A bstract In the central-eastern sector of the Southern Alps, the Upper Cretaceous is represented mainly by basinal deposits of the ScagliaRossa Formation. Shallow-water carbonates of the Friuli Platform crop out towards the northeast. Since the eighteenth century rudist bivalves in this area have been reported embedded in Scaglia Rossa basinal rocks. These rocks weredeposited tens of kilometers away from any known Late Cretaceous carbonate platform, which is normally considered the typical sourceof these mollusks. Paleontologic and sedimentologic studies carried out in the Lessini Mountains rule out the possibility that these rudists, represented by radiolitids, could have been transported by gravitational redeposition; instead it is assumed that they lived in situ elevatedabove the substrate or lying on one side with the commissure directed upwards. Evidence supporting this is (1) the great distance fromany carbonate platform source, (2) the lack of resedimentation features, and (3) the absence of other shallow-water organisms. To explain the occurrence of these radiolitids in such an anomalous setting, it has been hypothesized that the physiography and paleobathymetry of the studied area during late Turonian to Coniacian (Late Cretaceous) was characterized by a paleoenvironment whichfavored the existence of these rudist taxa in the lower photic zone of a basinal high.