Where do we stand on the origin of pterosaurs today?

For most of the last 200 years,
all hypotheses of tetrapod interrelationships had to await novel and random discoveries as the number of known fossil taxa slowly accumulated over time. Expertise, persistence, access to the literature, access to fossil-bearing localities, teamwork and luck all played equal parts in helping this list to grow.

Nowadays in 2020,
we’re sitting on top of two centuries of discoveries preserved in museums, private collections and the literature. So figuring out the ancestors and sisters of any genus no longer depends on access to fossil-bearing localities, luck or teamwork. With persistence and access to the literature anyone can assemble a large taxon list, couple it with a large trait list, and recover a cladogram of tetrapod interrelationships using available software. Larger taxon lists are better because that minimize taxon exclusion, the number one problem with smaller studies.

Figure 3. The origin of pterosaurs now includes Kyrgyzsaurus, nesting between Cosesaurus and Sharovipteryx.

Figure 1. The origin of pterosaurs now includes Kyrgyzsaurus, nesting between Cosesaurus and Sharovipteryx.

Back in 2011
PterosaurHeresies started with a 3-part review of pterosaur origins here, here and culminating here.  Peters 2000a, 2000b, 2002, 2007, 2009 and 2011 (plus a suppressed manuscript correcting earlier errors at ResearchGate.net), solved the problem of pterosaur origins and wing genesis. No new discoveries were required. Taxon inclusion neatly resolved the problem. That’s all it took… adding previously omitted taxa.

even in the present era of phylogenetic analysis by software (~1990 to the present), many pterosaur ‘experts’ continue to shrug their shoulders when the subject of pterosaur origins comes up (examples below). And they don’t really care about the genesis of pterosaurs either. If they did care, they would be running analyses that recover last common ancestors.

Ignoring the literature,
the PhDs are all still waiting for the discovery of an imaginary archosaur with a long fourth finger and a long fifth toe. For reasons unknown, the experts are overlooking the fact that archosaurs don’t have a long fourth finger or a long fifth toe. Even so, this ‘waiting for specimens’ tradition continues unabated in professional circles. Instead they should be looking for the last common ancestor of pterosaurs and its relatives among known fossil and extant taxa. Look here for an example cladogram that covers such a wide gamut of taxa that taxon exclusion is minimized: the large reptile tree (LRT, 1697+ taxa).

The imaginary dinosaur-pterosaur connection
is taught at all paleo universities. It is found in all college textbooks and popular books written by PhDs. It is repeated over and over in YouTube videos (see below). If you’re a paleo student and you want a passing grade, you have to give that answer to the professor, class after class, decade after decade, perpetuating the myth.

Given that the solution to pterosaur origins
has been in the peer-reviewed literature for the last 20 years, it’s almost comical how pterosaur workers dance around the question, “Where do pterosaurs come from?”.

“We don’t know,” is the most common answer.
The 20-year-old published hypothesis of pterosaur origins (Fig. 1, Peters 2000) continues to be ignored. That hypothesis was first labeled, “heterodox“(= different). Other PhDs (e.g. Mark Witton) labeled the author a crank. Still other PhDs (e.g. Darren Naish) attempted to divert the world away from solutions published online.

The more interesting quandary, however,
is the continuing predicament the PhDs have gotten themselves into and how it will continue indefinitely. Apparently there is just no way pterosaur workers are ever going to admit that an outsider solved the problem of pterosaur origins using the most common tool of the trade, phylogenetic analysis.

Apparently there is just no way any PhD or grad student is going to observe the specimens and repeat every aspect of the experiment that resulted in the 2000 solution to pterosaur origins. No one wants to be the second person to discover something, especially after it has been attacked from all sides or ignored for the last twenty years. Any move PhDs make now will make them all look bad. Not making any move also makes them look bad. They have a job to do. They should do it.

Pterosaur workers continue to ignore the pertinent taxa and omit the pertinent citations in favor of a myth (that pteros are dino cousins), even though they also loudly confess they have no evidence for support of that hypothesis. Often phytosaurs show up just outside the Pterosauria when fenestrasaurs are omitted or poorly scored.

In the following short video from 2009
watch German pterosaur experts Gunther Viohl and Peter Wellnhofer undercut previously published studies on pterosaur origins by remarking, the ancestors are not known” and “in fact, it is a mystery which group of reptiles prior to the Triassic, might have given rise to the pterosaurs. So we don’t actually have the ancestor to the pterosaurs in the fossil record.”

The delighted Creationist narrator is then free to claim,
“No transitional forms have been found showing a ground lizard slowly changing into a flying reptile. There are no fossils of a ground reptile with partially developed wings. All of the known pterosaur fossils are perfectly developed.”

we do know of several ground lizards slowly changing into a flying reptile (Figs. 1, 2). They were re-described by Peters 2000 (see ResearchGate.net for additions and corrections).

Figure 1. Click to enlarge. The origin of the pterosaur wing and the migration of the pteroid and preaxial carpal. A. Sphenodon. B. Huehuecuetzpalli. C. Cosesaurus. D. Sharovipteryx. E. Longisquama. F-H. The Milan specimen MPUM 6009, a basal pterosaur.

Figure 2. Click to enlarge. The origin of the pterosaur wing and the migration of the pteroid and preaxial carpal. A. Sphenodon. B. Huehuecuetzpalli. C. Cosesaurus. D. Sharovipteryx. E. Longisquama. F-H. Bergamodactylus, MPUM 6009, a basal pterosaur.

Hone and Benton 2007, 2008 had high hopes
when they decided to test the results of Peters 2000 (Cosesaurus and kin as pterosaur ancestors) against the results of Bennett 1996 (Scleromochlus as a pterosaur ancestor). In their two-part paper Hone and Benton used the Supertree Method. It joins previously published cladograms, trusting their accuracy without observing specimens firsthand. Dr. Benton may have been waiting for a student interested in pterosaurs for several years because Benton 1999 agreed with Bennett 1996 in suggesting Scleromochlus was a pterosaur ancestor. Both ignored the fact that Scleromochlus had vestiges for finger 4 and toe 5, among dozens of other invalidating traits. Peters 2000 introduced better candidates and showed both PhDs were wrong by testing more taxa in four separate phylogenetic analyses based on prior studies, including Benton 1999 and Bennnett 1996.

Problems arose for Hone and Benton when their supertree results recovered Cosesaurus and kin as pterosaur ancestors. Rejecting this result, Hone and Benton dropped all data and reference to Peters 2000 and gave Bennett 1996 credit for coming up with both competing views. They had the bullocks to ignore the premise of their experiment, perhaps thinking their status as PhDs would save them. So far it has. Most of the rest of the paleo community has silently witnessed this odd turn of events without raising an objection or pointing a finger. Only Bennett 2012, 2013 reported the mistakes reported by Hone and Benton were of their own doing. Even so, Bennett 2012, 2013 continued to ignore taxa proposed by Peters 2000. Strange. Why put blinders on?

David Hone at his blogsite
ArchosaurMusings reports, “To cut a long story short, pterosaurs are damned difficult to place in the reptile tree. The truth of the matter is that currently the best supported hypothesis is that pterosaurs derived from the dinosauromorphs and thus are very close relatives of the dinosaurs.” Actually it’s not ‘damn difficult’. It simply takes more taxa. By the way, ‘the best supported hypothesis’ is not the best supported hypothesis. Rather it’s the one they teach at university, the one that omits Peters 2000.

The American Museum of Natural History
is likewise culpable. In the following video watch pterosaur expert, Alex Kellner, and Museum Director, Mark Norell, tell you pterosaurs are dinosaur relatives. But you’ll never see evidence of that because they don’t have it. It’s a traditional myth they cling to due to peer group pressure, not science.

Venerable PBS
became a frenemy of pterosaurs with the following video that omits the actual evolution of wings in favor of the traditional myth. Sadly, the promise of the headline is not fulfilled in the video.

Likewise, in the ‘It’s Okay to Be Smart’ video
Mike Habib perpetuates the archosaur origin myth. He also promotes an invalid, impossible and dangerous quad-catapult take-off technique (Fig. 3) rather than leaping and flapping at the same time for maximum thrust from the first nanosecond (Fig. 4) as birds do. He also promotes the invalid hypothesis of giant pterosaur flight.

Unsuccessul Pteranodon wing launch based on Habib (2008).

Figure 3. Unsuccessful Pteranodon wing launch based on Habib (2008) in which the initial propulsion was not enough to permit wing unfolding and the first downstroke.

Successful heretical bird-style Pteranodon wing launch

Figure 4. Successful bird-style Pteranodon wing launch in which the already upraised wing provides the necessary thrust for takeoff from moment one. This assumes a standing start and not a running start in the manner of lizards and some birds. Note three wing beats take place in the same space and time that only one wing beat takes place in the hazardous Habib model (Fig. 3).

Good scientists observe and report.
Then other good scientists repeat the experiment again and again to make sure the hypothesis is correct, rectifying errors as they appear. Sadly, that’s not what we observe among pterosaur workers.

Taxon exclusion is a powerful tool.
Some of you might remember when I was able to nest pterosaurs with turtles by taxon exclusion and again retested when more taxa were present. False positives are possible when using small taxon lists.

I never imagined
pterosaur workers would end up avoiding and suppressing a valid hypothesis in favor of a myth they admit they cannot support with evidence. Twenty years later there are still no competing papers on pterosaur origins that include accurate scoring for taxa in the Fenestrasauria and Tritosauria. This could still be a hot topic, but, no one is interested in finding out how pterosaurs got their wings anymore. Their preferred answer continues to be, “We don’t know.” The unspoken takeaway is,”and we’re not even going to try to find out because the status quo has been working for us.

Bennett SC 2008. Morphological evolution of the forelimb of pterosaurs: myology and function. Pp. 127–141 in E Buffetaut and DWE Hone eds., Flugsaurier: pterosaur papers in honour of Peter Wellnhofer. Zitteliana, B28.
Bennett SC 1996. The phylogenetic position of the Pterosauria within the Archosauromorpha. Zoolological Journal of the Linnean Society 118: 261–308.
Benton MJ 1999. Scleromochlus taylori and the origin of the pterosaurs. Philosophical Transactions of the Royal Society London, Series B 354 1423-1446. Online pdf
Bennett SC 2012. The phylogenetic position of the Pterosauria within the Archosauromorpha re-examined. Historical Biology. iFirst article, 2012, 1–19.
Bennett SC 2013. The phylogenetic position of the Pterosauria within the Archosauromorpha re-examined. Historical Biology 25(5-6): 545-563.
Elgin RA, Hone DWE and Frey E 2011. The extent of the pterosaur flight membrane. Acta Palaeontologica Polonica 56 (1), 2011: 99-111. doi: 10.4202/app.2009.0145
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2 thoughts on “Where do we stand on the origin of pterosaurs today?

  1. As Darren Naish once typed.”When will you stop”. Also, this piece is really helping me dissect the mess of pterosaur taxonomy and the lack of convergent evolution in the analysis of this, and make an article about it.

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