Archive for May, 2012

The Horniman Museum aquarium

I spent yesterday catching up with my old friend and colleague Paolo Viscardi (known to fans of mystery biological objects as Zygoma). He’s a curator at the Horniman Museum, a small site in southeast London and one of those old style museums split between three major collections -  archaeological artefacts, musical instruments and natural history. While the latter part is well worth talking about and I have a number of posts lined up on various parts (including some very retro dinosaurs) there is also a small, but well stocked, aquarium attached. Some important breeding programs go on behind the scenes including work on various corals, seahorses and recently some cuttlefish too. It’s been a while since I’ve managed to cram a decent number of living species into these pages, so here, have some fish (and a lobster).

Oh, and a frog.

 

Academics on Archosaurs: Mike Habib

Michael Habib, University of Southern California
I primarily study the biomechanics of flying vertebrates, especially early birds and pterosaurs.

1. What first got you interested or involved in your research field?

I’m a classic – I declared loudly that I wanted to be a paleontologist at about the age of four.  The most important catalyst was probably the trips I took with my family to the National Museum of Natural History, in Washington, DC (I grew up in that region).

Perhaps a more interesting story is how I ended up in my particular speciality.  While I am really a rather general biomechanist, I think most Musings readers will know me as a pterosaur worker.  I’m quite pleased by that label, but it came as something of a lucky break – I really got rolling on pterosaurs after attending the 2007 Flugsaurier Conference in Munich, which I originally attended on something of a whim because I’d been playing with a few pterosaur bits at the USNM collections in between bird work. That was a real full circle moment because I’d loved pterosaurs as a kid.  Of course, as Musings folks will no doubt recall, Dave organized that conference!  Thanks Dave, it rocked.

2. What is your favourite piece of research?
Okay, no surprise here – I’m most pleased by the quadrupedal launch model for pterosaurs I proposed in 2008.  I think that has actually had a measurable impact on how we reconstruct pterosaurs, and it also seems to have affected how other scientists think about animal takeoff and flight evolution.  So that’s pretty darn cool.

To be fair, though, a paper I’m currently writing may end up being one of my all time favorites (it’s the much discussed anurognathid study with Mark Witton.  I know, I’ve been talking about it forever, but we keep adding stuff – this is going to be a wicked paper).

3. What do you think is the most interesting or important discovery in your field in recent years?
This is a much more difficult question for me.  For one thing, I’m not sure what my “field” really is.  If we assume it’s animal flight evolution, then I would have to list the discovery that functional wings existed in theropods outside Aves (which either means theropod flight should up more than once, or that theropod flight came before birds).  If we assume I’m a “pterosaur guy” then I suppose it would be the range of new soft tissue discoveries that have rapidly accrued, in part because of the outstanding UV imaging studies of individuals like Helmut Tischlinger.

4. What do you think is the biggest unanswered question in your field right now?

Within animal flight overall, the largest questions relate to the origin of flight in pterosaurs and bats.  While debate will range on about the details of the origin of avian flight, we have the base layer pretty well worked out now.  However, the early stages of flight in pterosaurs and bats are darn near completely unknown at this stage.  I’m waiting for some really excellent stem-pterosaurs to be discovered.

5. What advice would you give to students about research?
Remember that you are a professional writer.  You have to do good science to have things worthy of writing about, but at the end of the day, every academic scientist (and that’s practically every professional paleontologist) is basically a professional writer.  Own that fact, and live up to it.  Work hard to write well, and think carefully about your readership and how to reach the people you want to read your work.

No living relatives?

A week or two ago a short article appeared in The Times about the red panda. In it, the bold and quite ludicrous statement was made that the red panda is “not related to any other animal”. That would be news to anyone with any background in biology, but this kind of simple, yet gross, error is still commonplace.

I’m sure they simply meant that it had no close living relatives (which itself is debatable, since, well it’s not really in the same bracket of uniqueness as say an aardvark or platypus). However, the implication is that the red panda stands unique with no ancestry at all. While admittedly the use of ‘living’ hints at fossil pandas, it is being marked out as distinct and separate. It’s a fundamental implication of evolution that all species are ultimately, at some level, related and to suggest otherwise is clearly a nonsense.

Now I doubt too many creationists even spotted this, let alone made use of it, but it certainly doesn’t help trying to reach the public and pass on good science. But it’s the kind of error that can easily confuse people who don’t know better. It certainly sounds plausible and authoritative, and that’s just the kind of thing that people tend to accept, or if question, assume that it’s probably correct. It’s also the kind of basic error that’s so wrong, you wonder quite who wrote it, or just how limited their knowledge of biology must be.

OK, it’s not the first or last error of it’s kind and not even the most egregious. But really, it’s still pretty dreadful.

Academics on Archosaurs: Greg Erickson

Dr Gregory M. Erickson, Florida State University
Specialist in dinosaur paleobiology

1. What first got you interested or involved in your research field?
I liked dinosaurs when I was a kid but found other interests by the time I hit middle school. I was originally an engineering major and then a wildlife management major (my father was a large game biologist) at the University of Washington. I wasn’t sure what I wanted to do. During the summers I was a construction worker and was considering that for a career. My roomate was a geology major, and I realized that just by taking a few courses I could graduate and move on. I took a dinosaur class from John Rensberger. The course was inspired by Bob Bakker’s Dinosaur Heresies. John invited me on a dig. He encouraged me to consider a career in vert paleo. It was then that I realized my background in biology and engineering could provide for new insights in vert paleo. After a year or so of working in the miserable Seattle rain, I decided that I had had enough and decided to take the GRE and go to grad school. I was accepted into Jack Horner’s program. The rest is history.

2. What is your favourite piece of research?
I am most proud of the work I have done on dinosaur dentitions

3. What do you think is the most interesting or important discovery in your field in recent years?
The rediscovery that birds are dinosaurs.

4. What do you think is the biggest unanswered question in your field right now?
Hard to say. I think that if we could readily determine the sex of dinosaurs that it would have huge ramifications for our understanding of dinosaur paleobiology

5. What advice would you give to students about research?
Writing skills are critical for survivorship as a professional paleontologist. The pen is mightier than the pick.

The gliding Stegosaurus

Those in dinosaur research might well be aware of a joke SVP abstract a few years back that claimed Stegosaurus was a cursorial biped. That however has nothing on this report from 1920 that describes this substantial animal was a glider, using its plates for wing. As far as I can tell it’s quite genuine. It’s also awesome. Go read.

My hat is tipped in the direction of John Hutchinson and Jeff Martz for this.

Academics on archosaurs: You Hai-lu

Dr Hai-lu You, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences
Specialist in dinosaurs, especially Cretaceous ornithischian dinosaurs.

1. What first got you interested or involved in your research field?

By chance. I applied my Master degree for paleoanthropology, but was suggested to switch to dinosaurs.


2. What is your favourite piece of research?

My favorite piece of research is on the re-discovery and research on Gansus, an Early Cretaceous bird from northwestern China that at the beginning of the branch leading to modern birds. Before our research, only a partial foot was discovered, and our team now excavated ~100 specimens. Our result was published in Science, and the various medias reported it, including a documentary by Science Channel.

3. What do you think is the most interesting or important discovery in your field in recent years?

“Proto-feathers” from China , which changed our view on the concept of birds, and the evolution of the function of feathers.

4. What do you think is the biggest unanswered question in your field right now?

The using of PhyloCode, which will have fundamental influence on our view of the tree of life.

5. What advice would you give to students about research?
Go through everything on dinosaurs, from the field to preparation to research to museum activities.

Deinonychus at the AMNH

Since the theropods are doing well this week, it’s time to wheel out another image kindly sent in by Steve Cohen. I suspect there’s a nice mount of Deinonychus in a great many museums in North America, but for all my traveling, I’ve only ever seen two of them (part shown here) and didn’t have time to study either in any detail. Here though is an excellent and indeed famous mount in the AMNH of this dinosaur and it would probably be even more impressive if Steve hadn’t sent this to Heinrich Mallison as well and he’d not put it up a couple of weeks back….

Suchomimus

Yesterday I spotted a nice picture of a mount of Suchomimus on Twitter posted up by artist Brett Booth. On asking he was kind enough to provide me with the full set of things he’d taken and gave me permission to post them up. Years ago I got a chance to see a cast of the manus of this animal, but at the time I didn’t know much about dinosaurs and ironically the one other theropod I’d seen much of was Baryonyx, so the interesting robustness of these things rather passed me by.

Spinosaurs are popular and have done well in the last couple of years. In addition to Oxalaia last year we also have recent had Icthyovenator and Ostafrikasaurus and that’s before we mention the most important spinosaurid find of recent years (according to me) – half a tooth. However, while the ranks of the spinosaurs has been growing, Suchomimus remains the the most complete spinosaur known to date with most of the skeleton having been recovered compared to the masses of vertebrae, snouts and teeth that characterise rather too many of them. Only Baryonyx really comes close in terms of completeness, that that does at least have the advantage of having a good full description of the material.

Still, Brett’s photos help there as there are some nice ones. This looks to me like a good cast of the holotype material and there’s a bonus at the end of what looks like an original arm next to a human and T. rex for comparison. I actually forgot to ask Brett if he knew what the status of the mount was, or for that matter where this is being exhibited, but I’m delighted to be able to put it up here.

Late edit: Brett tried to add a comment but if having troubles. He sent me this in an e-mail that answers a few of my comments and queries:

This was at Lynx Exhibits in El Paso Texas, part of that traveling Supercroc exhibit. I believe it leaves after this weekend. It was on some sort of rig that would move if you pulled a few levers. Totally worth the trip!

The arm is original except for the metacarpals and first claw (the parts in blue.)

What didn’t come out was all the pitting and lines on the spine, very much like a stegosaurus plate. And there was some damage or warping to the pubis.

I have to say this was a HUGE animal. I was far more impressed with the size of this than I was when I saw Sue. I hit the knee and I’m 6’3″. Really impressive.

Academics on archosaurs: Heinrich Mallison

Heinrich Mallison, Researcher, Museum für Naturkunde – Leibniz Institute for Research on Evolution and Biodiversity at the Humboldt University Berlin.
I’m a geologist/palaeontologist trying hard to use digital techniques to unlock the remaining secrets of dinosaur locomotion.

1. What first got you interested or involved in your research field?

I guess – but given my age of roughly 6 years back then it’s kinda hard to tell – I guess it was a dinosaur book my Dad bought me in the Stuttgart Zoo’s shop (no idea why a dinosaur book).


2. What is your favourite piece of research?

The speedwalking dinosaur hypothesis I still need to publish.

3. What do you think is the most interesting or important discovery in your field in recent years?

That basal dinosaurs, and even basal dinosauromorphs, were so much more bird-like [and, by convergence, mammal-like]  with regards to lungs, metabolism, bone growth, etc. then previously imagined. Suddenly, many questions resolve themselves into a fitting picture, and many supposed/questionable convergences default into shared inheritance!

4. What do you think is the biggest unanswered question in your field right now?

Funding – when will politicians understand that basic research is more important than a short-time blip in the GNP?

5. What advice would you give to students about research?

Palaeontology is a true multidisciplinary science. Therefore, it does not matter what you study officially (geology, palaeontology, zoology, botany, climate research, physics, veterinary of human medicine, engineering, etc.) – you have to do them all anyway! Find a subject what can feed you if there is no research funding for dinosaurs.

Guest Post: A phylogeny of ankylosaurian dinosaurs

At least a few parts of the dinosaurian family tree are still relatively little studied and are controversial. One of these is the ankylosaurian dinosaurs, though a new paper seeks to delve into this problem and produced a new and comprehensive analysis. Lead author Rick Thompson takes us through it:

In 1842 Richard Owen coined the term “dinosaur”, helping to imbue the world with a fascination for the gigantic ‘terrible lizards’ of the prehistoric world. Owen’s work was based on the fossil remains of three distinct archosaurs; Megalosaurus and Iguanadon have become fixed in our consciousness as archetypal dinosaurs, while the third, Hylaeosaurus, is very much the ‘ugly-duckling’ of the trio. Hylaeosaurus is a member of the Ankylosauria, a group of Middle Jurassic to the Late Cretaceous heavily armoured herbivorous dinosaurs, closely related to the stegosaurs in the clade Thyreophora. The story of Hylaeosaurus somewhat mirrors that of its ankylosaur relatives; fragmentary, difficult to study and lacking the popularity of its theropod, ornithopod and sauropod cousins. The ankylosaurs barely even worked their way into Jurassic Park (apparently Ankylosaurus does appear in Jurassic Park III – if you can stand it…)! The lasting image of the Ankylosauria in the public consciousness is the classic battle between Ankylosaurus and Tyrannosaurus, with the ankylosaur determinedly swinging its tail club towards the leg of its powerful foe. Indeed, it is the presence of the tail club, widely regarded as a defensive weapon that could shatter bone (Arbour et al. 2009), which has helped to raise the profile of this fascinating dinosaur group.

Of course ankylosaurs are more than just a dinosaur with a weaponized tail. The Ankylosauria includes over 50 valid taxa, only a fraction of which possess this idiosyncratic armament. Fragmentary ankylosaur specimens have been recovered from every continent on Earth, though their record in North America and Asia is by far the best. It is their extensive covering of dermal armour, particularly that of the skull, that has proved to be both the blessing and bane of ankylosaur palaeontology. The high level of morphological diversity in the armour is probably responsible for the large number of ankylosaur taxa. The cranial ossifications completely cover the bony sutures of the skull, simultaneously providing a unique pattern to identify new species, while destroying a wealth of cranial characters that could help to resolve the interrelationships of the wider clade. Thus the evolution of the Ankylosauria is very poorly understood, and presents a tough challenge for systematic palaeontologists.

Traditionally the Ankylosauria is split into two families, the Ankylosauridae and Nodosauridae. The Ankylosauridae includes many of the more recognisable taxa including Ankylosaurus and Euoplocephalus. Ankylosaurids are generally identified by their short-broad skulls, which are ornamented with horn-like ossifications above (supraorbital), behind (squamosal) and below (quadratojugal) the eye, along with the presence of a tail club. The Nodosauridae generally have a more elongate skull, with a domed skull roof (parietal region) and boss-like rather than horn-like cranial ossifications. Their trunk armour often incorporates spike-like ossifications along their flanks, though no tail club is present. In recent years, a number of ankylosaurs, such Gastonia and the aptly named Gargoyleosaurus, have been found to possess combinations of these classic traits, thus blurring the distinction between ankylosaurids and nodosaurids. This has led some authors to erect a new group of ankylosaurs, the Polacanthidae, which includes many of these recent discoveries, along with a few older, fragmentary genera like Owen’s Hylaeosaurus.

 

A mounted skeleton of Gastonia burgei. Note the large shield over the pelvis, a character suggested to unite polacanthid taxa. Photo by Susie Maidment.

The validity of the polacanthid hypothesis has proved hard to test cladistically, as the majority of ankylosaur character sets are either heavily biased towards the skull, or include a limited number of taxa. As many of the potential polacanthid taxa are fragmentary, or predominantly postcranial, the incorporation of these taxa into ankylosaur phylogeny has been problematic. Studies including some polacanthid genera place them either towards the root of the Ankylosauridae, or as a new family (Polacanthidae), sister to the Ankylosauridae. During my Master’s Degree in Biosystematics at Imperial College, London, I was lucky enough to get the opportunity to try to resolve some of these issues in ankylosaur evolution. Paul Barrett and Susie Maidment offered me the chance to revise and update the unpublished PhD thesis of Jolyon Parish on ankylosaur phylogeny. My aim was to expand the taxon sample of Parish’s thesis, as well as modify his extensive character set. In this way I hoped to produce a ‘palaeontological total evidence’ phylogeny of the Ankylosauria, which included all valid taxa regardless of completeness, and a roughly even mix of cranial and postcranial characters.

The results of this project were recently published in the Journal of Systematic Palaeontology, and give some new insights into ankylosaur evolution. Encouragingly our data did support the traditional split between the nodosaurids and ankylosaurids; however, no polacanthid clade was recovered. Instead, all taxa that have been affiliated with the Polacanthidae by various authors (and Ankylosauridae by others) were resolved within the Nodosauridae. In the strict consensus tree (the tree which summarizes all of the information that each of the shortest possible evolutionary trees agree upon) the nodosaurid clade formed a polytomy – that is, we could say nothing about the internal relationships of the group. This poor resolution of the clade was in fact caused by a number of unstable taxa, whose position on the tree is highly variable. Unsurprisingly three of these unstable taxa have previously been attributed to the Polacanthidae. To counteract their influence we produced a derivative strict reduced consensus tree (shown in the figure). This tree prunes unstable taxa from the strict consensus tree, greatly increasing resolution. In this phylogeny it is clear that the ‘polacanthid’ taxa form a basal grade of nodosaurid dinosaurs, while the traditional nodosaurids (clade D) form a polytomy.

This result simultaneously highlights the strengths and weaknesses of the ‘palaeontological total evidence’ approach. By including all taxa (regardless of completeness) and a character set sampled from the whole skeleton, a large amount of missing data was guaranteed. This lowers the resolution of the tree, as seen in the traditional nodosaurid clade. However, it is the inclusion of such a broad sample of characters and taxa that has allowed completely new relationships to be revealed, placing ‘polacanthid’ taxa in the Nodosauridae. The problems have been further confounded by the extensive cranial ossification of the taxa. The variation in such complex ornamentation is exceptionally hard to capture using traditional discrete characters. This makes it very hard to test for presence of the evolutionary signal in the ornamentation. In the future, a study which incorporates extensive measurements of the cranial armour could better capture this variation, and more clearly reveal the relationships of the group. This is particularly important for the Nodosauridae, many of which are primarily distinguished by their cranial ornamentation.

The phylogeny of the Ankylosauridae was much better resolved, and broadly in agreement with existing studies, if the ‘polacanthid’ taxa are discounted. Again in this clade we see that the basal lineages do not conform to the traditional view of the Ankylosauridae, often having elongate skulls. The tip of the tail has not been recovered in many of these taxa, so the presence of a tail club is uncertain. However, our tree is the first cladistic analysis to place an ankylosaur that clearly lacks a tail club within the Ankylosauridae. Zhongyaunsaurus was originally described as a nodosaurid, though this assignment was subsequently corrected by Ken Carpenter (Carpenter et al. 2008). Our phylogeny confirms that Zhongyaunsaurus was indeed an ankylosaurid, and suggests that the most characteristic trait of the Ankylosauria is only present in the most derived ankylosaurids.

Unfortunately our study has done little to help the plight of the earliest known ankylosaur, Hylaeosaurus. Our analysis suggests that it is a member of the Nodosauridae, but its removal from the reduced consensus tree feels like a sad continuation of its rather anonymous history. Never the less, our study has helped to reveal a new perspective on the Ankylosauria. Although the ankylosaurid-nodosaurid dichotomy has been maintained, it appears that the classical characters of these groups only apply to the most derived of their forms. The earliest lineages of each family show greater levels of diversity in their armour and body form. This has made their classification difficult, and without more fossils, or newer forms of character, it is likely to remain so. There is still much work to do in order to understand the evolution of this extraordinary group of animals, but hopefully our study can serve to trigger a new wave of research in the coming years.

 

 

Academics on Archosaurs: David Fastovsky

David E. Fastovsky, University of Rhode Island
Mesozoic, terrestrial vertebrate-bearing paleoenvironments, vertebrate paleontology

1. What first got you interested or involved in your research field?

Roy Chapman Andrews:  All About Dinosaurs (1953).


2. What is your favourite piece of research?

Overall, I loved working on fluxes of vertebrate extinctions at the K/T boundary; I also loved working on some very interesting vertebrate-bearing paleoenvironments in NE Mexico; the rocks were crazy; the fossils were weird; it just doesn’t get better than that!

3. What do you think is the most interesting or important discovery in your field in recent years?

Feathered non-avian dinosaurs; the extinctions at the K/T boundary.

4. What do you think is the biggest unanswered question in your field right now?

We’ve begun to move from individual specimens to ecosystems.  That kind of work should continue; that’s how to really capture the great rhythms of life through time.

5. What advice would you give to students about research?

Be creative.

Guest Post: Yurgovuchia doellingi

Those keeping up with the scientific literature will know that a new dromaeosaur was described just the other day. One of the authors, Jim Kirkland, has been kind enough to pen a few lines about the discovery and has included some nice photos of the excavation too. Enjoy:

@Dave_Hone on Twitter

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