豫西马市坪盆地早白垩世热河昆虫群的发现及其地层学意义*

热河生物群是保存最好的白垩纪陆地生物群, 是世界上最重要的特异埋藏化石宝库之一。热河生物群的三阶段演化学说认为该生物群在第二演化阶段往南至秦岭、大别山一带, 包括河南西部和南部地区。早期研究记录表明河南西部地区产出热河生物群的代表分子三尾拟蜉蝣化石。本文首次报道了河南西部南召县马市坪盆地南召组衍蜓科稚虫化石, 并对其形态特征进行了简要描述, 同时报道了与之伴生的三尾拟蜉蝣稚虫化石。衍蜓科稚虫是热河生物群的代表化石之一, 先前均记录于辽宁西部义县组及相当地层, 属于热河生物群第二演化阶段的特征分子。河南西部新发现的昆虫化石证实了热河生物群在其第二演化阶段已经到达该地区。同时, 本研究确定马市坪盆地南召组可与辽宁西部义县组相对比, 南召组的地质时代属于早白垩世而非晚侏罗世。

Discovery of the Early Cretaceous Jehol Entomofauna from the Mashiping Basin, western Henan and its stratigraphic implications

The Jehol Biota is the best preserved Cretaceous terrestrial biota and one of the most important and exceptionally well-preserved lagerst?tten worldwide. According to the three-stage evolutionary theory of the Jehol Biota, this biota extended southward to the Qinling and Dabie mountains, including the western and southern regions of Henan Province, during the second stage. Earlier studies have documented Ephemeropsis trisetalis, a typical element of the Jehol Biota, from western Henan. In this paper, the larva fossils of Aeschnidiidae and Ephemeropsis trisetalis are first reported from the Nanzhao Formation in the Mashiping Basin, Nanzhao Country, western Henan Province. Aeschnidiid larvae were previously only recorded in the Yixian Formation and its equivalent strata. Aeschnidiid larvae belong to the characteristic element of the second stage of the Jehol Biota. The newly discovered insect fossils from western Henan confirm that the Jehol Biota had already reached this area during the second stage. This study further indicates that the age of the Nanzhao Formation is Early Cretaceous instead of Late Jurassic, and the Nanzhao Formation may be somewhat correlatable with the Yixian Formation in western Liaoning.