20 gennaio 2010

Intervista a Steve Brusatte

Alcuni lettori avevano chiesto se avessi qualche intervista in arrivo.  Credo che quella di oggi  risulterà di grande interesse.
Steve Brusatte è un giovane paleontologo dei vertebrati, che ha già all'attivo interessanti ricerche sui theropodi, in particolare allosauroidi, e che ha collaborato con ricercatori del calibro di Sereno (a Chicago), Benton (a Bristol) e Norell (a New York).
Sebbene Steve abbia svolto ricerche anche in altri ambiti, ho focalizzato le mie domande, ovviamente, sui suoi studi riguardanti i theropodi.
(Avvertenza per i lettori non-italiani: l'intervista è in inglese, quindi consiglio di NON utilizzare Google Translate)

Among your research areas, you’ve studied macroevolutionary disparity among Triassic archosaurs and non-avian theropod evolution. How could these studies be linked? In particular, tetanuran body plan range seems larger than ceratosaurian’s one (although new taxa as Limusaurus suggests that ceratosaurian disparity has been underestimated): what is your opinion about the study on theropod disparity?
Steve - This is a great question and you've hit right on my research plans over the next few years. I began my career in paleontology working on theropod dinosaurs, and then switched over to Triassic reptiles and quantitative methods while studying at Bristol with Mike Benton. I still work on both of these subjects today, and for the past year and a half I have been blending them as part of my PhD thesis at Columbia University/AMNH. My thesis focuses on coelurosaurian phylogeny (especially basal coelurosaurs) and the disparity, morphospace occupation, rates of morphological change, and morphometric skull change in theropods across the Mesozoic. It takes quite a bit of time to build up the datasets needed to do phylogenetic analyses (as Andrea knows very well with his large megamatrix!), disparity analyses, and evolutionary rates analyses, so I am working hard and hopefully will have some results within the next year or so.

You’ve been involved in many new studies concerning allosauroid morphology and phylogeny, with new forms described (a new species of Carcharodontosaurus, the new basal carcharodontosaurid Eocarcharia) and re-evaluations of known taxa (Shaochilong, Neovenator). In particular, I consider noteworthy the recognition of the “unknown” radiation of neovenatorids. What these new discoveries tell us about allosauroid and theropod macroevolution?
Steve - I've been very fortunate to have the chance to work on a lot of new theropods over the past few years, as well as redescribe and monograph some very important taxa such as Neovenator and Monolophosaurus that have been neglected. My initial research on allosauroids, with Paul Sereno, greatly supported the ideas that Acrocanthosaurus is a member of the carcharodontosaurid group, and that Sinraptor is the basal-most allosauroid. The work on Neovenator confirmed that it is a carcharodontosaurid, and the work on Monolophosaurus showed that it is not an allosauroid, but a very basal tetanuran. My latest work is in collaboration with Roger Benson and Matt Carrano. Roger and I monographed Neovenator together and have been working together, and also separately, on many theropod projects over the past five years. Over time it became clear to us, largely due to Roger's very comprehensive PhD thesis and his collections visits around the world, that many other, once-puzzling theropods, were close relatives of Neovenator. These include Megaraptor, Orkoraptor, Aerosteon, and Fukuiraptor. We were able to identify many characters linking these theropods, and argued in a paper in Naturwissenschaften that they form a clade of basal carcharodontosaurians, the Neovenatoridae. Many neovenatorids are small, sleek animals, with very large, raptorial hands and extreme postcranial pneumaticity. In many ways they are "coelurosaur mimics." The most important result of this research, I think, is that we have identified a major new clade of basal theropod dinosaurs. We were able to unite many taxa that had confused us, and many other researchers, for a long time. It is amazing that even a group as well studied as theropods can yield new secrets like this.

You’re studying tyrannosauroid evolution. Among the new taxa published in 2009, in my opinion the most unexpected is Raptorex, a small sized tyrannosauroid showing great morphological similarity with “giant” tyrannosaurids. You’re one of the authors of the paper describing it: what is your opinion about Raptorex?
Steve - Tyrannosauroid evolution is a major focus of my research right now. It is a large part of my PhD project, and I have spent the last year observing most of the basal tyrannosauroid specimens around the world. I was very fortunate to describe Raptorex (with Paul Sereno and other colleagues) and Alioramus altai (with Mark Norell, Thomas Carr, and other colleagues) last year. 2009 was really the "year of the tyrannosaur"! There were so many important new tyrannosauroids described and named, and other taxa (such as Proceratosaurus) were finally well-described for the first time. Of all of this flood of new research, I agree that Raptorex is the most interesting. Raptorex is about my size--it weighed about 65 kilograms and was about 2.5-3 meters long (most of which was tail). Its mass was about 1/100th that of its famous cousin, Tyrannosaurus. But, although it is much older and smaller than the classic Late Cretaceous tyrannosaurids, it shares many characters with these iconic dinosaurs. These include the deep and muscular skulls and the tiny forelimbs. For a long time paleontologists have thought that these classic tyrannosaurid features evolved in concert with large body size--in other words, they were necessary for a large theropod to hunt and move at gigantic size. But now we know they were present in a very small animal, telling us that they have nothing to do with body size and were probably characters that first evolved in small animals and were later simply scaled up as tyrannosauroids became enormous.

What is Taxon Search?
Steve - TaxonSearch is an online database that stores taxonomic information (in other words, it keeps records of taxon names and phylogenetic definitions). This was the brainchild of Paul Sereno, who was my undergraduate advisor at the University of Chicago. One of my first experiences in paleontology research was helping Paul compile records of taxonomic names and phylogenetic definitions for extinct archosaurs, which we organized into the TaxonSearch file that is now online. Numerous phylogenetic definitions have been proposed for many clades, and for the time being, there is no system to govern which names to use, or even a good system for organizing the names and definitions that have been published. PhyloCode may one day succeed in governing the names that are used, but TaxonSearch does a great job of organizing the information that is spread around the literature. The archosaur taxonomy file that is available online is a great resource for archosaur paleontologists, and I frequently use it still today in order to look up taxon names and definitions.

Aside your researches, are there poorly known areas of theropod paleontology that you would like to study in the future?
Steve - There are so many things that I want to do in paleontology, but only such little time! One of my most rewarding tasks is writing--papers, books, you name it. I have always loved writing, and during high school and college I worked summers and holidays as a journalist for my hometown newspaper in central Illinois (near Chicago). These days, I really consider myself a paleontological journalist each time I write a manuscript, because it is a great challenge, and also a great thrill, to take a new fossil or quantitative analysis or piece of information and describe it in writing. I have plans for some future writing projects that include some new books, so keep your eyes tuned. As for research subjects, one of my big interests these days is quantitative and phylogenetic methods. Finding and describing new fossils is cool, but I really like "big picture" projects that take into account a lot of information and attempt to say something about macroevolution--the major trends and patterns that characterize the evolution of organisms on million-year time scales. I am spending a lot of my time these days working with new statistical and quantitative methods for describing and understanding major patterns of morphological evolution over time, with dinosaurs and other fossil groups. There are many exciting projects, and although I'm not the most natural mathematician or statistician, I am really enjoying learning the new techniques. As far as theropods go, there is still a lot to learn about theropod phylogeny and morphological evolution, not to mention biomechanics and paleobiology. These are exciting times, indeed, for theropod workers!

Thank you very much, Steve.

Potete trovare la bibliografia completa di Steve qui.
Vi anticipo che a brevie tornerò a parlare di Steve, con un articolo di cui è primo autore e che attendevo con grande interesse.

1 commento:

  1. Wow! Amazing interview! In fact, a few weeks ago I asked Steve for an interview, but you've been faster! I'll look for new questions, so both posts will tell different stories. ;)