State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, 39 East Beijing Road, Nanjing 210008, China.
Department of Earth Sciences, The University of Hong Kong, Hong Kong Special Administrative Region, China.
Sci Adv. 2018 Sep 5;4(9):eaat1380. doi: 10.1126/sciadv.aat1380. eCollection 2018 Sep.
The Triassic represented an important period that witnessed the diversification of marine and terrestrial ecosystems. The radiations of terrestrial plants and vertebrates during this period have been widely investigated; however, the Triassic history of insects, the most diverse group of organisms on Earth, remains enigmatic because of the rarity of Early-Middle Triassic fossils. We report new insect fossils from a Ladinian deposit (Tongchuan entomofauna) dated to approximately 238 to 237 million years ago and a Carnian deposit (Karamay entomofauna) in northwestern China, including the earliest definite caddisfly cases (Trichoptera), water boatmen (Hemiptera), diverse polyphagan beetles (Coleoptera), and scorpionflies (Mecoptera). The Tongchuan entomofauna is near the Ladinian-Carnian boundary in age, providing a calibration date for correlation to contemporaneous biotas. Our findings confirm that the clade Holometabola, comprising most of the modern-day insect species, experienced extraordinary diversification in the Middle-Late Triassic. Moreover, our results suggest that the diversification of aquatic insects (a key event of the "Mesozoic Lacustrine Revolution") had already begun by the Middle Triassic, providing new insights into the early evolution of freshwater ecosystems.
三叠纪是一个重要的时期，见证了海洋和陆地生态系统的多样化。在这一时期，陆地植物和脊椎动物的辐射已经得到了广泛的研究；然而，由于早-中三叠世化石的稀有性，昆虫的三叠纪历史——地球上最多样化的生物群体——仍然是个谜。我们报告了来自中国西北地区晚三叠世（约 2.38 亿至 2.37 亿年前）的拉丁阶沉积层（铜川昆虫群）和卡尼阶沉积层（克拉玛依昆虫群）的新昆虫化石，包括最早的确定的石蛾（毛翅目）、水黾（半翅目）、多样的多食性甲虫（鞘翅目）和蝎蛉（长翅目）。铜川昆虫群的年龄接近拉丁阶-卡尼阶的边界，为与同期生物群的对比提供了校准日期。我们的发现证实，包括大多数现代昆虫物种的真昆虫类经历了中-晚三叠世的非凡多样化。此外，我们的研究结果表明，水生昆虫（“中生代湖泊革命”的关键事件）的多样化在中三叠世已经开始，为淡水生态系统的早期进化提供了新的见解。
