‘Rhamphorhynchus biter’, Aspidorhynchus, enters the LRT

On the subject of the Late Jurassic pterosaur biter, Aspidorhynchus,
Wikipedia reports, “Although it would have looked superficially similar to the present day gar, its closest living relative is actually the bowfin.” 

Figure 1. Aspidorhynchus overall. To the left, off screen, is the pterosaur, Rhamphorhynchus.

By contrast, 
in the large reptile tree (LRT, 1698+ taxa) Aspidorhynchus (Figs. 1, 2) nests with another swordfish-mimic from the Late Cretaceous Niobrara Sea, Protosphyraena (Fig. 3).

Figure 2. The face of the Wyoming Dinosaur Center CSG 255 specimen of Aspidorhynchus + Rhamphorhynchus with facial bones identified using DGS. The uppermost jugal plate (cyan) may be a postorbital based on phylogenetic bracketing,  but its disconnection from the circumorbital postorbital suggests a jugal replacement in that space.

Among living taxa,
the closest relative is the arowana, Osteoglossum, an Amazon River surface feeder. This may be one clue as to how several Aspidorhynchus specimens met several Rhamphorhynchus specimens, to their mutual doom.

Figure 3. Skull of Protosphyraena. Colors added to march tetrapod homologies and updated here from previous guesstimates. Comapare to figures 3 and 4.

If I’m not mistaken, 
this is a novel hypothesis of interrelationships based on taxon inclusion. If there is an earlier citation, let me know so I can promote it here. Googling the two genera just seems to bring up lists of genera without making a connection between the two.

---

References
Agassiz L 1843. Recherches sur les poissons fossiles: 5 vols, with atlas (Neuchâtel).
Blainville HMD de 1818. Poissons fossiles. Nouveau Dictionnaire d’Histoire Naturelle 27: 310–395.
Frey E and Tischlinger H 2012. The Late Jurassic pterosaur Rhamphorhynchus, a frequent victim of the ganoid fish Aspidorhynchus?. PLoS ONE. 7 (3): e31945. Bibcode:2012PLoSO…7E1945F. doi:10.1371/journal.pone.0031945.

wiki/Aspidorhynchus

Advertisement