Format: ORAL

Gobo, William Vieira; Fradret, Alice2; Nascimento Jr., Daniel Rodrigues3; Silva Filho, Wellington Ferreira3; Iannuzzi, Roberto¹; Kunzmann, Lutz4; Coiffard,

1 Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil 2 ENS de Lyon, Lyon, France 3 Universidade Federal do Ceará, Fortaleza, Brazil 4 Senckenberg Naturhistorische Sammlungen, Dresden, Germany 5 Freie Universität, Berlin, Germany

The Crato Formation of the Araripe Basin, northeast of Brazil is one of the best Fossil Konservat Lagersttte to access Early Cretaceous paleoecosystems in equatorial regions of Gondwana. There, the apparent dominance of gymnosperms splits attention with the emerging group of angiosperms. Despite intensive geological and taxonomic studies made in this area, approaches to elucidate the paleoecophysiological aspects of fossil plants are still rare. Interestingly, the gnetaleans, a gymnosperm lineage, which convergently evolved similar features with many angiosperms, might have occurred the same environments together with some early angiosperms. Until now, it is still lacking clear evidence showing the reason for intense diversification and radiation of both angiosperms and gnetaleans in the early to middle Cretaceous. Both plant lineages may be functionally similar and then subjects to similar selective pressures. One of the big questions is what caused the subsequent success of angiosperms and the coeval decline of gnetaleans. Did gnetalean taxa already differ, in the Crato flora, from angiosperms in terms of ecophysiological adaptations and tolerance ranges? Could this have influenced on the subsequent success of the angiosperms? In addition, does the ecological role of these plants differ significantly? To address these questions, 35 specimens of 17 angiosperm taxa and 70 specimens of 20 gnetalean taxa were preliminarily selected to analyze their paleoecophysiological leaf traits. The functional types of fossils and living taxa were included in our analysis, as well as the type of fossil association according to the mode of transport. The leaf energy balance model was used to infer the leaf temperature and transpiration from measurements of vein density and leaf width. As a result, the ecological requirements of fossil taxa of angiosperms and gnetalean gymnosperms were estimated and compared with those of related living plants in different habitats.