First record of the Mesozoic scroll coprolites: classification, characteristics, elemental composition and probable producers

Multiple, small, cylindrical scroll coprolites having rounded and tapering ends and pertaining to a new ichnotaxon have been recovered from the Upper Triassic Tiki Formation of India. This is the first record of scroll coprolites from the Mesozoic. Based on cross‐sectional geometry, external surface textures, and internal morphology, these coprolites are subdivided into three morphotypes. The coprolites contain several kinds of undigested food material in the form of ganoid fish scales, teeth, lower jaw and skeletal remains of various osteichthyans, chondrichthyans, archosauriforms and indeterminate reptiles. These inclusions are embedded in the groundmass separated by thin mucosal layers. The groundmass contains abundant gas vesicles, and secondarily‐filled shrinkage cracks. EDS analysis shows that the overall composition of the coprolites reflects Ca, P, C and O, suggesting calcium phosphate mineralogy, though other elements such as Fe, Mn, Al, Si are present in lesser proportions. Ba...研究人员从印度上三叠统提基组（Upper Triassic Tiki Formation）中发掘出多件小型圆柱螺旋状粪化石（scroll coprolites），这类粪化石两端圆润且逐渐收窄，隶属于一个全新的遗迹分类群（ichnotaxon）。这是中生代（Mesozoic）地层中首次发现螺旋状粪化石的记录。基于截面几何形态、外部表面纹理与内部结构特征，这批粪化石可被划分为3个形态类型（morphotypes）。该类粪化石内部包含多种未消化的食物残骸，具体包括硬鳞鱼鳞片、牙齿、下颌骨，以及各类硬骨鱼类（osteichthyans）、软骨鱼类（chondrichthyans）、主龙形类（archosauriforms）和未定名爬行动物的骨骼遗骸。这些内含物被包裹于基质（groundmass）之中，基质间由薄层黏膜层（mucosal layers）分隔开。该基质中富含气囊结构（gas vesicles），同时发育有次生充填的收缩裂缝。能量色散X射线光谱（Energy Dispersive X-ray Spectroscopy，简称EDS）分析显示，这批粪化石的整体化学成分以钙、磷、碳、氧为主，指示其矿物成分为磷酸钙；尽管铁、锰、铝、硅等其他元素占比较低，钡（Ba）……