A new look at Jidapterus (basal azhdarchid pterosaur)

Wu, Zhou and Andres 2017
bring us long anticipated details on Jidapterus (Early Cretaceous, Dong, Sun and Wu 2003) which was previously presented as a small in situ photograph lacking details. Even so a reconstruction could be made (Fig. 1). Coeval larger tracks (Elgin and Frey 2011) have been matched to that reconstruction.

Figure 2. Jidapterus matched to the Gansu, Early Cretaceous pterosaur tracks. The trackmaker was one-third larger than the Jidapterus skeleton.

Figure 1. Jidapterus matched to the Gansu, Early Cretaceous pterosaur tracks. The trackmaker was one-third larger than the Jidapterus skeleton.

Of interest today
is the fact that Jidapterus was originally and, so far, universally considered toothless. Its specific name, J. edentatus, refers to that condition. Wu, Zhou and Andres 2017 produced tracings (Figs. 2, 3) of the rostrum that are also toothless. However, they are crude and appear to miss the premaxilla and maxilla sutures, the palatal elements… and maybe some teeth. Those jaw rims are not slippery smooth like those of Pteranodon. Outgroups in the large pterosaur tree (LPT), all have tiny teeth.

Figure 2. Rostrum of Jidapterus (RCPS-030366CY) and traced according to Wu et al. and colorized using DGS to reveal skull sutures and possible teeth.

Figure 2. Rostrum of Jidapterus (RCPS-030366CY) and traced according to Wu et al. and colorized using DGS to reveal skull sutures and possible teeth. See figure 3 for details. What Wu, Zhou and Andres label the  “low ridge of rostrum” is here identified as the rostral margin above the palatal portion. 

The cladogram of Wu, Zhou and Andres
lacks dozens of key taxa found in the LPT that separate azhdarchids from convergent tapejarids and shenzhoupterids. In the LPT giant azhdarchids arise from tiny toothy azhdarchids once considered Pterodactylus specimens… and these, in turn are derived from tiny and mid-sized dorygnathids in the Middle Jurassic.

What Wu, Zhou and Andres label the  “low ridge of rostrum”
is here identified as the rostral margin rim at the edge of the palate.

Figure 3. Focus on the rostral tip of Jidapterus shown in figure 2. Are these teeth?

Figure 3. Focus on the rostral tip of Jidapterus shown in figure 2. Are these teeth? You decide. I present the data. 

As in all pterosaurs
each premaxilla of Jidapterus has four teeth according to this data.

Are these tiny teeth?
Or are they tiny occlusions and/or chisel marks. Let’s get even better closeups to figure this out. Phylogenetic bracketing indicates either tiny teeth or edentulous jaws could be present here.

References
Dong Z, Sun Y and Wu S 2003. On a new pterosaur from the Lower Cretaceous of Chaoyang Basin, Western Liaoning, China. Global Geology 22(1): 1-7.
Elgin and Frey 2011. A new azhdarchoid pterosaur from the Cenomian (Late Cretaceous) of Lebanon. Swiss Journal of Geoscience. DOI 10.1007/s00015-011-0081-1
Wu W-H, Zhou C-F and Andres B 2017. The toothless pterosaur Jidapterus edentus (Pterodactyloidea: Azhdarchoidea) from the Early Cretaceous Jehol Biota and its paleoecological implications. PLoS ONE 12(9): e0185486.

wiki/Jidapterus

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