Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada M5S 3B2.
Department of Natural History, Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario, Canada M5S 2C6.
Proc Biol Sci. 2023 Mar 8;290(1994):20222020. doi: 10.1098/rspb.2022.2020.
Avian skeletal morphology is associated with locomotor function, including flight style, swimming and terrestrial locomotion, and permits informed inferences on locomotion in extinct taxa. The fossil taxon (Avialae: Ornithurae) has long been regarded as highly aerial, with flight similar to terns or gulls (Laridae), and skeletal features resembling foot-propelled diving adaptations. However, rigorous testing of locomotor hypotheses has yet to be performed on , despite its notable phylogenetic position as one of the most crownward stem birds. We analysed separate datasets of three-dimensional sternal shape (geometric morphometrics) and skeletal proportions (linear measurements across the skeleton), to examine how well these data types predict locomotor traits in Neornithes. We then used this information to infer locomotor capabilities of We find strong support for both soaring and foot-propelled swimming capabilities in Further, sternal shape and skeletal proportions provide complementary information on avian locomotion: skeletal proportions allow better predictions of the capacity for flight, whereas sternal shape predicts variation in more specific locomotor abilities such as soaring, foot-propelled swimming and escape burst flight. These results have important implications for future studies of extinct avialan ecology and underscore the importance of closely considering sternum morphology in investigations of fossil bird locomotion.
鸟类骨骼形态与运动功能有关，包括飞行方式、游泳和陆地运动，并允许对已灭绝类群的运动方式进行有根据的推断。化石分类群（Avialae：Ornithurae）长期以来被认为是高度在空中的，其飞行方式类似于燕鸥或海鸥（Laridae），骨骼特征类似于足推进潜水适应。然而，尽管作为最冠层的鸟类之一，其系统发育位置显著，但尚未对 进行严格的运动假说测试。我们分析了三个独立的胸骨形状三维数据集（几何形态计量学）和骨骼比例（骨骼上的线性测量），以检验这些数据类型如何预测新鸟类的运动特征。然后，我们利用这些信息推断 的运动能力。我们发现，在 中，无论是翱翔还是足推进游泳能力都得到了强有力的支持。此外，胸骨形状和骨骼比例为鸟类运动提供了互补的信息：骨骼比例可以更好地预测飞行能力，而胸骨形状则可以预测更具体的运动能力的变化，如翱翔、足推进游泳和逃逸爆发式飞行。这些结果对未来研究已灭绝的鸟类生态学具有重要意义，并强调了在研究化石鸟类运动时密切考虑胸骨形态的重要性。
