| 초록 | Diverse forms of Lockeia are abundantly preserved in the dolomitic mudstone of the Middle Ordovician Yeongheung Formation, Yeongweol, Korea. On the basis of general morphology, five forms of Lockeia are recognized in the material from the Yeongheung Formation. L. siliquaria is a thin, seed-like form, and tapered at both ends. L. amygdaloides is a relatively plump, almond shaped form, and tapered at one end and the other end is obtusely pointed or somewhat rounded. L. triangulichnus nov. ichnosp. is a small triangular form with three ridges from apex, resembling a pyramid, preserved in convex hyporelief and concave epirelief. L. ichnosp. 1 is a pear-shaped form and L. ichnosp. 2 is an irregular form. Usually populations of Lockeia are monospecific and this occurrence is unique. The characteristic features of Lockeia, such as length, width, surface ornamentation, symmetry, convexity and tapering, seem to be related to the orientation and burrowing depth of shells, degree of sediment erosion, and possibly with the later environmental and diagenetic change, as well as original shape and behavior of trace makers. Lockeia is interpreted as a resting trace of a burrowing bivalve which may be oriented horizontally, obliquely and vertically. |
|---|