Chondrites targionii (Brongniart, 1828)

Dendritic burrow system with slightly curved branches and wellexpressed primary successive branching. Three to four orders of branching are observed and the branching angle is 25◦ − 46◦. The tunnels are about 3 mm wide.

Chondrites targionii (Brongniart, 1828)  is characterized by well-expressed primary successive branching and few secondary branches. Branching angle acute. Curved branches are common (Uchman, 1998, 1999; Rodríguez-Tovar and Uchman, 2004; Fan and Gong, 2016).

Description. Slightly winding or arcuate, branched flattened tunnels. Second-order branches are dominant. Third-order branches are very rare. Most of the tunnels are 3-5mm wide. They are filled with dark argillaceous background sediments. Branches are very long, some attaining at least 17 cm, and the whole burrow system may be up to 30 cm across. Weathered cross-sections of the upper part of the burrow system show clusters of small knobs or holes on horizontal bedding or parting surfaces.