Monday, 24 December 2012

SVP 2012 - And finally . . . . .


 
With Christmas and the New Year upon us, it is time to wrap up my review of this year’s SVP despite the fact that there are so many other interesting topics to look at. So here is a brief look at some other presentations that we may, perhaps, look at in some detail in the future.
Greg Brown, of the University of Nebraska State Museum, is a top preparator and a nice guy to boot and his presentation looking at techniques and tools for the microfossil preparator was completely invaluable for those of us with an interest in preparing such intricate specimens. During the Preparators’ Session Greg presented a comprehensive guide to making things easier that was curtailed in its infancy primarily due to the constriction of the 15 minute time slot.
There was considerable emphasis on the preparator being comfortable at his work station and the need for stability, concentration and that the use of the right equipment is paramount. We touched on briefly about stereo microscopes, light sources and I found the part on the need for a stable work holding jig or vice, such as those ball vices used by engravers, to be particularly useful. The use of different lighting to highlight fossil from matrix was interesting as well and we will be seeing a lot more of this technology used at all levels in the future.
Far too much detail for the time slot and I hope Greg will consider providing all this information as a PowerPoint presentation at some point in the future or maybe even a paper. It really was essential listening for even the most accomplished preparators out there.  
Keeping with microfossils and Patrick Druckenmiller, of the University of Alaska Museum, and colleagues have been analysing dinosaur diversity in the Maastrichtian Prince Creek Formation of Northern Alaska. Despite being familiar with the fauna of this formation for some time now, the authors wanted to get a more comprehensive faunal make up which would enable more rigorous hypotheses about how these animals may have survived or perhaps even migrated during the colder periods. 
So a comprehensive analysis of teeth recovered from microvertebrate beds in the Prince Creek has revealed a much more diverse community than originally thought. Animals similar to the ornithischian Orodromeus, the theropod Richardoestesia as well as possible avialans and crocodilians have added to an already prolific palaeoenvironment. The authors hope these new taxa will enable further temporal comparison with similar fauna to those of formations such as the Horseshoe Canyon Formation in Alberta.
Evidence for predator-prey interaction has long been a favourite interest of mine since fossils that bear puncture, drag and serration scars make these animals come to life and we often find such bones in the Jurassic and Cretaceous. But Susan Drymala, of the University of Maryland, gave us a glimpse of the same interaction between taxa of the Upper Triassic Chinle Formation in the Petrified Forest National Park of Arizona.
An aetosaur osteoderm has been recovered displaying multiple tooth punctures, pits and scoring obviously as a result of feeding activity. To try and identify the possible maker of these marks the author compared the morphologies of the various marks with known carnivores that were contemporaneous with the aetosaur.
Phytosaurs, theropod dinosaurs and non-archosaurian archosauriforms were ruled out which left a raisuchian as the likely candidate and, indeed, the shape, striation density, spacing and curvature all point to an animal such as Postosuchus kirkpatricki as being responsible for the marks. This in itself does not seem all that spectacular but, speaking to Susan, she said that any evidence for species interaction in the Triassic is extremely rare and, as such, the specimen is relatively important.
Bone histology and growth rates have featured heavily in this blog and, again, at this year’s SVP and Carolyn Levitt, of the Natural History Museum of Utah, has been looking at the bones of Kosmoceratops richardsoni and Utahceratops gettyi from the Upper Cretaceous Kaiparowits Formation of southern Utah.
These are amongst the first chasmosaurines to be histologically studied and Levitt ran comparisons, not only with the centrosaurines of Alaska and Alberta, but with basal ceratopsids such as Psittacosaurus and Protoceratops.  This enabled the author to check out the various growth strategies amongst taxa and how their palaeogeographical position may have affected them.
 
Some interesting points were highlighted of which one or two are worth a particular mention. There appears to be clear variation in lines of arrested growth (LAGS) ranging in taxa from the north to the south. Pachyrhinosaurus, a northern taxa, displays as many as 18 LAGS whilst there are only are two evident in the southern taxa such as Kosmoceratops. Centrosaurus, from Alberta, comes out somewhere in between, with around 7 LAGS.
You would expect this variation purely because of the obvious temperature variability from north to south but things are seldom as simple as that. The author highlights the variables that must be considered such as the fact that it was impossible to sample the same taxa over a wide range since most taxa appear restricted to their immediate endemic environment. This means that each taxon displays its own individual histological signal.
Temporal variation is another consideration but perhaps the biggest factor is the apparent amount of variation in the climate of Laramidia. As I have hypothesised in the past, Laramidia was likely composed of many pocket environments where the climate varied considerably and this would account for the variation in ontogenetic growth, rapidity and duration of growth. So this expected variation in latitudinal ceratopsids seems to be a genuine artefact and is further endorsed by similar histological evidence found in the hadrosaurid Edmontosaurus.
In Brief
A little closer to home now and Jeff Liston, of the National Museums Scotland (but now in China for a year I believe), has been looking at the growth, age and size of the pachychormid fish Leedsichthys problematicus. Some early estimates suggested sizes of up to 100 feet for this plankton feeder but we knew long ago that this was a clear overestimate. So how do you size up what is still a very large fish?
Well you gather up the five most complete available specimens, select those elements which provide the most consistency when trying to determine absolute size – in this case postcranial elements, section them and count the annuli to arrive at a best guestimate for age determination. The sizes of the specimens range from 8 to 16.5 metres and, when crossed referenced with the annuli counts, found the results compared favourably displaying rank by size and the specimens were found to be between 21 and 45 years of age.
Despite suffering from a lack of specimens (the bane of palaeontologists worldwide) Liston’s work provides a framework for further research and demonstrates that there is age and growth consistency within Leedsichthys and that this is entirely comparable with the big extant filter feeding chondrichthyans of today.
Jordan Mallon’s continuing work looking into the mega-herbivores of Dinosaur Provincial Park continues and looks at how so many different large taxa managed to co-habit with what would appear to be limited resources in the amazing continent of Laramidia.  We have mentioned this dichotomy many times in this blog and I have already mentioned about the possibility of multiple pocket environments within the continent each harbouring its own ecosystem featuring multiple taxa that are unique to that biosphere.
Mallon, of the University of Alberta, has been studying the possibility of dietary niche partitioning as a possible explanation to explain this conundrum and looked at feeding height, skull, beak and tooth morphology as well as jaw mechanics and dietary wear. Within each faunal composition the author was looking for comparisons (or lack of) which may indicate niche partitioning.
The results are encouraging and there is evidence that sympatric taxa, even those that are extremely closely related, do indeed exhibit tendencies that indicate dietary preference and speciality. The author quantifies this by highlighting the fact that it is likely that the large mega-herbivores of Laramidia were probably influenced to specialise because of direct competition from each other although whether these pressures were due to long term competition or driven by geographic separation remains unclear.
Apart from the usual presentations and posters there were other interesting projects on show and one that I am a huge admirer of is the Smithsonian’s attempt to gather the world’s field books together in a kind of super databank. The Field Book Project has been instigated to collect, integrate and digitise field books from around the world and make these unique sources of information available to academics and students worldwide.
Once the Field Book Registry has been created it will be made available to scientists of all capabilities and persuasions and will be a unique source of data to all. Field books have long been hidden from view and it is hoped that they will inspire further generations of aspiring palaeontologists. Keep a look out for this one as it develops – there is already a blog and website – and I cannot commend this project enough.
And, lastly, for this year’s SVP reports, comes the strange case of the pterosaur Scaphognathus crassirostris – did you know that these pterosaurs survived into the seventeenth century? No – nor did I but, according to some Young-Earth Creationists (YEC) they did and they have attempted to promote this strange theory in an attempt to discredit evolution.
But thankfully we have people around such as Pondanesa Wilkins and Phil Senter, both of Fayetteville State University, as our champions, ready to pour hot water on this puerile garbage. And yet, as the authors’ state, it is important to discredit such literature in an a constructive way that the true evidence cannot, and must not be denied.
According to the YEC, a skeleton of S. Crassirostris turned up in seventeenth century Italy that had apparently only recently been killed in the marshes near Rome. An anatomical drawing of the specimen was made and the YEC identified the specimen as S. crassirostris due its crest and long tail. However, when the authors checked out the specimen they found that, not only is it unlike S. crassirostris, but is actually unlike any known pterosaur whatsovever. In fact the “specimen” is actually a composite made up of dogs, bear and an eel tail – I kid you not. Even the skin has been faked and carefully manipulated to cover the joints where the bones articulate – or not as in this case. The wings are also, naturally enough, faked and do not even resemble those of pterosaurs.
So, thanks to the authors, this particular anti-evolutionary “evidence” can be completely and utterly refuted due to a combination of detective work and palaeontological and osteological research. Well done to Messrs Wilkins and Senter!
Er...this is what a pterosaur really looks like!
 
And Finally 
Well this wraps up my SVP reports for this year. It seems to have taken a long time to get through these reports since October and that is because it has. I have been very busy with different things over the last few months and have not blogged as regularly as I would have liked. I think it safe to say that I am going through a transitional stage just now and it really has taken up a lot of my time.
However, be that as it may, things are slowly coming back under control and I hope to blog a bit more frequently in the New Year. 2013 will also be busy – but I hope for all the right reasons and I have to admit to being VERY excited and, perhaps, a little nervous about a research project that I and a few colleagues started back in the winter of 2011 and that is slowly coming together right now.
More of this in time but until then, and to those of you who celebrate it, can I wish you all a very happy Christmas and hope you enjoy all the fun of the season. See you all soon!
References
Brown, G.W. 2012. Techniques and materials for microfossil preparation: maximizing success and minimizing stress. Journal of Vertebrate Paleontology, SVP Program and Abstracts Book, 2012, pp69.
Druckenmiller, P.S., Erickson, G.M., Brinkman, D.B. & Brown, C.M. 2012. Dinosaur diversity in the Arctic: new records of polar dinosaurs based on microvertebrate analysis from the Upper Cretaceous Prince Creek Formation, Northern Alaska.  Journal of Vertebrate Paleontology, SVP Program and Abstracts Book, 2012, pp88.
Drymala, S. & Bader, K. 2012. Assessing predator-prey interactions through the identification of bite marks on an aetosaur (Pseudosuchia) osteoderm from the Upper Triassic (Norian) Chinle Formation in Petrified Forest National Park (Arizona, USA). Journal of Vertebrate Paleontology, SVP Program and Abstracts Book, 2012, pp89.
Levitt, C.G. 2012. Variation in ceratopsian histology and growth: new data from southern Laramidia and implications for paleoenvironmental differences. Journal of Vertebrate Paleontology, SVP Program and Abstracts Book, 2012, pp127.
Liston, J. 2012. Growth, age and size of Leedsichthys, the largest bony fish. Journal of Vertebrate Paleontology, SVP Program and Abstracts Book, 2012, pp128.
Mallon, J.C. 2012. Dietary niche partitioning as a means for the coexistence of megaherbivorous dinosaurs from the Dinosaur Park Formation (Upper Campanian) of Alberta, Canada.  Journal of Vertebrate Paleontology, SVP Program and Abstracts Book, 2012, pp134.
Nakasone, S. & Pyenson, N.D. 2012. The Field Book Project: connecting field books with the world. Journal of Vertebrate Paleontology, SVP Program and Abstracts Book, 2012, pp148.
Wilkins, P. & Senter, P. 2012. A paleontological and neontological investigation of the claim that the pterosaur Scaphognathus crassirostris survived into the seventeenth century. Journal of Vertebrate Paleontology, SVP Program and Abstracts Book, 2012, pp193.

1 comments:

Anonymous said...

Hello sir, is now the pdf of SVP available?
If so, could you kindly send me a copy, please? Id be very grateful to you

http://www.tandfonline.com/doi/abs/10.1080/02724634.2012.10635175

Fabrizio

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