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[dinosaur] Tiktaalik (Devonian tetrapodomorph) feeding system (free pdf)




Ben Creisler
bcreisler@gmail.com


A new paper:

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Free pdf:


Justin B. Lemberg, Edward B. Daeschler, and Neil H. Shubin (2021)
The feeding system of Tiktaalik roseae: an intermediate between suction feeding and biting.
Proceedings of the National Academy of Sciences 118(7): e2016421118
doi: https://doi.org/10.1073/pnas.2016421118
https://www.pnas.org/content/118/7/e2016421118

Free pdf
https://www.pnas.org/content/pnas/118/7/e2016421118.full.pdf


NOTE: Online article HTML text has videos

https://movie-usa.glencoesoftware.com/video/10.1073/pnas.2016421118/video-1

https://movie-usa.glencoesoftware.com/video/10.1073/pnas.2016421118/video-2


Significance

The water-to-land transition is a major event in vertebrate history, involving significant changes to feeding structures and mechanics. In water, fish often use suction-feeding to capture prey, but this feeding strategy is not possible on land. Therefore, it has been traditionally believed that the invasion of land involved a shift from suction-based prey capture to mechanisms based on biting and snapping. Computed tomography analysis of Tiktaalik roseae, a key intermediate in tetrapod evolution, compared with extant analogs (gars and polypterids), reveals a rigid skull, capable of biting, with joint morphologies suggestive of cranial kinesis and suction generation. An intermediate condition that utilizes both feeding strategies helps explain some of the key morphological changes in cranial anatomy during the water-to-land transition.

Abstract

Changes to feeding structures are a fundamental component of the vertebrate transition from water to land. Classically, this event has been characterized as a shift from an aquatic, suction-based mode of prey capture involving cranial kinesis to a biting-based feeding system utilizing a rigid skull capable of capturing prey on land. Here we show that a key intermediate, Tiktaalik roseae, was capable of cranial kinesis despite significant restructuring of the skull to facilitate biting and snapping. Lateral sliding joints between the cheek and dermal skull roof, as well as independent mobility between the hyomandibula and palatoquadrate, enable the suspensorium of T. roseae to expand laterally in a manner similar to modern alligator gars and polypterids. This movement can expand the spiracular and opercular cavities during feeding and respiration, which would direct fluid through the feeding apparatus. Detailed analysis of the sutural morphology of T. roseae suggests that the ability to laterally expand the cheek and palate was maintained during the fish-to-tetrapod transition, implying that limited cranial kinesis was plesiomorphic to the earliest limbed vertebrates. Furthermore, recent kinematic studies of feeding in gars demonstrate that prey capture with lateral snapping can synergistically combine both biting and suction, rather than trading off one for the other. A âgar-likeâ stage in early tetrapod evolution might have been an important intermediate step in the evolution of terrestrial feeding systems by maintaining suction-generation capabilities while simultaneously elaborating a mechanism for biting-based prey capture.

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News:

https://phys.org/news/2021-02-clues-emerge-early-tetrapods-liveand.html

https://www.eurekalert.org/pub_releases/2021-02/uoc-nce012721.php


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