记河北省后城组新发现之小型兽脚类足迹(英文)

A NEW OCCURRENCE OF SMALL THEROPOD TRACKS IN THE HOUCHENG(TUCHENGZI)FORMATION OF HEBEI PROVINCE,CHINA

几十年前人们就已经开始研究中国东北侏罗纪—白垩纪界线附近地层中的小型兽脚类恐龙足迹,虽然这些遗迹化石比辽宁省义县组带羽毛的恐龙及其他实体化石逊色了许多。本文记述了河北省承德南双庙后城组(土城子组)最下部河流相沉积中发现的一组兽脚类恐龙足迹。南双庙足迹具有三趾,趾粗大,其形态与美国下侏罗统经典的"brontozoid"足迹(Gral- lator,Anchisauripus和Eubrontes)相符。虽然许多产自辽宁土城子组中基本同时的brontozoid足迹被鉴定为小型的跷脚龙足迹属(Grallator),但南双庙足迹更大一些(全长可达28.8 cm),可能应该归入安琪龙足迹属(Anchisauripus)。南双庙足迹很可能是一群小型兽脚类行走而产生。在辽宁义县组的兽脚类恐龙中,最可能留下这类足迹的是小型的窃蛋龙类——尾羽龙(Caudipteryx)。不过这个解释还很勉强,因为这些足迹缺乏鉴定性特征,而且河北的后城组与辽宁的义县组之间还有一定的时间及地理间隔。

Small theropod footprints have been known from the Jurassic-Cretaceous boundary strata of northeastern China for several decades, although these ichnofossils have been overshadowed by the feathered dinosaurs and other body fossils from the Yixian Formation of Liaoning Province. This paper describes a sample of several theropod footprints from a coarse fluvial deposit at Nanshuangmiao, in the lowermost Houeheng （Tuehengzi） Formation of Hebei Province. The Nanshuangmiao tracks exhibit a tridactyl, pachydactylous morphology corresponding to classic ＂brontozoid＂ ichnites （ Grallator, Anchisauripus and Eubrontes） from the Lower Jurassic of the United States of America. Although many brontozoid tracks from the roughly equivalent Tuchengzi of Liaoning have been previously assigned to the small ichnogenus GraUator, as G. ssatoi, the Nanshuangmiao tracks are larger （ up to 28.8 cm total length） and are probably referable to Anchisauripus. The Nanshuangmiao tracks were most likely produced by small theropods travelling in a group. Of the abundant theropod taxa known from the Yixian Formation of Liaoning, the small oviraptorosaur Caudipteryx is the most plausible trackmaker, but this interpretation remains uncertain because of a lack of diagnostic features in the tracks and because of the temporal and geographic gap between the Houcheng of Hebei and the Yixian of Liaoning.