Sometimes all that is discovered of a Santana pterosaur specimen is a big elongated wing. From past experience we know that two clades filled prehistoric Santana skies, members of the Ornithocheiridae close to Anhanguera, and members of the Tapejaridae close to Tupuxuara and Tapejara. Now Vila Nova and Sayão (2012) have cleared things up. Their new paper plots wing dimensions for both clades, recovering two separate clouds of data. That means wings without skulls can now be identified by dropping their data into the graph and seeing which cloud it nests in.
The Vila Vova and Sayao (2012) report highlights an important aspect to evolution. There is no modular evolution as discussed earlier. When a taxon evolves it does so from head to tail, sometimes unevenly, but this report on distinct wing finger proportions is directly in line with earlier reports of distinct free finger and feet proportions (Peters 2011).
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.
Peters D 2011. A Catalog of Pterosaur Pedes for Trackmaker Identification
Ichnos 18(2):114-141. http://dx.doi.org/10.1080/10420940.2011.573605
Vila Nova BC and Sayão JM 2012. On wing disparity and morphological variation of the Santana Group pterosaurs, Historical Biology: An International Journal of Paleobiology.