Abstract Detail

Paleobotanical Section

Nelson, Christopher [1], Jud, Nathan [2].

Lianas from the Miocene of Panama: anatomy and implications for paleo-environment.

Lianas, or climbing woody plants, are a species-rich and important functional component of tropical and subtropical forest ecosystems. Fossil lianas are therefore critical for our understanding of the history of tropical and subtropical forests, but they are rarely recognized in fossil wood assemblages. As of 2015 only 19% of megafossil occurrences in the “Fossil Record of Climbers” database are wood and/or stem fossils. We studied fossilized stems from the Lower Miocene Cucaracha Formation of Panama (19Ma) in order to (1) develop a protocol for recognizing fossil lianas by their wood anatomy and (2) to use the diversity and abundance of liana stems to make inferences about the paleo-environment. Our assemblage includes 33 stems of known or estimable diameters. We first classified the stems as lianas or self-supporters based on the presence or absence of cambial variants. Then, we classified them as lianas or self-supporters using a discriminant function built from a training data set of extant stems (n = 74) using stem diameter and maximum vessel diameter. After completing both of these analyses, we found a minimum liana proportion of 18% (6 specimens) in the sample and report at least 5 distinct liana morphotypes. In modern tropical forests, liana diversity and abundance is correlated with seasonality and also with disturbance. Strong seasonality is unlikely to explain the abundance of lianas in the Cucaracha flora because a growth ring analysis of co-occurring fossil woods along with oxygen-isotope data from mammalian teeth both suggest a humid, non-seasonal climate. However, there is independent evidence of several potential sources of natural disturbance, including volcanism, megafaunal disturbance, and fluvial processes. Therefore, we interpret the Cucaracha flora as a disturbance-prone humid tropical rainforest.

1 - Florida Museum of Natural History, Paleobotany, Dickinson Hall, 1659 Museum Road, Gainesville, FL, 32611, USA
2 - Florida Museum of Natural History, Dickinson Hall, 1659 Museum Road, Gainesville, FL, 32611, United States

Keywords:
Miocene
Lianas
Panama Canal
fossil wood
anatomy wood.

Presentation Type: Oral Paper:Papers for Sections
Session: 28
Location: Salon 13/The Shaw Conference Centre
Date: Tuesday, July 28th, 2015
Time: 8:45 AM
Number: 28004
Abstract ID:919
Candidate for Awards:None