Battle of the Monofenestrata (Stem Pterodactyloidea)

A new paper on pterosaur biogeography (Upchurch et al. 2014) includes a family tree from Andres et al. (2014) that puts a new spin on things. That’s the tree that introduced us to Kryptodrakon, which turns out to be just another Sericipterus (a large, gracile dorygnathid), found in the same locality. As you’ll recall, when that “long” metacarpal of Kryptodrakon was placed on the much larger bauplan of gracile Sericipterus, it wasn’t so long anymore.

More to the headline
The Andres tree demotes Darwinopterus to just another wukongopterid. And that’s to Andres credit! So the combatants for pterosaur tree domination now line up on three fronts, with shifting allegiances.

From their Upchurch et al. 2014 abstract: Although sampling biases and taxonomic problems might have artificially elevated the occurrence of sympatry, we argue that our results probably reflect a genuine biogeographical signal. We propose a novel model to explain pterosaurian distributions: pterosaurs underwent a series of ‘sweep-stakes’ dispersal events (across oceanic barriers in most cases), resulting in the founding of sympatric clusters of taxa.

I have no problem with that scenario or any other ‘rush and rest’ distribution system, but it needs to be built on a base of good phylogeny.

Triassic Pteros
In the Andres tree, their basal split is between Triassic pterosaurs and all others with Preondactylus + Austriadactlyus basal to the former group and DimorphodonParapsicephalus + Campylognathoides basal to the latter. Good golly, that’s a mixed bag already!

No outgroups were mentioned, but earlier trees by Andres used Euparkeria, an archosaur with no pterosaur affinities. And without a good foundation, how well can the house stand?

There aren’t many similarities between long-snouted Parapsicephalus and tall snouted Dimorphodon. And how does Campylognathoides match to these two? Not well. There are more parsimonious sister taxa out there.

The oddest and most controversial aspect of Andres’ tree is the nesting of Anurognathidae far from Peteinosaurus and Dimorphodon. He derives anurognathids like Dendrorhynchoides from Changchengopterus (but which one?), wukongopterids and Sordes (in order of increasing distance), at the base of the Pterodactyloidea, with Krypodrakon at the base.

Andres nests Anurognathidae within the Monofenestrata because he finds no bone to divide the naris from the antorbital fenestra in anurognathids (following the Bennett model) and they have short tails, like pterodactyloids. This needs to be tested with reconstructions. My tests don’t confirm Bennett’s model. I’d like to see someone else step up to the plate and see what they find. We need third and fourth party input.

There remains some traditional confusion about the sharp tooth and toothless pterodactyloids. In the Andres tree toothy Haopterus is basal to toothless, sharp-snouted Pteranodon + Nyctosaurus on one clade that produces more toothy ornithocheirids. And Haopterus is also basal to another toothless (except for dsungaripterids!), sharp-snouted clade, the tapejaridae + dsungaripteridae + azhdarchidae. Eopteranodon is separated from Eoazhdarcho. Noripterus is a sister to Thalassodromeus and other odd pairings abound.

And when did MoganopterusFeilongus and Huanhepterus start nesting with ctenochasmatids?

Perhaps key to the problems here:
No tiny pterosaurs, other than Eudimorphodon cromptonellus, and Nemicolopterus were included. When that happens, all hellzapoppin!

And this is why I always ask my submission editors to not send my work to these chaps to be refereed. They’re not seeing the red flags.

Andres B, Clark JM, Xu X. 2014. The earliest pterodactyloid and the origin of the group. Curr Biol. 24(9):1011–1016
Upchurch P, Andres B,  Butler RJ & Barrett PM 2014. An analysis of pterosaurian biogeography: implications for the evolutionary history and fossil record quality of the first flying vertebrates, Historical Biology: An International Journal of Paleobiology, DOI: 10.1080/08912963.2014.939077


Leave a Reply

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

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

Facebook photo

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

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.