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Reconstructing Dorygnathus from the palate up

Thursday, May 23, 2013 4:18
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(Before It's News)

The skull of the SMNS 51827 specimen of Dorygnathus is preserved palate side up (Figs. 1-6). Even so, enough is shown that we can put a pretty decent skull reconstruction together. Specimen images are from Padian (2009).

SMNS 51827 specimen of Dorygnathus

Figure 1. SMNS 51827 specimen of Dorygnathus

Dorygnathus SMNS 51827 colorized.

Dorygnathus SMNS 51827 colorized. Bones match reconstruction in figures 3 and 4. The dentary teeth point up. The rostral teeth all point down. The mandible appears to have been crushed wider than in vivo according to the reconstruction (Fig. 4) which cannot support such a wide splay posteriorly. Note the double tooth a the mandible tip. That’s the front half of the left nasal in dorsal view covering the top of the maxilla.

 Dorygnathus SMNS 51827 lateral view skull reconstruction

Figure 3. Dorygnathus SMNS 51827 lateral view skull reconstruction. Here the angle of the premaxilla and its depth are conjecture. So is the cranium.

Dorygnathus SMNS 51827 skull reconstruction palate view. Mandible in gray.

Figure 4. Dorygnathus SMNS 51827 skull reconstruction palate view. Mandible in gray. Not sure why the juncture of the vomers and pterygoids is so gracile. Perhaps that made it somewhat flexible.

This specimen was discovered in 1981 and is among the best for this genus.

Skull tracing of Dorygnathus SMNS 51827 by Padian 2009.

Figure 5. Skull tracing of Dorygnathus SMNS 51827 by Padian 2009. Fewer details are noted here with several bones blending into one another.  Colorizing the bones helps the mind see continuity when other bones overlap lower ones. 

Padian reported the fused symphysis of the mandible to be edentulous, but basal pterosaurs have a history of anteriorly projecting teeth there. To Padian’s point, the jaw tips of Campylognathoides and Eudimorphodon are edentulous, but distinct in texture from the rest of the mandible. The tip in Eudimorphodon is not sharp. In Campylognathoides and Dorygnathus it is sharp. So despite demarcation that probably marked the boundary of a keratinous extension, the jaws tips in Dorygnathus are edentulous.

Different species of Dorygnathus may be identified by the relative length of the antorbital fenestra, whether or not the naris is above the antorbital fenestra or not, and the relative depth of the mandible, among many other traits.

Reconstruction of Dorygnathus SMNS 51827.

Figure 6. Reconstruction of Dorygnathus SMNS 51827.

References
Padian K 2009. The Early Jurassic Pterosaur Dorygnathus banthenis (Theodori, 1830) and The Early Jurassic Pterosaur Campylognathoides Strand, 1928, Special Papers in Paleontology 80, Blackwell ISBN 9781405192248

wiki/Dorygnathus



Source: http://pterosaurheresies.wordpress.com/2013/05/23/reconstructing-dorygnathus-from-the-palate-up/

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