Taylor, David W. , Hu, Shusheng , Tiffney, Bruce H. .
Structure and relationships of a new fagaceous mesofossil flower from the Campanian of North America.
Dozens of similar three-dimensionally preserved flowers have been collected from the Campanian of Massachusetts. The flowers are small, mostly inferior with unicellular and peltate, multicellar trichomes. The flowers are pedicellate and are triangular to round in cross section. The six tepals are valvate in bud and concave, covering the axillary stamens and an enlarged, potentially glandular, area with many hairs. There are nine to twelve stamens with dorsifixed, nearly square, introse anthers with elongate multicellular structures on the connective facing outwards. The three carpellate ovary has three inwards-directed, capitate stigmas. Each locule has two smaller orthotropous to larger anatropous ovules. The single seeded dry fruit has an exocarp with large cavities and a thin spongy endocarp. Although apparently indehiscent, older sectioned fruits have evidence of a dehiscence line. Pollen is 9-10um, prolate, tricolporate, scabrate to vermiform, and tectate–collumellate. Using the topology and characters of the Angiosperm Phylogeny Website http://www.mobot.org/MOBOT/research/APweb/welcome.html, the fossil is a Core Eudicot based on numerous anthers, tricolporate pollen, three carpels, axile placentation, stigma not decurrent, dry (loculicidal) fruit. The fossil differs with tepals, 6-merous flower and indehiscent fruit. Affinity with Cucurbitales-Fagales is based on articulated anthers, inferior ovary, and single seeded, indehiscent fruit. Characteristics in Fagales are variable, but identified synapomorphies shared with the fossil include flowers very small, two pendulous ovules in each carpel poorly developed at pollination, fertilization delayed, fruits dry, and exotesta often enlarged and persisting. In conflict are the states inflorescence a spike (catkin), flowers unisexual, nectary lacking, anthers opposite petals, stigma linear, and small pollen with a granular layer below tectum. Based on the matching of characteristics, the fossil may be placed as a sister taxon to all living Fagales, as a sister taxon to all Fagales except Nothofagaceae or as a sister to all living members of Fagaceae.
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1 - Indiana University Southeast, Biology, 4201 Grant Line Rd, New Albany, IN, 47150
2 - Indiana University Southeast, Biology, 4201 Grant Line Rd, New Albany, IN, 47150, USA
3 - University of California Santa Barbara, Dept. of Earth Sciences and College of Creative Studies, Santa Barbara, California, 93106, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Lake Erie/Hilton
Date: Tuesday, July 10th, 2007
Time: 10:45 AM