This Fossil Friday options the early fowl Confuciusornis from the Lower Cretaceous of Liaoning in China. Last week I reported for Fossil Friday on a just-so story about ichthyosaur evolution and the way it fell aside (Bechly 2023). This week I would like use the chance to report yet one more case of a well-liked evolutionist just-so story that not too long ago was put to relaxation for good. It is in regards to the origin of avian flight.
An Old Debate About Birds
There is a long-running debate in evolutionary biology, asking whether or not birds took off by operating and flapping from the bottom up (cursorial speculation), or whether or not they jumped as gliders from the tree down (arboreal speculation). About twenty years in the past there was a modification of the cursorial speculation instructed by Dial (2003), based mostly on the remark in chicks of dwelling Chukar partridge: it’s the so-called wing-assisted incline running (WAIR) speculation, which instructed that wing flapping lifts the physique throughout uphill operating. This was additionally claimed to reply the old query “What use is half a wing?” (Dial et al. 2006), which clearly is not only an iconic query Darwin skeptics got here up with.
The WAIR speculation rapidly grew to become an increasing number of fashionable, with dozens of research revealed on varied facets, equivalent to aerodynamics (Tobalske & Dial 2007, Dial et al. 2008), mechanics (Bundle & Dial 2003), kinematics (Baier et al. 2013), and pc modelling (Heers et al. 2018). “According to the proponents of the WAIR hypothesis, adaptation to WAIR in avian ancestors prepared their locomotor apparatus for the subsequent evolution of forward flapping flight. In other words, WAIR is proposed as a preadaptation to full-fledged avian flapping flight.” (Kuznetsov & Panyutina 2022)
The Function of Wing Flapping
However, final yr a brand new examine by Kuznetsov & Panyutina (2022) confirmed that, opposite to earlier beliefs, the operate of the wing flapping throughout uphill operating is to not carry the physique, however to push it in the direction of a steep slope. This is the other adaptation to powered flight and requires very completely different muscle groups. Actually, “it follows that the action of the forelimb during WAIR cannot preadapt the musculature in a non-flying ancestor to free flapping flight. Furthermore, the wing action during WAIR [already] requires highly developed avian flight musculature.”
Therefore, the authors concluded that “Wing-assisted incline running should be regarded as a crown locomotor specialization of birds and is not an appropriate model for locomotion in avian ancestors.” Unsurprisingly, there was not a shred of paleontological proof for the WAIR speculation (Nudds & Dyke 2009), and non-avian feathered dinosaurs in addition to early birds arguably had been incapable of WAIR (Senter 2006), which is the other of the mannequin’s prediction. It seems like yet one more evolutionist just-so story bites the mud after empirical knowledge didn’t assist the imaginative storytelling.
References
- Baier DB, Gatesy SM & Dial KP 2013. Three-dimensional, high-resolution skeletal kinematics of the avian wing and shoulder throughout ascending flapping flight and uphill flap- operating. PLoS One 8(5): e63982, 1–16. DOI:
- Bechly G 2023. Fossil Friday: Ichthyosaur Birth, Another Evolutionist Just-So Story Falls Apart. Evolution News September 29, 2003.
- Bundle MW & Dial KP 2003. Mechanics of wing-assisted incline operating (WAIR). Journal of Experimental Biology 206(24), 4553–4564. DOI:
- Kuznetsov AN & Panyutina AA 2022. Where was WAIR in avian flight evolution? Biological Journal of the Linnean Society 137(1), 145–156. DOI:
- Dial KP 2003. Wing-Assisted Incline Running and the Evolution of Flight. Science 299(5605), 402–404. DOI:
- Dial KP, Randall RJ & Dial TR 2006. What use is half a wing within the ecology and evolution of birds? BioScience 56(5), 437–445. DOI: https://doi.org/10.1641/0006-3568(2006)056[0437:WUIHAW]2.0.CO;2
- Dial KP, Jackson BE & Segre P 2008. A elementary avian wing-stroke offers a brand new perspective on the evolution of flight. Nature 451(7181), 985–989. DOI:
- Heers AM, Rankin JW & Hutchinson JR 2018. Building a Bird: Musculoskeletal Modeling and Simulation of Wing-Assisted Incline Running During Avian Ontogeny. Frontiers in Bioengineering and Biotechnology 6: 140, 1–25. DOI:
- Nudds RL & Dyke GJ 2009. Forelimb posture in dinosaurs and the evolution of the avian flapping flight-stroke. Evolution 63(4), 994–1002. DOI:
- Senter P 2006. Scapular orientation in theropods and basal birds, and the origin of flapping flight. Acta Palaeontologica Polonica 51(2), 305–313.
- Tobalske BW & Dial KP 2007. Aerodynamics of wing-assisted incline operating in birds. The Journal of Experimental Biology 210(10), 1742–1751. DOI:
