describes the main objectivess of paleobotany and the role of paleobotanist

1. INTRODUCTION TO
PALEOBOTANY

2. WHAT IS PALEOBOTANY?
 Humans are by nature curious, and we are all interested
in the Earth on which we live and how various aspects
have changed through geologic time.
 It is natural to wonder about prehistoric life—how these
organisms lived, what their patterns of behavior were,
and even why they became extinct.
 the paleobotanist is a plant historian who attempts to
piece together the intricate and complicated picture of
the history of the plant kingdom.

3.  Fossil plants and floras from one period of geologic time
are different in size and shape, level of complexity, and
abundance from those of other time periods.
 The most logical explanation for these differences is that
the types of plants changed, or evolved, through
geologic time.
 By studying the record of fossil plants, it is possible to
assess the time at which various major groups originated,
the time each reached its maximum diversity, and, in the
case of certain groups, when they became extinct.

4. THE OBJECTIVES OF PALEOBOTANY
 One of the aspects of paleobotany, which
makes it unusual and interesting, is that it is and
can be approached from inherently
interdisciplinary either a biological or a more
geological perspective—or both together.
 Each perspective presents a variety of questions
that are unique to that discipline.

5. 1. RECONSTRUCTING THE PLANTS
 Because the majority of fossil plants are generally
preserved in rocks as disarticulated plant parts.
 a major aim of paleobotany is to reconstruct the whole
plant, that is to say, to put the pieces of the puzzle back
together.
 Once this is accomplished, the research can turn to other
areas, such as determining the group of living plants, if
any, to which the fossil is most closely related.
 how did these plants reproduce, and how and what
types of propagules were disseminated? Are….etc

6. 2. EVOLUTION OF PLANT GROUPS
 Paleobotanists are also interested in the origin and
subsequent evolution of major groups of plants and their
interrelationships.
 When did plants first inhabit the Earth and what did they
look like? When did the first representatives of different
groups of plants first arise?
 A number of paleobotanists study not only the plants
themselves, but also the interactions of the plants with
other organisms in the environment, especially the
symbiotic interrelationships between plants and other
organisms.

7.  Can we determine from the fossil record if plants
possessed certain features that served to attract
pollinators,
or produced edible seeds, or whether some plants
produced certain chemicals that deterred herbivory?
 The answer to all these questions is a resounding YES!
There is a multitude of information that can be
gleaned from careful examination of the plant fossil
record, and the types of information that we can
obtain are constantly increasing as more and more
research is done on fossil plants.

8. 3. FORM AND FUNCTION IN FOSSIL
PLANTS
 From many plant fossils, it is possible to understand the
relationship between form and function in ancient
plants, that is, what advantages or limitations are
imposed on the growth and development of a plant
based on certain biomechanical properties?
 Studies of this type examine the anatomical and
morphological properties of various fossil plants, often
using computer simulations to model growth, in an
attempt to better understand broad evolutionary
patterns of plant growth, as well as changes in growth
form through time

9.  Biomechanical studies have been especially useful in
delimiting adaptations necessary for plants to move onto
the land, including upright growth, size limitations, and
the nature of the conducting strand, and, once plants
became established in terrestrial environments, the
influences of gravity and wind on their reproduction, and
even aerodynamic features of pollen.
 Factors such as plant size and form can also be examined
over a broad spectrum of plant morphologies and thus
offer insights as to why certain plants and plant groups
have developed particular anatomical and
morphological characteristics.

10. 4. BIOSTRATIGRAPHY AND
CORRELATION
 Paleobotany has also played a key role in many areas of
geology, especially in biostratigraphy—placing rock
units in stratigraphic order based on the fossils within
them.
 Pollen grains and spores have been extensively used as
index fossils in biostratigraphy and in the correlation of
rock units, as have various forms of algal cells and cysts.
 Pollen and spores, as well as megafossils, are especially
useful in correlating terrestrial rocks, as these are
generally deposited in limited areas (former lakes,
ponds, river systems, etc.), making correlation by
lithology (i.e., rock characteristics) very difficult.

11. 5. PALEOECOLOGY: PLANTS IN THEIR
ENVIRONMENT
 Paleoecology, the study of past environments, is a
rapidly changing field that involves the integration
and synthesis of both botanical and geological
information.
 In recent years there has been a concerted effort
by many paleobotanists to understand the
paleoenvironment of fossil land plants more
completely.
 Paleoecological studies are very important in
revealing the diversity of fossil communities
inhabiting a geographic area (horizontal variation in
floras) at the same time.

12. Analysis of the plants preserved at different levels in these deposits not
only documents the partitioning of the habitat among the different
plant groups along ecological lines, but also records changes in the
depositional environment through time.

13. 6. DETERMINING PALEOCLIMATE
FROM FOSSIL PLANTS
 Understanding climates of the past has become more
and more crucial to appreciating the changes occurring
on our warming planet today.
 paleobotany is very important in providing baseline data
to reconstruct past climates and in calibrating
paleoclimate models based on physical parameters.
 This area is rapidly expanding, so we will only cover a
few of the many ways in which plant fossils can be used
to reconstruct paleoclimate:

14. 1. TREE RINGS
 Data from fossil tree rings (paleodendrology) represent an
important source of paleoclimate information, in some instances
with very fine resolution, for example, major atmospheric
disturbances.
 Based on the changes in radial cell diameter within the tree rings
and the variation in ring width, it is possible to extrapolate climate
information, which is especially useful when coupled with
information from megafossils, microfossils, and the sedimentological
record of the site.
 Taylor and Ryberg (2007) have examined tree rings in Permian and
Triassic woods from Antarctica. Based on their analysis using a
variety of techniques, they suggest that the small amount of
latewood indicates a very rapid transition to seasonal dormancy in
response to decreasing light levels at these high polar latitudes.

15. 2. NEAREST LIVING RELATIVE
 The nearest living relative (NLR) method has been in use since the
beginnings of paleobotany, particularly when dealing with late
Mesozoic or Cenozoic floras, as these are more likely to have close
living relatives.
 The paleobotanist compares as many fossils as possible within a
flora to their most closely related extant taxa; the more species in a
fossil flora that have NLRs, the more precise the paleoclimate
estimate, and the more closely related a fossil taxon is to an extant
one, the more precise the method.
 This method can provide a general estimate of paleoclimate, but is
limited by the fact that some fossil taxa do not have the same
climatic limitations as their modern counterparts.

16. 3. LEAF PHYSIOGNOMY
 Leaf physiognomy analysis is a powerful technique that has been
widely used in paleobotany to reconstruct Cenozoic
paleoclimates.
 It is based only on angiosperms, however, so its applicability before
the Cretaceous is uncertain
 Physiognomy is the general appearance of a plant, and it has long
been known that plant physiognomy, especially leaf physiognomy,
can be related to climate.
 Physiognomy is primarily independent of taxonomy, for example
plants with thick water-storing stems and leaves tend to grow in arid
regions of the world, even though they may belong to a number of
different families of plants.

17.  There are presently two methods of leaf physiognomic
analysis that are in general use: leaf-area and leaf-margin
analysis.
 Leaf area directly correlates with mean annual
precipitation (MAP).
 Leaf-margin analysis (LMA) relies on the relationship
between leaf margin (toothed versus entire) and
climate.
 Specifically, the proportion of leaves in the flora with
toothed margins can be correlated with mean annual
temperature (MAT), as toothed leaves are more
abundant in wet environments.

18. 4. STOMATAL INDEX
 The stomatal index (the ratio of the
number of stomata to the total number of
epidermal cells plus stomata within a
given leaf area expressed as
percentages) has been widely used in
recent years to reconstruct past ρCO 2
levels, as the stomatal index is inversely
proportional to atmospheric CO 2 levels.