Crato Flora: A 115-Million-Year-Old Window into the Cretaceous World of Brazil

The Crato Fossil Lagerstätte, excavated from the Early Cretaceous (likely late Aptian) Crato Formation of the Araripe Basin in Ceará (NE Brazil), is a worldwide known konservat (conservation) lagerstätte comprising both animal and plant fossils. The present chapter focuses on plant fossils, which are predominantly excellently preserved, displaying a striking percentage of almost complete individual plants. Here, we summarize the state of knowledge on the Crato flora based on literature and our own unpublished observations. From a multidisciplinary point of view, we want to not only show the main achievements of scientific investigations but also work out remaining gaps in our knowledge on the Crato ecosystem. In doing this, we conclude on essential challenges for future studies aiming toward an integrated analysis of this fossil lagerstätte. The Crato flora has been exclusively sampled from the informal C6-laminated limestone unit of the Crato Formation, a lacustrine sediment. Presently, 41 elements (some are whole-plant taxa) have been scientifically described and validly published. They are available in different preservation modes such as compressions (coalified remains with cuticles preserved), iron oxide replacement fossils, and impressions. Most of the taxa occur in various layers across the lithostratigraphic section of the C6 limestone. Some of the plant remains are charred referring to paleo-wildfire. Several gymnospermous species exhibit abundant resin ducts in specific organs, such as cones, which are likely producers of amber clumps dispersed in the limestone. It has to be stated that this lagerstätte, including its plant fossils, are known for decades, but a controlled excavation of plant fossils has never been conducted. Hence, our knowledge on the spatio-temporal distribution of the floristic elements in the section is still rather limited, making any reconstruction of vegetational units (plant communities), or successions of communities, currently impossible. Besides, recognizing the positions of fossil plants in the network of the Crato ecosystem is the most critical challenge for future studies.