Fabbri Matteo, Navalón Guillermo, Benson Roger B J, Pol Diego, O'Connor Jingmai, Bhullar Bhart-Anjan S, Erickson Gregory M, Norell Mark A, Orkney Andrew, Lamanna Matthew C, Zouhri Samir, Becker Justine, Emke Amanda, Dal Sasso Cristiano, Bindellini Gabriele, Maganuco Simone, Auditore Marco, Ibrahim Nizar
Negaunee Integrative Research Center, Field Museum of Natural History, Chicago, IL, USA.
Department of Earth Sciences, University of Cambridge, Cambridge, UK.
Nature. 2022 Mar;603(7903):852-857. doi: 10.1038/s41586-022-04528-0. Epub 2022 Mar 23.
Secondary aquatic adaptations evolved independently more than 30 times from terrestrial vertebrate ancestors. For decades, non-avian dinosaurs were believed to be an exception to this pattern. Only a few species have been hypothesized to be partly or predominantly aquatic. However, these hypotheses remain controversial, largely owing to the difficulty of identifying unambiguous anatomical adaptations for aquatic habits in extinct animals. Here we demonstrate that the relationship between bone density and aquatic ecologies across extant amniotes provides a reliable inference of aquatic habits in extinct species. We use this approach to evaluate the distribution of aquatic adaptations among non-avian dinosaurs. We find strong support for aquatic habits in spinosaurids, associated with a marked increase in bone density, which precedes the evolution of more conspicuous anatomical modifications, a pattern also observed in other aquatic reptiles and mammals. Spinosaurids are revealed to be aquatic specialists with surprising ecological disparity, including subaqueous foraging behaviour in Spinosaurus and Baryonyx, and non-diving habits in Suchomimus. Adaptation to aquatic environments appeared in spinosaurids during the Early Cretaceous, following their divergence from other tetanuran theropods during the Early Jurassic.
次生水生适应性特征从陆生脊椎动物祖先独立演化而来超过30次。几十年来，非鸟类恐龙被认为是这一模式的例外。只有少数物种被推测部分或主要为水生。然而，这些假说仍存在争议，主要是因为难以在已灭绝动物中识别出明确无误的适应水生习性的解剖学特征。在此，我们证明现存羊膜动物骨骼密度与水生生态之间的关系为推断已灭绝物种的水生习性提供了可靠依据。我们用这种方法评估非鸟类恐龙中水生适应性特征的分布情况。我们发现棘龙科具有水生习性的有力证据，这与骨骼密度显著增加有关，这种增加发生在更明显的解剖学变化演化之前，这一模式在其他水生爬行动物和哺乳动物中也有观察到。棘龙科被揭示为具有惊人生态差异的水生专家，包括棘龙和重爪龙的水下觅食行为，以及似鳄龙的非潜水习性。在早白垩世，棘龙科从早侏罗世与其他坚尾龙类兽脚亚目恐龙分化后，就出现了对水生环境的适应。
