2026-01-22 スウォンジー大学
<関連情報>
- https://www.swansea.ac.uk/press-office/news-events/news/2026/01/asteroid-that-wiped-out-dinosaurs-had-limited-impact-on-sharks-and-rays-major-ai-driven-study-shows.php
- https://www.cell.com/current-biology/fulltext/S0960-9822(25)01638-0
過去1億4500万年にわたるサメとエイの多様性の隠れたパターンを明らかにする Revealing the hidden patterns of shark and ray diversity over the past 145 million years
Amanda Gardiner ∙ Gregor H. Mathes ∙ Rebecca Cooper ∙ … ∙ Jaime A. Villafaña ∙ Daniele Silvestro ∙ Catalina Pimiento
Current Biology Published:January 22, 2026
DOI:https://doi.org/10.1016/j.cub.2025.12.017
Graphical abstract
Highlights
- Neoselachian diversity steadily increased throughout the Cretaceous
- K/Pg boundary shows only ∼10% species loss instead of mass collapse
- Maximum diversity is reached in the mid-Eocene, surpassing modern levels
- A prolonged decline follows Eocene maximum, leaving modern richness depleted
Summary
Neoselachians (a monophyletic group including modern sharks, rays, and skates and their extinct relatives)1,2 have an extensive fossil record and a long evolutionary history,1,2,3 with over 1,100 extant species today.4 Previous reconstructions of their evolutionary history suggest a diversity peak in the Cretaceous, a severe decline across the Cretaceous-Paleogene (K/Pg),5,6,7,8,9 and a prolonged stability thereafter,7,8 aside from a small decline in the Pliocene.10 However, our knowledge of past neoselachian diversity has been mostly based on high taxonomic levels (e.g., genera or families),8 or from studies restricted to particular regions,11,12,13 time periods,5,9 or shark orders.14,15 This is further complicated by spatiotemporal biases,16,17 which can lead to apparent diversity changes, even when bias-correction methods are employed.16,17 Using an extensive dataset of fossil occurrences18 and a deep-learning model that explicitly accounts for spatiotemporal and taxonomic sampling variation,19 we reconstruct the neoselachian diversity trajectory over the past 145 million years. We found a long-term increase during the Cretaceous, in which neoselachians reached modern diversity levels. Throughout the K/Pg, we recovered only a small (10%) decline, suggesting high turnover rather than a major extinction. Diversity then surged, culminating in a mid-Eocene peak, when neoselachians reached maximum richness. This peak was followed by a fluctuating yet downward trajectory toward the present, which overall resulted in a 41% loss of species and left modern diversity depleted compared to their thriving past. Together, our results reveal patterns hitherto obscured by multiple biases, challenging previous paradigms about neoselachian diversity.
