A Competing Pterosaur Tree – Andres, Clark and Xing 2010

One of the most recent competing pterosaur trees was published recently by Andres, Clark and Xing (2010, Fig. 1).

Andres, Clark and Xing 2010 tree

Figure 1. Pterosaur tree from Andres, Clark and Xing 2010. Color added. This tree differs from all others by nesting anurognathids with derived pterosaurs ("pterodactyloids").

Some Good Pairings
The Andres, Clark and Xing (2010) paper sought to nest a partial skeleton, Sericipterus and it is basically correctly nested here. In the large pterosaur study Sericipterus nested close to the Uppsala specimen of Dorygnathus (R 156), in the lineage of Harpactognathus and Angustinaripterus, but not quite there. The anurognathids are all nested together. Sordes nests as a sister to Scaphognathus not far from Dorygnathus. The outgroup taxa, Ornithosuchus, Herrerasaurus and Scleromochlus correctly nest together. Campylognathoides is close to Sordes which is more or less correct, but missing some intervening taxa.  Peteinosaurus and Dimorphodon are correctly nested as sisters. Eudimorphodon and Austriadactylus are correctly nested as sisters.

Odd pairings recovered in the Andres, Clark and Xing (2010) tree.

Figure 2. Odd and improbable pairings recovered in the Andres, Clark and Xing (2010) tree.

Some Unusual and Improbable Pairings
Andres, Clark and Xing (2010) found Scleromochlus and Preondactylus to be sisters. Since Scleromochlus has tiny hands and lacks a pedal digit 5 and Preondactylus has an enormous wing finger and an elongate pedal digit 5, among dozens of other differences noted here, this relationship seems improbable and is not supported on the large reptile tree. This by default nesting is probably due to a lack of lepidosaur tritosaur fenestrasaurs in the mix, which would have produced a better set of outgroup taxa with a gradually accumulating list of pterosaurian traits missing in the ScleromochlusHerrerasaurus/  outgroup.

Andres, Clark and Xing (2010) found Dimorphodon and Campylognathoides to be sisters. Here Eudimorphodon and several other taxa bridge this morphological gap.

Andres, Clark and Xing (2010) nested Preondactylus, Dimorphodon apart, but the large study found them to be sisters.

Andres, Clark and Xing (2010) found Anurognathus to nest with Sordes and with Pterodactyloidea (here represented by Pterodactylus), but these taxa were widely separated in the large study. Andres, Clark and Xing (2010) determined that no maxillary ascending process could be identified in Jeholopterus and Batrachognathus, creating a confluent naris and antorbital fenestra. This is incorrect as shown here and here. Much of this mistake can be laid on the earlier misinterpretation by Bennett (2007) of the antorbital fenestra as the orbit in the flathead anurognathid.

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.

Andres B, Clark JM and Xing X 2010. A new rhamphorhynchid pterosaur from theUpper Jurassic of Xinjiang, China, and the phylogenetic relationships of basal pterosaurs, Journal of Vertebrate Paleontology 30: (1) 163-187.
Bennett SC 2007. A second specimen of the pterosaur Anurognathus ammoni. Paläontologische Zeitschrift 81(4):376-398.


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