150 million years of pterosaur flight efficiency

Venditti et al. 2020
attempts to chronicle an increase in pterosaur flight efficiency over their 150 million year long clade span.

From the Venditti et al. abstract:
“The long-term accumulation of biodiversity has been punctuated by remarkable evolutionary transitions that allowed organisms to exploit new ecological opportunities. Mesozoic flying reptiles (the pterosaurs), which dominated the skies for more than 150 million years, were the product of one such transition. The ancestors of pterosaurs were small and probably bipedal early archosaurs (Andres et al. 2014), which were certainly well-adapted to terrestrial locomotion.”

Citation and taxon exclusion here. Andres et al. 2014 cherry-picked four euarchosauriform outgroups for the Pterosauria: Euparkeria, Ornithosuchus, Herrerasaurus and Scleromochlus. All of these taxa have a short to vestigial manual digit 4, the opposite of pterosaurs. This list followed the direction of co-author Mike Benton, well known for citation and taxon exclusion to promote his pet hypotheses, invalidated by Peters 2000, 2007, 2009. Readers have seen Benton omissions many times. The actual ancestors of pterosaurs were not archosaurs, but these lepidosaurs: Cosesaurus (Fig. 1), Sharovipteryx and Longisquama. So Venditti et al. 2020 starts off poorly, without a proper phylogenetic context.

By the way, Andres et al.  2014 did not find ‘the earliest pterodactyloid,’ but bits and pieces of a gracile dorygnathid, Sericipterus found in the same formation.

Figure 1. Cosesaurus flapping - fast. There should be a difference in the two speeds. If not, apologies. Also, there should be some bounce in the tail and neck, but that would involve more effort and physics.

Figure 1. Click to enlarge and animate. Cosesaurus flapping – fast. There should be a difference in the two speeds. If not, apologies. Also, there should be some bounce in the tail and neck, but that would involve more effort and physics.

Continuing from the Venditti et al. abstract:
“Pterosaurs diverged from dinosaur ancestors in the Early Triassic epoch (around 245 million years ago); however, the first fossils of pterosaurs are dated to 25 million years later, in the Late Triassic epoch.”

False: Pterosaurs diverged from fenestrasaur ancestors (Peters 2000).

“Therefore, in the absence of proto-pterosaur fossils, it is difficult to study how flight first evolved in this group.”

False. We have those proto-pterosaur fossils and pterosaur ancestors all the way back to Cambrian chordates. Adding taxa resolved this problem in Peters 2000, 2007, 2009 and that continues today.

“Here we describe the evolutionary dynamics of the adaptation of pterosaurs to a new method of locomotion. The earliest known pterosaurs took flight and subsequently appear to have become capable and efficient flyers. However, it seems clear that transitioning between forms of locomotion2,3—from terrestrial to volant—challenged early pterosaurs by imposing a high energetic burden, thus requiring flight to provide some offsetting fitness benefits.”

Or the other way around, as documented by the four fenestrasaurs listed above.

“Using phylogenetic statistical methods and biophysical models combined with information from the fossil record, we detect an evolutionary signal of natural selection that acted to increase flight efficiency over millions of years.”

What is ‘flight efficiency’? Are hummingbirds more efficient? Or are albatrosses? Or ducks? Did the authors use the proper pterosaur wing shape (Fig. 2) ? Or the traditional invalid batwing-shape preferred by those in the Benton arc.

The Vienna Pterodactylus.

Figure 2. The Vienna Pterodactylus. Click to animate. Wing membranes in situ (when folded) then animated to extend them. There is no shrinkage here or in ANY pterosaur wing membrane. There is only an “explanation” to avoid dealing with the hard evidence here and elsewhere.

“Our results show that there was still considerable room for improvement in terms of efficiency after the appearance of flight.”

Without valid outgroups, how do they know? They don’t.

“However, in the Azhdarchoidea4, a clade that exhibits gigantism, we test the hypothesis that there was a decreased reliance on flight5,6,7 and find evidence for reduced selection on flight efficiency in this clade.”

Odd that these authors do not include the many examples of flightless pterosaurs, including derived and sometimes giant members of the Azhdarchidae.  They only say ‘there was a decreased reliance on flight.’

“Our approach offers a blueprint to objectively study functional and energetic changes through geological time at a more nuanced level than has previously been possible.”

There is no ‘blueprint’ here, only more misdirection and mythology. Sad that the works of professor Mike Benton have now become suspect following the present continuation of his long-standing pattern of cherry-picking and taxon exclusion favoring the textbooks and lectures that provide his income.


References
Andres B, Clark J and Xu, X 2014. The earliest pterodactyloid and the origin of the group. Current Biology 24:1011–1016 (2014).
Peters D 2000a. Description and Interpretation of Interphalangeal Lines in Tetrapods.  Ichnos 7:11-41.
Peters D 2000b. A Redescription of Four Prolacertiform Genera and Implications for Pterosaur Phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106 (3): 293–336.
Peters D 2002. A New Model for the Evolution of the Pterosaur Wing – with a twist. Hist Bio 15: 277–301.
Peters D 2009. A reinterpretation of pteroid articulation in pterosaurs. Journal of Vertebrate Paleontology 29: 1327-1330
Venditti C, Baker J, Benton MJ, Meade A and Humphries S 2020. 150 million years of sustained increase in pterosaur flight efficiency. Nature https://doi.org/10.1038/s41586-020-2858-8

From the Nature comments section:
“The ancestors of pterosaurs were recovered twenty years ago (in Peters 2000) by simply adding Langobardisaurus, Cosesaurus, Sharovipteryx and Longisquama to four previously published analyses. Peters (2007) nested these bipedal taxa within the Lepidosauria by once again simply adding taxa. Omitting citations and omitting taxa results in statements like the following found in the Venditti et al. 2020 abstract: “in the absence of proto-pterosaur fossils, it is difficult to study how flight first evolved in this group.” Had the authors included Cosesaurus they would have known this taxon was flapping without flying due to a locked down, stem-shaped coracoid otherwise found only in birds and pterosaurs. Bats flap anchored by an analogous clavicle.”

 

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