Junk in the Trunk Redux

Today I’ve got another interview from Scott Persons! Scott’s going to tell us all about his new paper on the tail of Carnotaurus, which follows his paper on the tail of Tyrannosaurus published last year. Enjoy!
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You can pick your friends, and you can pick your nose…and you can definitely pick your ankylosaur’s nose.

Say hello to Euoplocephalus, the best known ankylosaur you’ve never heard of. Besides Pinacosaurus from Mongolia and China, there are more specimens referred to Euoplocephalus than to any other ankylosaurid, and it is certainly the most well represented ankylosaurid from North America. Yet Euoplocephalus often gets overlooked because its younger cousin is THAT ankylosaur, the one that starred at the World’s Fair and was in Jurassic Park III and Clash of the Dinosaurs and Dinosaur Revolution and gets all the cool toys and, you know, is the namesake of the group. You know, Ankylosaurus. Well, hopefully you’ll be hearing more from me about Euoplocephalus over the coming months. Today we’ll be picking its nose. Continue reading

Ankylosaur tail pathologies.

My most recent paper with my coauthor and supervisor Phil Currie appeared online at Historical Biology this week. It is the last of the chapters from my MSc on ankylosaur tail club biomechanics (although I am still working on ankylosaurs, the focus is now on the phylogenetic relationships within the ankylosaurids and their biogeography). However, it contains very little about the biomechanics of tail clubs…

Most of my MSc thesis used a lot of math and fancy-dancy computer modeling to look at whether it is biologically feasible for ankylosaurids to have used their tail clubs for forceful impacts (and therefore as offensive or defensive weapons). But another way to look for evidence of behaviour is to look for injuries, which can sometimes, if you’re lucky, give you clues about some of the more dramatic moments in an animal’s life. So as I was looking at specimens for my MSc (and into my PhD), I always kept an eye open for anything unusual or abnormal that could be a pathology. Continue reading

Congratulations Phil Bell!

Some congratulations are in order for my fellow grad student Phil Bell, who successfully defended his PhD thesis today!

Phil’s thesis is titled “Systematics and palaeobiology of the crested hadrosaurine Saurolophus, from Canada and Mongolia.” He’s been working for the Philip J. Currie Dinosaur Museum (previously the River of Death and Discovery Dinosaur Museum) since last fall.

You can read more about his work on Saurolophus in these papers; I’m sure there will be several more to come:

Bell PR, Evans DC. 2010. Revision of the status of Saurolophus (Hadrosauridae) from California, USA. Canadian Journal of Earth Sciences 47:1417-1426.

Bell PR. 2011. Redescription of the skull of Saurolophus osborni Brown 1912 (Ornithischia: Hadrosauridae). Cretaceous Research 32:30-44.

Bell PR. In press. Cranial osteology and ontogeny of Saurolophus angustirostris from the Late Cretaceous of Mongolia with comments on Saurolophus osborni from Canada. Acta Palaeontologica Polonica.

I like ankylosaur butts, and I cannot lie.

Yes, I seem to have this recurring fascination for the derrière of these dinosaurs. In 2009 I published a paper (with my fellow grad students Mike Burns and Robin Sissons) on Dyoplosaurus, in which we argued that the pelvis (specifically, the sacral ribs) is different than that of Euoplocephalus. I reconstructed the muscles of the tail and pelvis in my 2009 PLoS ONE paper on tail clubbing. Twice now I have spent significant portions of my summer preparing the pelvis of two different ankylosaur specimens. And now this month I have another paper (again with Mike Burns and my supervisor Phil Currie) on the ankylosaur pelvis, this time on the armour of the pelvic region.

The lovely behind of Aletopelta, from my visit to the San Diego Natural History Museum in 2009. It is an excellent museum, you should check it out!

It has been recognized for a long time now that some ankylosaurs were doing really weird things with the armour over their pelvis. In some taxa, the osteoderms fuse together to form a carapace-like shield over the hips. Previously, the presence or absence of this shield has been used in phylogenetic analyses to examine whether or not a third group of ankylosaurs, the Polacanthidae, is a valid taxon (in addition to the Nodosauridae and Ankylosauridae). However, it is not just the presence or absence of the pelvic shield, but the way that the pelvic shield is constructed, that may be important.

In this paper I and my coauthors propose a revised way of looking at the pelvic shield that breaks shields up into three categories: 1. fused, rosette pattern, 2. fused, uniform-sized polygons, and 3. not fused. “But Victoria, if the osteoderms aren’t fused, then why call it a pelvic shield?” you may ask. Well, after looking at the AMNH’s Sauropelta and the BMNH’s Euoplocephalus, I noticed that although the osteoderms of the pelvis weren’t coossified, there also weren’t any transverse bands segmenting the body in that region (see image below of BMNH R5161, the holotype of Scolosaurus discussed in this post). Although the osteoderms aren’t fused together, they still form a continuous shield over the pelvis.

The always exciting headless, clubless, BMNH R5161, modified from Nopsca’s 1928 paper and as seen in Arbour et al. 2011.

More interesting, though, is what happens when we look at the other two categories – rosettes vs. uniform polygons – in a stratigraphic and geographic context. Rosettes are restricted to the Jurassic and Lower Cretaceous, whereas uniform polygons are primarily Upper Cretaceous. Uniform polygon shields are only found in North America (with the possible exception of Antarctopelta…which is from Antarctica). We did not run a phylogenetic analysis for this paper, but I plan to incorporate this data into subsequent analyses stemming from my PhD thesis on the phylogenetic relationships and biogeography of the Ankylosauridae. I will be very interested to see if any clades show up that reflect these stratigraphic and geographic patterns.

Here’s the paper! (behind a paywall, unfortunately…):

Arbour VM, Burns ME, Currie PJ. 2011. A review of pelvic shield morphology in ankylosaurs (Dinosauria: Ornithischia). Journal of Paleontology 85:298-302.

More papers about ankylosaur pelves!

Arbour VM, Burns ME, Sissons RL. 2009. A redescription of the ankylosaurid dinosaur Dyoplosaurus acutosquameus Parks, 1924 (Ornithischia: Ankylosauria) and a revision of the genus. Journal of Vertebrate Paleontology 29:1117–1135.

Arbour VM. 2009. Estimating impact forces of tail club strikes by ankylosaurid dinosaurs. PLoS ONE 4: e6738.

Ankylosaurus through the Ages

I saw a post up at Love in the Time of Chasmosaurs today – did you know Ankylosaurus could fly? The original Sinclair World’s Fair Ankylosaurus was being lifted by crane from the Houston Museum of Natural History as the museum undergoes expansion and renovations.

This got me thinking about a talk I gave for the Alberta Palaeontological Society annual meeting last March: “My ankylosaur is a big dumb tank! Ankylosaur reconstructions in the scientific literature and popular media.” I talked about why ankylosaurs are reconstructed in certain ways, both accurate and inaccurate. Darren Naish at Tetrapod Zoology has been talking about memes in palaeontological illustration, and how certain wacky reconstructions and poses pop up again and again. I think this is perhaps especially well illustrated by several ankylosaur taxa and today I’d like to talk about Ankylosaurus.

Brown 1908. The Ankylosauridae, a new family of armored dinosaurs from the upper Cretaceous. AMNH Bulletin 24:187-201. Continue reading

Ice to Meet You

Several weeks ago, I talked about the Antarctic dinosaur Cryolophosaurus. As Phil and Eva’s Antarctic adventure winds down, I thought it was high time to write a little bit about another Antarctic dinosaur, Glacialisaurus.

This is not Glacialisaurus, but it is still awesome. Ice sculpture competitions like Ice on Whyte are one of the winter benefits of living in the frozen tundra of Edmonton. And this year, there were several teams from China participating! Continue reading