Trace fossils and their palaeoecological significance in Lower Cretaceous lacustrine conservation deposits, El Montsec, Spain

La Pedrera and La Cabrua at El Montsec, Spain, are two Lower Cretaceous lac ustrine conservation deposits (Konservat-Lagerstatten) that have provided a rich, diverse, and well-preserved faunal and floral fossil record. Althoug h the lithographic limestones where the body fossils are found are finely l aminated and essentially undisturbed by bioturbation, epigenic trace fossil s occur on the surface of certain laminae. Trace fossils at La Pedrera incl ude the fish trail Undichna britannica and the arthropod trackway Hamipes d idactylus, while the ichnospecies found at La Cabrua are Steinsfjordichnus brutoni, Gordia arcuata, Cochlichnus anguineus and Undichna britannica, all but the last corresponding to the activity of small invertebrates. The tra ce fossil occurrences record short-term events in a lake bottom that did no t support ally benthic life for most of its history. Differences in the tra ce fossil assemblages for the two localities agree with sedimentological da ta in attributing a more distal position for La Pedrera. (C) 2000 Elsevier Science B.V. All rights reserved.