FIRST EARLY JURASSIC SMALL ORNITHISCHIAN TRACKS FROM YUNNAN PROVINCE, SOUTHWESTERN CHINA

Lida Xing,Martin G Lockley,Hendrik Klein,Zhenzhen Wang,Jeong Yul Kim,Richard T Mccrea,W Scott Persons,Jianping Zhang,Tao Wang,Peter L Falkingham

doi:10.2110/palo.2015.074

Abstract

In 2015, a group of small predominantly tridactyl tracks was discovered in the lower Shawan Member of the Lufeng Formation during an expedition to the Dalishu area, Lufeng County, Yunnan Province, China. The tracks are attributable to Anomoepus, and although mostly tridactyl, they include a few examples with characteristic tetradactyl morphology. Although considered a characteristic index ichnotaxon of a footprint-based Lower Jurassic biochron, Anomoepus has often been overlooked in assemblages dominated by theropod tracks. This is one of the earliest Anomoepus records from the Jurassic of China, and the fifth report of Anomoepus from China at all. To date, four reports represent sites inferred to be Lower or Middle Jurassic in age, with one dated as Upper Jurassic. It is an important component of Early Jurassic ichnofaunas because it points to the presence of ornithischian trackmakers, which are often rare or missing in the local skeletal faunas (Lufengosaurus faunas).

Highlights

Measurements are based on standard parameters such as maximum length of footprint (ML), maximum width of footprint (MW), ML/MW ratio, divarication angle between digit traces II–IV, mesaxony value based on length/width of anterior triangle (AT) using the method of Weems (1992), pace length (PL), stride length (SL) and pace angulation (PA) (Table 1)
Small predominantly tridactyl tracks from the lower Shawan Member of the Lufeng Formation in the Dalishu area, Lufeng County, Yunnan represent the fifth report of Anomoepus from the Jurassic of China
Most reports of Anomoepus from China are associated with sites dated as Lower or Middle Jurassic

Summary

INTRODUCTION

Abundant well-preserved materials allowed the Anomoepus trackmaker to be recognized as an early ornithischian (Olsen and Rainforth 2003; Lockley and Gierlinski 2006) and provided detailed information on morphological diagnostic characters such as manus impressions (e.g., Hitchcock 1858). In China, Anomoepus tracks are primarily found in Lower–Middle Jurassic formations in the southwest of Sichuan Province (Lockley and Matsukawa 2009) and in the Ordos Basin, including Jiaoping (Young 1966; Xing et al 2015), Shenmu (Li et al 2012), and Zizhou (Xing et al 2015). The Upper Jurassic Nan’an site in Chongqing municipality, southwestern China, preserves Anomoepus tracks (Xing et al 2013). Authors LX, TW, and ZW of this report were part of this expedition and discovered a group of tridactyl tracks approximately 600 m northwest of the main Dalishu tracksite, where large ornithischians and theropod tracks were discovered (Xing et al 2016). In the following we give a detailed description of this assemblage, which is important because it documents the presence of small ornithischians as a significant component of the Lower Jurassic Lufeng Formation, not reflected in the skeletal record far

METHODS

CONCLUSIONS