SVP abstract – 16 : on water launch in Nyctosaurus

Monday, November 14, 2022 21:17

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Welch and Habib 2022 report:
“Nyctosaurid pterosaurs have previously been interpreted as rapid-soaring specialized pelagic animals.

I have never heard the term ‘rapid’ associated with nyctosaurids or pterosaurs.

Figure 1. The clade of Nyctosaurus. Click to enlarge. Lacking here are partially known taxa.

Welch and Habib 2022 continue:
However, there have been limited efforts to quantitatively validate these interpretations. Using a composite reconstruction of Nyctosaurus, we applied a numerical modeling approach to test existing interpretations of the in-flight behavior of this unusual pterosaur taxon, as well as to investigate its potential launch performance from both land and water.

There is no need to create “a composite reconstruction of Nyctosaurus.” Several are complete or nearly so (Fig 1). Each one is different. Which ones did the authors rebuild like a Frankenstein monster?

Unfortunately, Mike Habib was caught cheating Santandactylus anatomy when he first came up with the untenable, but popular hypothesis of the quad launch (Fig 2), which you can read all about here.

Figure 2. Errors in the original Habib/Molnar reconstruction of the pterosaur manus

Then Habib cheated again in a Scientific American cover story (Fig 3), this time lengthening the free fingers, but also mis-locating them on top of the axially rotated wing metacarpal in order to plant the wing metacarpal and phalanx on the ground to stretch a tendon between them building up to a catapult, like a grasshopper leg or a flea leg. No manus impressions ever show anything more than the three free fingers. Habib was young and new to paleontology then. That doesn’t excuse cheating anatomy to get what you want.

Figure 3 Quad launch hypothesis from Habib’s SciAm article. He cheats the position of metacarpals 1-3 and does not show what happens after the leap. Habib’s hypothesis depends on wing finger contact with the substrate. Tracks and anatomy show this never happens.

Welch and Habib continue:
“We relate our flight performance analysis to previously reconstructed conditions around the ancient Western Interior Seaway (WIS) to elucidate details of the likely ecology of Nyctosaurus. To account for uncertainty in wing shape and total mass in our Nyctosaurus reconstruction, we built five models with varying wing dimensions and body mass.

While no nyctosaurs preserve wing membranes, all other pterosaurs share the same narrow chord bauplan. Five models are not necessary — unless Habib is attempting to cheat for a third time Figs 2, 3). His models (Fig 3) follow the invalid bat-wing deep-chord membrane myth based on misinterpretation of Sordes and workers who claim ‘shrinkage‘ (Elgin, Hone and Frey 2011) when they encountered evidence for a narrow wing chord.

Figure 4. The UNSM 93000 specimen of Nyctosaurus in dorsal view. Wing extension and flexion is animated here.

Welch and Habib continue:
“Published span-to-mass relationships for pterodactyloids were used to estimate a baseline mass.

Borrowing data from other sources relieves these authors from 1) doing the work themselves; 2) taking responsibility for results.

“Our numerical models take into account known relationships between wing shape, body mass, fluid density, lift generation efficiency, and flapping kinematics.

Since these authors confess they have no idea which of their five wing shapes is correct, how can the numbers they generate have any accuracy or relevance? Especially since they said they were building a composite model from several specimens.

“We incorporated recently published water launch models for a pterosaur “quadrupedal water launch”.

More fantasy (Fig 5) won’t help.

Figure 5. GIF animation from the American Museum of Natural History showing how their Pteranodon managed to hop off the surface of the water until suddenly able to flap and fly. Totally bogus.

Welch and Habib continue:
“Our median model (for both body mass and aspect ratio) estimated steady state stall speeds of 7.4 m/s and steady cruising speeds near 11.00 m/s. Heavier mass versions would fly even faster. At a launch angle of 55 degrees from horizontal launch times ranged from a minimum of 0.04 s to 0.08s with vertical velocities of a minimum 4.09 to 7.27 m/s. Thanks to the highest aspect ratio estimated for any pterosaur (at least 18), Nyctosaurus was exceptionally efficient at extracting energy while soaring.

Finally, something that makes sense. But this is not news. This is widely assumed based on convergent proportions in extant sea birds.

“Our estimates of minimum sink ranged from 0.15 to 0.22 m/s – low enough to rise even in weak ocean thermals. These results suggest a relatively fast soaring animal, which could indicate gust-soaring specialization. However, performance in large diameter thermals was also excellent. Geologic evidence from turbidites in the Niobrara formations suggest that the WIS experienced regular storms. The warm conditions and relatively shallow depth would have been ideal for marine thermal production. These habitat data, combined with our results, suggest a paleoecology for Nyctosaurus that included both gust flying and thermal flying, switching based on conditions. These results help us bring together a more detailed image of the flight mechanisms and life history of Nyctosaurus in the late Cretaceous.”

Not really. All this is traditional thinking. Pterosaurs fly and pelagic taxa soar. Disney showed us how that worked in Fantasia (1940).

Figure 6. Unsuccessful Pteranodon wing launch based on Habib (2008) in which the initial propulsion was not enough to permit wing unfolding and the first downstroke.

Figure 7. Successful bird-style Pteranodon wing launch in which the hind limbs produce far less initial thrust because the first downstroke of the already upraised wings provides the necessary thrust for takeoff in the manner of birds. This assumes a standing start and not a running start in the manner of lizards. Note three wing beats take place in the same space that only wing wing beat takes place in the widely accepted wing launch model of Habib (2008).

I should not be the only way objecting to
those who cheat and ignore anatomy to further their pet hypotheses. Habib has been flogging this idea for 12 years (Habib 2008), but then again, he is a PhD, a made man.

References
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Welch I and Habib MB 2022. From sea to sky: water launch and soaring performancei n the Late Cretaceous pterosaur, Nyctosaurus. SVP abstracts: 359.
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