Know Your Ankylosaurs: Gondwana Edition

Last time, I talked about the ankylosaurids of China, and today we're talking about Gondwanan ankylosaurs. Gondwana basically refers to the continents of today's southern hemisphere; when the supercontinent Pangaea broke apart, it split into two large continents – Laurasia in the north, and Gondwana in the south. Gondwana includes South America, Africa, Australia, and Antarctica, and, somewhat nonintuitively, India (India kind of beelined into Asia from Australia and that's why we have the Himalayas). Almost all of the ankylosaurs we know about are from the Laurasian continents, which means that the few found in Gondwana are phylogenetically and biogeographically interesting: do they represent southern branches of the ankylosaur family tree, or new migrations into Gondwana from Laurasia? Let's take a closer look:

Minmi paravertebra and Minmi sp.

Minmi is the iconic Australian ankylosaur. Most people, when they think of such things, think of the spectacular referred skeleton with agood skull and in situ armour.

The Smithsonian has a cast of the specimen - here's a section of the ribcage, showing some of the osteoderms in their original arrangement.

Sadly, the holotype is extremely fragmentary and has few elements to make a diagnosis with. Originally, one of the most striking features of Minmi paravertebra was the presence of paravertebral elements, thin rod-shaped bones along the dorsal vertebrae. These were originally interpreted as ossified tendons of the dorsal muscles, and although these are cool to see in Minmi, they are not really unique to Minmi or even to ankylosaurs, since ossified tendons are ubiquitous throughout Ornithischia. One unusual aspect of these ossified tendons is that one set has a flattened, expanded front end. These were interpreted as possible ossified aponeuroses (aponeuroses are sheets of connective tissue in between muscles and tendons). This particular aspect of the ossified tendons IS very unusual, because ossified aponeuroses are extremely rare in animals. While I was hunting around for information about ossified aponeuroses, I came across a very odd case study about mouse deer (Tragulus) – the males completely ossify the aponeuroses above their pelvis and back, creating a carapace-like structure! This is super weird and I would love to investigate this further at some point.

WHAT THE WHAT.

Ossified aponeuroses have since been identified in the European nodosaur Hungarosaurus, which poses a bit of a problem for Minmi: since this feature was one of the only diagnostic characters for Minmi, and since it is now found in an animal that is very unlikely to be Minmi given the spatial and temporal distance between the two, Minmi paravertebra is left without diagnostic characters. A sticky situation that will hopefully be resolved in the future by people who have spent time with the original fossil material!

Antarctopelta

Did you know that the first dinosaur discovered in Antarctica was an ankylosaur? Cryolophosaurus might get all the buzz, but Antarctopelta was first to the press. Antarctopelta is a very interesting little ankylosaur, which I had the chance to study during my visit to Argentina back in 2011. The material is fragmentary but tantalizing, with some pieces of the pelvic armour that are reminiscent of ankylosaurs like Stegopelta and Glyptodontopelta from North America. Unfortunately, in the course of my research I noticed that some of the bones attributed to Antarctopelta and used to help diagnose the taxon didn't quite seem like they came from an ankylosaur. The material was found on an ancient beach strandline with some marine fossils mixed in, and it looks like some of the material originally interpreted as ankylosaurian might be better interpreted as belonging to a mosasaur and a plesiosaur. In the end, we weren't left with any diagnostic characters for Antarctopelta and we should consider that a nomen dubium for now, but there's definitely an Antarctic ankylosaur and I hope at some point some better material is recovered so we can determine the best name for this guy.

The Argentinian ankylosaur

Finally, I also had the chance to study the only described ankylosaur from Argentina. This is also a fairly fragmentary specimen, and it came from a channel lag deposit so it's possible that more than one individual is represented. There are osteoderms, some vertebrae, and a femur, and all are very small – about the same size as the juvenile Anodontosaurus (originally described by Coombs as Euoplocephalus) from Alberta. The femur is interesting because it has some very prominent ridges running lengthwise on it, which seem to be intermuscular lines; these are present but very faint on some other ankylosaurs, and I haven't encountered anything like that in other ankylosaurs. There also may be fragments of the cervical half rings preserved as part of this specimen, since there are some unusual curved osteoderms with multiple peaks and keels. These don't bear any resemblance to other half rings I've looked at, and cervical half ring morphology seems to be taxonomically informative for ankylosaurs. Together, the weird intermuscular lines and unusual cervical half ring fragments might be enough to diagnose the Argentinian specimen as a new taxon, although we withheld from doing so at present.

Here's the specimen on display at the Museo Carlos Ameghino in Cipoletti!

There have been reports of some possible ankylosaur material from India and Madagascar, although much of this material is either very fragmentary (a single tooth from Madagascar), or has not been described (material from India). Stay tuned to find out more about how these rare ankylosaurs fit into the big picture of ankylosaur evolution!


Next up: a grab bag of everybody else!


Arbour VM, Currie PJ. In press. Systematics, phylogeny and palaeobiogeography of the ankylosaurid dinosaurs. Journal of Systematic Palaeontology.

Did the sauropod Leinkupal survive the End Cretaceous mass extinction?

No.

Discovery News has a short video up discussing a new paper in PLOS ONE, Gallina et al.'s "A diplodocid sauropod survivor from the Early Cretaceous of South America". I think it is really great that they want to showcase this interesting new find! But the DNews report leaves an awful lot to be desired.

The news report is titled "There's a dinosaur that survived mass extinction!", which would lead most people to think that some kind of post-Cretaceous dinosaur has been discovered. At about 25 seconds in, the reporter says this is the first time scientists have found a dinosaur that survived the great extinction, presumably referring to the End Cretaceous mass extinction that happened 66 million years ago. Right away, it seems that there's a huge misunderstanding here – there have been multiple mass extinctions in the history of life, not just the one that killed the non-avian dinosaurs. Additionally, the 'great extinction' should really refer to the End Permian extinction, by all accounts the most devastating mass extinction ever.

Anyway, Gallina et al. have described a new diplodocid sauropod, called Leinkupal, from the Early Cretaceous (probably about 140-130 million years ago) in Patagonia. This is significant because diplodocid sauropods were pretty abundant in Jurassic rocks from North America, Europe and Africa, but seem to have disappeared from the fossil record after the Jurassic. Since diplodocids were present in the Jurassic of Africa, it was also thought that they were probably present in the Jurassic of South America, but no fossils had ever been found. So, Leinkupal confirms one hypothesis (that diplodocids were present in South America), and also rejects another (diplodocid sauropods went extinct at the end of the Jurassic). Good stuff all around! But Leinkupal does not tell us that dinosaurs survived the 'great extinction' (whatever that is), and it certainly did not survive the End Cretaceous extinction, on account of it having been dead for about 70 million years before that happened.

Vertebrae from Leinkupal, from Gallina et al.

This little video is an amazing microcosm of misconceptions about evolution and palaeontology, and it's really frustrating to see this coming from Discovery News. Here's some other little snippets:

* "The diplodocid sauropod is a family" – I hate to nitpick over grammar (wait, who am I kidding – I love nitpicking over grammar!), but the grammatical failure here I think represents a pretty basic misunderstanding of how taxonomy works. Later on, the reporter says of diplodocids that "the species was thought to be an exclusively North American dinosaur". Diplodocids are a subset of sauropods, in the same way that sauropods are a subset of dinosaurs. Diplodocidae is the formal 'family' name for this group, and Diplodocidae contains many genera and species. Some of these are familiar, like Diplodocus and Apatosaurus, some are less familiar, like Tornieria and some are new, like Leinkupal. We use classification systems to understand how animals are related to each other, and to understand the scale of certain biogeographic patterns. Getting this stuff right is both relatively easy and also important!

The imposing figure of "Seismosaurus" hallorum, a diplodocid from New Mexico on display at the New Mexico Museum of Natural History & Science. "Seismosaurus" is thought by some authors to be the same genus as Diplodocus.

*At one point, the reporter says that diplodocids were "assumed to have gone extinct", which is kind of true but also takes a lot of the science out of the story! Palaeontologists didn't just assume diplodocids were extinct, they observed the pattern in the fossil record in which diplodocids were present in some layers and then not in others, and concluded that either 1) diplodocid sauropods went extinct at the end of the Jurassic or 2) we have incomplete data, and sauropods may just not be preserved in the post-Jurassic rocks we've looked at. It turns out that the latter idea was correct!

* The reporter comments that the Patagonian discovery is the earliest record of diplodocids. It's easy to get mixed up with this sometimes, but Leinkupal represents the youngest, and therefore latest record of the group. The earliest record of a group would be the first record, and therefore the oldest record. Since this is the main point of this story, they should really get this right!

* The reporter also states that Leinkupal was found in a place that palaeontologists never expected (South America), when in fact the biogeographic pattern of known diplodocids hinted strongly at the possibility of South American diplodocids. This is so great! We were able to use our knowledge of the fossil record to predict where we might find a kind of dinosaur that we had not found there before.

* Finally, the segment opens with the reporter making a show of how hard it is to pronounce the new dinosaur's name. It's true that Leinkupal doesn't have the familiar Something-saurus structure that lots of dinosaurs have, but it's not overly difficult to pronounce. There are two things that bother me here: 1) Why, Discovery News, are you making your female presenter pretend to be dumber than she surely is? and 2) An unfamiliar foreign word is made out to be this super weird and difficult thing, when they could have taken a moment to point out that this unusual name means "Vanishing family" in Mapudungun. It's a beautiful and evocative word that reflects the significance of the specimen, and highlights a local language that most of us are not familiar with. A moment that could have been used to learn something new was instead used to indicate that new things are weird and learning is hard.

This is really shallow and lazy writing. All of the important points to cover in a video segment of this length can be found in the three-paragraph introduction of the open-access paper. There's no excuse to not get it right. Instead of highlighting how this discovery shows the power of scientific predictions, we got a video that can't get basic facts correct, and pretends that this stuff is really hard rather than working to make it accessible to everyone.

Ultimate ROM

This summer, the Royal Ontario Museum unveiled a brand-new exhibit all about the dinosaurs of Gondwana. When Pangaea rifted apart during the Triassic, it split into two continents - Laurasia, represented by the modern northern continents of North America, Europe, and Asia, and Gondwana, represented by the modern southern continents of South America, Africa, Australia, and Antarctica, plus India, Madagascar, and New Zealand. The dinosaurs and other extinct terrestrial vertebrates of Gondwana differed from their northern neighbours, and we don't often see them in exhibitions in North America.

 

Ultimate Dinosaurs: Giants of Gondwana features lots of interesting and sometimes obscure dinosaurs, some really great artwork, and some neat technological things (of which I am sometimes skeptical, but can wholeheartedly endorse here).

 

 

 

After a brief but informative introduction to plate tectonics, we're introduced to some of the earliest dinosaurs, like Herrerasaurus, Eoraptor, and the early ornithischian Pisanosaurus. In an exhibit that is definitely dominated by saurischian dinosaurs, it was neat to see this little fellow! Take note of the beautiful murals in the background, painted by Canadian palaeoartist Julius Csotonyi.

 

 

 

Ah, Cryolophosaurus. My second favourite dinosaur from Antarctica! ;)

This restoration of Cryolophosaurus definitely seems to have a more Dilophosaurus-y look to the skull, perhaps a result of recent phylogenetic analyses recovering a close relationship between the Antarctic taxon and other early, crested theropods.

 

 

 

As we move into the Cretaceous, the dinosaurs are arranged by geographic area on platforms. First off are African dinosaurs, including Malawisaurus, Nigersaurus, Carcharodontosaurus, and (shown here), Suchomimus.

 

 

 

I was super excited to see a mounted skeleton of Ouranosaurus, a bizarre sail-backed iguanodontian.

 

 

 

Ok, hands-down my favourite critter featured in this exhibition was one of the smaller skeletons, and not a dinosaur! I am sorry, dinosaur colleagues! But his adorable stubby tail and marvelous coat of osteoderms stole my heart. This is Simosuchus, a herbivorous crocodilian from Madagascar.

 

 

 

 I'll perhaps also add that the Madagascar 'pod' of Majungasaurus, Rapetosaurus, Masiakasaurus, and Rahonavis was probably my favourite part of the exhibition, just because I've never seen any of these taxa as mounted skeletons before, and because they're just so, so weird. Also, Majungasaurus just wants a hug, WHY DON'T YOU LOVE ME, RAPETOSAURUS?

 

 

 

I was very fortunate to get to see a lot of Patagonian dinosaurs last November during my visit to Argentina, but I'd never seen Austroraptor before. He is BIG! This 'pod' also features Buitreraptor, Carnotaurus, and Amargasaurus.

 

 

 

 

Although the dinosaurs are the main attraction, the main take-home messages of the exhibition are 1) continents move and 2) evolution happens. The dinosaurs are just the vehicle for delivering an exhibit that is actually all about the effects of plate tectonics on evolution, and I think that's awesome. Palaeogeography is prominently featured throughout the exhibition, and there's even an interactive team puzzle where you reassemble the continents into Gondwana. However, one of the most incredible things in the exhibit were the two giant Blakey palaeomap globes, animated to show the drifting of the continents. As you enter the exhibit, Pangaea breaks apart, and as you leave, the continents assemble into their current positions, and then keep going into the future! The video projections are staggeringly beautiful.

 

Honestly, I think this is one of the best dinosaur exhibits I have seen. It is bright, colourful, up to date, and packed with really good information not just about dinosaurs, but about broader themes in geology and evolution as well. Ultimate Dinosaurs is at the ROM for a limited time (I think until the end of 2012) and then it (hopefully!) goes on tour. GO SEE IT!

Birds at the Museo Argentino de Ciencias Naturales

After finishing up with the dinosaur hall at the Buenos Aires natural history museum, I was pleasantly surprised to find more dinosaurs when I headed upstairs. I can't recall a time where I've actually seen dinosaurs in the bird gallery - often the dinosaur story ends with the origin of birds, but when the birds are on display it's usually more about extant bird diversity and conservation. So it was really nice to see the origin of birds explained right at the very beginning of this exhibit.

Right after the origin of birds we are treated to this display of extremes in bird skeletons, which really highlights the adaptations for particular lifestyles in different groups: the long, long wings of albatrosses, the oversized feet of raptorial birds, the hilariously gigantic heads of toucans and parrots, and the long legs and short arms of ostriches. They have also cleverly placed a hummingbird in front of the ostrich to highlight the great size range of extant birds.

Lots of museums have exhibits displaying birds of different habitats, but not as many include urban environments. I guess Argentina is also lucky for having such a wide array of interesting and colourful backyard birds, but I think this is something that could be done in a lot of museums. This is also particularly helpful for people who are just visiting the city who like to keep track of their birds, but don't get out into the countryside for the more 'exotic' species.

Fossils make an appearance yet again when we get to the function and diversity of feathers. There are casts of Sinosauropteryx, Microraptor, and Caudipteryx. Again, you don't often see a lot about the evolution of particular traits within exhibits featuring extant animals, so this was nice to see.

I love visiting the bird exhibits in most museums for the sheer 'ooh! cool! pretty!' factor, and there is certainly a lot of that here. But the weird and wonderful structures found in modern birds is organized such that you can learn a lot while still marveling at all the strangeness. For example, there are sections discussing how different colours are produced, how feathers on the body vary and what their functions are, and how feathers are modified to form display structures.

There's so much I love about this gallery that I could just go on and on. I'll finish here with a photo of the entrance to the museum, guarded by a pair of wise and watchful owls.

Dinosaurs at the Museo Argentino de Ciencias Naturales

After a little break over the holidays, let's finish up these Argentina posts, shall we? After my research visits to the Museo Carmen Funes, Museo Carlos Ameghino, and Museo de La Plata, it was nice to be able to visit the main natural history museum in Buenos Aires as just a tourist. If you're in Buenos Aires, it's well worth a visit.

The dinosaur hall is large and with a lot of Gondwanan dinosaurs you don't see very often. I particularly liked this sprinting Carnotaurus that fits nicely with Scott's recent paper on the tail of Carnotaurus.

Amargasaurus is one of my favourite sauropods. Who can resist those incredible cervical vertebrae? But even better is that this is one of the only dinosaurs I know of that is mounted in an egg-laying pose. It's really refreshing to see a variety of behaviours presented by skeletal mounts, and it is especially nice to see a herbivore doing something other than fleeing or eating.

Although a lot of this mount of Bonatitan is reconstructed, it is interesting to see such a small sauropod, and there was just something pleasing about the whole thing.

A bunch of early dinosaurs and dinosauromorphs are also featured, including a reconstructed Marasuchus, Hererrasaurus, and this Eoraptor.

Argentina of course has wonderful mammal fossils as well, and there was a great exhibit about the fossils found near Buenos Aires. I liked seeing this glyptodont without its carapace.

And who would have thought that ground sloths could be so dramatic?

There's also a really nice comparative osteology hall, with one of my favourite exhibits being this exploded crocodilian head.

This museum has one of the best bird galleries I've been to, so I'll save that for its own post, coming up next...

Museo de La Plata

Those regal cats at the entrance to the Museo de La Plata aren't just any ol' big cats - look closely and you'll see that a pair of Smilodon greet you at this museum.

The Museo de La Plata is in a beautiful park and is a great old-school kind natural history museum, which I mean in the best of ways. Others have said it better before me, but natural history museums are at their best when they are full of natural history objects, and this museum delivers on that front. I was delighted to see a hall of marching skeletons and flying whales, which is one of my favourite ways that comparative osteology is showcased.

I liked the glass cases used to display the taxidermy mounts, since you could look at the animals from all sides.

In the fossil galleries, I was pleased to see this cast of a meiolaniid turtle! I love how much these guys look like ankylosaurs.

There was a mounted skeleton of the small ornithopod Gasparinisaura with this excellent life-size model next to it.

And there was a cast of the Carnegie Diplodocus in its own very nice gallery, along with some femora of the giant titanosaur Antarctosaurus.

Next up: the Museo Argentino de Ciencias Naturales.

Museo Carlos Ameghino

From the Museo Carmen Funes I headed to the town of Cipoletti to visit the Museo Carlos Ameghino. This is the home of an unnamed ankylosaur collected from Argentina, and it was great to be able to check this material out for myself. Gondwanan ankylosaurs are relatively rare; in addition to this specimen, there's Minmi from Australia, fragmentary remains from New Zealand, and Antarctopelta from Antarctica.

The Museo Carlos Ameghino is a neat museum in an cool old house, and houses several holotypes of interesting taxa. The picture above is of Kritosaurus australis, which juusst fits in the room.

The abelisaurid theropods are a really interesting and weird group of theropods, with very reduced arms and strange tails. So it was great to see the skull of Abelisaurus, the namesake of the group, on display.

Just across from Abelisaurus is a cast of the skull of Carnotaurus, another abelisaurid theropod. Having the two skulls close together really highlights how weird Carnotaurus is, even compared to other members of its own group. The skull is so anteroposteriorly short!

That's all for Cipoletti. Next time we head to La Plata!

Museo Carmen Funes

After my Argentinian fieldwork finished up, the crew headed to Plaza Huincal, and the Museo Carmen Funes, home of the giant sauropod Argentinosaurus and the also giant theropod Mapusaurus. I thought I would share some photos of some perhaps less well known Argentinian dinosaurs displayed in their galleries.

The alvarezsaur Patagonykus runs away from the dromaeosaur Unenlagia.

Abelisaurid theropods had really, really reduced arms, with the best example being Carnotaurus (although you wouldn't know it from shows like Terra Nova). But another good example is Aucasaurus, which also had pretty tiny arms.

And I couldn't resist snapping this photo of the tail of Aucasaurus, showing those weird hooked transverse processes on the caudal vertebrae that Scott talked about in his last guest post.

And finally a little love for the little guys. Here's Anabisetia, a basal ornithopod known from four really nice specimens that I had the good fortune to study while I was there.

Next up, the Museo Carlos Ameghino!

Ambling Around Argentina.

Guess where I’ve been? The boots don't lie...

Just three days after the SVP meeting in Las Vegas, I flew to Argentina to see what the other side of the Andes looked like. I joined Dr. Rodolfo Coria’s team at a site in Neuquen province, about two hours away from Plaza Huincal.

The formation we were working in is relatively unexplored, so it will be exciting to see how the research develops over the next few years.

Most of my time was spent helping at a quarry that was worked earlier this year – my friend and former Currie Lab student Dr. Phil Bell posted about his experiences at this quarry over at the Philip J. Currie Museum’s Blogosaur. We had help lifting some of the large jackets out of the quarry, which made a big difference!

I also drank a lot of mate, a tea you drink through a straw out of a little gourd-cup that gets passed around to everybody. It is quite sociable.

And to celebrate at the end of the week, we had two cevitos! (They were delicious.)

I’ve been roaming around Argentina visiting museums for the last few days, and will post more photos upon my return to Edmonton. See you soon!