2025-09-01 ミシガン大学
Whole skeleton of Dipterus, an extinct lungfish from the Middle Devonian epoch. Specimen (UMMP 16140) from the University of Michigan Museum of Paleontology. Image credit: E.M. Troyer
<関連情報>
- https://news.umich.edu/bite-by-bite-how-jaws-drove-fish-evolution/
- https://www.sciencedirect.com/science/article/abs/pii/S0960982225010395
硬骨魚類初期拡散における巨視的進化の役割逆転 Macroevolutionary role reversals in the earliest radiation of bony fishes
Emily M. Troyer, Rafael A. Rivero-Vega, Xindong Cui, Min Zhu, Tuo Qiao, Hadeel H. Saad, Rodrigo T. Figueroa, James V. Andrews, Alice M. Clement, Oleg A. Lebedev, Robert Higgins, Benjamin Igielman, Stephanie E. Pierce, Sam Giles, Matt Friedman
Current Biology Available online: 1 September 2025
DOI:https://doi.org/10.1016/j.cub.2025.08.008
Highlights
- Early bony fishes exhibit contrasting patterns of jaw-shape evolution
- Devonian ray-finned fishes possess slow rates of jaw evolution and low disparity
- Devonian lungfishes and coelacanths had especially diverse, rapidly evolving jaws
- This represents an inversion of present-day patterns
Summary
The evolution of jaws is hypothesized to have fueled radiations among vertebrates, contributing to their overwhelming success in the present day. Past work shows rapid early expansion of diversity in jaw structure in many lineages; however, the evolutionary dynamics underlying this pattern are unclear and hindered by the lack of a robust comparative framework. Here, using a macroevolutionary approach, we explore the diversification of lower jaws in early bony fishes, a major contributor to this initial radiation. Using newly generated three-dimensional mandibular shape data from 86 species, we find evidence of adaptive radiation in jaws during the earliest interval of bony fish evolutionary history (423–359 Ma). These patterns are principally driven by early lungfishes and coelacanths, which display high rates of jaw diversification, rapid shifts into novel functional regions of trait space, and substantial innovation in jaw morphology and feeding ecology, standing in contrast to their “living fossil” descendants of today. Conversely, ray-finned fishes and tetrapodomorphs, morphologically diverse groups in the present day, show little indication of their future success, possessing slow rates of jaw evolution and low functional diversity. This profound inversion of patterns in modern taxa highlights the significance of paleontological data in understanding drivers of evolutionary diversification and the limitations of approaches using only living species. Overall, our findings provide insight into the evolutionary dynamics associated with the evolution of jaws and provide context for the role of jaws in vertebrate success.
