Preserved ligament in a radiolitid rudist bivalve and its implication of mantle marginal feeding in the group

摘要: Fibrous ligament and aragonitic shell material have been found preserved in two specimens of radiolitid rudists (cf. Radiolites angeoides (De Lapeirouse)) from the Lower to Middle Coniacian Tirol, Austria. The invaginated apparently comprised torn overgrown non-functional strings, one each valve, connected medially by a thin strip active ligament. original dimensions estimated, for shells 4 5 cm commissural diameter, at 0.58 mm2 cross-sectional area 1.3 mm length, with closed. Using data on adductor muscle Recent oysters results compression tests carried out samples oyster fibrous ligament, it is estimated that these opened less than 1 life; their gaping was highly restricted. This taken support proposal expanded mantle margins (principally right, attached valve) were responsible food particle entrapment, rather gills as most other bivalves. It suggested tentaculate flange extruded through narrow gap between valves during feeding. pair pronounced radial bands posterior flanks are interpreted marking pseudofaecal faecal ejection sites. Finally, speculated slime (possibly poisonous or foul-tasting) tentacles inhibited predators.