allosaurus, Torvosaurus and Ceratosaurus together, Sinraptor and Monolophosaurus, Charcarodontosaurus and Spinosaurs and so on. Even when it comes to tyrannosaurines we find the smaller Daspletosaurus and Albertosaurus together (not to mention our old favourite Gorgosaurus). However, Tyrannosaurus seems to have lived alone as it were (and you can argue Nanotyrannus, but it’s quite a bit smaller) and Tarbosaurus may not have been really troubled by Alioramus. While we have no direct evidence that Tarbosaurus and Zhuchengtyrannus overlapped directly their fossils are being recovered from very similar times and only a few hundred kilometers apart. It’s really quite likely that they met and of course ZT is itself accompanied by another large tyrannosaur from the same quarry so there could have been quite a party going down.

To employ a much overused phrase, this does rather leave T. rex as the exception that proves the rule – it’s increasingly looking like the only big theropod which doesn’t come with at least one accompanying near-equally sized alternate carnivorous theropod. Despite the ever increasing similarities between the Late Cretaceous faunas of North America and Asia, T. rex does still seem to be, in at least one way, still the undisputed king of his own backyard.

28 Responses to “The ecological implications of Zhuchengtyrannus”

  1. 1 Tim Donovan 02/04/2011 at 1:47 pm

    I think the difference between Tyrannosaurus and other big theropods is that the others were more specialized, whereas rex could take on anybody. For example, Russell once suggested D. torosus preyed largely on ceratopsids while the less robust Gorgosaurus went after hadrosaurs. I don’t necessarily buy that, but there must’ve been some resource partitioning. In the late Maastrichtian, however, rex had everything–powerful legs to chase hadrosaurs and robust teeth and bite power to handle combative types.

    • 2 David Hone 02/04/2011 at 3:48 pm

      But that doesn’t really work Tim. If Tarbosaurus and Zhuchengtyrannus are as similar as we think then they are virtually identical. You don’t need to be adapted differently morphologically to do different things, it can be behavioural or habitat based – lions and tigers overlap in India and are extremely close morphologically, and all three hyena species overlap in parts of Africa. You can select different prey, or hunt at different times of day, or prefer grassland over savanah and still overlap in space and time while retaining an almost identical morphology. I’d also add that I don’t see any significant differences between Gorgosaurus, Daspletosaurus and Albertosaurus, but that doesn’t seem to have bothered them much. Obviously there are a bit different, but not much – not anything like say the differences between cheetah, lions, leopards, hunting dogs and hyena, all of which are significant predators of impala for example.

  2. 3 Brad McFeeters 02/04/2011 at 2:31 pm

    I suppose this might be the right time to ask, what’s up with your paper implying that Sigilmassasaurus is an abelisaurid?

  3. 4 Paul W. 02/04/2011 at 3:08 pm

    I second Brad’s question; also, don’t you think Carcharodontosaurus, its self, was also in the same size range as some of the others that were mentioned?

    • 5 David Hone 02/04/2011 at 3:53 pm

      It’s just a badly written sentence. What we mean is that there is a large abelisaurid, and Sigilmassasaurus etc. We’re not suggesting it IS an abelisaur.

      As for the size thing Paul, yeah Carch. is certainly smaller than Spinosaurus, though the latter has been scaled up a bit far according to Thierren and Henderson (and I agree, it’s not a 17m giant) which cuts down the difference a bit, but it’s not much smaller than either the abelisaur or Siggi. In any case the general point is still (i think) entirely valid, you simply don’t normally get one big theropod and then a big gap in body size before the others turn up, you tend to get a whole bunch and while some might be bigger than others, the fact is it’s not like you get one 12 m one then a drop to 5-7m etc.

  4. 6 Paul W. 02/04/2011 at 4:08 pm

    Thanks David, being admittedly ignorant on the subject, I would have thought population sizes could have a bit to do with ecological niches. Anyway, I guess I meant I took Carcharodontosaurus as being in the Tarbosaurus size range, for instance. Also does the big Abelisaur have anything to do with Deltadromeus/Bahariasaurus?

    • 7 David Hone 02/04/2011 at 4:44 pm

      Well populations sizes can be important, though of course the vast majority of the time we have too few theropods to get any idea of the real population. Scaling this kind of thing is all but impossible since of course taxon A could have a population just 1% of that of taxon B, but if A lives in the flood plain and B slightly further inland it’ll be preserved far more often and the apparent ratio in the fossil record might be 100:1 in the other direction!

      The big abelisaur might well be one of those, the issue is the lack of data on those taxa (since the original descriptions there’s pretty much noting in the literature) and the list of taxa in the paper repeated here are basically those of the dinosaur distribution chapter in the Dinosauria 2nd ed. It’s perhaps therefore an oversimplification of ours, but then we are simply trying to make a point and not get bogged down in the detailed taxonomy / synonymy of some taxa from one formation based on a whole bunch of paper. I wouldn’t quite call it laziness on our part (though some might), more avoiding an unnecessary complication when the point it already made. 😉

  5. 8 Andy 02/04/2011 at 9:33 pm

    The thing that’s intriguing to me is that so much of what is in the Zhucheng dinosaur assemblage – tyrannosaurs, hadrosaurs, ceratopsids, and leptoceratopsids – is truly gigantic. Must have been something in the water.

    • 9 David Hone 02/04/2011 at 9:42 pm

      I didn’t think Sinoceratops was that big? And while ZT is big, it’s pretty much ‘normal’ for a big tyrannosaurine. And I’m told there are very big specimens of well known N Am hadrosaurs out there, so Shantungo. may not be that big.

      • 10 Tim Donovan 03/04/2011 at 1:10 pm

        Lol, Shantungo. is big alright but so was Lambeosaurus laticaudus. At least one Anatotitan specimen is said to rival S. giganteus, leading to speculation that the two might be coeval i.e. the Zhucheng exposures could be as young as late Maastrichtian, but IMO a somewhat older age is best.

      • 11 Andy 03/04/2011 at 2:34 pm

        Sinoceratops is pretty darned big for a ceratopsid. . .certainly larger than any other centrosaurine (except maybe Pachyrhinosaurus canadensis), and approaching Triceratops in skull size.

      • 12 David Hone 03/04/2011 at 2:39 pm

        I’ve not actually got hold of the paper for that yet believe it or not and hadn’t realised it was in this size class. Can you bung me a PDF if you have one Andy? Cheers.

    • 13 Tim Donovan 03/04/2011 at 1:25 pm

      With the exception of Shantungosaurus, nothing in the local assemblage is “truly gigantic.” Btw David, is there any strat. data i.e. does Zhuchengtyrannus occur above or below Sinoceratops? Maybe they’re all in one big bonebed at the same level?

      • 14 David Hone 03/04/2011 at 1:48 pm

        I’m still waiting on that myself, to my knowledge no geologists have got in there to compare all the quarries and work out their exact extent, connectivity and relative depths.

    • 15 Tim Donovan 03/04/2011 at 3:18 pm

      Well, the size of Sinoceratops and its centrosaurine affinities, are consistent with the age estimate.

  6. 16 Zhen 02/04/2011 at 11:59 pm

    Hey Dave, I’m reading in-between the lines here, but could the second unnamed Tyrannosaur be just as big as Zhuchengtyrannus? I mean, if the bones or Tyrannosaurus got mixed together with Dasplateosaurus, you should at least be able to discern them from the size of the bones, right?

    Even though you’re not heading up the research, can you tell us more about the second one? Don’t get me wrong, your discovery is just as exciting, but I’ve already read all there is to read about it for now, and I’m thirsty for more knowledge.

    • 17 David Hone 03/04/2011 at 8:49 am

      Sorry Zhen, I’m not really in a position to give much away about the second specimen right now, but I guess there’s no harm in revealing that it is a bit smaller than ZT. However, that doesn’t solve the problem of the other material since we have to factor in the natural variation in size of a population and the possibilty of juveniles or at least non-adults. A slightly younger or smaller ZT would be about the same size as the second one, so based on size alone, you couldn’t separate out the bones into plies and call one ZT and the other taxon X.

      Glad you’re enjoying the new dinosaur.

  7. 18 Zhen 03/04/2011 at 4:37 pm

    Either way, this would mean there were 3 Tyrannosaurs living in Asia around the same time. Any theories on why these 2 Tyrannosaurs got jumbled together? Simple coincidence, or could they be a family? There’s enough to distinguish this X specimen from Zhuchangtyrannus, right?

    • 19 David Hone 03/04/2011 at 10:10 pm

      We think these are different taxa so there’s nothing in terms of them being a group. Their being together could either be chance, or more likely (I think) the bones were washed together in a flood plain which is why there’s all manner of things in there and the bones are generally isolated and mixed.

  8. 20 Mario 04/04/2011 at 3:01 pm

    Hello David Hone

    I have thre question.
    1. do you think its possible that deltadromeus was a seperate animal from Bahariasaurus and the paratype which was 13 m long still belongs to Bahariasaurus and not deltadromeus ??

    2.Also could that new abelisaurid and sigilmassasaurus be relatives of Bahariasaurus/deltadromeus too ??
    3. How big is that new abelisaur ??

    • 21 David Hone 04/04/2011 at 3:56 pm

      Hi Mario,

      I’m sorry but I really can’t answer your questions properly. I don’t really work on the allosaurs or carcharodontosaurs and abelisaurs. I’ve never seen any of these specimens and most of the descriptions are very short. As such I can’t really say anything meaningful about the taxonomy of this lot than is already in the literature.


  9. 22 Rappy 04/04/2011 at 7:20 pm

    Out of curiosity, where does Jengizkhan fit into this? Or is that no longer a valid genus, and I’m simply woefully out of date on Asiatic tyrannosaurs?

    • 23 David Hone 04/04/2011 at 7:32 pm

      Well I don’t think anyone but the original author ever really considered that a valid genus. That and a bunch of others were sunk straight back into Tarbosaurus. Subsequent revisions and examinations of Tarbosaurus have show that it does have a basic ontogenetic pattern and variaiton like T. rex and others and that there’s no good reason to thik there’s more than one species there.

      • 24 Rappy 07/04/2011 at 3:48 pm

        Alright, good to hear. I haven’t taken any time to read up on non-North American tyrannosaurs lately (or tyrannosaurs in general, really; abelisaurids have been my big draw lately), so I really should begin to rectify that.

  10. 25 Andrew 08/01/2012 at 10:53 pm

    Sorry for the late comment; I had a bit too much spare time on my hands and was reading through your blog. You mention Tyrannosaurus rex as being the exception to the rule of large theropods being found in association with each other. I remember reading a book edited by Peter Larson and Ken Carpenter titled something like “Tyrannosaurus rex, the tyrant king” that mentioned the possibility of another species of Tyrannosaurus (or something along those lines, it’s been a while) called Tyrannosaurus ‘x’. What’s your opinion on this?

    • 26 David Hone 08/01/2012 at 11:06 pm

      I’ve not looked at any of this material in detail and I’m not overly familiar with the paper (I did read it a while back) . However, what I would say is that I don’t know of any other theropod / tyrannosaur worker who is convinced by the idea that there is another big tyrannosaur in there.

  1. 1 OK, so I’m just milking it now – final Zhuchengtyrannus roundup « Dave Hone's Archosaur Musings Trackback on 05/04/2011 at 10:00 am
  2. 2 More on dromaeosaurs vs azhdarchids « Dave Hone's Archosaur Musings Trackback on 05/03/2012 at 8:40 am
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