2024-04-10 バーミンガム大学
<関連情報>
- https://www.birmingham.ac.uk/news/2024/3d-mouth-of-an-ancient-jawless-fish-suggests-they-were-filter-feeders-not-scavengers-or-hunters
- https://royalsocietypublishing.org/doi/10.1098/rspb.2023.2258
デボン紀のヘテロストラカンの3次元的に連結された口腔器具が古生代の無顎魚の摂食に光を当てる The three-dimensionally articulated oral apparatus of a Devonian heterostracan sheds light on feeding in Palaeozoic jawless fishes
Richard P. Dearden,Andy S. Jones,Sam Giles,Agnese Lanzetti,Madleen Grohganz,Zerina Johanson,Stephan Lautenschlager,Emma Randle,Philip C. J. DonoghueandIvan J. Sansom
Proceedings of the Royal Society B Published:27 March 2024
DOI:https://doi.org/10.1098/rspb.2023.2258
Abstract
Attempts to explain the origin and diversification of vertebrates have commonly invoked the evolution of feeding ecology, contrasting the passive suspension feeding of invertebrate chordates and larval lampreys with active predation in living jawed vertebrates. Of the extinct jawless vertebrates that phylogenetically intercalate these living groups, the feeding apparatus is well-preserved only in the early diverging stem-gnathostome heterostracans. However, its anatomy remains poorly understood. Here, we use X-ray microtomography to characterize the feeding apparatus of the pteraspid heterostracan Rhinopteraspis dunensis (Roemer, 1855). The apparatus is composed of 13 plates arranged approximately bilaterally, most of which articulate from the postoral plate. Our reconstruction shows that the oral plates were capable of rotating around the transverse axis, but likely with limited movement. It also suggests the nasohypophyseal organs opened internally, into the pharynx. The functional morphology of the apparatus in Rhinopteraspis precludes all proposed interpretations of feeding except for suspension/deposit feeding and we interpret the apparatus as having served primarily to moderate the oral gape. This is consistent with evidence that at least some early jawless gnathostomes were suspension feeders and runs contrary to macroecological scenarios that envisage early vertebrate evolution as characterized by a directional trend towards increasingly active food acquisition.
