A preliminary survey of Eocene angiosperm leaves from the Peruvian Andes
Kelly Martin Penn State Altoona Spring 2020
Research Advisor: Sarah E. Allen Location
El Bosque Petrificado Piedra Chamana Sexi, Department of Cajamarca, Peru
Map from: Woodcock et al., 2017 Geologic Context
Radiometrically (40Ar/39Ar) dated at 39 million years old Ashfall and lahar deposits indicate volcanic or volcanoclastic origin Fossil Flora
➢ Both petrified wood and fossilized leaves present ➢ Wood well documented; more than 40 species of flowering plants identified ➢ Fossil leaves collected in 2005 and 2007 ➢ Previous wood studies suggest a seasonal mangrove forest, near a higher elevation forest.
Scale bars = 250 µm Paleoclimate
Known from studies of fossilized wood structure and leaf physiognomy Seasonal precipitation alternating between wet and dry periods High average temperatures; ~25-30 C Fossil Leaves
Over 200 specimens under study using high resolution photographs Stored at The Museo de Historia Natural in Lima, Peru Being sorted into morphotypes (species-like groups) using the Manual of Leaf Architecture Fossil Leaves cont.
Characters used for morphotyping include: apex angle, base angle, base shape, primary vein framework, lobation, etc. Many leaves are incomplete or fragments Excurrent Secondary Vein Attachment Obtuse Apical Angle 1 cm Intersecondary Veins Intersecondary Eucamptodromous Secondary Vein Terminal End Pinnate Primary Venation Oblong Leaf Shape Decurrent Secondary Vein Attachment Tertiary Vein Fabric Future Goals
Finalize morphotype number Identify leaves Compare leaves and wood Perform paleoclimate analyses References
Ellis, B., et al., Manual of Leaf Architecture. New York Botanical Garden Press, 2009. Woodcock, D.W., et al. “Geologic and Taphonomic Context of El Bosque Petrificado Piedra Chamana (Cajamarca, Peru).” GSA Bulletin, vol. 121, no. 7-8, 2009, pp. 1172– 1178., doi:10.1130/b26359.1. Woodcock, D.W., et al. “The Piedra Chamana Fossil Woods (Eocene, Peru).” IAWA Journal, vol. 38, no. 3, 2017, pp. 313–365., doi:10.1163/22941932-20170175. Woodcock, D.W., et al. “The Piedra Chamana Fossil Woods (Eocene, Peru), II.” IAWA Journal, vol. 40, no. 3, 2019, pp. 551-595., doi:10.1163/22941932-40190231.