Bennett 2014: Lumping Scaphognathus

Among paleontologists we have lumpers and splitters. Dr. S. Christopher Bennett is definitely a lumper. That’s not necessarily a bad thing, but sometimes, ironically, it blinds one to the subtle but important differences that are key to understanding relationships. In his latest paper he takes another look at the SMNS 59395 specimen of Scaphognathus.

From the Bennett 2014 abstract: “A new complete and fully articulated juvenile specimen of the rhamphorhynchoid pterosaur Scaphognathus crassirostris from the Upper Jurassic Solnhofen Limestone of southern Germany is only the third known specimen of the species. The specimen is described and compared to the other two specimens. Based on the comparisons, the skull of Scaphognathus is reinterpreted as having two premaxillary, six maxillary, and five dentary teeth per jaw side, and a broad boat-shaped snout. Scaphognathus is compared to Jianchangnathus robustus, and revised diagnoses of the genus and family are presented. In addition, the position of the cervico-dorsal transition in the vertebral column of pterosaurs is reviewed, and an apparent constraint to nine cervical vertebrae is noted.”

The SMNS 59395 specimen of Scaphognathus. Even numbered neck vertebrae are pink. Note the ninth has dorsal ribs that extend into the chest cavity despite the fact that they do not contact the sternal complex. The ninth vert is also much smaller than #8.

Figure 1. Both images from Bennett 2014. The SMNS 59395 specimen of Scaphognathus. Even numbered neck vertebrae are pink. Note the ninth has dorsal ribs that extend into the chest cavity despite the fact that they do not contact the sternal complex. The ninth vert is also much smaller than #8. That’s why I say pterosaurs had eight cervical vertebrae, not nine. The ninth is inside the torso.

It all depends on how you count that 9th vert.
Bennett considers it a cervical because the ribs do not contact the sternal complex. I consider it a dorsal vertebrae because the ribs are long, completely embedded in the torso and the vertebra is more similar in size and shape to #10 than #8.

Only two pmx teeth?
Bennett 2014 also reports that this specimen had but two premaxillary teeth (Fig 2). Four is the typical number and four teeth are visible here, but Bennett calls two of the teeth “replacement” teeth, even though both are close to one longer tooth. Two teeth would be an autapomorphy for most pterosaurs with teeth. No other pterosaurs have just two premaxillary teeth. IMHO, four teeth mean four teeth, especially if the pattern matches other pteros.

Figure 3. Scaphognathus SMNS 59395 with anterior skull bones colorized. There are four teeth there. Are two replacement teeth? That would be an autapomorphy.

Figure 2. Scaphognathus SMNS 59395 with anterior skull bones colorized. There are four teeth there. Are two replacement teeth? That would be an autapomorphy. Here we see the anterior naris dividing. Descendants had both widely divided. The anterior one I call the secondary naris. 

Lumping another genus into Scaphognathus
Bennett 2014 revised the genus Scaphognathus to include the former Jianchangnathus robustus, which he renamed S. robustus. Phylogenetic analysis in the large pterosaur tree does not support this name change. Nor does analysis support the juvenile status of the smaller Scaphognathus specimens. If Jianchangnathus is within the genus Scaphognathus then all of the wukongopterids and Pterorhynchus must also be included, but Bennett doesn’t report that.

According to Bennett (2014) the clade Scaphognathidae HOOLEY 1913,  includes these genera.

  1. – Dorygnathus WAGNER 1860,
  2. – Scaphognathus WAGNER 1861
  3. – Sordes SHAROV 1971

Unfortunately, this is not a monophyletic clade as phylogenetic analysis shows. Any clade that includes Sordes must also include all pterosaurs other than basal eudimorphodontids (with multi cusp teeth) and dimorphodontids. Any clade that includes Dorygnathus also includes all azhdarchids and pre-azhdarchids, ctenochasmatids and pre-ctenochasmatids.

References
Bennett SC 2014. A new specimen of the pterosaur Scaphognathus crassirostris, with comments on constraint of cervical vertebrae number in pterosaurs. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen, 271(3): 327-348.

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