Preface Introduction What's in a Scientific Name? Geology & Evolutionary Biology Interview: Dr. Stephen Ervin Evolution Paleobotany Morphology In Paleontological Terms Land Plant to Trees & Birds Antarctica Australia Asia Africa South America Paleoforestry & Conservation Lore Metaphysical Lapidary Interview: Jackie Lapin Links Endnotes Article Contributors Photo & Graphics Credits Suggested Reading Invitation to Members Past Minerals of the Month Member's Gallery		Tietea singularis, 250 myo Tree fern, Brazil Photo by and courtesy of Steve Speer, ©2006 Sticks-in-stones.com	Red Australian Petrified Wood Sphere (Below): Three spheres Photos by and courtesy of Jackie Lapin, ©2006 SpheresToYou.com
		Pleistocene Petrified Wood, Odessa, Delaware Photo by and courtesy of Karissa Hendershot  ©2006	Microslide of Indonesian petwood ©2006 Sticks-in-stones.com
		Don't be scared... ...it may not look like wood, but it is petrified!

Preface

     We begin in Petrified Wood: Part II, with plant matters.  From the microscopic cell
structures to macroscopic grain patterns, our search today favors paleobotany.  As certain
lapidary processes bring out these structures for our perusal, we will add these to our cache of
last month’s feature.

     With an international eye on our world’s paleoforests, we will travel the globe in search
of petrified wood itself, and some cultural lore that surrounds it.  We will touch upon the
metaphysical briefly, but will base ourselves in the concrete science of evolving plant forms
over time.  Our “evolution” will take us to Pangea, and its subsequent proto-continents,
China, Brazil, Antarctica, and places better known for sighting our logged quandary.

     So, pack your hard hats and safety sunglasses.  We’re off to explore collections of trunked
wonders worldwide.   Let’s go!

Introduction

     Good morning, everyone!  I hope you are bright-eyed, bushy-tailed, and excited to depart,
as we are leaving in a few minutes.  No need for airline tickets, since we will board our club’s
charter flight to points all over.  Please grab your backpacks and all aboard, while I get the
morning beverage and in-flight lesson prepared.

     Our itinerary will list the places we will visit.  They include: Argentina, Brazil, Antarctica!

     All of our club gear is already stowed, per our captain.   We have everything from sunscreen
to winter parkas, for our comfort and convenience!

     Flying from our local New Castle County Airport, we will cross the Pacific Ocean to Asia,
then on to frozen Antarctica.  To thaw out, we'll stop at sunny Australia, and next to Africa and
South America. In between, we will hit Europe, and other spots on the globe.

     As we’ve had our primer on petrified wood, today’s interactive discussion will feature plant
biology, and its changes over time.  We won’t be able to cover all of geologic time, but will hit
upon a representation of many parts of the scale, depending on the locales we’ll be visiting.

     We’ll cover lapidary, and the other subjects on successive jaunts on our voyage.  Are you
ready?  Let’s go!

What’s In a Scientific Name?

     Paleobotany and botany have one thing in common; they both use scientific names in the
same manner.  According the Linnean system of taxonomy, set down by Carolus Linnaeus
some time ago in 18th century Sweden.  He based his work on upon a hierarchy in which living
things can be categorized in an ascending/descending order, per their similar features.

     Latin is used here, so a working knowledge of rootwords can help, but is not necessary to
begin with.  Just by rote learning a few names, we can jump start our exposure into another
language

     His system goes: Kingdom, Phylum (Division for plants), Class, Order, Family, Genus,
Species, with the first categories being the most general (Kingdom: Animal, Plant).  Modern
scientists have developed the system that he popularized.[i]

     Today, the International Code of Botanical Nomenclature (ICBN), set forth by the
International Botanical Congress, outlines the taxonomic designations that we will use in
our article.  Three major differences are the addition of Domain before Kingdom, “sub-“
designations to every step, and “Variety” and “Form” below Species, for plants.[ii]

     We will focus upon “trees”, and refer here on in to Genus/Species only, if no other
hierarchy is required to differentiate an argument.  An example from last month’s article
is: Araucarioxylon arizonicum.

     It is interesting to note that Linnaeus had originally designated three Kingdoms:
Plants, Animals, and Minerals.  I wonder into which category would he position petrified
wood?  We shall place it in Kingdom Plantae.

     I list a a few, representative (to this article), in a mix of fossil, extinct, and modern tree
classifications below:

	Eukaryotic Kingdoms PLANTAE (Plants) "Gymnosperms" (Spermatophytes, or seed plants) Conifers ---Araucariaceae ---Cephalotaxaceae ---Cheirolepidaceae ---Cupressaceae (redwoods & junipers) ---Pinaceae (pines, cedars, firs, etc) ---Podocarpaceae ---Sciadopityaceae ---Taxaceae (yews) ---Voltziales (basal conifers) Cycadales (cycads) ---Cycadaceae ---Stangeriaceae ---Zamiaceae Ginkgoales (ginkgos) Glossopteridales Lyginopterids (earliest seed plants)[iii] Photos by and courtesy of: Fossil Araucaria cone, Steve Ervin Modern Pine cone and Sweet-gum seedpod, Ken Casey ©2006		Modern pine cone
			Fossil Araucaria cone
			Sweet-gum seedpod, A Tertiary relict
	http://www.ucmp.berkeley.edu/help/taxaform.html

Where is petrified wood?

     Anywhere that there was a forest, tree, or wood set within conditions conducive towards
mineralization, there may lie under our feet petrified wood.  As we understand the basic
sedimentary principle of one layer of rock-forming material covering over another over time,
we can surmise that many of the paleoforests of time lie some feet under our boots. Active
geologies over eons have exposed our mineral woods for our exploration.  It is these visible
features that we will access this trip.  We will leave the ‘big digs’ for another article.  Except
for some hot weather, we won’t even have to break a sweat.  Isn’t that cool?!

Before we go, let’s review:

     There are three main steps towards permineralization of living plant matter: (1.) encapsulation,
or removal from an environment that causes decomposition, (2.) introduction of sufficient quantity
of a mineral-laden solution to bring about chemical-biochemical replacement of cell structure,
and (3.) time. Our global search takes us to many places, so keep your eyes peeled!

Geological History and Evolutionary Biology

     Let’s talk about Pangea, the ancient supercontinent which is the starting place for continental
drift in our chapter on paleobotany.  We’ll need a little history to ramp us up to speed.

	Drawing courtesy of the University of Texas		Fossilized Coral Photo by Ken Casey ©2006

     As an avid student of geology at Edinburgh University, Charles Darwin became embroiled in
the great geological debates of the 1820s and 1830s.  Darwin received acclaim not only by his
later works as a biologist, but as a geologist, as well.  “Darwin's most successful application of
simple geology and his most lasting contribution to the science was his explanation of the origin
of coral reefs. (They build up on the sides of slowly subsiding seamounts.)”[iv]

     Though he could not successfully build upon Lyell’s work directly beyond this marine theory,
his geographic explorations aboard The Beagle pushed his focus to biology.  His highly
controversial theory of evolution paved the way for us to now understand more on our changing
landscape of petrified wood.  We can combine biology and geology into an earth science that
supports our studies here.  We will begin with his conclusions upon return from his grand
adventure.

     As similar species covered the single landmass, when broken apart, some went with each
continent.  As Darwin noted that isolated populations are likely to speciate, subspeciate, or
evolve, a similar process is purported by many of today’s scientists when Pangea separated
into Laurasia and Gondwanaland.  That process is known as vicariation.  Examples are the
creatures of the Galapagos Islands, and those of Australia versus those lineages of Eurasia
and the Americas.

     Though it has done so with little or no change, it did survive; whereas, many co-existing
species did not.  It was, and is, the fittest.  This example would also support the newer theory
spurts and stasis.  This dicot gymnosperm (twin-leafed deriving from naked, or fruitless, seed),
native to China, can be found in yards, parks, and preserves for us to enjoy.

Cycad seed Photo courtesy of Steve Ervin		Glossopteris, Antarctica Photo courtesy of Dr. Bernie Gunn		Psaronius, extinct tree fern, Late Carboniferous-Permian Photo courtesy of Steve Ervin

     Some species did not.  They are extinct.  There are many examples: Glossopterids, Psaronius,
and Cordaites are but a few.

     The Cycads are still here, though today’s palm trees (Genus: Cycas) are believed to have
some relation to Gingkos, perhaps in an anagenetic lineage,as they are both spermatophytes. 
The extinct genus Cordaites is structurally somewhat between Cycads and Gingkos. The
Cordaites lineage can be traced back to Late Paleozoic times.

     Glossopteris, a bald cypress-like tree, is believed to have covered all of today's continents
at one time.  Psaronius lived as a great tree-fern from the Carboniferous until the Late Permian.

     Five major extinction events can be marked on the geologic time line.  The Devonian marked
one of them.  At about 364 mya, most of the great fishes disappeared.  This event, marked by
the Frasnian-Famennian boundary, does not greatly defeat the land plants.  In fact, the
megaflora’s success may have been the catalyst to marine faunal extinctions.

     By understanding the Carbon Cycle, we can appreciate that the greenhouse gas CO₂
used up by the burgeoning plant community reduced atmospheric levels, thus generating a
global cooling.  The resulting glaciation may have chilled the oceans too much for the great
cold-blooded fishes to survive.  As usual, the generalist species survived to adapt and swim
on.[vi]  The remainder of the organic carbon became deposited on and in the ground, to
eventually be metamorphosed into coal and peat.

     Today’s fossil and paleoclimatological evidence points to mass extinctions.  Though
this puts a dent into the “Snowball Earth” theory, massive environment changes seemed
to have produced modified groups of species.  Cold-hardy trees could have weathered this
eonic storm.

     Could this have been the dawning time of evergreens and deciduous winter-sleepers? 
In the Permian (290-248 mya), drier inland conditions may have caused adaptations in plants,
such as the introduction of angiosperms (seed-bearing trees).

Modern Pine tree		Modern pine cone		Modern Pine tree bark
Photos by Ken Casey   ©2006

     “Also, the great forests of fern-like plants shifted to gymnosperms, plants with their
offspring enclosed within seeds. Modern conifers, the most familiar gymnosperms of today,
first appear in the fossil record of the Permian.”[vii]

     The transitional Triassic (248-206 mya) supports recovery of plant biota after a mass
extinction.  “The holdovers included the lycophytes, glossopterids, and dicynodonts. While
those that went on to dominate the Mesozoic world include modern conifers, cycadeoids,
and the dinosaurs.”[viii]  Plant and insect taxa exploded in numbers, during the Triassic.  

     The Jurassic (206-144 mya) was overtaken by lush ferns and palm-type cycads.  Early
seed plants, they still exist today.[ix]

     Pangea began to break-up in the Jurassic, which contributed to mass vicariation, based
upon hemisphere (northern, southern), and climate change.   With the dawn of the Cretaceous
(144-65 mya), many of the lifeforms (especially trees) we know today lived then.

For example, today’s beech forests of New Zealand took root in the Mid-Cretaceous.  With the advent of pollen and seed plants(angiosperms), recolonization of desolate areas took place.  Before that, in the Early Cretaceous (~135 mya) Gondwanian flowering plants, such as the kauri (mentioned in Petrified Wood, Part I), arrived on the islands. (Left): Petrified Beech wood, polished slab Photo permission courtesy of the Iron Hill Museum Newark, Delaware (From their display case at our March 4-5, 2006 Show)

     “Among the first angiosperms to reach New Zealand was the wind-pollinated southern
beech tree (Nothofagus species). It arrived between 80 and 110 million years ago, after New
Zealand had separated from the Australian part of Gondwana, but before it had separated
from the Antarctic region. For several million years, the beech forests stretched continuously
from Tasmania, and through what is now New Zealand and Marie Byrd Land in Antarctica, on
into South America. Even today, the beech forests of New Zealand and South America
resemble each other so closely that each has the same parasitic fungi, mosses and flightless
sucking bugs inhabiting their bark (Stevens et al., 1995).”[x]

     In ancient Europe, now England, a Cretaceous to Jurassic paleoforest looms.  There were
cypress, junipers, and cycadophytes, some similar to those of the Mediterranean today. 
“The Fossil Forest, west of Lulworth Cove, Dorset, southern England, is a classic geological
locality with the remains and moulds of late Jurassic or early Cretaceous coniferous trees
rooted in a palaeosol (ancient soil), the Great Dirt Bed. Above the trees is stromatolitic
limestone and over this the unusual Broken Beds, a limestone breccia that was originally
evaporitic.”[xi]

     Nearby, at Fossil Forest at Victoria Park in Glasgow, Scotland Lepidodendron tree stumps
can be found in their original growth positions.  Otherwise known as the “scale tree” from the
Greek, it was deposited during the carboniferous in sandstone.[xii]

Evolution

     Plants and trees have developed over time, giving us rich history to explore. Charles Darwin,
noted naturalist, assumed a gradual modification over generations of descendants; whereas,
some modern biologists work with the premise of bursts of changes, then periods of stasis
(punctuated equilibrium).  Mass extinctions and long episodes of statis seem to support the
latter theory.  One could assume that with pseudoextinction, an example being the recognition
of modern birds as the dinosaur’s descendants, that dinosaurs must today exist; however, in a
different form.

     Darwin received acclaim not only as a biologist, but as a geologist, as well.  So, his eye for
our current subject matter could guide us in our basic understanding of how trees (evidenced
by petrified wood) have changed over geologic time.

Paleobotany

			It will also be helpful for us to learn "morphology" (tree parts) and some biology.  Don’t worry, just enough to aid us in identifying on species from another.  For example, xylem, phloem, and bark, cambium, precambium, etc. “In vascular plants, xylem is one of the two types of transport tissue in plants, phloem being the other one. The word “xylem” is derived from  classical Greek xúlon, "wood", and indeed the best known xylem tissue is wood. The xylem transports sap from the root up the plant: xylem sap consists mainly of water and inorganic ions, although it can contain a number of organic chemicals as well.”[xiii]       It is most likely one development that encouraged or supported gigantism. (Left): Tree Anatomy in cross-section

     Water and nutrient uptake is key to survival of plants.  “Xylem appeared early in the history
of terrestrial plant life. Fossil plants with anatomically preserved xylem are known from the
Silurian (more than 400 million years ago), and trace fossils resembling individual xylem cells
may be found in earlier Ordovician rocks.”[xiv]

     Food is handled by the phloem.  “In vascular plants, phloem is the living tissue that carries
organic nutrients, particularly sucrose, to all parts of the plant where needed. In trees, the phloem
is part of the bark, hence the name, derived from the Greek word for "bark".”[xv]

Petrified Gymnosperm wood radial-section		Petrified dicot wood cross-section		Dicot petrified wood cross-section
Photomicrograph slides by and courtesy of John D. Curtis, Nels R. Lersten, and Michael D. Nowak ©2002

     The vascular cambium is a lateral meristem: The vascular cambium is the source of both
the secondary xylem (inwards) and the secondary phloem (outwards), and hence is located
between these tissues in the stem. The vascular cambium usually consist of two types of cells:

• Fusiform initials (tall cells, axially-oriented)
• Ray initials (almost isodiametric cells - smaller and round to angular in shape)

Vascular cambium is a part of the plant's meristem - series of tissues consisting of embryonic
(incompletely differentiated) cells from which other (and more differentiated) plant tissues
originate.[xvi]

     We will cover such tree groups as: Angiosperms (deciduous), Gymnosperms (coniferous),
Cycads, and extinct fossil trees.

     To get our inquisitive engines going, I’ll ask if anyone knows what is believed to have been
the first tree? 

That’s right: Archaeopteris (~370 mya), a
Progymnosperm.

Morphology

     Now that we’ve covered how our petrified trees evolved and got placed over geologic time,
we are ready to go over plant anatomy.  We’ll need to know their parts (living and fossil), if we
are going to be successful in identifying different species in the field.

     Let’s start with the basics.  Many fossil trees, like modern trees, have branches, trunks,
and roots.   We can easily identify these major parts as tree-like.  Grain pattern have been
preserved in many specimens, thus aiding us in our comparson to modern woods.

     The colorful concentric rings comprising the trunk’s log structure also aid us.  Sometimes,
we have clues deposited nearby, such as leaf impressions, fossilized seeds, cones, or amber. 
Even remnants of insect infestation, as in Mesozoic Antarctic woods can help. You might even
remember your high school biology class lesson on plants and trees.  “The key elements of a
tree are: xylem, phloem, cambium…"

     If that doesn’t bring it back, well, let’s try a picture. Take a look above at the tree in
cross-section.

Pressure-treated Pine wood-grain		Petrified gymnosperm wood cross-section		Petrified gymnosperm wood radial-section
Photomicrograph slides by and courtesy of John D. Curtis, Nels R. Lersten, and Michael D. Nowak ©2002 P-T Pine photo by Ken Casey  ©2006

     After, we’ll go into some advanced stuff, like “plant stones”, and such. A “plant stone”
(or Phytolith) serves to add structural stability to plants.  These microscopic bodies can be
made from silicon or calcium oxalate.  In paleobotany, these phytoliths often remain behind,
serving as fossil evidence in identifying ancient flora.  A relationship between these plants
and fossil herbivores can be forged.  From this evidence, changes in extinct animal diets,
and their resulting evolutions, can be measured and compared.  The chief faunal evidence is
found within coprolites.  It is interesting to note that Charles Darwin mentioned “plant stones”
in his writings.[xvii]  

     “About 75% of flowering plants produce calcium oxalate crystals in some or all of their organs.
Because these crystals occur in various shapes and hydration states that are specific and
consistent within each organ, they have been used periodically as an internal taxonomic
character. Since crystals and their macropatterns are usually retained in the mature leaves
and stems even after they die or drop off the plant, such information should be useful for
identification purposes, possibly in forensics.”[xviii]  

Development of the calcium oxalate crystal macropattern in pomegranate (Punica granatum, Punicaceae)  Photo by and courtesy of Harry T. Horner		Modern Plum (Genus: Prunus) Photo by Ken Casey  ©2006 Note: After having taken this picture, I promptly consumed the plum for my lunch.  Then, I got back to writing.

In Paleontological Terms

     When paleontologists and paleobotanists study and reconstruct lifeforms over evolutionary
time, they require a context, called “phylogeny”.  This biological context connects groups of
organisms by “ancestor/descendant relationships”.   Extinct organisms, fossil forms of those
today extant, and living trees require a structure to show how they are interrelated, called a
“cladogram”.

     This genealogy of species can be ensconced in field of “systematics”.  Taxonomic science,
or the naming and classifying of lifeforms, underlies the study of these relationships.[xix]

     If you would like to know more, UC Berkeley offers some resources:

Journey Into Phylogenetic Systematics
Phylogenetics Resources
Introduction to Cladistics

     When making a phylogenetic analysis of organisms, say Gingko biloba, the best modern
acceptable method is “cladisitics”.  “Cladistics is a particular method of hypothesizing
relationships among organisms.”[xx]

     The basis for cladistics are “synapomorphies, or the shared derived characteristics of
organisms compared.[xxi]

     Another example of applying phylogenetics in paleobotany is the contention to accept
a pre-Silurian plant record.  By studying the microfossil evidence of cyrptospores, Professor
Wilson A. Taylor of the University of Wisconsin at Eau-Claire in his paper, “The case for a
land flora in the Cambrian - ultrastructural evidence”, proposes this hypothesis as a pivotal
evolutionary event.[xxii]

     Some Paleobotany being conducted today I have recently perused an abstract on a
presentation on Miocene Maryland fossil endocarp (nut shell) evidence.  There are scads
of resources for paleontologists and paleobotanists. I will list a few at the end of the article,
many of which were presentations at the 2004 and 2005 Botany Conferences. Some current
work by botanists have literally unearthed aspects on paleoenvironments for our modern
reconstruction upon the fossil record.  The gamut here runs from plant forms surviving
extinction events, the earliest insect pollinations, paleoclimatic changes in temperate
Antarctica, and early proof of autumn leave color changes.

     Beyond just taking a paleo-snapshot of a fossil-forming environment, new volumes of data
have been plotted to demonstrate trends in climate change and evolution.  For example,
various paleogeographic reconstructions suggest that the climate warmed during the Late
Cretaceous partly due to accumulation of greenhouse gases.[xxiii]

Inversand Greensand Mine, Sewell, New Jersey Our club's local collecting area encompasses these fossil-laden sands at the Cretaceous-Tertiary (K-T) Boundary. Photo by Ken Casey  ©2005

     Moreover, derived from evidence about the differing chronostratigraphy surrounding the
Cretaceous-Teritiary Boundary (K-T) Event, the faunal and floral extinction dynamics
suggest a new interpretation.  Professors W. A. Green and L. J. Hickey of Yale University
offer that “[t]his substantiates some of our standing assumptions about the selectivity of
extinctions at the end of the Cretaceous, which may have eliminated taxa but do not seem
to have restructured plant ecosystems significantly. It provides an example of ecosystem
stability under environmental perturbation and highlights the influence of evolutionary
innovation o­n evolutionary history.”[xxiv]

     Some palynologists have proposed that Middle Triassic cycads were insect pollinated,
like those today. They use fossil pollen and insect coprolites as evidence on these
gymnosperms (seed plants).[xxv]

     Biologists at the University of Kansas have presented on the topic of paleoclimate in
Permian-Triassic Antarctica:

     “Tree rings are well preserved in Late Permian and Middle Triassic permineralized peats
from the central Transantarctic Mountains, and can be used as paleoclimate indicators.
During both of these time periods, the Earth had a greenhouse climate, with temperatures
in polar regions sufficient for plant growth.  Previously there has not been much paleoclimate
information obtained from Gondwana Triassic wood, and the permineralized material
represents an important source of data on growing conditions in Antarctica at this time.”[xxvi]

     My favorite development is the amazing preservation of leaf material from Idaho, which
shows us that Fall leaves did indeed change color seasonally some millions of years ago. As,
an interesting correlation has been made between fossil and living tree genera from the Late
Tertiary (~15 mya) in northern Idaho.  Fossil foliage has been superbly well preserved
“[b]ecause of cold, anoxic bottom water and a high rate of sedimentation, preservation of
the local biota was excellent.  During the last 15 million years this area has remained
tectonically stable, resulting in little post depositional change of any biota remains trapped
in the sediments. Leaves often show original fall colors (brown, red, and yellow). Some even
contain Chloroplasts and show the original green color. Biochemistry, unique in each modern
genera of plant species correlates well with similar fossil species.”[xxvii]

     When we piece the paleo-puzzle together, we can see trends of lifeform changes, known
as evolution.  I will proffer an example that can bring a picture to our paleo-view by building
upon an image most of us have witnessed in our lives: a bird perching upon a tree.  Our
question, ‘How did he or she get here from a long travel over generations?’  Let’s find out.  

Evolution: Dinosaurs, Birds, and Trees

     Let’s start from a certain geologic point in time.  About 550 mya, the “Cambrian Explosion”
occurred.  Most of the major continents have moved into the southern hemisphere, thus
forming the supercontinent Pangea. First plants on land? They occurred at least 400 mya,
in the Early Paleozoic.  Vascular plants (xylem, phloem, etc.) grew in by the Silurian
(443-417 mya), then the Devonian (417-354 mya) brought about tree diversification.[xxviii]

     The earliest trees occurred and spread globally about 370 mya, as ”[t]rees evolved
some 180 million years after the Cambrian explosion when the land masses were mostly
south of the equator and Pangea had begun to form. Because the land masses were fairly
close together, the forests were able to spread across the land quite rapidly.”[xxix]

     The Devonian (410-360 mya) brought about the rise of Archaeopteris, now believed
to be the earliest tree.  Its eventual biotic provinces were Laurasia and Gondwana. It’s
upright growth and shallow roots took advantage of water and minerals more deeply
below the surface than its ancestors.[xxx]    3D Image of Archaeopteris  

From Land Plant to Trees with Birds

     During the Carboniferous (360-286 mya), forests of lychophytes towered to greater
than 100 feet!  These behemoth scale trees share the trait of being the first vascular plants,
which still survive in albeit a relatively miniature form today.  A differentiating trait is in their
leaf structure.  Lycophytes evolved separately as microphylls, which have “…only a single
unbranched strand of vascular tissue, or vein, whereas megaphylls, found in other plants
with leaves, have multiple veins, usually branching one or more times within the leaf.”[xxxi]

     “The Division Lycopodiophyta (sometimes called Lycophyta) is a tracheophyte subdivision
of the Kingdom Plantae. It is the oldest extant (living) vascular plant division and includes
some of the most "primitive" extant species. These species reproduce by shedding spores
and have macroscopic alternation of generations, although some are homosporous while
others are heterosporous. They differ from all other vascular plants in having microphylls,
leaves that have only a single vascular trace (vein) rather than the much more complex
megaphylls found in ferns and seed plants.”[xxxii]

     Leading up to the Triassic Period (248-206 mya), global climate change occurred at about
the time of Earth’s largest extinction event: the Permo-Triassic extinction.   On Pangea,
survivors included lycophytes and glossopterids.  Typical Triassic tree flora included cycads
and conifers, along with ferns growing in the understory.  Evolution prompted the introduction
of ancestors to our modern conifers and cycadeoids.  The glossopterids, however, became
extinct by the end of the period.  Dinosaurs, as we have traditionally known them, also roamed
the planet, until the K-T Event.[xxxiii] 

     Triassic Mesophyta plants (middle flora) of the Late Permian to Middle Cretaceous
included ever smaller lycopods, Calamites-type plants, and ferns.  Variations occurred,
according to climate and geography, such as giant seed ferns overtowering trees in part of
Gondwana.  Whereas, cycads and gingkos inhabited drier, interior climes, such as in
northern Pangea.  And, “Araucariacean conifers were the predominate large trees in
Laurasia, with primitive gingkoaleans (e.g. Sphenobaiera and Glossphyllum) and cycads
as lower story and underbrush.”[xxxiv] 

Chinese conifer (Petrified Wood) Photo by and courtesy of Steve Speer of Sticks-in-stones.com  ©2006		Calamites (Permian), Brazil Photo courtesy of Steve Ervin

     Before Trees and up to Flight Before trees, there was moss and algae.  Tree evolution
includes the development of a vascular system with roots.  Dr. Robert Banner of Yale
University presented his findings at Earth Systems Processes, a multidisciplinary meeting
in Edinburgh, Scotland.  It is hosted jointly by the Geological Society of London (GSL) and
the Geological Society of America (GSA). His presentation, “How trees changed the world”,
offers evidence of radical geological change deriving from such shifts in a new biota
ecosystem.  He argues that changes in Earth’s atmosphere and the natural Carbon Cycle
have been advanced.  As we shall see:

“The first trees soaked up nutrients from rocks at a rate never before seen. This
enhanced the weathering of calcium (Ca) and magnesium (Mg) silicate minerals,
which in turn removed carbon dioxide from the atmosphere as Ca and Mg became
locked together with carbonate ions in lime-rich sediments in the world’s oceans.
The removal of CO2 from the atmosphere by this method and by increased
photosynthesis (fixation) led to atmospheric CO2 stabilising at lower levels than
the world had known for most of its previous 4200Ma history.”[xxxv]

     Increased erosion levels occurred from root-splitting, as trees took their nutrients from
rocks.  The procress proceeds with wood lignin becoming buried into these sediments. 
Atmospheric carbon dioxide used up by these large plants led to proportional deposition
of removed carbon.  Organic carbon is removed from the wood, thus becoming coal.  As
large plant photosynthesis advanced globally, greater percentages of atmospheric oxygen
occurred.

     Enriched air brought about faunal evolution, in that gigantism took over for a bit of
geologic time.  The early resulting insect populations became huge, compared to even
today’s largest dragonfly, for example.[xxxvi]

     It wasn’t long after (in millions of years), that pollinating insects helped spread flowering
trees and plants conquer the globe. Dinosaurs, then birds perched in trees, or flew from the
ground first.  Both sides of the origin of flight debate still rage today.

     The first tree-dwelling bird (dinosaur descendent, Archaeopteryx) must have evolved after
trees. Or, when did the earliest avian perch on trees? The debate rages, whether avians
evolved from Mezozoic thecodonts, theropods, (or dinosaurs, at all).  Still the topical question
is, ‘Which came first, the tree-dwelling dino, or the flight-adaptive bird?’  Ornithologists differ
in opinion as to a “ground flight” or a “tree flight” origin.  Another question looms: ‘Did flight
occur before trees evolved?’  If so, then the latter opinion on flight origin could hold true. 
Professor Gary Ritchison of Eastern Kentucky University, in his BIO554/754 Ornithology
Lecture Notes 1: “Introduction to Birds”, poses such questions.[xxxvii]

Archaeopteryx (Artist's rendition) Artwork by Luis V. Rey ©2003		Microraptor zhaoianus (Artist's rendition) Painting by