A cherry-picked pterosaur cladogram to avoid

Longrich, Martill and Andres 2018
discuss several new, but scrappy Late Cretaceous Moroccan pterosaur bits and pieces and… then discuss the mass extinction of pterosaurs at the end of the Cretaceous.

From the abstract
“At least 3 families — Pteranodontidae, Nyctosauridae, and Azhdarchidae — persisted into the late Maastrichtian. Late Maastrichtian pterosaurs show increased niche occupation relative to earlier, Santonian-Campanian faunas and successfully outcompeted birds at large sizes. These patterns suggest an abrupt mass extinction of pterosaurs at the K-Pg boundary.”

That’s all well and good.

Unfortunately the authors (#1)
spread the traditional myth, “Pterosaurs were winged cousins of the dinosaurs.” This has never been shown to be true without taxon exclusion. Earlier we discussed the professional ramifications (enforced retraction) of mislabeling specimens here.

Unfortunately the authors (#2)
provided a patchy cladogram of pterosaur relations (Fig. 1, click to enlarge) that was strong on scrappy specimens and weak on complete specimens. The authors provide no outgroup taxa. The authors omitted several dozen pertinent pterosaur taxa, including a variety of Scaphognathus and Dorygnathus specimens that lead to four origins for the pterodactyloid-grade (Peters 2007). Then they held on to invalidated interpretations that were originally presented for their headline value. For instance, the scraps that Andres et al. 2014 used to create Kryptodrakon as a basal pterodactyloid-grade pterosaur, were in reality just another Sericipterus (a slender dorygnathid from the same formation).

Figure 1. Click to enlarge. The Longrich, Martill and Andres cladogram, colors added to show differences with the LPT.

Figure 1. Click to enlarge. The Longrich, Martill and Andres cladogram, colors added to show differences with the LPT.

By contrast,
the large pterosaur tree (LPT, Fig. 2) is strong on complete specimens and tends to avoid scrappy material that is too easily misinterpreted (based on the Andres example above). The LPT employs 250 taxa, including several outgroup taxa. The LPT recovers four pterodactyloid-grade clades following a transitional series of tiny taxa omitted by Longrich, Martill and Andres. The authors cherry-picked taxa, which is never to be encouraged.

Figure 1. LPT with pterosaurs colorized according to geography.

Figure 2. LPT with pterosaurs colorized according to geography. Click to see the 2020 cladogram which includes 250 taxa.

Why no pterosaurs crossed the K-Pg boundary.
Earlier we looked at the real reason.  In short, there were no tiny pterosaurs. Hummingbird-sized pterosaurs were the only ones that produced descendants after the Late Jurassic faunal turnovers (Peters 2007). This topic was ignored or avoided by Longrich, Martill and Andres who avoided discussing tiny Solnhofen pterosaurs in a phylogenetic context. Traditionally these hummingbird-sized taxa are considered juveniles, but that can’t be true because they are morphologically distinct and adding them to analyses nests them as transitional taxa. Instead, Longrich, Martill and Andres 2018 cherry-picked and omitted large swathes of taxa and thereby completely missed the validated observation that phylogenetic miniaturization gave rise to four distinct pterodactyloid-grade clades arising in parallel in the Late Jurassic.

The question you should ask yourself is this:
if the tables were turned, and the professionals employed all the best known taxa, avoided the scrappy material, and in the process recovered the LPT, what would you think of some outsider who cherry-picked taxa, avoided pertinent complete fossils just because they were small and provided no pterosaur outgroups?

As mentioned earlier,
the lecture and textbook incomes for professional paleontologists are protected by ignoring taxa that upset the status quo. That’s a little short-sighted because once accepted the new validated and comprehensive status quo would not have to be protected again in perpetuity.

Andres B, Clark J and Xu X 2014.The Earliest Pterodactyloid and the Origin of the Group. Current Biology. 24: 1011–6.
Longrich NR, Martill DM and Andres B 2018.
 Late Maastrichtian pterosaurs from North Africa and mass extinction of Pterosauria at the Cretaceous-Paleogene boundary. PLOS Biology. 16 (3): e2001663.
Peters D 2007. The origin and radiation of the Pterosauria. In D. Hone ed. Flugsaurier. The Wellnhofer pterosaur meeting, 2007, Munich, Germany. p. 27.



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