Early Cretaceous (Valanginian) brachiopods from the Rosablanca Formation, Colombia, South America: Biostratigraphic significance and paleogeographic implications

Abstract

The Mesozoic fossil record of brachiopods in northern South America is relatively scarce and their biogeographical history is not well understood. Cretaceous brachiopods in this region are restricted to carbonate platforms of Colombia. Here we examine the brachiopod fauna from the middle part of the Rosablanca Formation near the town of Zapatoca, Eastern Cordillera of Colombia. We describe Sellithyris elizabetha nov. sp. combining traditional morphometrics and serial sectioning. This new terebratulide species shows morphological similarities with other species of the genus Sellithyris, including a Valanginian species from the ancient Gulf of Mexico. Using a semi-quantitative taphonomic analysis, we identified reworked specimens restricted to a single stratigraphic horizon, and consistent with a large-scale erosional hiatus that may affect the biochronology of the Rosablanca Formation. In addition, phosphatic shells of the lingulide Lingularia sp. were recovered from two stratigraphic horizons and are valuable for local correlations. Although much of the material is fragmentary, it represents the oldest occurrences of Cretaceous lingulides in the region so far. Lingulide brachiopods have traditionally been considered as rare elements in Cretaceous near-shore marine communities, however, the material reported here suggests that they may have been common locally.