Skiphosoura bavarica enters – then exits the LPT

Hone et al 2024 reported
on a complete, but disarticulated Late Jurassic German pterosaur, Skiphosoura bavarica (Fig 1) “that helps bridge the gap between current intermediate pterosaurs and the pterodactyloids.” The specimen is curated by the Lauer Foundation: LF 4157.

This is not the first time such claims of transitional forms have been made.

Unfortunately the authors did not realize the pterodactyloid-grade was achieved 5 times by convergence in the large pterosaur tree (LPT, 263 taxa) going back to Peters 2007.
Adding taxa makes this clear.

IMHO there’s a better headline for this specimen. See below.

The authors borrowed
a previous dataset/cladogram from Pegas 2024, which was hobbled by taxon exclusion. Borrowing also involves an element of trust. Pterosaur experts should build their own LPT – and make it as complete as possible.

The authors created a freehand reconstruction
of Skiphosoura bavarica (Fig 1). This is usually not a good idea. See below for ramifications. Better to use DGS methods to assure accuracy.

The authors nested
Skiphosoura bavarica four nodes more primitive than the traditional, but invalid clade, “Pterodactyloidea”.

More accurately then, the new pterosaur – precedes – the current intermediate pterosaurs leading to ‘pterodactyloids’ in their cherry-picked world view. It fills no gaps.

As mentioned above, the former clade “Pterodactyloidea” was invalidated in Peters 2007 by adding previously omitted taxa. Since then the former clade has been a grade.

When added to the LPT
Skiphosoura nested with Jianchengopterus (Fig 2) and the STM 19-59 specimen (Fig 2) then considered to be a Kunpengopterus juvenile nesting apart from Kunpengopterus in the LPT. Jianchengopterus is not mentioned in the authors’ text, nor listed on their cladogram.

Do you see the headline yet? See below.

With
Skiphosoura the LPT recovered 1200 trees.

Without
Skiphosoura the LPT recovered just 8 trees. So the drawing (Fig 1) likely contains several errors, perhaps based on rebuilding scattered parts, including tiny parts. We won’t know what those errors are unless the disarticulated specimen bonebed is made available to replicate the reconstruction using more precise DGS methods. And even then it may be impossible.

That’s why Skiphosoura cannot remain in the LPT, except as one of the ‘red’ taxa.

From the abstract:
“For over a century, there was a major gap in our understanding of the evolution of the flying Mesozoic reptiles, the pterosaurs, with a major morphological gap between the early forms and the derived pterodactyloids.”

No such gap exists in the LPT, which tests more and more complete taxa.

“Recent discoveries have found a cluster of intermediate forms that have the head and neck of the pterodactyloids but the body of the early grade, yet this still leaves fundamental gaps between these intermediates and both earlier and more derived pterosaurs.”

Again, this assumes the validity of the former clade, “Pterodactyloidea.” The authors are holding on to a flea-bitten, bed-time blanket they need to discard.

“Here, we describe a new and large Jurassic pterosaur, Skiphosoura bavarica gen. et sp. nov., preserved in three dimensions, that helps bridge the gap between current intermediate pterosaurs and the pterodactyloids.”

The authors made up a non-existing problem, perhaps for a splashier headline (see ‘Publicity’ below.

In the old days (prior to the Internet) a paper would just come out without such claims because only a few people on the planet were interested – and I met nearly all of them at symposia a few decades ago. Post Jurassic Park that list has gotten longer, and so has the number of authors listed on each paper.

“A new phylogeny shows that there is a general progression of key characteristics of increasing head size, increasing length of neck and wing metacarpal, modification to the fifth toe that supports the rear wing membrane, and gradual reduction in tail length and complexity from earlier pterosaurs into the first pterodactyloids.”

With freehand drawings and cherry-picked taxa, that’s easy to do.

“This also shows a clear evolution of the increasing terrestrial competence of derived pterosaurs.”

Does it? None of the images show the pterosaur on the ground. For the mythological backstory on pterosaur terrestrial competence see this recent blogpost.

“Furthermore, this closes gaps between the intermediates and their ancestors and descendants, and it firmly marks the rhamphorhynchines and ctenochasmatid clades as, respectively, being the closest earliest and latest groups to this succession of transitional forms.”

I kind of know what the authors are trying to say here, but it’s just not so, unless a long list of taxa are omitted, which is what they have done.

And that, kids, is how you get published in the Post-Jurassic Park era.

David Hone was the lead author on this paper.
He assigned a co-author to build the reconstruction. He borrowed a cladogram. The word ‘gap’ appears 5 times in this abstract, which is odd since Skiphosoura does not fill any recognized gaps neither in their own cladogram nor in the LPT.

What’s the better headline here?
‘A Chinese fossil pterosaur has been found in Germany.’

First find the fossil.
Then extricate the fossil from the substrate. Then add the fossil to a wide gamut phylogenetic analysis to determine what it is. Don’t shirk this last step. Don’t cherry-pick taxa. Don’t omit pertinent citations. Cover all your bases so you’ll get a glowing report when the fossil is published. You’ll sleep better then.

References
Hone DWE et al (4 co-authors including Mr and Mrs Lauer) 2024. A new and large monofenestrata reveals the evolutionary transition to the pterodactyloid pterosaurs, Current Biology (2024). DOI: 10.1016/j.cub.2024.10.023. www.cell.com/current-biology/f … 0960-9822(24)01377-0
Pegas RV 2024. A taxonomic note on the tapejarid pterosaurs from the Pterosaur Graveyard site (Caiua´ Group,?Early Cretaceous of Southern Brazil): evidence for the presence of two species. Hist. Biol. 1–22.
https://doi.org/10.1080/08912963.2024.2355664.
Peters D 2007. The origin and radiation of the Pterosauria. In D. Hone ed. Flugsaurier. The Wellnhofer pterosaur meeting, 2007, Munich, Germany. p. 27.

Publicity
phys.org/news/2024-11-fossil-reveals-evolution-flying-reptiles

“It’s a superb illustration of the evolution of a group for which the transition has been far from clear before.”

“Both Dearc and Skiphosoura are unusually large for their time, also suggesting that the changes that enabled the pterodactyloids to reach enormous sizes were appearing even in these transitional species.”

“Dr. David Hone, from Queen Mary University of London, said, “This is an incredible find. It really helps us piece together how these amazing flying animals lived and evolved. Hopefully, this study will be the basis for more work in the future on this important evolutionary transition.”

“René Lauer of the Lauer Foundation said, “The specimen was disarticulated with bones of varying quality often overlaid upon one another. Digital photography of the specimen taken in both visible and UV light significantly aided in the process to identify these elements and to better analyze finer details that were not discernible in normal daylight alone.”

“Bruce Lauer of the Lauer Foundation said, “The Lauer Foundation is proud to have the opportunity to bring this important specimen to science and further the understanding of pterosaur evolution.”

“Stefan Selzer, an author on the project who prepared the specimen, said, “As a preparator I have worked on more than 60 pterosaur specimens from Solnhofen limestone. I recognized during the final prep this specimen showed features that combined characteristics of both major groups of pterosaurs, with the shortened tail as the most important diagnostic feature.”

Source: https://pterosaurheresies.wordpress.com/2024/11/19/skiphosoura-bavarica-enters-then-exits-the-lpt/