Know Your Ankylosaurs: Mongolia Edition!

After a whirlwind couple of weeks with a bunch of international travel, I've finally had a chance to sit down and write about my most recent paper on the ankylosaurs of the Baruungoyot and Nemegt formations of Mongolia. I've been interested in these ankylosaurs for a long time now, both because of their interesting cranial anatomy and their relationships to the ankylosaurs of North America (especially Alberta). So, here's a plain-language summary of some complicated taxonomy! Hooray!

Part the first: Dyoplosaurus giganteus

A toe!

We need to start here because Dyoplosaurus giganteus is the first of the ankylosaurs in this manuscript to have been named. Based on a fragmentary postcranium, Dyoplosaurus giganteus was considered similar to the North American Dyoplosaurus acutosquameus (pre-dating the synonymy of Dyoplosaurus with Euoplocephalus), but larger. Unfortunately, the holotype lacks any diagnostic characters that can differentiate it from specimens discovered since its original description, and so D. giganteus must be considered a nomen dubium. Which is important because...

Part the second: Tarchia

...it was partly synonymized with the newly-named genus Tarchia, based on similarities between the osteoderms, which then included Tarchia gigantea and Tarchia kielanae. Most people picture the beautifully preserved skull in the PIN collections as 'the' Tarchia, but in fact it is not the holotype of either D. giganteus or Tarchia kielanae. T. kielanae's holotype is a partial skull roof. Later, Tarchia kielanae was considered a junior synonym of Tarchia gigantea because it's quite fragmentary and there weren't any obvious differences between the two skulls. But here's the catch: the holotype skull of Tarchia kielanae does indeed preserve a diagnostic character that is not present in the PIN 'Tarchia' skull – a weird little ossification that sits on/in front of the squamosal horn, but isn't the squamosal horn. This feature is found only in one other described specimen – the holotype of Minotaurasaurus ramachandrani.

On the left, a sketch of T. kielanae's holotype from Maryanska's 1977 paper; on the right, a cast of the holotype of Minotaurasaurus.

The end result is that:

1.  Tarchia kielanae is valid

2. Minotaurasaurus is a junior synonym of T. kielanae

3. There are no diagnostic features in D. giganteus and no reason to refer the PIN skull to Tarchia, so T. gigantea is redundant.

4.  I'm sorry other ankylosaur workers, this really messes things up.

The Minotaurasaurus holotype is much more complete than the T. kielanae holotype and provides most of the anatomical information for Tarchia kielanae. Tarchia kielanae has extremely narrow squamosal horns, a prominent prefrontal caputegulum, four internarial caputegulum, a huge mandibular caputegulum, and that distinctive ossification above the squamosal horn.

Part the third: What about Saichania?

The Museum of Evolution in Warsaw has a cast of Saichania with the elements in situ.

Saichania is safe! This is an easily diagnosed taxon based on a GREAT holotype which includes a skull and front half of the postcrania and osteoderms that were articulated at the time of discovery (a cast of the in situ specimen shows the original arrangement). But, Saichania is probably not what you think it is – most people (well, at least those who think about such things) will probably visualize the mounted skeleton found in several museums/traveling exhibits. In one of my previous papers I argued that this skeleton should not be referred to Saichania based on several differences of the postcranial anatomy, and its provenance from the Djadokhta Formation rather than the Baruungoyot Formation. (The skull on this mounted skeleton is a cast of the holotype Saichania skull, and so unfortunately there isn't a lot of overlapping material.) Instead, that skeleton is possibly a relatively mature Pinacosaurus, or something different entirely.

Not Saichania, unfortunately! (Except for the head.) But maybe a big Pinacosaurus?

What about the PIN 'Tarchia' skull? 

So amazing!

Although it has a few small differences compared to the holotype Saichania skull, my best assessment right now is that this skull should also be referred to Saichania, not Tarchia. Both skulls have robust squamosal horns compared to the rediagnosed Tarchia, a small prefrontal caputegulum and large loreal caputeglae, and only a single internarial caputegulum. Eventually, as more specimens are found and described, it might be worth creating a new species of Saichania for the PIN skull, especially given that it was found in the Nemegt Formation and the holotype of S. chulsanensis is from the Baruungoyot Formation. Alternately, there might just be a single species of Saichania in both formations – a better understanding of the dinosaur biostratigraphy of Mongolia is much needed!

Part the fourth: A new kid on the block!

Meet Zaraapelta nomadis, a new ankylosaurid from the Baruungoyot Formation! This specimen was collected during the 2000 Dinosaurs of the Gobi expedition organized by Phil Currie and Nomadic Expeditions. 

Please enjoy this beautiful life restoration of Zaraapelta by my lovely and talented friend Danielle Dufault!

Zaraapelta has some features that indicate it's relatively closely related to Tarchia, including prominent prefrontal ornamentation. However, it has a couple of unique features that show that it is distinct – the squamosal horns are deep, like in Saichania, and there is extensive ornamentation behind the orbit. The squamosal horn also has a weird double-layered texture that I haven't encountered in any other ankylosaurid. At the moment we only have a skull for Zaraapelta, but I'm hoping that with the revision of ankylosaurid taxa I've proposed in this manuscript, future workers will be able to identify more specimens for these taxa as well!

And many thanks to Jessica Tansey, who did the technical illustrations of the skull for me while she was an undergrad at the UofA!

Part the fifth: Tail club conundrums

A cast of the ZPAL MgD I/113 tail club in the UALVP collections.

One really neat thing that I've mentioned in a couple of previous papers is that one specimen collected by the Polish-Mongolian expeditions in the 70s has a weird and unique tail club morphology. In pretty much all ankylosaurids, the tail club handle vertebrae look like a nested series of Vs in dorsal view, and the angle formed by the point is about 20-22 degrees. Ankylosaurus is the odd one out because it has distinctive U-shaped vertebrae. And ZPAL MgD I/113 has a morphology that's in between these two – not quite U-shaped, but not as sharply pointed as the V-shaped morphology in other ankylosaurids. There are also specimens from Mongolia with the V-shaped morphology, so we've got at least two species represented by tail club handles. But here's the problem: although we've got some really great skulls, partial skeletons, and skeletons with in situ osteoderms, there actually aren't any skeletons with both a skull and a tail club from these formations in Mongolia! Do either of the tail club morphotypes belong to the named species from Mongolia? Or does the unusual tail club handle represent a new species in the Nemegt Formation? We'll only be able to figure this out if we find a skull and tail club in the same specimen, but it would be pretty exciting if we were able to name another new ankylosaur from the Gobi.

So, that's a brief overview of the taxonomic stuff from the new paper. But before we finish, I want to pause for a moment to acknowledge one of my coauthors who couldn't see the paper in its final published form. Very sadly, our friend Badam passed away suddenly last December, which came as a shock to those of us who've benefited from her kindness and generosity while we've visited Mongolia. I wish I had had more time to spend with Badam, but I'm extremely grateful for the times I got to spend with her in Mongolia and when she visited Edmonton a few years ago. She is a presence that will be missed.

Miriam, Badam and I at Nemegt in 2007. A happy time. We miss you, Badam.

I'm glad to see this paper finally published - it was another one of those multi-year projects to visit lots of museums in order to see all of the necessary specimens - and it was a nice send-off for my time at the University of Alberta. Last weekend I moved down to Raleigh, North Carolina to begin a postdoc with Lindsay Zanno at the North Carolina Museum of Natural Sciences/North Carolina State University. I had an amazing time in Edmonton and I'm sure that's not the last Alberta will see of me, and I'm hoping to accomplish some fun things here in Raleigh. To new adventures!

If you want to learn more about Zaraapelta and friends, try:

Arbour VM, Currie PJ, Badamgarav D. 2014. The ankylosaurid dinosaurs of the Upper Cretaceous Baruungoyot and Nemegt formations of Mongolia. Zoological Journal of the Linnean Society 172:631-652.

Watch my awkward face on Global TV! (Also with footage from the Discovering Dinosaurs exhibit!)

Big screaming hairy dinosaurs.

Kulindadromeus, a little ornithischian from the Jurassic of Siberia, has the palaeosphere abuzz with talk of fluff, feathers, scales, and all kinds of interesting integumentary goodness. Kulindadromeus has scales on its feet, hands, and tail, but the head, body, and upper limbs are covered in three different kinds of filamentous integument. 

Beautiful restoration of Kulindadromeus by Andrey Atuchin, via National Geographic.

Feathers and fluff are extensively known in coelurosaurian theropods (and possibly other theropods as well), but are more controversial in ornithischians. Bristle- or quill-like structures are known in the little ceratopsian Psittacosaurus, and in the 'heterodontosaur' Tianyulong, but since these structures are so different than the filaments and feathers of theropods, there's been some debate about whether or not they evolved independently of true feathers.

A not-so-great photo of a cast of the quilled Psittacosaurus specimen at the Carnegie Museum (look towards the top of the photo for the long, thin filaments), and a life restoration in the museum as well.

In Kulindadromeus, the torso and head are adorned with simple filaments that are thinner than the quill-like bristles in Psittacosaurus and Tianyulong. There are tufted plumes, where multiple filaments converge to a scale-like base, on the upper arm and upper leg. Finally, there are some ribbon-like clusters of filaments on the shins. The tufted plumes still aren't really like anything in the theropods, but the fact that they are branching filaments certainly suggests these are more feather-like than the quills of other ornithischians.

Besides its amazing fluff, Kulindadromeus is pretty neat for a couple of other reasons: 1) we don't really have a lot of dinosaurs from Siberia, so anything new from this region is cool!, and 2) basal things are always interesting, and 3) its non-feathery integument is super interesting! Kulindadromeus is a little more derived than Agilisaurus or Stormbergia, but is still in a relatively basal position in Neornithischia, the clade of ornithischian dinosaurs that includes everything except thyreophorans (ankylosaurs and stegosaurs), 'heterodontosaurs' like Heterodontosaurus, Fruitadens, and Tianyulong, and the most basal ornithischians like Pisanosaurus. The scales on its tail remind me of aetosaur osteoderms, but lack any bone and so aren't osteoderms, but true epidermal structures.

Anyway, I've been thinking about dinosaur skin a lot lately, having written papers on ankylosaur scale pattern diversity and soft-tissue crests in Edmontosaurus. In particular, I'm intrigued by the idea of scaly and fluffy ornithischians. We know that hadrosaurs and ankylosaurs had scaly skin, but does that preclude having fluff too? Well, Kulindadromeus shows you can totally have skin and fluff in different regions of the body. On the other hand, lots of large mammals today lack hair over most of their body, so large dinosaurs may have done the same.

Most of the ankylosaur skin impressions I know of come from Alberta, where the conditions are not ideal for preserving feathers and fluff. However, it's not impossible – feathers have been reported from ornithomimids from Alberta, so maybe we just need to look more carefully in the future. I think the idea of a fluffy ankylosaur probably seems preposterous – how could such an armoured, osteodermy animal have filaments in addition to its tough scales? And it's true – most animals today with osteoderms, like crocodiles, turtles, and lizards, don't have fluff. But there's one group of animals around today that very definitely have osteoderms and fluff:

Via Arkive.

Here's the big hairy armadillo, Chaetophractus villosus. It's one of the fuzziest of the armadillos, with lots of coarse hair on its belly, but also hairs growing off of the individual scutes (if I understand correctly). I'm not going to argue that ankylosaurs definitely had this kind of morphology – armadillos, being mammals, have totally different osteoderms than ankylosaurs that evolved on their own independent evolutionary pathway, and mammal hair/skin and ankylosaur skin are very different. Additionally, we now have evidence for branching filamentous structures as far back as Neornithischia, but ankylosaurs lie outside of that clade (Tianyulong, with its quills, is more basal than ankylosaurs). But being an armoured, osteodermy animal does not always rule out also being a gross hairy thing. Because seriously, look at that guy.

So here, have a big hairy Pseudoplocephalus. He's not so bad, is he?

Or better yet, make it a screaming hairy Pseudoplocephalus, like Chaetophractus vellerosus.

Papers! (And if anyone has any literature on big hairy armadillos, please send it my way!)

Arbour VM, Burns ME, Bell PR, Currie PJ. 2014. Epidermal and dermal integumentary structures of ankylosaurian dinosaurs. Journal of Morphology 275:39-50. [Paywalled! Accessible post here.]

Bell PR, Fanti F, Currie PJ, Arbour VM. 2014. A mummified duck-billed dinosaur with a soft-tissue cock's comb. Current Biology 24:70-75. [Paywalled! Accessible post here.]

Godefroit P, Sinitsa SM, Shouailly D, Bolotsky YL, Sizov AV, McNamara ME, Benton MJ, Spagna P. 2014. A Jurassic ornithischian dinosaur from Siberia with both feathers and scales. Science 345:451-455. [Paywalled! Accessible post here.]

Mayr G, Peters SD, Plodowski G, Vogel O. 2002. Bristle-like integumentary structures at the tail of the horned dinosaur Psittacosaurus. Naturwissenschaften 89:361-365. [Paywalled! Accessible post here.]

Zelenitsky DK, Therrien F, Erickson GM, DeBuhr CL, Kobayashi Y, Eberth DA, Hadfield F. 2012. Feathered non-avian dinosaurs from North America provide insight into wing origins. Science 338:510-514. [Paywalled! Accessible post here.]

Zheng X-T, You H-L, Xu X, Dong Z-M. 2009. An Early Cretaceous heterodontosaurid dinosaur with filamentous integumentary structures. Nature 458:333-336. [Paywalled! Accessible post here.]

5 Questions for Phil Bell

Hot on the heels of yesterday's interview with Caleb, here's an interview with Phil Bell of the Pipestone Creek Dinosaur Initiative. Phil is a former Currie Lab member who completed his PhD last spring, focusing on the Mongolian and North American hadrosaur Saurolophus. He recently published a paper on skin impressions in Saurolophus. Thanks to David Lloyd of the Tyrrell Museum for the great photos of work at the Dragon's Tomb in 2010!


1. What inspired you to conduct this study?

Actually, it was entirely by accident. Like so many advances in science, it came from an unresolved problem: were these two species of Saurolophus (S. osborni from Alberta and S. angustirostris from Mongolia) actually different or were they the same thing? I was at the American Museum in New York in the process of looking at the bones and skeletons of Saurolophus to try and answer that question. I mean, that’s what you do if you work with dinosaurs, you look at the bones. But I immediately struck upon a load of skin impressions. Like most people before me, I thought “that’s cool” but being the first time I had worked with skin impressions, I took the time to photograph, and draw, and measure the hell out of them. When I got to Mongolia later that year, I had the chance to visit one of the great (but little known) palaeontological treasures of the world, the Dragon’s Tomb (see Q3). This site preserves a herd of ‘mummified’ Saurolophus and you can still find loads there today. It was here that I started to notice differences in the skin impressions between the two species and from there I began my search for more specimens with skin impressions that have been stashed in museums from Mongolia, Poland, to Russia.

Phil with a block of Saurolophus at the Dragon's Tomb, Gobi Desert, Mongolia, 2010.

2. Who is Saurolophus?

Saurolophus is a hadrosaur or duck-billed dinosaur. Like it’s more famous cousin, Parasaurolophus (which actually means, ‘like Saurolophus’), it had a rod-like crest sticking out of the back of its skull, but unlike Parasaurolophus, this crest was solid. There are two species: Saurolophus osborni from Alberta grew to around 10 m in length, whereas the Mongolian Saurolophus angustirostris was a giant growing to 12 m in length.

Phil at the Paleontological Institute in Moscow in 2010.

3. What is the Dragon’s Tomb?

The Dragon’s Tomb is the name given to a site discovered by Russian palaeontologists (well, actually, it was one of their drivers who found it) in 1947 in the heart of Mongolia’s Gobi Desert. When they arrived, they found not just one but six or seven Saurolophus skeletons lying on a rocky ledge, most with skin impressions. The Russian’s named it the Dragon’s Tomb for obvious reasons and since then many more Saurolophus skeletons have been found there. Unfortunately though, fossil poachers have also relocated the spot and have caused irreparable damage by using dynamite to blast out skulls and skeletons to sell on the black market. But the place is so rich you can still find great stuff there. I’m involved in a project with Michael Ryan (Cleveland Museum) and David Evans (Royal Ontario Museum) to further explore this site and to figure out why exactly tens of Saurolophus died there.

The Dragon's Tomb, Gobi Desert, Mongolia, in 2010.

4. What is special about the skin of Saurolophus?

Well, for the moment it’s the most complex scale pattern ever seen in a dinosaur. People have known of dinosaur ‘mummies’ for 100 years (actually, last year was the 100^th anniversary of the discovery of the first, and in my opinion the best ‘mummy’ ever found; that of Edmontosaurus now on display in New York) but the complexity of their scale patterns has not been really appreciated until now. The stripy pattern on the tail of S. angustirostris was a complete surprise – one that I didn’t even believe when I first saw it. I thought it was a trick of the light or something to do with how the animal was preserved. But when I started to see it on more and more specimens, there was no denying it.

Preparing latex molds of skin. Fittingly, the latex brand is called "Dragon Skin".

5. Can different scale patterns tell us anything about the colour or colour pattern of Saurolophus?

That’s always a tricky question but without the actual colour preserved (as some people have shown with fossilized proteins that produce pigment) we can never be certain. One way of testing that question is to look at modern animals with scales (crocs, lizards, snakes). If you look closely at any of these animals you will notice that not all scales are born equal – some are big, some are small, some are long, circular or hexagonal. And they all have a function of some kind. Take a snake for example; most of the scales along its back are diamond-shaped and coloured in some way. But look at its underside and the scales are really wide, spanning the entire width of the animal, which they use to grip the ground when they’re on the move. They’re also usually a different colour to the top side. So, different shape, different function, and different colour. I’m not saying this is the way it always is but it’s a pretty compelling notion wouldn’t you say?

Thanks very much, Phil!

You can read the original paper here:

Bell PR. 2012. Standardized terminology and potential taxonomic utility for hadrosaurid skin impressions: a case study for Saurolophus from Canada and Mongolia. PLoS ONE 7(2): e31295.

And also see "Saurolophus skin suggests speciation" at Superoceras, and "Judging a dinosaur by its cover" at Dinosaur Tracking, for more coverage of this paper.

From Russia with Love.

Tetsuto is kind enough to let me post some of his excellent photos from our trip to Russia. Thanks Tetsuto!

This was our somewhat unconventional walk to the museum in the morning, through a very nice park between our hotel and the museum. Although we never found the exact path to the museum, and had to cross a field and squeeze under a fence to get there one day...




I certainly had not expected Moscow to be so green! It was wonderful to be so near a park, which had fairly abundant plant and animal diversity. There were plenty of songbirds that were mostly new to me, like the very cute white wagtail (Motacilla alba), as well as the hooded crows (Corvus cornix) that I had seen last year in Poland. We even had a few sightings of European hedgehogs (Erinaceus europaeus)!

Here's an excellent shot of the courtyard at the museum.

In addition to the native fauna, Moscow has an enormous amount of (surprisingly polite) street dogs. It was always a bit of a surprise to see them lounging around the Metro underpasses.

We had visited a very nice touristy market but were caught in a sudden DOWNPOUR that thoroughly drenched everything and then just as suddenly ended. The rest of the week was beautiful and sunny, probably because we were inside all day at the museum.

Into the Gobi....in Mother Russia.

Guess where I was last week?

Later this summer I'm heading into the Gobi for the second time, but beforehand I wanted to look at some important and famous ankylosaur specimens that had been collected in the 1940s. But where were these specimens located? In Moscow! So, off I went with three of my labmates to spend a week at the Paleontological Institute in Moscow.

We spent a day touring around Moscow, mainly around the Red Square.

Phil with a rather large Saurolophus leg.

Tetsuto with a rather small Tarbosaurus.

Miriam with a slightly bigger Tarbosaurus.

And me, with a very nice Pinacosaurus! Victoria approves!

It was a splendid museum, and although I work on dinosaurs it was really wonderful to be able to see the enormous collection of Permian vertebrates on display in the Palaeozoic Hall. If for some reason you are visiting or passing through Moscow, make a point of visiting the museum. It is a bit off the main tourist track, but quite accessible by the Metro on the orange line.

Pareiasaurs and a very cool chandelier in the Palaeozoic Hall.

There was also a very nice courtyard with excellent and diverse statues!

Many thanks to all of the folks who helped us out during our stay, and put up with our nearly complete lack of Russian language ability. I hope to return someday!