Microtuban, a New Basal Azhdarchid

Microtuban altivolans (Elgin and Frey 2011) is a new basal azhdarchid pterosaur with the characteristic tiny fourth phalanx. Only the mid-section of this pterosaur is preserved, including smashed wing parts.

Sisters to Microtuban

Figure 1. Sisters to Microtuban include No. 42 (more primitive) and Jidapterus (more derived).

Juvenile? No.
The scapula and coracoid are unfused and the extensor tendon process includes a large suture. Elgin and Frey (2011) considered these to be ontogenetic signals that inferred the specimen was a juvenile or sub-adult, as in archosauromorphs. Unfortunately this is false. Pterosaurs are lizards and they don’t follow archosauromorph growth patterns. The sister taxa (Fig. 1) all have similar fusion patterns and they are adults.

Africa? No.
Elgin and Frey (2011) considered Microtuban, from the of Early Cenomanian (Late Cretaceous) of Lebanon, “the most complete pterosaur fossil discovered from Africa.” Oops. Lebanon is actually in the Middle East. Minor faux pas.

Phylogenetic Nesting
Elgin and Frey (2011) reported, “The phylogenetic placement of M. altivolans within the Azhdarchoidea [the Tapejaridae, the Thalassodromidae, the Chaoyangopteridae, and the Azhdarchidae] therefore remains uncertain.” They considered it a “thalassodromid/ chaoyangopterid.

Here, in a larger study, Microtuban nests readily at the base of the Azhdarchidae [Jidapterus through Quetzalcoatlus] and was derived from a sister to No. 42. (By the way, in the larger study Chaoyangopterus was not at all related to Thalassodromeus.) The manual phalanx proportions in Microtuban were identical to those of its azhdarchid and protoazhdarchid sisters, none of whom, no matter their size, fused the scapula to the coracoid until Quetzalcoatlus.

A Reduced Phalanx 4
While more primitive than other azhdarchids, wing phalanx 4 was relatively shorter (less than 5% of the total wing finger) in Microtuban, probably because it represents a late-surviving clade member on its own branch. The reduction of phalanx 4 is also found in Sos 2428, the flightless pterosaur, which is another Microtuban sister. I suspect that another sister, Huanhepterus, also had such a short phalanx 4, but no one I know has actually seen the post-crania.

Loss of Phalanx 4 in Other Pterosaurs?
Elgin and Frey (2011) reported that Anurognathus, Beipiaopterus and Nyctosaurus all had only three wing phalanges. This is true only for derived Nyctosaurus. Check it out.

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.

References
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

Advertisements

2 thoughts on “Microtuban, a New Basal Azhdarchid

  1. Pingback: Microtuban altivolans « Pterossauros

  2. Lebanon is in the African continental plate in the Cretaceous though…

    And as much as I would like to see the hard bits of the specimen, and all the involved scientists’ hard work, it’s sad to say that the paper had been paywalled, really, whether one support an archosaurian lineage, or squamate lineage for pterosaurs, I think we could all agree that having interesting papers paywalled is not pleasant, right?

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