宁夏六盘山地区早白垩世恐龙足迹研究

本文记述了发现于宁夏六盘山地区的恐龙足迹化石。共计5个化石点,分别位于宁夏六盘山地区固原市隆德县和泾源县,赋存地层为下白垩统六盘山群和尚铺组、李洼峡组和马东山组,包括蜥脚类和鸟脚类恐龙足迹化石,其中以蜥脚类为主。足迹可识别的有4条行迹,其中,隆德县香水镇行迹所代表的恐龙个体较小,臀高仅1.44m,其余3组行迹代表的恐龙较大,臀高在2.79～3.27m之间;鸟脚类恐龙臀高约为0.48 m,为小型鸟脚类恐龙。采用Alexander的速度计算方法对造迹恐龙的速度进行研究,表明六盘山地区蜥脚类造迹恐龙速度为0.34～1.41m/s之间,复步长与臀高的比值小于2,均为正常行走状态。足迹保存层面岩性主要为粉砂质泥岩、细砂岩,具水平层理、波痕、泥裂、雨雹痕等沉积构造,含植物碎片化石,并发育有大量的无脊椎动物潜穴化石。根据岩性及沉积构造判断,造迹恐龙活动环境为离湖岸较近的浅水地带。

A Study of Early Cretaceous Dinosaur Tracks in Liupanshan Area, Ningxia

This paper is based on the investigation of the dinosaur footprints found in Liupanshan area of Ningxia. The footprints were discovered from 5 fossil localities which belong to the Lower Cretaceous Heshangpu Formation, Liwaxia Formation and Madongshan Formation in Longde County and Jingyuan County, Guyuan City, Liupanshan area, Ningxia. These fossils consist of the sauropod and the ornithopod footprints, dominated by sauropod ones, including four trackways. Among them, the dinosaur individuals from the Xiangshui Town in Longde County are smaller, whose hip height are only 1.44 m long, the rest of the other trackways represent larger dinosaurs, and their hip heights are between 2.79 and 3.27 m. The hip height of ornithopod dinosaur is about 0.48 m, suggesting small ornithopod dinosaurs. On the basis of the Alexander''s speed calculation method, the speeds of dinosaurs are estimated. The results show that the speed of sauropods was 0.34~1.41 m/s, and the ratio of stride length to hip height was less than 2, both indicating normal walking states. The footprints are mainly preserved in silty mudstone and fine-grained sandstone, with horizontal bedding, ripple marks, mud cracks, hail marks and other sedimentary structures, bearing plant fragment fossils as well as a lot of invertebrate burrows. Judging from the lithological and sedimentary study, the dinosaur tracks were preserved in lake-shore.