The Pterosaur Palate: More workers coming on board.
Pinheiro and Schultz (2012) recently reported on an “unusual” pterosaur palate from Brazil. (Actually it was not so unusual, IMHO, having reconstructed hundreds of them).
They claimed that the palatal elements were misidentified by Osi et al. (2010) who echoed Peters (2000). (Actually their labeling and interpretation of Pterodactylus micronyx (BSP 1936 I 50) was identical to those earlier interpretations. Their other interpretations for the most part followed suite.
Pinheiro and Schultz (2012) reported, “Only recently was a new interpretation of the pterosaur palate made, in a study that utilized the Extant Phylogenetic Bracket to identify homologous structures in the palates of pterosaurs, birds and crocodiles.” Actually, by now everyone should know that pterosaurs belong to an extinct clade of lizards, not crocs or birds. There has never been support, except in the absence of lizards, for a pterosaur-bird-croc relationship. The long fifth toe, the long fourth finger, the ossified sternum and the extreme thinness of the egg shell are traits pterosaurs share with living lepidosaurs to the exclusion of living archosaurs. If an antorbital fenestra is key, it only takes one reminder to note that this structure appears four times by convergence within the Reptilia.
But this brings up an interesting point. Why were the palatal shelves of pterosaurs ever considered palatines (See all works by Bennett and Wellnhofer) if they are maxillary in origin in crocs and birds??
So where did Pinheiro and Schultz (2012) go right?
They correctly identified the palatal shelves as belonging to the maxilla, separated only by the vomers. Most pre-2000 studies (anything by Bennett, Wellnhofer, other early workers) mistakenly labeled these palatines. They correctly identified the pterygoids. They correctly identified the palatines in most of their pterosaurs, but they did not understand that the palatines and ectopterygoids both fuse and diverge diagonally in Pteranodon (so their ectopterygoid is the ectopalatine). This becomes obvious after a study of Germanodactylus palates.
And where did Pinheiro and Schultz (2012) go wrong?
Other than the aforementioned misconceptions, Pinheiro and Schultz labeled the posterior portion of the shelf of the new pterosaur as the palatine, ignoring their own graphics showing the palatine and ectopterygoid merge in most pterosaurs to form a single small L-shaped bone, the ectopalatine. Tiny, fragile and easily lost, the ectopalatine is missing from the new skull fragment of their study.
Their second mistake was using only highly derived taxa, like Pteranodon, Anhanguera and Tupuxuara, to identify palatal elements. Their single basal pterosaur, the Dorygnathus of Osi et al. (2012) was not relabeled, contra their earlier pronouncement. Their identification of the premaxilla/maxilla in Dorygnathus follows without criticism the mistake made by Osi et al. (2009) reviewed earlier here.
Pinhiero and Schultz (2012) blindly follow earlier analyses that link broad-snouted, toothy Anhanguera with sharp-snouted, toothless Pteranodon. On the face of it, what were they not thinking??? (Oh, yes, they were following tradition without critical thinking).
Their drawings show only the ventral view, but the tiny ectopalatines are often dorsal to the pterygoids.
Their lateral view reconstructions were not of the specimens employed, but were of generic and non-generic relatives. BSP 1936 I 50 belongs to the cycnorhamphids, not Pterodactylus.
Earlier pterosaurheresies covered nearly every aspect of pterosaur palate evolution starting here and going on for seven (occasionally interrupted) chapters. You can also Google “pterosaur palate” under the “images” choice.
In conclusion, I’m glad to see more workers are jumping on board with the maxilla shelf identification, and correctly identifying the palatine, but not sure why they think this is such a new thing.
As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.
Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.
References
Ösi A, Prondvai E, Frey E, Pohl B 2010. New interpretation of the palate of pterosaurs. The Anat Rec 293: 243–258. doi: 10.1002/ar.21053.
Peters D 2000b. A Redescription of Four Prolacertiform Genera and Implications for Pterosaur Phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106 (3): 293–336.
Pinheiro FL, Schultz CL 2012. An Unusual Pterosaur Specimen (Pterodactyloidea, ?Azhdarchoidea) from the Early Cretaceous Romualdo Formation of Brazil, and the Evolution of the Pterodactyloid Palate. PLoS ONE 7(11): e50088. doi:10.1371/journal.pone.0050088
2012-11-23 11:01:13
Source: http://pterosaurheresies.wordpress.com/2012/11/23/the-pterosaur-palate-more-workers-coming-on-board/
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