Evolution of the Pterosaur Palate – part 6: Eudimorphodon to Cearadactylus

Earlier we looked at basal pterosaur palatesdimorphodontoid palatescampylognathoid palates, pre-azhdarchid palates and pre-ctenochasmatids. Here in part 6 we’ll look at the pterosaur palate from Eudimorphodon to Haopterus (Fig. 1, following the phylogenetic order recovered in the large pterosaur tree), then finish up with three more derived ornithocheirds (Fig. 3).

The evolution of the pterosaur palate from Eudimorphodon to Haopterus.

Figure 1. Click to enlarge. The evolution of the pterosaur palate from Eudimorphodon to Haopterus.

Jianchangnathus
The ectopalatine and pterygoid of the primitive scaphognathid, Jianchangnathus, were little changed from those of Dorygnathus the Donau specimen.

The ectopalatine (pink) and pterygoid (green) of Jianchangnathus.

Figure 2. The ectopalatine (red) and pterygoid (green) of Jianchangnathus.

Pterorhynchus
Distinct from the Donau specimen of Dorygnathus, the palate of Pterorhynchus was longer with (perhaps) a shorter maxillary contribution to the palate. The lateral processes of the ectopalatine were more robust.

Scaphognathus, specimen No. 109
Distinct from Jianchangnathus, the palate of the No. 109 specimen of Scaphognathus had a shorter ectopalatine and V-shaped anterior processes to the pterygoid, which was largely ventral to the ectopalatine.

Scaphognathus, specimen No. 110
Overall much smaller than No. 109, in No. 110 the pterygoids were laterally bowed with a longer lateral process than medial one.

Gmu 10157
Distinct from the 110 specimen of Scaphognathus, Gmu 10157 was overall much smaller and had a much larger pterygoid with several medial processes. Overall the skull was much broader posteriorly to accommodate the large eyeballs.

TM 13104
Another tiny pterosaur, TM 13104 reduced the length of the main body of the pterygoid, but elongated the lateral process to underlap both processes of the ectopalatine.

No. 30
Distinct from TM 13104, the palate of No. 30 is similar, but the pterygoids have a lateral process that contacts the cheek. The two ectopalatine process and the anterior pterygoid all lap each other.

Cycnorhamphus
Overall much larger than No. 30, Cycnorhamphus had a similar palate with forward angled pterygoid lateral processes lined anteriorly by the ectopalatine. The vomers were fused and robust.

Feilongus
Distinct from Cycnorhamphus the palate of Feilongus was extremely elongated. The pterygoid was also elongated and the lateral processes were angled posteriorly, as in No. 30. The lateral process of the ectopalatine was round and robust.

Haopterus
Distinct from No. TM 13104 (No. 34) the palate of Haopterus was elongated with a largely exposed set of vomers. The palatine portion of the ectopalatine was dorsal to and largely hidden by an anterior process of the pterygoid. The ectopterygoid portion was parallel to these processes, but also produced a lateral process to contact the cheek.

Ornithocheirid palates.

Figure 3. Ornithocheirid palates.

Coloborhynchus
Distinct from Haopterus, the palate of Coloborhynchus included a smaller, layered  and very gracile ectopalatine and pterygoid.

Criorhynchus
Distinct from Coloborhynchus, the palate of Criorhynchus had a more robust pteroid and ectopalatine.

Cearadactylus
Distinct from  Criorhynchus, the palate of Cearadactylus was much longer and narrower overall with a longer medial maxilla suture ventrally.

Trends
In this clade (which we will finish next), the trend, once again, is to expand the maxillary portion of the palate posteriorly while the ectopalatine and pterygoid became more robust. Apparently it happened more gradually or slowly in the ornithocheirid clade. The posterior elements became layered one over the other beginning with the small Scaphognathus specimens. In cycnorhamphids the pterygoid produced a lateral process that contacted the cheek.

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.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s