Curvolithus Fritsch, 1908

Diagnosis:  Straight  to  curved,  horizontal,  subhorizontal to  rarely  oblique,  ribbon-like  or  tongue-like,  flattened,  unbranched,  essentially  endostratal  traces  with  three  rounded lobes on upper surface and up to four lobes on concave or convex  lower  surface.  Central  lobe  on  upper  surface  wider  that than outer lobes and separated from them by shallow, angular furrows. Faint, narrow central furrow dividing central lobe in upper surface may be present (after Buatois et al. 1998).

Emended diagnosis.-Straight to curved, horizontal, subhorizontal to rarely oblique, ribbonlike or tonguelike, flattened, unbranched, essentially endostratal traces with three rounded lobes on upper surface and up to four lobes on concave or convex lower surface. Central lobe on upper surface wider than outer lobes and separated from them by shallow, angular furrows. Faint, narrow central furrow dividing central lobe in upper surface may be present.
Remarks.-Curvolithus is distinguished from similar forms (e.g., Aulichnites, Gyrochorte, Psammichnites) by its trilobate upper surface.

Curvolithus com­ monly is associated with shallow-marine facies, either of normal or slightly brackish salinity (Fig. 9).