Sprecher
Beschreibung
The Aptian–Albian interval of the Early Cretaceous (121.4–100.5 Ma) was a pivotal phase in land plant evolution, marked by rapid angiosperm diversification, major vegetation restructuring, greenhouse climate conditions, elevated global temperatures, and repeated oceanic anoxic events.
The Une flora, a recently discovered compression flora from the Une Formation in Colombia, preserves evidence of an Aptian-Cenomanian low-latitude assemblage. Nearly complete leaves, leaf fragments, seeds, fruits and flowers are preserved in siltstone lenses of deltaic sandstone deposits, and were extracted through bulk maceration. This assemblage preserves diverse gymnosperms including Araucariaceae, Cupressaceae, Podocarpaceae, Cycadales, Ginkgoales, Bennettitales, and Gnetales, as well as monocot and non-monocot angiosperms and early flowers with in situ stamens and pollen grains. Lycopodiopsida are also present. Abundant epiphyllous fungi, including mycelia, sporomata, and spores, occur throughout the assemblage.
The Podocarpaceae foliage represents the first Aptian–Cenomanian record for the family from northwestern Gondwana, supporting a long-standing tropical distribution. The flora also suggests humid climatic conditions, consistent with palynological evidence.
The abundant, well-preserved fossil leaves of the Une flora provide a framework for future atmospheric CO2 reconstruction during the Aptian–Cenomanian greenhouse interval using the Franks gas-exchange model. We also plan to infer relative genome size in both angiosperms and gymnosperms based on guard cell dimensions. Initial genome-size results show variation in guard cell length among morphotypes, potentially reflecting differences in ploidy level or repetitive DNA content. Our multi-proxy approach to the Une flora aims to further illuminate tropical Gondwanan plant diversity, ecosystem structure, paleoclimate, and Cretaceous plant biogeography.