Pterosaurs NOT an enigmatic group, contra Belben and Unwin 2019

The following abstract
was presented during the most recent SVPCA meeting in 2019.

Belben and Unwin 2019
are both associated with the University of Leicester. Sadly, Dr. Unwin has been responsible for many of the inaccurate to totally wrong ideas many current pterosaur workers and artists now consider as canon. Think Sordes and the deep chord bat-wing membrane stretching to the ankles hypothesis and the incorporation of pedal digit 5 into the single uropatagium stretching between the two. Think pterosaur eggs laid deep under brush or under ground. Think the archosaurian genesis for pterosaurs. Think the Monofenestrata hypothesis of relationships.

I’ll break down today’s abstract for you
as yet another example of Dr. Unwin stuck in his own groove outside of science and reality, much of it due to inaccurate observation and taxon exclusion, both of which are curable maladies.

From the Belben and Unwin 2019 abstract:
“Quantitative taphonomy [see below for definition] has huge potential for furthering our understanding of vertebrate palaeobiology. So far, however, it has been a neglected field with little development. Here we show how quantitative taphonomy can be used to determine the ‘bauplan’ of pterosaurs.

With well over 250 good fossils, many complete skeletons, some of these with extensive soft tissue, we already know the ‘bauplan’ of pterosaurs very well (Fig. 1). Start here for an introduction and links.

“With no descendants and a unique morphology, pterosaurs remain an enigmatic group despite a high degree of research interest for over 200 years.”

Pterosaurs do not have a unique morphology, nor are they an enigmatic group. Peters 2000a b, 2002, 2007, 2009 showed the pterosaur ‘bauplan’ arose gradually from a clade of taxa Dr. Unwin refuses to recognize, the Fenestrasauria, nor does he cite the above references. Dr. Unwin prefers to keep his objects of study in the ‘enigmatic’ jar for reasons that should baffle any reputable scientist. If you wonder why I have to self-cite, welcome to the world of paleo politics where academics don’t argue against a hypothesis, they don’t cite it.

“One aspect still debated is the basic construction and extent of the wing membrane, fundamental to locomotory abilities and other key aspects of their biology.”

The wing membrane question was settled over a decade ago and need not be debated because every example of pterosaur wing membrane presents the same conservative pattern: stretched between elbow and wing tip with a fuselage fillet. (Peters 2002). Precursor membranes are known in Cosesaurus (Peters 2009) and are less obvious in Longisquama. The pteroid and preaxial carpal arise from a migration of two centralia (Peters 2009). Details summarized here.

“Did the wing membrane connect all four limbs, bat-like, forming a single flight surface and single anatomical module? Were they bird-like, with separation of limbs to create four anatomical modules? Or were they a unique two or three module construction?”

This has never been a question for Dr. Unwin before. He has always promoted the invalid bat-like wing design and the invalid single uropatagium design.

Click to animate. This is the Vienna specimen of Pterodactylus, which preserves twin uropatagia behind the knees.

Figure 1. This is the Vienna specimen of Pterodactylus, which preserves twin uropatagia behind the knees and a precise impression of the wing membranes as they were. The animation extends the limbs into the flight configuration.  

“Soft tissue evidence is patchy and found in only a tiny number of species, and the insights it provides is limited.”

False. Dr. Unwin knows better. There are many excellent examples of soft tissue only one of which (Fig. 1) would be necessary to answer the wing membrane and uropatagia issues. The rest confirm the first (Peters 2002).

“Quantitative taphonomy, through metrics of completeness, articulation, and joint geometry, can test limb association, and help identify anatomical modules.”

Dr. Unwin, why don’t you stop avoiding the number one issue and just once accurately trace your first pterosaur specimen with soft tissue. Study it. Play with it. Reconstruct it. Animate it. Score it for a wide range of traits against all the 240 best known pterosaur specimens, as shown here. I think you’ll find the process enlightening and you’ll finally be able to teach your students something about your favorite subject without cloaking pterosaurs in question marks. Don’t be seen as the bumbling professor who held back pterosaur research for several decades by sticking to your invalid postulates. When the word gets out, you may find it hard attracting students, which is your livelihood.

Examining the quantitative taphonomy (= depositional setting, = everything but the pterosaur itself) only delays the inevitable day of reckoning when you will have to finally, seriously and precisely trace a pterosaur specimen and present your findings for critical review.

“Over 100 pterosaurs have been analysed thus far, with an intended data set of 200+ individuals from more than 40 species representing all principal clades. This will allow different models to be mapped across the phylogeny.”

Are you examining the quantitative taphonomy of 200+ individuals or the 200+ individuals themselves? Sounds like the former is in play. Please don’t attempt to map the different taphonomic models across your incomplete cladogram to find out what a pterosaur ‘bauplan’ is. Instead, start with the Vienna specimen of Pterodactylus (Fig. 1). Get precise with it. Don’t pass the chore down to a grad student seeking approval and fearing for their grade. Use the large pterosaur tree (LPT, 240 taxa) for sister taxa. Trace and reconstruct your own specimens. You can pull yourself out of your self-inflicted academic muck!

“Fossil birds and bats will be similarly analysed in order to provide context and constrain the models, as their bauplan can be safely inferred from extant forms.”

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.

That’s nice. But birds and bats are not related to pterosaurs nor to each other. Why not stop wasting your time and go see Cosesaurus, Sharovipteryx and Longisquama. Don’t forget Langobardisaurus, Macrocnemus and Huehuecuetzpalli. Don’t stop until you can reconstruct and score them in your sleep. Dr. Unwin, you’re stuck in the tail-dragging dark ages. You’re supposed to be a pterosaur expert, so quit calling them enigmas. You need to turn your mind around. The following citations might help.

Belben R and Unwin D 2019. Quantitative taphonomy – they key to understanding the pterosaur bauplan?
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. – Historical Biology 15: 277–301.
Peters D 2007. The origin and radiation of the Pterosauria. In D. Hone ed. Flugsaurier. The Wellnhofer pterosaur meeting, 2007, Munich, Germany. p. 27.
Peters D 2009. A reinterpretation of pteroid articulation in pterosaurs. Journal of Vertebrate Paleontology 29:1327-1330.

Quantitative taphonomy = “This approach uses the hypothesis that taphonomic alteration varies in a predictable way with depositional setting. In other words, each specific environment (e.g., low-salinity muddy bay, storm-dominated clastic shelf) is characterized by a unique suite of physical, chemical and biological processes: these processes imprint a unique and predictable “taphonomic signature” on the death assemblage.” Davies et al.  2017


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