SupplementaryData1.docx

Researchers described the first crown bird from the Late Cretaceous (Maastrichtian) Hell Creek Formation. They identified a well-preserved synsacrum, with traits linking it to Neornithes. Phylogenetic study places it as a presbyornithid, an extinct anseriform group previously hinted at but not confirmed in the Hell Creek Formation. This study provides new insights into the origins, radiation, and paleoecology of early neornithines before the K-Pg mass extinction event.

研究人员首次描述了产自晚白垩世（马斯特里赫特阶）地狱溪组的冠群鸟类（crown bird）。他们发现了一件保存完好的综荐骨（synsacrum），该骨骼的特征显示其与今鸟亚纲（Neornithes）存在演化关联。系统发育研究（phylogenetic study）将其归类为黄昏鸟科类群（presbyornithid）——一类已灭绝的雁形目（anseriform）类群，此前该类群仅在地狱溪组中被推测存在，但始终未得到证实。本研究为白垩纪-古近纪（K-Pg）大灭绝事件之前的早期今鸟亚纲类群的起源、辐射演化与古生态提供了全新的认知。