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Cretaceous tropical Alismatales in Africa: diversity, climate and evolution

2018; Oxford University Press; Volume: 188; Issue: 2 Linguagem: Inglês

10.1093/botlinnean/boy045

1095-8339

Clément Coiffard, Barbara Mohr,

Paleontology and Stratigraphy of Fossils

Alismatales are the second oldest diverging clade of monocots and are dominated by Araceae, a major component of the tropical rainforest understorey. The fossil record of Alismatales has increased in recent decades but remains concentrated in northern mid-latitudes. Here, we describe a new assemblage of Alismatales from the Cretaceous (Campanian) of Egypt. This assemblage is especially diverse, containing five araceous taxa, including stem Lemnoideae and crown Aroideae and one member of Alismataceae. Aquatic Araceae are quite similar to mid-latitude taxa, whereas helophytic/terrestrial Araceae are more similar to Cenozoic taxa. Two taxa in this assemblage display affinities with taxa commonly found in tropical rainforests and are apparently extinct in Africa, suggesting an early appearance of this biome, followed by extinction of many lines in Africa.