Wednesday, 24 October 2012

SVP 2012 - A Great Conference!


So the annual SVP (Society of Vertebrate Paleontology) meeting is over for another year – and what an excellent meeting it has turned out to be. Every meeting has its plus and minus points but I don’t think I know of a meeting in recent times which has met with such universal acclaim. And it appears that I am far from being alone since everybody I have spoken to about it has agreed. Indeed, there has not been one dissenting voice – not that I am aware of anyway.
I arrived in Raleigh a little later than intended and unfortunately missed out on the previously mentioned Witmer talk, “Fleshing Out the Past…..in 3D!” but this was generally well received by those that attended and, I am told, enjoyed by the general public which is always important for the science of palaeontology.
However, I did attend more or less all of the important events over the following four days. And these really were full days since no sooner had you finished one day then you were getting up bright and early to start the next one. I was staying at one of the SVP affiliate hotels, the Clarion, a brisk fifteen minute walk to the Raleigh Convention Center which was connected to the Marriott City Center hotel – the base for much of the SVP membership.
 
The Raleigh Convention Center
 
The overall set up was impressive. There were plenty of signs to direct you to where you needed to go and once around the circuit was all you needed to familiarise yourself with the layout. The bottom floor was the hub of all operations. Here could be found the registration desk, various SVP related tables and a superb display from the different exhibitors which included the Black Hills Institute who had a magnificent cast of Gorgosaurus libratus on display, Triebold Paleontology, who were displaying a superb skull cast of the pliosaur Megalocephalosaurus and Research Casting International, who were displaying a wonderful cast of juvenile tyrannosaurid Jane (BMRP2002.4.1). Both the pliosaur and tyrannosaurid skulls were kindly donated toward the SVP Annual Benefit & Social Auction.
The display from Paleotools and the SVP Preparator’s table were right next to each other which was excellent for us preparators that were in attendance. At the back of the hall were the poster boards and these were large and plentiful. There was a reasonable amount of standing room in between the posters and the poster sessions were always lively and enjoyable affairs. A conveniently placed seating area was located at the front of the hall which was always popular and seldom empty.
Three stories up were the three session halls – ballrooms A, B and C. In reality these were one massive hall but the partitions were so effective and virtually soundproof that you would not know it – only the sound of applause would filter through to you as a technical talk ended. There were the usual minor issues with the visual display aids not always working fluidly and sometimes breaking up an author’s talk as they struggled to change frame or get a video to run but these did not take anything away from the talks at all. There were plenty of seats for all and these were fairly comfortable and set out well.
 
Check out the Acrocanthosaurus in the window!
 
Special events included the welcome reception held at the North Carolina Museum of Natural Sciences. This was extremely well attended and we were well looked after. The museum is a superb example of how a modern museum should be set out with lots of state-of-the-art interactive displays designed to engage the visiting public of all ages. I found the preparation laboratory set up of particular interest and spent quite a while examining the skull of Acrocanthosaurus atokensis of which I was one of many.
The SVP live and silent auctions took place on the Friday night and were again well attended. The auctions were held in ballroom B and there was plenty of room for all except in the scrimmage to get final bids in during the silent auction! This year’s fancy dress theme for the auctioneers was the Avengers and they all looked splendid in their costumes and they ran the live auction with huge enthusiasm and took part in some great interaction with the audience.
 
Brent Breithaupt in his element!
 
Particular highlights included Andy Farke’s winning bid for a snazzy Holtz-inspired dinosaur waistcoat (which does actually suit you Andy!), Larry Witmer’s superb tussle with Phil Currie for the cast skull of juvenile tyrannosaurid Jane and a wonderfully entertaining bidding war between veterans Brent Breithaupt and David Varricchio. Phil Currie did gain some compensation by outbidding me for a cast of a T.rex arm – I was a little miffed since Phil has loads of tyrannosaurs at his disposal! But it was all for a good cause so well done Phil!
I gained a little compensation in the silent auction by successfully bidding for a copy of Jack Horner’s Prosaurolophus monograph – a superb paper and really what I was looking for as I enlarge my library dedicated to hadrosaur cranial morphology and also to help with identifying some indeterminate hadrosaur material.  
 
The silent auction on progress
 
The final evening saw the awards banquet and after hours party. No doubt you will have heard and seen many of the reviews and references that have been all over the social media network during the last few days. Suffice to say that the awards banquet was a great occasion and made enjoyable by sharing a table with likes of John Hutchinson, Andy Farke, Stephen Gatesy, Robert Kambic, Peter Falkingham, Ryan Carney, Frank Varriale and Anthony Maltese.
The after hour’s party was great fun and everyone was happy to let their hair down after four days of presentations and functions. Everyone got into the spirit of things and it was a great way to finish the week. I have not included everything that went on during the week but I am sure it all went off well with equal success.
For me, I learnt an awful lot and I was glad to catch up with colleagues whom I had not seen for a while. It was also the opportunity to make new friendships and I have been touched by the amount of time and advice given by various people along the way – so thank you to you all. In particular I am grateful to Jeff Liston, Yasemin Tulu, Hanneke Meijer, Stephen Brusatte, Thomas Carr, Nina Sverdlova, Stu Pond, Mike Triebold and particularly Anthony Maltese who was very generous with his time in both discussion and at a social level – it really was very much appreciated.
So coming up – a multitude of posts regarding some of the content from this year’s conference of which some will have already been mentioned, some that won’t and a selection of goodies somewhere in between. It really has been a great conference and everyone is already looking forward to Los Angeles next year.
Megalocephalosaurus courtesy of Triebold Paleontology
 

Tuesday, 16 October 2012

SVP 2012


When this post is published, I will be half way across the Atlantic on my way to the Society of Vertebrate Paleontology’s annual meeting – this year being held in Raleigh in the state of North Carolina. If I am lucky I should be able to catch Dr. Lawrence Witmer’s public presentation at the North Carolina Museum of Natural Sciences tonight – “Fleshing Out the Past…in 3D!” Looking forward to this one.
As is always the case, with each and every year, this meeting is eagerly awaited and there are many significant and fascinating contributions to see and hear as four packed days of talks and posters get underway tomorrow.
Unusually, theropods, and particularly my tyrannosaurs, get first billing tomorrow and a few of the talks that I am most interested in all happen before ten o’clock in the morning! This is unusual since these talks tend to be toward the end of the meeting and you kind of build yourself up to them normally but there you go – at least it will be different.
In fact the first day is my most frantic day for talks as I will be moving back and forth between the different halls to catch those I am most interested in. On the plus side that means the rest of the week should be a much more chilled affair whereupon I can digest what has been presented on the previous days whilst taking in the new.
I am also really looking forward to meeting so many of my colleagues again and also to meet some for the very first time. The social side of the meeting is just as important since so often the only correspondence you have with your peers is via email or the web and you can learn so much more by actually meeting and talking to people. And my experience at SVP had always been positive and the people have always been kind and courteous.
So there you are – that’s where I’ll be for the next four days. And, of course, my review of the meeting will start shortly after and there is a wealth of material to reveal believe you me. Happy days!

 

Saturday, 13 October 2012

Tyrannosaurid Origins

 
The Bering Land Bridge is often the focus of attention by researchers looking at the origins of specific groups of dinosaurs that inhabited both Asia and North America. These include hadrosaurs, ceratopsids and, of course, tyrannosaurids but the actual processes that led to the varied faunal dispersals during the Cretaceous are poorly understood, complex and sometimes controversial.

It seems likely that during the Early Albian the two continents were still separated and this is supported by the dispersal patterns of both ammonites and belemnites which had cool water preferences suggesting that water from the Arctic was able to penetrate into the Boreal-Pacific basin (Iba & Tanabe 2007).
However, by the early-middle Late Albian, the land bridge has appeared since evidence for cooling water is absent and supplemented at this time by an increase and diversification in plants, such as ferns, cycads and some early conifers (Zakharov et al 2011). These are plants that thrive and require warmer conditions.
At about the same time, circa 100 million years ago, it is worth noting that hadrosaurids appear in the fossil record in both Asia and North America and it seems reasonable to assume that the first faunal exchanges took place at this time. The land bridge remained intact throughout the Cenomanian and the majority of the Turonian before disappearing again in the Coniacian and most of the Santonian before emerging yet again with the onset of the Campanian. There is conflicting evidence whether the land bridge remained in place throughout the Maastrichtian (eg Herman 2007 a, b; Krassilov 1981; Krassilov et al, 1990) although the recent increase and diversity in dinosaur fossils from Alaska suggests that it may have.    
I’ve previously referred to the origins of Tyrannosauridae and briefly discussed the different theories but it is one of those issues that have seemingly limitless permutations. I believe it is safe to say that the general consensus for many years is that Asia provided the likely launch pad for the clade but is it really as simple as that when basal tyrannosauroids are known, not only from Asia, but also from Europe, North America and, perhaps, even Australia (Benson et al 2010).
Asia does seem, on the face of it, to have a number of factors supporting its position as the launch pad for Tyrannosauridae. Certainly, tyrannosaurids in Asia often display primitive characteristics in relation to their American cousins and retain these basal traits throughout. Indeed, as I pointed out during my review of the Alioramus monograph, Tarbosaurus, in particular, displays several primitive characteristics that you would not expect to see in more derived American tyrannosaurines.
And yet, where the original tyrannosaurid ancestor originated from is still a matter of conjecture but there are more clues gradually being uncovered. A poorly preserved tyrannosauroid premaxillary tooth from the Aptian/Albian Cloverly Formation of North America (Zanno &Makovicky 2011) may be indicative of an endemic tyrannosauroid clade because the tooth lacks serrations. This is interesting because premaxillary teeth in all Asian tyrannosauroids predating Xiongguanlong (also Aptian/Albian)  lack serrations.
Since Late Jurassic tyrannosauroids are poorly represented in the fossil record by such animals as Stokesosaurus, and there are no premaxillary teeth known for these Morrison theropods, it is extremely difficult to make comparisons but it does preclude the possibility that characteristic unserrated premaxillary teeth may have originated in North America and spread to Asia via the land bridge.
 But I suggest that premaxillary teeth are not the best providers of morphological evidence when it comes to recognising genera and taxa. Aublysodon is the classic example of this and it is generally recognised that the unserrated premaxillary teeth that were attributed to this “taxon” are actually the juvenile teeth of other tyrannosaurids such as Daspletosaurus.
Of course, this kind of hypothesis poses massive problems – not least the lack of proper specimens.  In fact the whole interfaunal land exchange process suffers due to a combination of taphonomic distortion, poor preservation and simple straight forward sampling bias. Indeed, the fact that faunal exchange took place in the first place was almost certainly responsible for localised extinction and faunal turnover as disease was very likely spread between populations and animals from either continent likely to out compete those less evolved to survive. 
Appalachiosaurus
In addition to the origin of tyrannosaurids in western North America and Asia we also have the interesting, yet similar, situation regarding those on the other side on the Western Interior Seaway – the tyrannosaurs of Appalachia. Effectively cut off from the western radiation of Tyrannosauridae proper, these are represented by such animals as Dryptosaurus aquilunguis and Appalachiosaurus montgomeriensis and represent yet another grey area. The phylogenetic affinities of Appalachiosaurus and Dryptosaurus are still uncertain although it does seem likely that they are phylogentically closer to Tyrannosauridae as opposed to primitive Asian forms such as Xiongguanlong (but see about skull shape later). Appalachiosaurus is the older tyrannosauroid (Mid Campanian) whilst Dryptosaurus, despite its basal affinities, is Mid Maastrichtian.
 
The enigmatic Alectrosaurus

More basal tyrannosauroids are slowly coming to life. Averianov and Sues (2011) report on non-tyrannosaurid tyrannosauroid remains from the Turonian of Uzbekistan – some 10 million years older than Appalachiosaurus. Interestingly, and actually coeval with this new skeletal material, is the somewhat mysterious Alectrosaurus olseni from Mongolia. Despite its fragmentary nature, Alectrosaurus clearly demonstrates tyrannosauroid affinities that are similar to the Appalachian forms.
 
The fly in the ointment (or perhaps the missing cog in the wheel) may very well be the Cedar Mountain tyrannosauroid which is even older (Cenomanian). This animal is represented by a number of isolated incrassate maxillary and dentary teeth (Kirkland et al 1997) and has been used to support faunal interchange between Asia and North America. Without more skeletal remains, however, the Cedar Mountain form remains enigmatic.
The other significant tyrannosauroid of note is Bistahieversor sealeyi from the Upper Campanian of New Mexico but this deep snouted form is very tyrannosaurid-like, albeit more basal, and was obviously part of the diversification and proliferation of Tyrannosauridae throughout Laramidia. It is interesting to note, however, that the Appalachian forms, such as Appalachiosaurus, retained the more primitive shallower snout of Asian tyrannosauroids, such as Dilong, after the Western Interior Seaway inundated the continent (Carr & Williamson 2010).
Thus it appears we may have two distinct clades of tyrannosaurs, Tyrannosauridae in the west and a more basal clade in the east although this hypothesis is unsupportable at the moment – but it is rather intriguing (Brusatte et al 2011).
So for now, at least, it does seem likely that the ancestry for all North American tyrannosaurs is likely to be Asian but that there is still the distinct possibility that an immigrant from North America may have planted the seed. I suspect that since the two continents were connected for a much longer period of time, than was first suspected, that tyrannosaur faunal  interchange took place on a much more frequent basis. Certainly, the biggest radiation within Tyrannosauridae itself was within North America and there is a distinct possibility that different taxa crossed back over the bridge to establish the tyrannosaurid dynasty of Asia including animals such as Alioramus and Tarbosaurus.

References

Averianov, A., Sues, H.-D., Skeletal remains of Tyrannosauroidea (Dinosauria: Theropoda) from the Bissekty Formation (Upper Cretaceous: Turonian) of Uzbekistan, Cretaceous Research (2011), doi: 10.1016/j.cretres.2011.11.009
Benson, R.B.J., P.M. Barrett, T.H. Rich, and P. Vickers-Rich. 2010a. A southern tyrant reptile. Science 327: 1613.
Brusatte, S. L. and Benson, R. B. J. and Norell, M. A. (2011) The Anatomy of Dryptosaurus aquilunguis (Dinosauria: Theropoda) and a Review of its Tyrannosauroid Affinities. American Museum Novitates, 3717. pp. 1-53. ISSN 0003-0082
Carr, Thomas D. and Williamson, Thomas E. (2010) 'Bistahieversor sealeyi, gen. et sp. nov., a new tyrannosauroid from New Mexico and the origin of deep snouts in Tyrannosauroidea', Journal of Vertebrate Paleontology, 30: 1, 1 — 16
Herman, A.B., 2007a. Paleoclimatic effects of Late Cretaceous–Paleocene straits from data on terrestrial biota. In: Baraboshkin, E.Y. (Ed.), Prolivy Severnogo Polushariyav Melu i Paleogene (The Straits of the Northern Hemisphere during Cretaceous and Paleogene). Geologicheskij Fakultet Moskovskogo Gosudarstvennogo Universiteta, Moscow, pp. 119–136 (in Russian).
Herman, A.B., 2007b. Comparative palaeofloristics of Albian through the Early Paleocene of Anadyr-Koryak and Northern Alaska subregions. Paper 3. Comparison of floras and floristic changes at the Cretaceous–Paleogene boundary. Stratigrafiya. Geologicheskaya Korrelyatsiya 15 (5), 74–82 (in Russian).
Iba, Y., Tanabe, K., 2007. Albian ammonite paleobiogeography in the North Pacific. 7th International Symposium: Cephalopods — Present & Past (Sept. 2007), pp. 98–99. Abstract Volume. Sapporo.
Kirkland, J.I., Britt, B., Burge, D.L., Carpenter, K., Cifelli, R., Decourten, F., Eaton, J., Hasiotis, S. and Lawton, T., 1997, Lower to Middle Cretaceous dinosaur faunas of the central Colorado plateau: a key to understanding 35 million years of tectonics, sedimentology, evolution and biogeography. BYU Geology Studies, 42, 69−103.
Krassilov, V.A., 1981. Changes of Mesozoic vegetation and the extinction of dinosaurs. Palaeogeography, Palaeoclimatology, Palaeoecology 34, 201–224.
Krassilov, V.A., Golovneva, L.B., Nesov, L.N., 1990. Cycadophyte from the Late Cretaceous dinosaurs locality in North Koryakia. In: Krassilov, V.A. (Ed.), Non-marine Cretaceous of the USSR. Dalnevostochnoye Otdeleniye Rossijskoy Akademii Nauk, Vladivostok, pp. 213–215 (in Russian).
Zakharov, Y. D., Shigeta, Y., Popov, A., et al., 2011. Cretaceous Climatic Oscillations in the Bering Area (Alaska and Koryak Upland): Isotopic and Palaeontological Evidence. Sedimentary Geology, 235(1–2): 122–131, doi:10.1016/j.sedgeo.2010.03.012
Zanno, Lindsay E. and Makovicky, Peter J. (2011) 'On the earliest record of Cretaceous Tyrannosauroids in western North America: implications for an Early Cretaceous Laurasian interchange event', Historical Biology, First published on: 24 February 2011 (iFirst) To link to this Article: DOI: 10.1080/08912963.2010.543952