Thursday, May 22, 2014

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.



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.

Friday, May 16, 2014

Many animals have skeletons besides dinosaurs.

I was reminded of an old post on this blog today when someone brought up the all too common question of "Is that real?" in museums. In 2011 I had visited the Smithsonian natural history museum for some of my Euoplocephalus research, and spent a day browsing the galleries and shamelessly eavesdropping on people's conversations. I was dismayed by the number of people saying things like "What's that!" and then walking away without finding out, or saying "Look, a T. rex!" to things that were patently not T. rex. In the comments on that post, there was some discussion of the fact that visitors to museums often mistake any skeleton as a dinosaur skeleton.

Anyway, that in turn reminded me of a photo I took in the Nova Scotia Museum of Natural History's marine gallery a while ago:


Despite being surrounded by all manner of marine specimens, including a fleshed out model of a sei whale up above, the museum has to explicitly say that a pilot whale is not a dinosaur. In fairness, the museum (sadly!) does not have any dinosaur skeletons, what with Halifax being located on top of the Cambrian-Ordovician Meguma Terrane, and with the Fundy Geological Museum fulfilling the role of the dinosaur-having museum in Nova Scotia.

What lessons can we learn from this?
1. Museum people: put a dinosaur in your museum. There's no excuse not to have one.
2. Everybody else: many animals have skeletons besides dinosaurs.
3. ????




*Bonus! Sable Island is a super neat place that not many people have heard about outside of the maritime provinces - you can read more about it at their National Park page!

Wednesday, May 14, 2014

The Systematic Position of the King of the Monsters

A few weeks ago I was really excited to be contacted by Danielle Venton, a freelance writer working on a piece for Popular Mechanics about the biology of Godzilla! With a new big-screen appearance by Godzilla right around the corner, I thought this was a fun exercise in speculative biology. The piece is out now at Popular Mechanics and I highly recommend checking out "The Impossible Anatomy of Godzilla".

I've always been a fan of B-movies (especially ones that have been MST3K'd) and monster movies, so, in preparation for the new Godzilla film, I've been trying to brush up on my kaiju history. Perhaps unfortunately, my introduction to Godzilla was with 1998's TriStar film, which seems to be uniformly considered not that great an entry into the monster's filmography. In the process of helping out with Venton's piece about Godzilla, I also came across some really fun previous discussions of Godzilla's anatomy. I heartily recommend checking out Darren Naish's "The science of Godzilla, 2010" and "The anatomy of Zilla, the TriStar 'Godzilla'" over at Tetrapod Zoology, and Brian Switek's "What kind of dinosaur is Godzilla?" over at Smithsonian.com.

[Some of what I find is very silly. Godzilla flies using his rocket breath in Godzilla vs. the Smog Monster!]


Most discussions of Godzilla's anatomy use dinosaurs (for classic Godzilla) or lizards (for Zilla) as starting points, and it's generally understood that the original Godzilla design was a melding of an Allosaurus, Iguanodon, and Stegosaurus. However, it occurred to me that another group of diapsids might serve as plausible candidates for Godzilla's heritage: the pseudosuchians (or crurotarsans, if you prefer)!

Today's only living pseudosuchians, the crocodilians, have osteoderms in their skin, if somewhat less flamboyant than Godzilla's. The 'scale' pattern on their heads is actually formed through cracking of the skin during development, resulting in a texture similar to what's seen on Godzilla's body, which in turn is apparently supposed to resemble the keloid scars of nuclear explosion survivors.


West African dwarf crocodile (Osteolaemus tetraspis) at the Toronto Zoo.

All living crocodilians are aquatic quadrupeds with powerful tails, and Godzilla seems to be a pretty good swimmer using his tail as a propulsive mechanism. Although many pseudosuchians were quadrupeds, some, like the poposauroids, were bipedal! Pseudosuchians seemed to have typically retained most fingers on the hand, like Godzilla, but unlike most theropod dinosaur lineages.

As far as I know, and I certainly haven't done a thorough literature search on this, there are no known pseudosuchians with nuclear breath....but alligators can produce a mighty bellow during breeding season.

ARKive video - Male American alligators, courtship displays


Could Godzilla represent a long-lost and enigmatic lineage of pseudosuchian? Should there be a Godzillasuchus? Tell me what you think in the comments!


Wednesday, April 9, 2014

Nitpicking Euoplocephalus

A friend of mine posted this amazing video on Facebook, and I must share it!



I really like how the Geek Group have obviously put a lot of time into researching the anatomy of the dinosaurs they're featuring, and the stylized animations are super cool. I'm obviously biased towards this episode, but I'm looking forward to seeing more!

For those who are interested in learning more about the anatomy of Euoplocephalus, may I offer these blog posts?:

Baron von Nopcsa, Scolosaurus, and the spiky-clubbed ankylosaur.

You can pick your friends, and you can pick your nose...and you can definitely pick your ankylosaur's nose.

Who-oplocephalus
Who-oplocephalus: Is Euoplocephalus 'real'?
Who-oplocephalus: Heads for tails.
Who-oplocephalus: The Fellowship of the Half Ring
Who-oplocephalus: Everything old is new again.

Scaling up


And for the keeners, you can also check out a lecture I did for the Royal Tyrrell Museum's lecture series via their YouTube page!





Bonus: The Dinosaur Toy Blog also enjoys nitpicking the accuracy of dinosaur toys!

Saturday, April 5, 2014

Name that Specimen, Canadian Museum of Nature edition

I haven't done one of these for a while! See if you can guess what specimen is which!

1.

2.

3.

4.

5.

























 1. It's spiky side up for this Styracosaurus!
2. Here's the shovel-beaked maw of a hadrosaur.
3. Don't get too close to the business end of an ankylosaurid – the tail club can pack a wallop!
4. Did you guess Edmontosaurus? Here's the pelvic girdle of this iconic hadrosaur.
5. The reconstructed skin of Vagaceratops is very colourful!

Wednesday, April 2, 2014

Scaling Up

Let's turn our attention from hadrosaur skin to ankylosaur skin, a topic which has received surprisingly less attention in the published literature than I would have thought. I should qualify that statement, however, by saying that by 'ankylosaur skin' I mean ankylosaur skin impressions, because ankylosaur dermal elements are well known and the focus of many a paper – I refer of course to osteoderms, which form within the dermis of the skin and which give ankylosaurs their spiky and armoured appearance.

For a couple of years now I've been keeping notes about occurrences of skin impressions in ankylosaurs, which eventually lead to a paper by myself, Mike Burns, Phil Bell, and Phil Currie. We reviewed the morphology of scale patterns in the few specimens that preserve skin, and found that there were some intriguing differences in scalation between different ankylosaurs.

The holotype of Scolosaurus cutleri, NHMUK R5161, has the best preserved integument for any North American ankylosaur, and has loads  of scale impressions lying overtop of the in situ osteoderms. In Scolosaurus, the scales form rosettes around the osteoderms. The largest scales are generally found closest to the osteoderms, but some large scales are scattered in between the osteoderms as well. Underneath the scales, small ossicles (little osteoderms less than 1 cm in diameter, but usually only 2-4 mm wide) fill the spaces between the larger osteoderms.




Scolosaurus is hard to photograph well, sorry!


In contrast, a very unusual specimen (ROM 813) has a completely different morphology. This specimen includes unusual long, rectangular osteoderms that aren't present in NHMUK R5161. The scales are on average much smaller, don't form much of a rosette pattern around any of the osteoderms, and are more uniform in size overall. ROM 813 is a little bit difficult to interpret because it is partially disarticulated (which is also intriguing given that such large portions of the integument are intact), but our best guess for the preserved portions is shown here.



Another super cool thing about ROM 813 is that it preserves the epidermal covering of an osteoderm, and it is the only example of this in an ankylosaur that I know about. In the photo below, the smooth side of the osteoderm is the epidermal scale, and the rough side of the osteoderm is the true bony part of the osteoderm.



Moving over to Mongolia, a specimen referred to Tarchiagigantea lacks the small pavement of ossicles seen in the Albertan ankylosaurs, and the epidermal scales are huge and more rectangular. In the portion of the integument preserved, osteoderms are separated by only one row of scales.



There's enough overlapping material between these specimens to allow us to compare scale patterns among different ankylosaurs, and the differences support the hypothesis that these are different taxa. Unfortunately, right now we can't assign ROM 813 to any known ankylosaurid taxon from Alberta – this could represent the postcrania of Euoplocephalus tutus, or Dyoplosaurus acutosquameus, or (less likely) a new taxon of ankylosaurid from the Dinosaur Park Formation. I think it's safe to say that the differences between Scolosaurus and ROM 813 represent true taxonomic differences, a finding that is in line with previous work by Phil Bell on scalation differences between Saurolophus angustirostris and Saurolophus osborni.

Illustrations by Lida Xing and via PLOS ONE.


One more comment about ankylosaur skin: In 2010 I had the opportunity to study the holotype of Liaoningosaurus paradoxus, and very interesting little ankylosaur from the Liaoning Formation of China. The original authors described Liaoningosaurus as possessing a ventral plastron (bony shield, like that found in turtles), which would have been a highly unusual anatomical feature given that no other ankylosaurs possess a plastron. Having looked at this specimen, I think a better interpretation for the plastron is that this is a segment of skin impressions from the belly region – there didn't seem to be any bony texture around the edges of this area, and the pattern is more consistent with scales than any osteoderms in other ankylosaurs.

Belly scales for Liaoningosaurus. The scale bar is in millimetres.



Papers!

Arbour VM, Burns ME, Bell PR, Currie PJ. 2014. Epidermal and dermal integumentary structures of ankylosaurian dinosaurs. Journal of Morphology 275:39-50.

Arbour VM, Lech-Hernes NL, Guldberg TE, Hurum JH, Currie PJ. 2013. An ankylosaurid dinosaur from Mongolia with in situ armour and keratinous scale impressions. Acta Palaeontologica Polonica 58:55-64. Many thanks to Dr. Hurum for inviting me to help describe this specimen!


Xu X, Wang X-L, You H-L. 2001. A juvenile ankylosaur from China. Naturwissenschaften 88:297-300.

Sunday, March 30, 2014

Cock-a-doodle-doo

I've finally got the time and gumption to sit down and write again, so let's do some research blogging! And let's show some skin while we're at it!

The first paper I'll talk about is not one that I'm lead author on, but which was a really fun project to be involved in. This was the description of a super cool specimen of a hadrosaur from the area around Grande Prairie with some impressive skin impressions. UALVP 53722 was collected as a large block that had fallen along the creekside. Unfortunately, the rest of the skeleton could not be located, which might mean it's still in situ somewhere with nothing visible, or it had already broken apart into unrecognizable pieces. The block preserves the back of the skull with the neck arched over the shoulders, the classic 'death pose' seen in many dinosaur skeletons. Most of the skull is missing, but what is present shows that it is an Edmontosaurus regalis, the slightly older species of Edmontosaurus


Flat-headed Edmontosaurus at the Denver Museum of Nature and Science.


And sitting on top of the skull is a round, relatively smooth lump of soft tissue, like the comb on a rooster's head. 

My primary contribution to the paper was to examine the CT scans of the specimen to confirm that there wasn't a bony structure within the crest, so that we could be confidant that it truly was a soft tissue structure only. The UofA put together a short video about CT scanning the fossil that is worth a watch:





The fleshy comb in UALVP 53722 the first time we've seen anything like this in a dinosaur, and was totally unexpected – Edmontosaurus is one of the 'flat-headed' hadrosaurs that lacks the bony crest characteristic of lambeosaurines like Corythosaurus or Lambeosaurus. I love this discovery because it is such a great example of how much soft tissues contribute to the appearance of an animal. It also goes to show how a new fossil, even for a relatively well known dinosaur like Edmontosaurus (which is known from many skeletons and bonebeds) can still give us new information. 

Crested Edmontosaurus based on UALVP 53722.


I was also a big fan of the book "All Yesterdays", and I feel like this specimen kind of fits in with some of the more adventurous reconstructions of dinosaurs with elaborate soft tissues that have become more fashionable of late. And like all good discoveries, we end up with more questions that need to be answered: did all Edmontosaurus regalis have this fleshy comb, or was it restricted to adults, or even just adult males? If males and females both had the comb, was it larger in one sex than the other? Was it brightly coloured? Did Edmontosaurus annectens have a fleshy crest? We'll only be able to answer these questions with more specimens.

Anyway, go check the paper out! UALVP 53722 was on display in Edmonton for a short time earlier this year – stay tuned for more information on where it will be on display next! Many thanks to Phil Bell (a former Currie Lab student and now at the University of New England in Australia) for inviting me to help out with this paper.



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.

Horner JR. 2014. Paleontology: a cock's comb on a duck-billed dinosaur. Current Biology 24.

And for those who are extra keen, here's my Quirks & Quarks radio interview from January 2014.