title: Aponogetonpollen from the Cretaceous and Paleogene of North America and West Greenland: Implications for the origin and palaeobiogeography of the genus.
abstract: The fossil record ofAponogeton(Aponogetonaceae) is scarce and the few reported macrofossil findings are in need of taxonomic revision.Aponogetonpollen is highly diagnostic and when studied with light microscopy (LM) and scanning electron microscopy (SEM) it cannot be confused with any other pollen types. The fossilAponogetonpollen described here represent the first reliable Cretaceous and Eocene records of this genus worldwide. Today,Aponogetonis confined to the tropics and subtropics of the Old World, but the new fossil records show that during the late Cretaceous and early Cenozoic it was thriving in North America and Greenland. The late Cretaceous pollen record provides important data for future phylogenetic and phylogeographic studies focusing on basal monocots, especially the Alismatales. The Eocene pollen morphotypes from North America and Greenland differ in morphology from each other and also from the older Late Cretaceous North American pollen morphotype, indicating evolutionary trends and diversification within the genus over that time period. The presence ofAponogetonin the fossil record of North America and Greenland calls for a reconsideration of all previous ideas about the biogeographic history of the family.
authors.affiliation: University of Vienna, Department of Palaeontology, Althanstraße 14 (UZA II), Vienna, Austria.
authors.forename: Friðgeir
authors.initials: F
authors.lastname: Grímsson
authors.affiliation: University of Vienna, Department of Palaeontology, Althanstraße 14 (UZA II), Vienna, Austria.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Zetter
authors.affiliation: University of Vienna, Department of Structural and Functional Botany, Rennweg 14, Vienna, Austria.
authors.forename: Heidemarie
authors.initials: H
authors.lastname: Halbritter
authors.affiliation: Swedish Museum of Natural History, Department of Palaeobiology, Box 50007, 10405 Stockholm, Sweden.
authors.forename: Guido W
authors.initials: GW
authors.lastname: Grimm
keywords: Alismatales; Aponogetonaceae; aquatic plant; basal monocot; early angiosperm; subtropical plant