‘Primer Pterosaurs 2021’ needs a primer on pterosaurs

Here we go again.
More of the same pterosaur myths promoted by Academia.

A few years ago
Jagielska and Brusatte 2021 presented a ‘Primer Pterosaurs’ that must have been intended for the popular audience. For instance, in the first paragraph of this short heavily illustrated (with freehand cartoons) review of current myths you’ll find this sentence, “The animal fossilised with sprawled arms and jaws agape — as if in shock and disbelief.”

This is a work of fiction masquerading as information.

What makes this paper fictional?
“Pterosaurs are closely related to dinosaurs”

This is the traditional myth professors still teach at universities. After testing in phylogenetic analysis, pterosaurs are fenestrasaur tanystropheid lepidosaurs (Peters 2000, 2007) far from dinosaurs. Jagielska and Brusatte 2021 prefer the myth, not the evidence.

“They are specialised flying reptiles within the archosaur family.”

The archosaur antorbital opening also appears by convergence in Fenestrasauria (Figs 1, 8, 9, Peters 2000) as well as other taxa, including mammals.

“our understanding of pterosaur behaviour and evolution is still in its infancy. The fault mostly lies with the pterosaurs themselves,”

No. The fault lies with the current crop of pterosaur experts who have omitted taxa and citations for over twenty years in order to keep their textbooks from becoming out-of-date.

“As in birds, the pneumatised bones allowed pterosaurs to grow bigger without becoming heavier.”

This is impossible for any object with mass.

“Their primary airfoil, which is observable in some remarkably well preserved fossils, was a skin membrane that stretched between the hyper-elongate fourth finger and the hindlimbs.

This is incorrect. The membranes stretched between the wingtip and elbow, with a fuselage fillet running back to mid thigh (Peters 2002) as all soft tissue pterosaur fossils indicate. No exceptions. Jagielska and Brusatte don’t want you to know this.

“and in some species, there was yet another membrane extending between the legs.”

This is a misidentification of a displaced wing membrane (Peters 1995, 2002).
Jagielska and Brusatte omitted competing citations.

“Their shape was maintained by a network of fibers called actinofibrils, and they could be elegantly folded against the body when not in use.”

‘Elegantly folded’ is not possible unless the wing membrane was stretched only between the wingtip and elbow. Look at any illustration that shows the deep chord membrane. It always sags inelegantly.

“Pterosaurs were incredibly front-heavy, with the head and neck being the longest and most robust body portions, which would have pushed their centre of gravity forward.”

This is true only for the flightless azhdarchid pterosaurs (Fig 5). The volant pterosaurs are well-balanced over their feet directly below the center of gravity at the wing root (Peters 2002, Figs 5, 8), at the shoulder joint, as in birds.

“This has led some researchers to argue that pterosaurs took off via a ballistic jolt forwards and upwards using their forelimbs in what is known as a quadrupedal launch.”

This method (Figs 2, 3) would have led to an inevitable crash because the wings remain folded in this hypothesis until some time in mid-air after the pterosaur has stopped doing the bat-like push-up, then extending its wings, then raising its wings for the first flap, then the first flap for thrust. Much easier, and more bird-like is to stand bipedally, open the wings, raise the wings, then hop and flap into the air at the same moment (Fig 4).

The catapult launch was based on cheating pterosaur hand morphology – putting the wing finger on the ground (Fig 3). Ichnites show this never happened. A second version of the cheat (Fig 3) put the free fingers on top of finger 4. Bizarre. Jagielska and Brusatte accepted anatomical cheating – perhaps because it came from another academic. Professional courtesy? Or fear of being refereed? Either way the same myth was promoted, not tested or critically appraised.

“This is similar to the launch of vampire bats.”

When a vampire bat launched off the ground in this video, it did not take flight the first time. Rather it took a ‘running start’, partly in the air, before coming back to earth then finally extending the wings on the second hop. Instead pterosaurs took off like birds do (Fig 4). Easily and elegantly powered by much longer, narrower rapidly flapping wings together with one ore powerful leap from a bipedal configuration = balanced over its feet.

Another bat takeoff video, this time in a box to limit its travel
shows the bat leaping vertically, then raising its wings, then opening its wings, then flapping great scoops of air downward without any forward motion. Pterosaurs don’t have short, deep-chord, parachute-like wings. They all had long, narrow-chord wings (Peters 2002).

“the enormous azhdarchids had narrow wings with curved tips that reduced
drag when thermally soaring over open habitats.”

Narrow wings? Earlier the authors said, “stretched between the hyper-elongate fourth finger and the hindlimbs.“ You can’t have it both ways. Perhaps the authors meant short wingspan from tip to tip because azhdarchids had the smallest wingspans relative to their overall dimensions. By contrast, they should have the largest wings if they were going to fly. Remember, weight increases by the cube as size increases.  More weight needs more power and more lift. None of this is pertinent, because azhdarchids were flightless front-heavy large to giant pterosaurs.

And that fact enabled them to grow so large and front-heavy. We also know they were flightless because the wings had vestigial distal phalanges = clipped wings, the opposite of what they needed to fly.

“Some, however, are known from dozens of exquisitely preserved skeletons, from hatchlings to adults (like Pterodaustro guinazui and Rhamphorhynchus muensteri).

Pterodaustro hatchlings, juveniles and adults are known (Fig 6). Only one juvenile Rhamphorhynchus has been identified. Smaller specimens with distinct morphologies are phylogenetically more primitive, not younger.

“researchers are not always sure if they are observing true characters of the anatomy or just registering nuances brought about by sex, age, deformation or natural variation.”

The authors don’t understand that hatchlings were identical to adults, only 8x smaller. Isometry is a lepidosaur trait. Allometry is an archosaur trait. No gender differences (other than the presence of an egg or two) have ever been identified in pterosaurs. All attempts have been falsified. Differences are due to phylogeny, not ontogeny.

> The authors’ Figure 3 presents a quadrupedal lagerpetid as ancestral to pterosaurs

This is false 2x. Lagerpetids were bipedal and derived from proterochampsids, not related to pterosaurs and not related to archosaurs including dinosaurs (see above). Jagielska and Brusatte don’t want you to know this.

“A new generation of paleontologists is on the hunt, and we are currently living through a
pterosaur renaissance,”

Actually the new generation is teaching the myth, not the evidence. IMHO they appear to be under the thumbs of the aging professors who control the grant money and curriculum. The new generation want new generic names for new species. They want to fill gaps that don’t exist.

Based on the myths promoted by Jagielska and Brusatte these days are still the dark ages of pterosaurs in terms of understanding what they were and how they flew and grew.

“One of the biggest mysteries of pterosaur evolution is its very start.”

Case in point: Peters 2000, 2009 described several pterosaur ancestors recovered after several phylogenetic analyses. Authors Jagielska and Bruseatte appear loathe to recognize this published discovery and any other published works by this independent author.

“These  are not [= There are no?] transitional species, capturing an in-between stage of evolution when a Triassic reptile was morphing into a pterosaur.

Peters 2000, 2009 described several pterosaur transitional species.
You can read about them here and here and here and here.

“Unlike the dinosaur– bird evolutionary transition, we are missing a pterosaur equivalent of
Archaeopteryx,”

This is wrong. We have Langobardisaurus, Cosesaurus, Sharovipteryx and Longisquama (Figs 8, 9). As Peters 2002 documented, the wings came last, as in birds. Jagielska and Brusatte don’t want readers to know this.

“The lack of remains of early pterosaur ancestors is not surprising. They probably were small, light and inhabited terrestrial environments,”

This description generally, but accurately describes the above four taxa in the lineage of pre-pterosaurs (Peters 2000, Figs 8, 9). This description does not match any lagerpetid (Fig 7) or dinosaur ancestor, all of which are larger taxa.

“These lagerpetids show similar jaw, dentition and hind limb anatomy to pterosaurs, and they had hooked manual claws, ideal for climbing, and inner ears that provided a keen sense of balance — hinting that pterosaurs might have been tree-dwellers before learning
to fly.”

Too many reptiles have hooked claws and a keen sense of balance. No lagerpetid has multicsuped teeth, as in primitive pterosaurs. The hind limbs of lagerpetids lack toe 5, which, by contrast, is large and metapodial in pterosaurs, identical to those lateral toes found in Langobardisaurus, Cosesaurus, Sharovipteryx and Longisquama… and Tanystropheus. Jagielska and Brusatte don’t have the curiosity to test these taxa.

“With that said, there are no features of the lagerpetid skeleton that indicate any gliding, flying, or other airborne activities.”

Missing from this list is ‘flapping’. Cosesaurus, Sharovipteryx and Longisquama had flapping traits = elongate locked down coracoids on a bipedal Bauplan, as in birds. And we have the occasionally bipedal Rotodactylus tracks that match the pes of Cosesaurus. Jagielska and Brusatte ignore these solutions.

“Painting in broad strokes, researchers divide pterosaurs by their body plans: non-pterodactyloids — an evolutionary grade of more basal forms, which share a primitive
anatomical bauplan — and pterodactyloids — a monophyletic group, or clade, of more derived pterosaurs that share unique derived characteristics of their anatomy.”

This was falsified by Peters 2007 and confirmed In the large pterosaur tree, which minimizes taxon exclusion by including many more pertinent taxa than any other pterosaur cladogram, the pterodactyloid grade was attained 5x. So it is a grade, not a monophyletic clade. Jagielska and Brusatte cling to this out-dated hypothesis because it is in their textbooks and lecture notes.

“the anurognathids. These wee fliers had short, nimble wings with hooked claws, broad jaws and enormous eyes held in place by sclerotic rings,”

This was falsified by noting Bennett 2007 had misidentified a maxilla as an enormous sclerotic ring. The actual eye rings were smaller and set in the usual place, in the back half of the skull. Details here.

“and their bodies were covered in branching, hair-like pycnofibers that  may share a deep homology with the feathers of dinosaurs and birds.”

Pycnofibers are also found in Cosesaurus, Sharovipteryx and Longisquama. These omitted taxa are tanystropheid lepidosaurs, not related to dinosaurs and birds.

“Pterodactyloids differ substantially from their basal relatives: the long decorative tail is gone, replaced by a short stud,”

Not always (Figs 10, 11). Try not to generalize with pterosaurs.

“the hindlimbs become sturdier and much more suitable for terrestrial locomotion.”

Not that I’ve seen. Zhenyuanopterus (Fig 11) and other ornithocheirids had tiny feet.

“Pterosaurs switched from widespread generalists into localized specialists.”

They were all specialists. Every pterorsaur had its own special trait.

“Azhdarchids… were the largest animals to ever fly.”

No. They were flightless and achieved giant sizes
because they were flightless, as in the biggest birds.

“What we know for sure is that the kids differed substantially from their parents.”

No. Just the opposite. Even hatchlings were identical to parents. When you find differences those are phylogenetic, as demonstrated in the large pterosaur tree.

“we know that young pterosaurs grew rapidly and slowed when reaching nearly adult size. This probably aligned with the time when they reached sexual maturity.”

No. Just the opposite. We know that sexual maturity was reached at half the adult size (Chinsamy et al 2008).

“Nyctosaurus was ill-fitted for walking, to the point where it lost its hands entirely and
greatly reduced its hindlimbs.”

No. The hands = the wings where not lost entirely. They remained quite large, even huge. They were wings. Only the three free fingers were small vestiges on nyctosaurs. [Fingers do not equal hands.] The hindlimbs were not reduced. They just look small compared to those huge hands = wings.

“While preying on fish, they were also attacked by fish. Some excellent fossils show young
Rhamphorhynchuses speared by the ice-pick snout of an intimidating Aspidorhynchus fish.”

No. The rotten corpse of the pterosaur on the anoxic seabed attracted the fish to its doom, where the fish suffocated.

“They were the first vertebrates to achieve the nigh on impossible feat of flight, and achieved it with a style unlike that of any bird or bat.”

“unlike that of any bird“ is a false statment. Evidence indicates pterosaurs developed flapping, then wings, then flight in the same manner and order as in Late Jurassic Solnhofen birds (Peters 2002).

“Pterosaurs lack contemporary analogues and therefore captivate us with their baffling anatomy.”

Birds are pterosaur analogs. Study pterosaurs and their known ancestors. The authors’ baffling will turn to your understanding. Anatomy is only baffling when one ignores the literature that explains the anatomy.

If the authors find pterosaur anatomy baffling, they should not be penning articles on pterosaur anatomy.

Isn’t it odd that an enthusiast from outside Academia has to tell university-level pterosaur experts something about pterosaur anatomy, phylogeny and behavior? Academics refuse to test what they have read in the literature.

Why is this so? Academics understand that they have to toe the academic line (= peer group pressure) because only professors referee manuscripts, not enthusiasts. Rebels are no longer welcome in this decade, whether they come from inside or outside the system.

The authors, Jagielska and Bruseatte, are PhDs
paid to understand pterosaurs. As documented here, they demonstrated the little they do know is sadly overshadowed by the myths they promoted. If they were indeed independent academics they would not omit citations and competing hypotheses, but argue for or against them.

Let this be a cautionary tale for all readers: Stay independent.

References
Chinsamy A, Codorniú L and Chiappe LM 2008.Developmental growth patterns of the filter-feeder pterosaur, Pterodaustro guinazui. Biology Letters, 4: 282-285.
Jagielska N and Bruseatte S 2021. Primer Pterosaurs. Current Biology 31, R973–R992, August 23, 2021.
Peters D 1995. Wing shape in pterosaurs. Nature 374, 315-316.
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.
Peters D 2018. Cosesaurus aviceps, Sharovipteryx mirabilis and Longisquama insignis reinterpreted. ResearchGat.net PDF here.

wiki/Pterosaur

What exactly IS a pterosaur? – part 3 of 3

Pterodaustro isometric growth series

“Why we think giant pterosaurs could fly” (…NOT!)

Source: https://pterosaurheresies.wordpress.com/2024/12/19/primer-pterosaurs-2021-needs-a-primer-on-pterosaurs/