THE FIRST RECORD OF LOWER CRETACEOUS LINGULIDAE (BRACHIOPODA) FROM THE TROPICAL AMERICA
An extensive field survey in the northern South America (Western Cordillera of Colombia) uncovered multiple occurrences of lower Cretaceous lingulids. Two stratigraphic sections of the Valanginian-Hauterivian Rosablanca Formation (65 m and 140 m in thickness) were logged. A total of 45 well-preserved valves of Lingularia? sp. were collected from three stratigraphic horizons of slightly bioturbated siltstones at the base of the unit. Lingulids in at least one of these horizons could be tracked laterally for almost 1000 m. The size of the collected specimens ranged from 4.5 to 15.0 mm in shell length. No preferential orientation of those shells in relation to the bedding plane was observed. The occurrence of single valves and fragments of lingulids, and also disarticulated bivalves and crabs in those levels, suggests that the material was transported prior to deposition. This study documents the oldest occurrences of lingulid brachiopods in the region so far. The new Cretaceous material should help us to reconstruct the biogeographic history of the group more accurately. Although lingulids are considered to have been rare in Cretaceous near-shore marine communities the results reported here suggest that they may have been common locally.