BIVALVES ON THE MOVE: THE INTERPLAY OF EXTRINSIC AND INTRINSIC FACTORS ON THE MORPHOLOGY OF THE TRACE FOSSIL PROTOVIRGULARIA

LOPEZ CABRERA MI; MÁNGANO, M. GABRIELA; BUATOIS, LUIS A.; OLIVERO, EDUARDO B.; MAPLES, CHRISTOPHER G.

PALAIOS

SEPM-SOC SEDIMENTARY GEOLOGY

Lugar: Lawrence; Año: 2019 vol. 34 p. 349 - 363

0883-1351

ABSTRACT: Tide-influenced deposits of the Pennsylvanian Rock Lake Shale Member, Stanton Formation, Missouriand Kansas (U.S.A.), contain well-preserved evidence of the burrowing activities of protobranch bivalves, includinglocomotion (Protovirgularia) and locomotion-resting (Protovirgularia-Lockeia) trace fossils. Protovirgularia shows threedistinct morphotypes, the morphological variability of which was controlled by external factors such as substrateconditions, toponomy, and undertrack deficiency. Extreme morphological modifications of Protovirgularia and/orLockeia, represented by irregular bilobate structures, probably result from erosion and subsequent partial passivefilling of the original biogenic structures. In addition, very well-preserved trace fossils showing intergradation of a fanshapedcluster of ridges with Protovirgularia-Lockeia structures are interpreted as a compound biogenic structure thatrepresents locomotion, resting, and feeding activities of burrowing protobranch bivalves.