Trichichnus linearis Frey, 1970

Remarks. Trichichnus occurs mostly in fine-grained, shallow-water (e.g. Frey, 1970) as well as from deep-sea deposits e.g. Kennedy, 1975; Wetzel, 1981). A strong tendency to pyritization is typical of this form (e.g. Werner and Wetzel, 1981).

DIAGNOSIS.—Rarely branched, dominantly vertical, threadlike, cylindrical trichichnid burrows having distinct walls, commonly lined with diagenetic minerals.

Descroption. This is a differently oriented, curved-to-slightly winding, rarely branched, thin, thread-like trace fossil. Its fill is rustyferruginous, probably after oxidization of pyrite. The external diameter ranges from 1 to 2.5 mm, but its original size was smaller, and it seems that the ferruginous material expanded outward due to concretional growth. The ferruginous halo can attain 5 mm in diameter.