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Abstract Detail

Paleobotanical Section

Salvi, Amanda M. [1], Smith, Selena Y. [1], Benedict, John C. [1], Leong-Škorničková, Jana [2], Specht, Chelsea [3].

Re-Examining Zingiberales Fossils Using Leaf Venation.

Zingiberales are a diverse order of monocot flowering plants native to tropical and subtropical habitats worldwide, and comprise more than 2500 species in eight different families: Zingiberaceae (gingers), Musaceae (bananas), Heliconiaceae (heliconias), Strelitziaceae (bird-of-paradise), Costaceae (spiral gingers), Cannaceae (canna lilies), Marantaceae (prayer plants), and Lowiaceae (Orchidantha). Leaf architecture, which has not been examined in great detail across Zingiberales, is useful for distinguishing between families in the order and is relevant to better understanding their fossil record. The leaf fossil record for Zingiberales extends back to the Late Cretaceous but many fossils are not confidently placed to family. Leaves of extant members of families in Zingiberales are found to be distinguishable using vein pattern type, vein length per area (VLA), and other aspects of vein architecture such as angle of vein divergence. Three main types of venation are recognized: the Zingiber-type, with square to vertically elongate areoles; the Costus-type, with horizontally elongate areoles; and the Orchidantha-type with cross veins spanning multiple parallel veins. VLA data show different patterns of length of cross vs. parallel veins that correlate to families and reflect overall venation patterns of each family. Divergence angles of parallel veins from the costa were measured as an additional characteristic for family identification. Preliminary results suggest that Costaceae and Zingiberaceae have the most acute divergence angles (<25°), Cannaceae and Marantaceae have moderately acute divergence angles, while Heliconiaceae, Musaceae, Lowiaceae, and Strelitziaceae have divergence angles between 40° and 80°. Seven different taxa of zingiberalean leaf fossils were re-examined within the context of these new data. Canna flaccidafolia from the Eocene/Oligocene of Montana, USA has features consistent with Zingiberaceae, and is unlikely to be Cannaceae. ?Costus from Eocene of the UK has features consistent with either Costaceae or Cannaceae. An undescribed fossil from the Eocene of Messel, Germany is tentatively interpreted as Marantaceae. Several fossils of Zingiberopsis magnifolia, Zingiberopsis attenuata, and Zingiberopsis isonervosa from the Late Cretaceous–Eocene of North America were studied and found to be consistent with their published description in Zingiberaceae. Finally, Donax lishensis from the Late Miocene of India is interpreted as likely being Zingiberaceae, and does not show features consistent with Marantaceae. Thus, our findings support the family identification of some Zingiberales leaf fossils while suggesting different family identifications for others. More precise identification of their fossil record will allow us to understand the evolutionary history of Zingiberales and their use in reconstructing past climates.

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1 - University of Michigan, Department of Earth and Environmental Sciences, 2534 CC Little Building, 1100 North University Avenue, Ann Arbor, MI, 48109-1005, USA
2 - Singapore Botanic Gardens, Herbarium, National Parks Board, Singapore
3 - University of California at Berkeley, Plant and Microbial Biology, Integrative Biology, 431 Koshland Hall, Berkeley, CA, 94720, USA

vein length per area
vein divergence angle

Presentation Type: Oral Paper:Papers for Sections
Session: 15
Location: Salon 5/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 2:15 PM
Number: 15004
Abstract ID:769
Candidate for Awards:Isabel Cookson Award

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