A eudicot leaf from the Lower Cretaceous (Aptian, Araripe Basin) Crato Konservat-Lagerstätte.

Abstract

The Crato Konservat-Lagerstätte in Brazil preserves an exceptionally rich assemblage of plant macrofossils from the Early Cretaceous (late Aptian), including rare early angiosperm fossils related to Nymphaeales, monocots, and magnoliids, and a variety of angiosperms of uncertain affinities. Macrofossils of eudicot angiosperms have not been described previously, despite the presence of tricolpate pollen. We describe a fossil leaf with morphology characteristic of eudicot angiosperms. The fossil was collected from a quarry in the Lower Cretaceous (late Aptian) Crato Formation of northeastern Brazil in the state of Ceará. We compared the leaf architecture with that of ferns, gymnosperms, and similar living and fossil angiosperms. The leaf of Baderadea pinnatissecta gen. et sp. nov. is simple and petiolate, with leaf architecture similar to that of some herbaceous Ranunculales. The blade is 5 cm long and the margin is untoothed and twice pinnately lobed with narrow lobes (pinnatisect). The primary vein framework is pinnate and there are multiple orders of reticulate venation. The combination of characters preserved in the fossil supports the interpretation that B. pinnatissecta was an herbaceous eudicot similar to some members of Ranunculales and distinguished from other lobate Aptian angiosperms by leaf shape, presence of multiple orders of reticulate venation, and the absence of glandular teeth. The presence of eudicots in the flora of the Crato was already supported by pollen; the discovery of macrofossils like these provides additional information about their morphology and ecological role in low-latitude Early Cretaceous plant communities.