Saturday, November 24, 2012

GUEST POST: Felipe Pinheiro and the Raiders of the Lost Palate


2012 has been a good year for pterosaurs, with several new taxa and important papers being published. This trend continued this week with the description of a fragmentary but intriguing pterosaur palate from the famous Cretaceous Santana Formation of Brazil, authored by Felipe Pinheiro and Cesar Schultz of the Universidade Federal do Rio Grande do Sul. Avenida Bento Gonçalves, Brazil, and Bayerische Staatssammlung für Paläontologie und Geologie, Germany, respectively (image of the new material is shown above. Image courtesy Felipe Pinheiro). Felipe asked if we could big up the paper here at the Pterosaur.Net bog, but I'm a little too pushed for time to write a post worthy of the article, which not only describes the specimen but sheds much needed light into pterosaur palatal anatomy. Felipe was kind enough to provide his own illustrated summation of the story however, so we could still cover the paper here at the blog. On that note, I'll hand you over to our guest blogger, and be sure to check out his open access paper for more details on this new discovery. 

MPW 24/11/12

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The fragility of pterosaur skeletons is always working against us, the paleontologists devoted to understanding these flying archosaurs. Independently if our research deals with systematics, anatomy or paleobiology, we’re often confronted with the fact that our research subject is badly crushed and a great deal of useful information is simply lost. A very good example of this issue is the pterosaur palate: although new pterosaur taxa are being published all the time, only a handful of well-known specimens have this structure preserved, thus, limiting our knowledge of its anatomy and evolution within the group. Luckily, some rare sedimentary deposits were kind enough and maintained the original, three-dimensional shape of their fossils, allowing the study of otherwise inaccessible anatomical features, like, of course, the pterosaur palates. (Pterosaur specimens showing palatal regions below. Image courtesy Felipe Pinheiro)

Our understanding of pterosaur palatal anatomy changed considerably after the recent work by Attila Ösi and colleagues (2010). Analyzing pterosaur palates under an evolutionary perspective and utilizing the Extant Phylogenetic Bracket as a tool, the authors identified homologue structures between pterosaurs, birds and crocodiles, demonstrating some bones that were misinterpreted throughout the literature. The best example is the conclusion that, in pterosaurs, most of the palate is composed by palatal blades of the maxillae, instead of the palatines. Although this identification was also proposed by some old researchers, like Newton (1888) and Seeley (1901) and, more recently, Peters (2000), common sense was still that the palatines composed most of pterosaur palatal surface.

As the work of Ösi et al. (2010) was mainly focused on stem “non-pterodactyloids”, especially Dorygnathus, a new look on pterodactyloid palate was still needed and this is the main subject of our new paper, titled “An Unusual Pterosaur Specimen (Pterodactyloidea, ?Azhdarchoidea) from the Early Cretaceous Romualdo Formation of Brazil, and the Evolution of the Pterodactyloid Palate”.
Besides describing a new fragmentary (but interesting) palate from the Romualdo Formation (the Early Cretaceous concretion-bearing strata of the Santana Group, northeastern Brazil), we analyzed and redescribed a number of well-known pterosaur specimens with palatal preservation, such as “Pterodactylus” micronyx, Anhanguera and Pteranodon. Also, the palate of the Iwaki Tupuxuara specimen is described and illustrated for the first time. As a result, our work shows that pterodactyloids had often complex palatal morphologies with, sometimes, interesting “reversions” to the non-pterodactyloid condition, with three pairs of lateral openings. Also interesting is the extreme reduction of elements in some taxa, such as the almost vestigial ectopterygoids of anhanguerids. (Possible evolutionary pathways of the pterosaur palate shown below. Image courtesy Felipe Pinheiro.) 


This morphological disparity is probably an evidence of complex feeding habits among derived pterodactyloids, with ecological implications that is, presently, the research subject of our working group, at the Universidade Federal do Rio Grande do Sul, Brazil.

I hope you all read our paper (don’t worry, it’s open access). We’re opened to all kind of criticism and discussions by my personal e-mail: fl_pinheiro@yahoo.com.br.
Enjoy!

Felipe L. Pinheiro
Laboratório de Paleontologia de Vertebrados, Instituto de Geociências, Universidade Federal do Rio Grande do Sul.

References:
  • Ösi A, Prondvai E, Frey E, Pohl B (2010) New interpretation of the palate of pterosaurs. The Anat Rec 293: 243–258.
  • Newton ET (1888). On the skull, brain and auditory organ of a new species of Pterosaurian Scaphognathus purdoni), from the Upper Lias near Whitby, Yorkshire. Philos Trans R Soc Lond B Biol Sci 179: 503–537.
  • Peters D. (2000). A re-examination of four prolacertiforms with implications for pterosaur phylogenies. Riv Italiana Paleontol Strat 106: 293–336.
  • Seeley HG (1901) Dragons of the Air: an account of extinct flying reptiles. New York: Appleton & Co.; London: Methuen & Co.

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