Figure S1 from Giant gar from directly above the Cretaceous–Palaeogene boundary suggests healthy freshwater ecosystems existed within thousands of years of the asteroid impact

The Cretaceous–Paleogene (K–Pg) mass extinction was responsible for the destruction of global ecosystems and loss of approximately three-quarters of species diversity 66-million-years ago. Large-bodied land vertebrates suffered high extinction rates, whereas small-bodied vertebrates living in freshwater ecosystems were buffered from the end-Cretaceous mass extinction. Here, we report a new species of large-bodied (1.4–1.5 m) gar based on a complete skeleton from the Williston Basin of North America. The new species was recovered 18 cm above the K–Pg boundary, making it one of the oldest articulated vertebrate fossils from the Cenozoic. The presence of this freshwater macropredator within approximately 1.5–2.5 thousand years after the asteroid impact suggests the rapid recovery and reassembly of North American freshwater food webs and ecosystems after the asteroid impact.

白垩纪-古近纪（K–Pg）生物大灭绝发生于6600万年前，此次事件造成全球生态系统崩溃，约四分之三的物种多样性丧失。大型陆生脊椎动物灭绝率极高，而栖息于淡水生态系统中的小型脊椎动物则得以在晚白垩世大灭绝中幸免于难。本研究基于北美威利斯顿盆地（Williston Basin）出土的一具完整骨骼，报道了一种新的大型雀鳝物种，其体长可达1.4至1.5米。该新物种的化石出土于K–Pg界线之上18厘米处，使其成为新生代已知最古老的关节连接完整脊椎动物化石之一。这一淡水大型捕食者的生存时间距小行星撞击事件仅约1500至2500年，表明北美淡水食物网与生态系统在撞击后实现了快速恢复与重建。