Over the elbow or under? Pterosaur wing folding problem solved.

Finally a pterosaur that preserves the wing finger over the elbow solves the minor problem of wing folding.

Figure 1. Finally a pterosaur that preserves the wing finger over the elbow solves the minor problem of wing folding. This is hard evidence that means, over time, I’m going to have change a few reconstructions. Also note the robust ribs and wide scapulae here. The coracoid was not fused to it. Elbows are back, not out. There’s also a notarium you can see.

Pterosaurs folded their wings so tightly that the membrane virtually disappeared between a parallel antebrachium and wing finger (unlike the widely disseminated traditional view that keeps the wing finger open to handle the false deep chord wing membrane construction). The only question has been, does the wing finger fold medial (inside) to the elbow or lateral (outside) to the elbow? Having built several model skeletons, I thought the inside offered better protection and didn’t violate any rules.

Now we have a specimen attributed to Noripterus GIN125/1010 (Lü et al. 2009) that preserves this configuration lateral (outside, dorsal) to the elbow. The specimen is quite a bit smaller than the Noripterus holotype. Distinctively the metacarpus is shorter with regard to the tibia on GIN specimen, so the two are probably not conspecific (or congeneric, depending if you’re a splitter or a lumper). The GIN specimen is closer to Germanodactylus.

This is also the first specimen of a dsungaripterid I’ve seen that preserves the scapula, which appears to NOT fuse to the coracoid, similar to what we see in Shenzhoupterus, Noripterus and basal tapejarids. On the other hand, the more primitive Germanodactylus has a fused scapulocoracoid. So, fancy that, the smaller taxon has a fused s/c and the larger ones don’t (until we come to the larger tapejarids).

The new Noripterus to scale with Germanodactylus cristatus (left) and a chimaera of Phobetor and the holotype of Noripterus (right).

Figure 1. The new Noripterus to scale with Germanodactylus cristatus (left) and a chimaera of Phobetor and the holotype of Noripterus (right). Long-legged bastards, aren’t they? Here you can also see proportional differences between the holotype Noripterus (on the right) and the attributed specimen (in the middle). 

References
Lü J, Azuma Y, Dong Z, Barsbold R, Kobayashi Y and Lee Y-N 2009. New material of dsungaripterid pterosaurs (Pterosauria: Pterodactyloidea) from western Mongolia and its palaeoecological implications. Geological Magazine, 146(5): 690-700.

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