Griffin et al 2024 choose the wrong pterosaur take-off pose – again
You have to feel sorry
for lead author and newly minted PhD, Benjamin W Griffin. He is fulfilling the errant wishes and dreams of his supervisors and co-authors, rather than pursuing his own studies. or perhaps proving them wrong by independent study.
Kids, this is how you get a PhD in paleontology in only 8 years.
For those new to this blogpost, a little backstory:
Pterosaurs were able to become flappers, which led to flight, because they were bipedal. like birds. Despite the fact that many pterosaurs used their forelimbs for ski-poles, all kept their center of balance over their feet, like birds, so they could quickly unfold their wings and start flapping to become airborne (Fig 1), whether with a running start or not.
Successful heretical 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).
” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2011/07/pteranodon-wing-launching3.gif?w=300″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2011/07/pteranodon-wing-launching3.gif?w=584″ tabindex=”0″ role=”button” class=”size-full wp-image-110″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2011/07/pteranodon-wing-launching3.gif” alt=”Successful heretical bird-style Pteranodon wing launch” width=”584″ height=”171″ />
Figure 1. Successful heretical 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).
Over the past decade and a half,
a cadre of workers have promoted the quad-launch hypothesis by cheating pterosaur anatomy (principally by removing the three free fingers (Fig 3) or removing their contact with the substrate (Figs 5, 6), as proven by pterosaur ichnites. In the quad-launch scenario the wings can’t provide thrust and lift until it is too late (Fig 2).
Unsuccessful Pteranodon wing launch based on Habib (2008) in which the initial propulsion was not enough to permit wing unfolding and the first downstroke.
” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2011/07/pteranodon-wing-launching2.gif?w=300″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2011/07/pteranodon-wing-launching2.gif?w=584″ tabindex=”0″ role=”button” class=”size-full wp-image-109″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2011/07/pteranodon-wing-launching2.gif” alt=”Unsuccessful Pteranodon wing launch based on Habib (2008).” width=”584″ height=”171″ />
Figure 2. Unsuccessful Pteranodon wing launch based on Habib (2008) in which the initial propulsion was not enough to permit wing unfolding and the first downstroke.
1. Quoting the Griffin et al 2024 paper,
“Due to the likely inability of the bipedal take-off motions to fully access the larger moment arms of the forelimb without damaging its wings”.
Something is wrong here when the pterosaur cannot flap its wings while standing erect and bipedally, like a bird. Flapping is how pterosaurs started flying back in the Late Triassic.
The word ‘chord’ does not appear in the text. The authors have been traditional adherents to the invalid deep-chord bat-wing membrane hypothesis, not the narrow chord fact observed by Zittel 1882 and later authors in all pterosaurs.
Figure 2. Model ornithocheirid from Griffin et al 2024. Note the lack of the 3 free fingers and feet. Their model cannot work without the wing finger pressing into the substrate. Fossil indicate this NEVER happened.
” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/08/skeleton.anhanguerid.griffin588.jpg?w=290″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/08/skeleton.anhanguerid.griffin588.jpg?w=584″ tabindex=”0″ role=”button” class=”size-full wp-image-88073″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/08/skeleton.anhanguerid.griffin588.jpg” alt=”Figure 2. Model ornithocheirid from Griffin et al 2024. Note the lack of the 3 free fingers and feet. Their model cannot work without the wing finger pressing into the substrate. Fossil indicate this NEVER happened. ” width=”584″ height=”604″ />
Figure 3. Model ornithocheirid from Griffin et al 2024. Note the lack of the 3 free fingers and feet. Their model cannot work without the wing finger pressing into the substrate. Fossil indicate this NEVER happened.
2. The words ‘finger’ and ‘digit’ are not found in the text.
Worse yet, the three free fingers are missing from all models. This recalls Habib’s freshman assertion that the wing finger impressed on the substrate (Figs 5, 6). Ichnites show it never did.
Figure 3. This is also figure 3 from Griffin et al. 2024. Note the only two models that actually take off are bipedal. Scientists should recognize this, and not leave it to amateurs to point this flagrant error out to them.
” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/08/3launches588.gif?w=300″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/08/3launches588.gif?w=584″ tabindex=”0″ role=”button” class=”size-full wp-image-88075″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/08/3launches588.gif” alt=”Figure 3. This is also figure 3 from Griffin et al. 2024. Note the only two models that actually take off are bipedal. Scientists should recognize this, and not leave it to amateurs to point this flagrant error out to them.” width=”584″ height=”413″ />
Figure 4. This is also figure 3 from Griffin et al. 2024. Note the only two models that actually take off are bipedal. Scientists should recognize this, and not leave it to amateurs to point this flagrant error out to them. Those giant flapping wings produced a great deal of thrust and lift.
3. The authors’ figure 3 compares three take-off modes.
Note that only the two bipedal launches result in losing contact with the ground with wings raised. The quad launch image never gets off the ground. That’s an error by the authors.
Quote from the paper’s Introduction:
`Portions of this text were previously published as part of a thesis: https://researchinformation.
bris.ac.uk/ws/files/348718716/Final_Copy_2022_12_06_Griffin_B_W_PhD_
Redacted.pdf
That link does not work. This one does work.
Figure 9. 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.
” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2019/09/habib-quad-launch588.jpg?w=290″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2019/09/habib-quad-launch588.jpg?w=584″ tabindex=”0″ role=”button” class=”size-full wp-image-39076″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2019/09/habib-quad-launch588.jpg” alt=”Figure 9. 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.” width=”584″ height=”605″ />
Figure 5. Quad launch hypothesis from Habib’s SciAm article. He cheats the position of metacarpals 1-3 and does not show what happens after the moment after take-off. The three free fingers are always anterior to the wing finger, as in all other tetrapods with fingers, including birds.
An earlier image of the pterosaur free fingers
(Fig 6 left, click here to enlarge) imagined smaller fingers. This was done without looking at actual pterosaur fossils. A corrected version (Fig 6 right) matches all other pterosaur ‘hands’. Note the wing finger never touches the substrate, as proven by ichnites.
Figure 1. Left: The so-called catapult mechanism in pterosaurs. Right. The actual design of pterosaur (in this case Anhanguera/Santandactylus) fingers.
” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2012/01/catapult-mechanism588.jpg?w=300″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2012/01/catapult-mechanism588.jpg?w=584″ tabindex=”0″ role=”button” class=”size-full wp-image-3774″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2012/01/catapult-mechanism588.jpg” alt=”The so-called catapult mechanism in pterosaurs” width=”584″ height=”263″ />
Figure 6. Left: The so-called catapult mechanism in pterosaurs. Right. The actual design of pterosaur (in this case Anhanguera/Santandactylus) fingers. Click to enlarge.
You might remember
first author Griffin was selected from all applicants to this advert from Bristol U back in 2016:
“The main objective of this proposal is to investigate the effectiveness of the quadrupedal launch [of pterosaurs] and by comparing it with the bipedal launch of birds, test if it was one of the factors that enabled pterosaurs to become much larger than any bird, extant or extinct.” (Fig. 1 – and note: they are not testing the hypothetical quad launch of pteros against the hypothetical bipedal launch of pteros).
Choose to accept this assignment and you will be asked to:
“Create anatomical reconstructions of possible azhdarchid morphologies and using kinematic simulation software to create a simple baseline bipedal launch model, validated against published data for birds and humans and tested for sensitivity to assumptions and modeling detail.”
Your reward for doing so:
“The student will join the large and vibrant Bristol palaeobiology community and receive training in anatomical and computational techniques.”
Main supervisor:
Prof Emily Rayfield
Co-supervisor(s):
Dr Colin Palmer (University of Bristol),
Ms Elizabeth Martin (University of Southampton)
In science, the way it is supposed to be done
we test and observe to see what the results are. We don’t come up with the results first.
Eight years later = 2024,
Griffin’s task is complete to the satisfaction of the supervisors, who are also co-authors. More on this sad state of affairs and the Bristol U assignment here, from 2016.
References
Griffin BW et al (6 co-authors) 2024. Modeling take-off moment arms in an ornithicheiraean pterosaur. PeerJ 12:e17678 http://doi.org/10.7717/peerj.17678
U of Bristol workers cheat pterosaur anatomy again, create a Frankensaur
SVP 2021 abstracts – 17: Bristol’s pterosaur quad launch study from 2019 returns
Source: https://pterosaurheresies.wordpress.com/2024/08/08/griffin-et-al-2024-choose-the-wrong-pterosaur-take-off-pose-again/
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