The study of ancient angiosperm fossils has provided important information on the timing and pattern of geographic dispersal of flowering plants. Paleobiogeographical research on micro- and macrofossil floras suggested that geologically oldest angiosperms are found near the equator, while the younger ones are also discovered at higher paleolatitudes, during the Early Cretaceous. However, paleobiogeographic studies are hampered by the relatively fewer, detailed studies of early angiosperm floras, particularly from the paleoequatorial regions. Our previous work used the relative concentration and appearance of the biomarker oleanane to support hypotheses that angiosperms were rare during the earliest Cretaceous and had a major increase by the end of the Early Cretaceous and another expansion by the end of the Cretaceous. We are applying this technique to test the hypothesis that angiosperms initially occurred and diversified near the paleoequator and later extended geographically toward the poles. We have begun to collect biomarker data from the Jurassic-Cretaceous sediments from Israel and Jordan (near the paleoequator) and England (mid-latitude), and to compare the earliest occurrence and the increasing patterns of oleanane in these regions. We also have begun to examine Early Cretaceous deltaic and more terrestrial sediments from different paleolatitudes. Our preliminary data show strong biomarker support for the hypothesis that angiosperms first appeared in paleoequatorial regions and dispersed towards the poles during the Aptian and later. Additional data from mid- and upper latitudes from both the northern and southern hemisphere are needed to confirm this pattern.

Key words: angiosperm radiation, angiosperms, Early Cretaceous., Oleanane, paleobiogeography