EARLY ANGIOSPERMDIVERSIFICATION: THEDIVERSITY OF POLLENASSOCIATED WITHANGIOSPERMREPRODUCTIVESTRUCTURES IN EARLYCRETACEOUS FLORAS FROMPORTUGAL'Else Marie Friis,2Kaj Raunsgaard Pedersen,: andPeter R. Crane'ABSTRACT Studies of five mesofossil floras from the Early Cretaceous (Barremian or Aptian?) of Portugal document a previouslyunrecognized diversity of angiosperms exceeding that currently known from other localities of this age. At the Famalicaio.Vale de Agua, and Buarcos localities angiosperms are represented hy alboui 10) different kinds of flowers, fruits, seeds.and stamens. At the other two localities (Torres Vedras and Catefica) angiosperm diversity is lower but still significant.At each of the five localities between 7 and 26 types of angiospermni pollen have heen recognized based on pollen grainsin situ within anthers, or on stigmatic or fruit surfaces. Monocolpate. dicolpate. periporate. and tricolpate angiospermpollen have been recognized, but in ail cases monocolpate grains, of probable magnoliid or monocotyledonous affinity.are the most diverse element. The diversity of angiosperm pollen in sitn. or associated with other angiosperm repro-ductive structures, is greater than that of the dispersed palynoflora from thle sane localities. The diversity and abundanceof angiospermns in the Portuguese mesofloras contrast strongly with the apparent paucity of angiosperm pollen indispersed palynofloras, as well as the scarcity of angiosperrn wood and leaves in Barremian-Aptian fossil plant assem-blages. This discrepancy may reflect the widespread occurrence of botlh insect pollination and herbaceous habit amongthe angiosperms in the initial phases of their Early Cretaceous dliversification. Numerous fossil floras of Cretaceous age thatcomprise three-dimensionally preserved angio-sperm flowers, fruits, seeds, and dispersed stamenshave been discovered within the past 15 to 20years. These floras are particularly abundant in Up-per Cretaceous sediments and have been reportedfrom widely separate geographic regions in theNorthern Hemisphere. The first comprehensivestudies were based on European material, and richLate Cretaceous floras are known from Cenonanianto Maastrichtian strata of the Czech Republic, Ger-many, Austria, the Netherlands, Portugal, and Swe-den (Friis & Skarby, 1981, 1982; Friis, 1983, 1984;Knobloch & Mai, 1984; Friis, 1985a, b; Knobloch& Mai, 1986; Friis et al., 1988; Friis & Crane,1989; Friis, 1990; Knobloch & Mai, 1991; Friis etal., 1992; Eklund et al., 1997; Eklund & Kva�ek,1998). In North America, similarly rich Late Cre-taceous floras are known from Cenomanian to Cam-panian strata of Massachusetts, Maryland, New Jer-sey, North Carolina, and Georgia (Friis, 1988; Friiset al., 1988; Drinnan et al., 1990, 1991; Heren-deen, 1991; Herendeen et al., 1993; Nixon & Cre-pet, 1993; Crepet & Nixon, 1994; Herendeen et al.,1994; Crane & Herendeen, 1996; Frumin & Friis,1996; Magall6n-Puebla et al., 1996, 1997). In Asia,fossil flowers and fruits have been reported fromConiacian to Campanian strata of Japan (e.g., Nish-ida & Nishida, 1988; Nishida, 1994; Nishida et al.,1996) and have recently been discovered from Cen-omanian-Turonian strata of Kazakhstan (Frumin &Friis, 1996, 1999). The angiospermns recovered in ' We thank J. A. Doyle. I. K. Ferguson. and I S. lHerenideen for valalhle conmmcnts on the manuscript. B. I arsen.University of Aarhus, Denmark. for assistance with lieldwork anld preparliiion ot th PoIrtuguese samples, and YvonneArremo, Swedish Museum of Natural History, Sweden, for help in preparing the illustrations. We gratefully acknowledgefinancial support from the Carlsberg Foundation (KRP, EMF), the Swedish Natural Sciences Research Council (EMF),and the U.S. National Science Foundation (EAR-9614672, PRC). 2 Department of Palaeobotany, Swedish Museum of Natural History. Box 50(X)7, S-10405 Stockholmhn. Sweden. Dl)epartment of Geology, University of Aarhus, Universitetsparken, DK-8(X0) Aarhus C. Denmark. SDepartment of Geology, The Field Museum, Roosevelt Road at Lake Shore Drive. Chicago. Illinois 60605, U.S.A. ANN. MIssouRI BOT. GARD. 86: 259-296. 1999.
BioStor
