The Pennsylvania State University The Graduate School College of Earth and Mineral Sciences AUSTRALIAN ANALOGS FOR AN EOCENE PATAGONIAN PALEORAINFOREST A Thesis in Geosciences by Lisa Merkhofer Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Science August 2014 The thesis of Lisa M. Merkhofer was reviewed and approved* by the following: Peter Wilf Professor of Geosciences Thesis Advisor Mark Patzkowsky Professor of Geosciences Timothy Bralower Professor of Geosciences Lee Kump Professor of Geosciences Head of the Department of Geosciences *Signatures are on file in the Graduate School. ii ABSTRACT The diverse Laguna del Hunco (LH) paleoflora from early Eocene Patagonia, Argentina, has striking similarities to subtropical and tropical Australian rainforests. Previous research recognized the Simple Notophyll Vine Forests (SNVFs) of montane New South Wales, Australia, as potential analogs for the paleoflora in terms of diversity, floristic composition, leaf size, and environment. In this study, I test this hypothesis by: (1) inferring the Laguna del Hunco rainforest type; (2) quantitatively comparing the paleoflora to 596 Australian rainforest plots; and (3) comparing these results to non-Australian regions in Australasia and Southeast Asia where Laguna del Hunco’s nearest living relatives also occur. First, I inferred rainforest type using paleofloristics and fossil dicot leaf area. Fossil leaf area was measured directly or estimated with the Cain and Castro formula, the Raunkiaer-Webb size classes, or vein scaling, a new method that has not yet been applied to fossils and uses a scaling relationship between leaf area and secondary vein density. By testing all three methods on 159 fossil leaves with intact areas, I found that vein scaling was as accurate at predicting leaf area as the Raunkiaer-Webb size classes, but more applicable to fragmentary leaves. When I used vein scaling to reconstruct the areas of 94 fragmented specimens from LH, the paleoflora’s grand mean leaf area increased by ~360 mm2, recovering large leaf areas that were previously undetected. Across 1152 fossil leaves representing 154 dicot species, Laguna del Hunco’s mean leaf size was 1755 mm2, or large microphyll. The paleoflora’s leaf size index and floristic composition were found to support its similarity to an SNVF. Secondly, I found that subtropical rainforests with moderate, but not montane elevations, were the closest Australian analogs for LH both in terms of leaf size, family composition, and the generic occurrences of Laguna del Hunco’s nearest living relatives (NLRs). Lastly, I found that Laguna del Hunco’s NLRs occurred in three non-overlapping climate regions: cool-dry areas in subtropical Australia, hot-wet areas in tropical Australia, and cool-wet areas not found in Australia, but in montane Australasia and Southeast Asia. These results suggest that Australia no longer has the cool, wet montane environment needed to support some of the lineages from the paleoflora. This study uses a novel, quantitative method of fossil-modern comparison that can be applied to other paleofloras, allowing paleoecological interpretations to be more precisely based on both taxon-free and taxon-informed data. iii TABLE OF CONTENTS LIST OF TABLES ....................................................................................................................... V! LIST OF FIGURES .................................................................................................................... VI! ACKNOWLEDGMENTS ........................................................................................................ VII! INTRODUCTION ......................................................................................................................... 1! Leaf area in paleorainforest reconstructions ................................................................................... 1! The Laguna del Hunco paleoflora ................................................................................................... 4! Australian rainforests as modern analogs ....................................................................................... 5! MATERIALS AND METHODS ................................................................................................. 8! Laguna del Hunco setting ............................................................................................................... 8! Paleofloristics and nearest living relatives ...................................................................................... 9! Fossil specimens and repository ................................................................................................... 13! Dicot leaf area analysis ................................................................................................................. 13! Australian rainforest dataset ......................................................................................................... 18! Analog rainforest analysis ............................................................................................................. 20! Climate space analysis .................................................................................................................. 22! RESULTS .................................................................................................................................... 25! Accuracy of the vein scaling method ............................................................................................ 25! Laguna del Hunco dicot leaf size .................................................................................................. 25! Leaf size comparisons ................................................................................................................... 29! Floristic comparisons .................................................................................................................... 33! Climate space comparisons ........................................................................................................... 36! DISCUSSION .............................................................................................................................. 39! Including fragmented leaves in fossil leaf area measurements ..................................................... 39! Assessing taphonomic bias in leaf area ........................................................................................ 40! Laguna del Hunco as a Simple Notophyll Vine Forest ................................................................. 42! Closest analog rainforests ............................................................................................................. 43! Australian climate spaces .............................................................................................................. 45! CONCLUSIONS ......................................................................................................................... 47! LITERATURE CITED .............................................................................................................. 49! APPENDIX A. SUPPLEMENTAL LEAF AREA METHODS AND RESULTS ................. 60! APPENDIX B. ADDITIONAL FOSSIL-MODERN COMPARISON RESULTS ............... 95! iv LIST OF TABLES Table 1. Taxa from Laguna del Hunco paleoflora used in floristic analyses ............................... 10! Table 2. Breakdown of fossil specimens used for Laguna del Hunco leaf area ........................... 17! Table 3. Geography, environment, and species diversity of living Australian rainforests ........... 19! Table 4. Climate ranges of selected nearest living relatives of fossil species .............................. 22! Table 5. Taxon-specific leaf area for Laguna del Hunco and Australian nearest living relatives 31! Table 6. Living Australian rainforests with the highest number of Laguna del Hunco’s nearest living relative genera ............................................................................................................. 37! v LIST OF FIGURES F igure 1. Measurement technique for estimating leaf area vein scaling ...................................... 15! Figure 2. Evaluating methods for measuring fossil leaf area ........................................................ 26! Figure 3. Accuracy of the vein scaling method ............................................................................ 27! Figure 4. Laguna del Hunco fossil dicot leaf areas. ...................................................................... 28! Figure 5. Leaf areas of Laguna del Hunco fossils and Australian nearest living relatives ........... 30! Figure 6. Grand mean leaf areas of Laguna del Hunco and living Australian rainforests ............ 32! Figure 7. Family compositions of Laguna del Hunco and living Australian rainforests .............. 34! Figure 8. Occurrences of Laguna del Hunco’s Australian nearest living relative genera ............ 35! Figure 9. Climate spaces of Laguna del Hunco’s nearest living relatives .................................... 38! vi ACKNOWLEDGMENTS I owe many thanks to my advisor Dr. Peter Wilf for his unflagging guidance throughout the course of this project. The many hours he devoted to commenting on drafts, ensuring that I had all necessary resources, and interpreting troublesome results was invaluable, as was his ever- present jovial encouragement. I would also like to thank to my committee members, Dr. Mark Patzkowsky and Dr.