Aerotitan. A new South American Azhdarchid.
A recent paper by Novas et al. (2012) brings us the partial rostrum of a new South American azhdarchid, Aerotitan sudamericanus MPCN-PV 0054 (Fig. 1). Today we’ll take a closer look at that rostrum, identifying data overlooked by the authors.
Figure 1. Click to enlarge. Aerotitan partial rostrum, the right side flipped left for comparison and symmetry. Below, as originally presented. Middle, contrast adjusted to bring out details. Above, rostral elements colorized: yellow = premaxilla; green = maxilla; pink = jugal.
There is little question that this is an azhdarchid rostrum due in large part to the nearly parallel jaw rami. In other words, azhdarchids don’t have pointed jaws in dorsal or ventral view.
Some purported azhdarchids, such as Bakonydraco, are eopteranodontids, derived from similarly pointed Germanodactylus and related to similarly pointed Nyctosaurus and Pteranodon. Pseudo-azhdarchids can be eliminated by this single rostral feature.
Novas et al. (2012) thought they had a virtual blank slate in their new rostrum. Knowing (on some level) that the rostrum must consist of a premaxilla and maxilla, they did not attempt to map out the divisions between the rostral elements, but they did find slight “slit-like lateral foramen” along the path of the anterior extension of the jugal. Although the elements are largely fused to one another, their borders are still barely visible in high contrast. Here (Fig. 1) those divisions become more apparent. In more primitive pterosaurs these divisions and sutures are more apparent. In azhdarchids and other derived pterosaurs, those sutures are largely fused.
Note the anterior extension of the laminated and largely buried jugal. It’s clearer in more derived taxa. Less apparent, but still visible, here. The naris is visible in more primitive taxa. It is gone here.
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.
Reference
Novas FE, Kundrat M, Agnolín FL, Ezcurra MD Ahlberg PE, Isasi MP, Arriagada A and Chafrat P 2012. A new large pterosaur from the Late Cretaceous of Patagonia, Journal of Vertebrate Paleontology, 32:6, 1447-1452.
2012-11-02 23:08:30
Source: http://pterosaurheresies.wordpress.com/2012/11/03/aerotitan-a-new-south-american-azhdarchid/
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