The cranial anatomy of an extinct fish reveals an intermediate stage in the evolution of feeding systems in vertebrates, a study finds. During the transition from water to land, vertebrates shifted from a suction-based mode of prey capture to a biting-based feeding strategy. To shed light on this major step in vertebrate evolution, Justin Lemberg, Edward Daeschler, and Neil Shubin used high-resolution micro-computed tomography to analyze the anatomy of four specimens of Tiktaalik roseae, an extinct lobe-finned fish and a key intermediate in the evolution of four-limbed animals. The authors compared the anatomy of T. roseae to that of modern and extinct vertebrates with analogous features. Similar to many groups of fishes, the skull of T. roseae is extensively jointed to enable separate movements between cranial elements and, therefore, may have been capable of large expansion to draw in food through suction. On the other hand, the braincase, skull roof, and the midline-roof of the mouth are all integrated together into a rigid inflexible unit, which may have facilitated prey capture through biting. In addition, the anatomy of the tooth row is suggestive of snapping. According to the authors, the findings suggest that T. roseae may have used a synergistic, gar-like feeding strategy that combined snapping and suction, without necessarily trading off one for the other.
Article #20-16421: "The feeding system of Tiktaalik roseae: an intermediate between suction feeding and biting," by Justin B. Lemberg, Edward B. Daeschler, and Neil H. Shubin
Proceedings of the National Academy of Sciences