Systematics of Miocene angiosperm woods from the Panama Canal, and their ...

441 Pages·2015·38.17 MB·English

Systematics of Miocene angiosperm woods
from the Panama Canal, and their
palaeoenvironmental implications
Oris Rodríguez Reyes
Royal Holloway, University of London
A thesis submitted for the degree of Doctor of Philosophy
October, 2014
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Declaration of authorship
I, Oris Rodríguez Reyes, hereby declare that this thesis
Systematics of Miocene angiosperm woods from the Panama
Canal, and their palaeoenvironmental implications
The work presented in it is entirely my own. Where I have consulted the work of others,
this is fully cited and referenced, and/or with the appropriate acknowledgment given.
Signature:
Date: 20 October 2014
Miss Oris Rodríguez Reyes
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ABSTRACT
Systematics of Miocene woods from the Panama Canal, and their
palaeoenvironmental implications
Miocene fossil woods exposed during the recent widening of the Panama Canal are
described and their palaeoecological, palaeoclimatic and biogeographic implications are
discussed. The woods occur in the Cucaracha Formation (early to mid-Burdigalian, 18 –
20 Ma) and comprise (1) a forest of charred and silicified stumps preserved in growth
position by a pyroclastic flow and (2) calcareous permineralised trunks, bored by
Teredolites and transported within fluvio-estuarine channel deposits. Woods were
identified using a searchable authoritative online database (Inside Wood) and through
detailed comparison with modern woods, mostly at the Jodrell Laboratory, Kew, UK.
The two assemblages differ at genus-level, and to some extent, family-level. The
permineralised wood assemblage contains dicots and is dominated by Malvaceae with
some Leguminosae, Cannabaceae and Elaeocarpaceae. It includes representatives of
several extant genera tolerant of flooding and exposed coastal conditions, consistent
with the estuarine setting inferred from the geological evidence. In contrast, the
charcoalified wood assemblage contains monocot palms (Arecaceae) but also includes
dicots (Leguminosae, Malvaceae, Sapotaceae, ?Melastomataceae, Meliaceae) and dicot
indeterminate forms. The extant relatives of this assemblage include a mixture of
coastal and forest interior taxa representing a more diverse floodplain forest.
Reflectance data from the charred stumps indicate that entombing pyroclastic flows
reached minimum temperatures that ranged from 490 – 505ºC. Palaeoclimatic
inferences, based on anatomical comparison of fossil woods and present-day woods and
floras from Panama, suggest that Miocene forests were somewhat cooler and drier than
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modern equivalents. The fossil wood assemblages contain several taxa endemic to
South America, despite Panama being part of the North American continent in Miocene
times. This implies that the collision of the Americas, which was traditionally thought to
have occurred around 3 – 4 million years ago (mid – to late Pliocene) may have begun
much earlier, with intercontinental exchange of tree species beginning by 18 – 20 Ma.
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ACKNOWLEDGMENTS
I would like to express my deepest thanks to my supervisors: Dr. Howard
Falcon-Lang and Dr. Margaret E. Collinson that patiently gave me thoughtful guidance
from my very first day in Royal Holloway until the last days of my thesis writing; as
well as to Dr. Carlos Jaramillo who inspired this work in the first place and constantly
supported me to continue in the field of palaeobotany. Very special thanks go also to
Dr. Peter Gasson in the Jodrell Laboratory (Royal Botanic Gardens Kew), who kept my
motivation in the study of wood anatomy and gave me invaluable guidance, teaching
and support.
I would like to acknowledge the advice from Dr. Gary Nichols, Dr. Elisabeth
Wheeler and Dr. Pieter Baas during the first years of the project and to Dr. Pieter Hietz,
during my internship in Vienna. They have been of greatest inspiration and helped to
greatly improve this research project. Advice from Dr. Emiliano Peralta-Medina was
also important during the first years of my thesis.
I am very thankful to Kevin D’Souza, Neil Holloway and Sharon Gibbons that
offered excellent aid in the imaging, preparation and analysis of samples, respectively.
I would also like to thank to Dr. Sergio Cevallos-Ferriz and Dr. Laura Calvillo-Canadell
(UNAM, Mexico) for the preparation of some of the samples included herein.
Thanks to the paleontology/geology team in CTPA (Center for Tropical
Palaeoecology and Archaelogy, STRI, Panama), but particularly to Dr. Camilo Montes,
who provided with important information about the geology of the field area. Thanks to
Aldo Rincón, Catalina Suárez, César Silva, Carlos De Gracia, Maritza Moya, Jorge W.
Moreno, Federico Moreno, Enrique Moreno, Felix Rodríguez, Juan David Carrillo,
María Camilla Vallejo, Andrés Baresch, Luz Elena Oviedo, María Inés Barreto and
Liliana Londoño for all the help during fieldwork. Thanks to Alina Screuer and Sabine
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Rosner for all the help with the samples during my internship in the BOKU in Vienna.
Valuable comments from my examiners, Professor Will Chaloner and Dr. Jakub
Sakala greatly improved this thesis. I am also grateful for all those valuable
suggestions from my colleagues and friends: Vicky Hudspith, Francy Carvajal, Gabriela
Doria, Fabiany Herrera, Monica Carvalho, Camilla Crifó, Emilio Estrada-Ruiz, Luis
Palazzesi, Silvia D’apolito, LuisDanise and Heather Graham.
Very special thanks to my good friends that gave me all the strength and support
in the good and weakest moments: Ivan Hernández, Miguel Andrés Martínez, Celine
Tschirhart, Lidia Rodríguez, Gerd Winterleitner, Sila Pla Pueyo, Arnaud Gallois,
Sebastian Zimmermann, Silvia Crosetto, Giulia Zazzeri, Damiano Della Lunga,
, Jéssica García, Eldert Advokaat, Giovanni Pezzati, Jorge Belenguer, Zsuzsanna
Döbröntei, Elena Ros, Denise Gutiérrez, Liliane Mendoza, Eva Baker, Maria Reilly,
Irina Calero Bieberach and Elena García Antón. Muchas gracias!
My deepest love and thanks go to my family for their constant and incredible
support: my mom, Lilia Reyes de Rodriguez; my father, Alfonso Rodríguez and my
siblings, Lily, Edwin and Osiris.
Finally, I take this space to say thanks to you, Mena Schemm-Gregory. Among
paleontologists, you were my greatest model to follow because of your perseverance
despite all adversities. You would have been so happy and proud watching me
submitting this work. Thanks for encouraging me so much during my Phd.!
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Title page ................................................................................................................................ 1
Declaration of authorship ........................................................................................................ 2
Abstract ................................................................................................................................... 3
Acknowledgments ................................................................................................................... 5
List of contents ...................................................................................................................... 7
CHAPTER 1: INTRODUCTION ...................................................................................... 27
1.1 THESIS STRUCTURE .......................................................................................................... 27
1.2 SIGNIFICANCE OF THIS THESIS .................................................................................... 28
1.3 TIMELINESS OF THIS THESIS ........................................................................................ 28
1.4 INTRODUCTION TO MIOCENE EPOCH ................................................................ 29
1.4.1. Major tectonic events ...................................................................................... 30
1.4.2. Global climatic trends ..................................................................................... 32
1.4.3. Miocene savannas with special reference to the Americas ............................. 34
1.5 PANAMA DURING THE MIOCENE .................................................................... 35
1.5.1. Tectonic hypothesis for convergence of Americas ......................................... 36
1.4.2. The Panama Canal Basin and its stratigraphy ................................................. 40
CHAPTER 2: GEOLOGICAL CONTEXT OF STUDY SITES .................................... 42
2.1 INTRODUCTION ..................................................................................................... 42
2.2 BACKGROUND OF THE CUCARACHA FORMATION .................................. 42
2.2.1. Previous works in the Cucaracha Formation ................................................... 42
2.2.2. Age of Formation ............................................................................................ 44
2.2.3. Stratigraphic succession .................................................................................. 46
2.2.4. Fossil fauna of the Cucaracha Formation ........................................................ 48
2.2.5. Fossil flora of the Cucaracha Formation ......................................................... 50
2.3 NEW FIELD INVESTIGATIONS: LOCALITIES AND CORRELATION ...... 52
2.4 SEDIMENTARY FACIES ....................................................................................... 54
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2.4.1. Description ...................................................................................................... 54
2.4.2. Palaeoenvironmental interpretation ................................................................. 57
2.5 FOSSIL WOOD ASSEMBLAGES .......................................................................... 58
2.5.1. Permineralised woods .................................................................................... 59
2.5.2. Charcoalified fossil forests .............................................................................. 59
2.5.2.1. Forest layer description .................................................................... 61
2.5.2.2. Tree orientation, inferred blast direction and probable location of
volcanic cone ................................................................................................. 61
2.5.2.3 Forest composition ............................................................................ 63
2.5.2.4 Tree size and inferred tree height ...................................................... 63
2.5.2.5 Tree spacing and inferred forest density ........................................... 67
2.5.2.6 Associated leaf adpressions ............................................................... 67
2.6 INITIAL FOREST INTERPRETATION ............................................................... ...68
CHAPTER 3: METHODS FOR WOOD SYSTEMATICS ............................................ 69
3.1 INTRODUCTION ..................................................................................................... 69
3.2 WOOD ANATOMY AND GENERAL TERMINOLOGY ................................... 70
3.2.1. How is wood or secondary xylem formed? .................................................... 70
3.2.2. Main cells and elements of the secondary xylem ............................................ 72
3.2.3. Types of woods ............................................................................................... 74
3.2.3.1. Main characters to describe and identify dicotyledonous woods ................. 76
3.2.4. Palm “woods” .................................................................................................. 90
3.3 PREPARATION OF SAMPLES FOR SYSTEMATICS ANALYSIS ................. 92
3.3.1. Thin sectioning ................................................................................................ 92
3.3.2. Acetate peels ................................................................................................... 97
3.3.2. Scanning Electronic Microscopy (SEM) methods for charcoalified woods ... 97
3.4 IDENTIFICATION METHODOLOGY FOR DICOTYLEDONOUS
WOODS…………………………………………………………………………………98
3.4.1. IAWA coding and feature description ............................................................ 98
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3.4.2. Inside Wood Database searches .................................................................... ..99
3.4.3. Comparison with wood collections of extant data ........................................ 100
3.4.4. Dimensional changes and shrinkage during charring of woods ................... 100
3.4.5. PCA morphometrics methods ...................................................................... 101
CHAPTER 4: TAXONOMY OF PERMINERALISED FOSSIL WOODS (PART 1):
CANNABACEAE, FABACEAE AND ELAEOCARPACEAE .................................... 103
4.1 INTRODUCTION ................................................................................................... 103
4.2 FOSSIL WOOD TYPE 1 ........................................................................................ 103
4.2.1. Description .................................................................................................... 105
4.2.2. Affinities and justification ............................................................................. 111
4.2.3. Comparison with Celtis ................................................................................. 114
4.2.4. PCA morphometrics ...................................................................................... 121
4.2.5. Systematics and ecology of Celtis ................................................................ 123
4.2.6. Fossil record of Celtis .................................................................................. 124
4.2.7. The new report of Celtis in the Isthmus of Panama ..................................... 125
4.3 FOSSIL WOOD TYPE 2 ........................................................................................ ....126
4.3.1. Description .................................................................................................... 127
4.3.2. Affinities and justification ............................................................................. 134
4.3.3. Affinities with Caesalpinioideae .................................................................. 135
4.3.4. Affinities with the Detarieae ........................................................................ 136
4.3.5. Fossil record of Fabaceae ............................................................................. 143
4.3.6. Biogeographical and environmental implications ........................................ 146
4.4 FOSSIL WOOD TYPE 3 ....................................................................................... 147
4.4.1. Description .................................................................................................... 147
4.4.2. Affinities and justification ............................................................................. 149
4.4.3. Comparison with Elaeocarpus ...................................................................... 155
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4.4.4. Fossil woods of Elaeocarpaceae ................................................................... 159
4.4.5. The new report of Elaeocarpus in the Isthmus of Panama .......................... 160
CHAPTER 5: TAXONOMY OF THE PANAMA CANAL PERMINERALISED
WOODS: MALVACEAE ................................................................................................ 161
5.1 INTRODUCTION ................................................................................................... 161
5.2 FOSSIL WOOD TYPE 4 ........................................................................................ 162
5.2.1. Description .................................................................................................... 162
5.3 FOSSIL WOOD TYPE 5 ........................................................................................ 169
5.3.1. Description of inferred mature specimens ................................................... 171
5.3.2. Description of inferred juvenile specimens (Plate V): ................................ 172
5.4 JUSTIFICATION FOR ATTRIBUTION TO MALVACEAE .......................... 179
5.5 OCCURRENCE OF TILE CELLS WITHIN THE MALVALES .................... 179
5.6 OCCURRENCE OF TILE CELLS WITHIN THE MALVACEAE SENSU APG
III ................................................................................................................................... 181
5.7 IDENTIFICATION OF THE MALVALEAN WOOD TYPES ......................... 185
5.7.1. Identification of Fossil Wood Type 4 specimen .......................................... 185
5.7.2. Identification of Fossil Wood Type 5 specimens ......................................... 194
5.8 PCA MORPHOMETRICS .................................................................................... 201
5.9 COMPARISON WITH FOSSIL WOODS PREVIOUSLY ASSIGNED TO
MALVACEAE .............................................................................................................. 206
5.9.1. Cretaceous woods ......................................................................................... 206
5.9.2. Paleocene-Eocene woods ............................................................................. 207
5.9.3. Oligocene-Miocene woods ........................................................................... 208
5.9.3.1. Miocene specimens of Grewioxylon ............................................. 209
5.10 DISCUSSION ........................................................................................................ 210
5.10.1. Phylogeny and evolution ............................................................................ 210
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