Download Chapter 6—Life on Earth: What Do Fossils Reveal?

The Earth Through Time
CHAPTER 6—LIFE ON EARTH: WHAT DO FOSSILS REVEAL?
CHAPTER OUTLINE FOR TEACHING
I. Modes of Preservation
A. Permineralization
B. Replacement
C. Carbonization
D. Molds and Casts
E. Soft Tissue Preservation (for example, in amber)
F. Trace Fossils
1. Tracks and trails
2. Burrows
3. Borings
II. Nature of Fossil Record
A. Hard versus Soft Parts
B. Rapid versus Slow Burial (Favorable and Unfavorable Places)
III. Rank and Order (Linnaean taxonomy, c. 1750)
A. Concept of a species as fundamental unit
1. Biologic concept
2. Paleontologic concept
B. Taxonomic Order (Hierarchy)
1.
2.
3.
4.
5.
6.
7.
Kingdom
Phylum
Class
Order
Family
Genus
Species
C. Taxonomy of the Three Domains
1. Domain Archaea – methane-producing bacteria and bacteria capable of
living in extreme conditions
2. Domain Bacteria – cyanobacteria and many other prokaryotes
3. Domain Eukarya
a. Kingdom Protista (mostly single-celled organisms)
(1) heterotrophs – food devourers
(2)
autotrophs – photosynthesizers
(3)
saphrophytes – decomposers
b. Kingdom Fungi (multicellular eukaryotes, many of which are
saprophytes)
c. Kingdom Plantae (autotrophic multicellular eukaryotes)
d. Kingdom Animalia (heterotrophic multicellular organisms)
IV.
Organic Evolution
A. Lamarck’s Theory (c. 1815)
1. All species descended from others
2. New structures appear out of “need” or “want”
3. Once acquired, structures can be passed on
B. Darwin’s Mechanism of Natural Selection (1859)
1. Cause of variation was not known
2. Variations in a population are common
3. Favorable ariations in population allow survival
C. Mendelian Principles of Inheritance (1865)
1. Cause of variation was not known
2. Variation documented experimentally
D. Modern Genetics
1. Genes are determiners
2. DNA molecule active in hereditary transmission
3. Genes as part of DNA
4. Chromosomes as links within DNA
E. Cell Division and Reproduction
1.
2.
3.
4.
5.
6.
Chromosomes kind and numbers are constant for a species
Diploid cells – cells with paired homologous chromosomes
Mitosis – regeneration of new cells in organisms
Meiosis – occurs in sexual reproduction when gametes are formed
Haploid cells – reproductive cells without paired chromosomes
Variation in offspring
a. mixing parental chromosomes
b. crossing over (exchange of severed segments during chromosome
division)
F. Mutation as the Source of Variation
1. Mutation can occur spontaneously (without specific cause)
2. Mutation via UV-light, cosmic rays, gamma-rays, chemicals
3. Sex cell mutation strongly affects evolution
G. Modern Organic Evolution
1.
2.
3.
4.
5.
6.
7.
Change due to: mutation, natural selection
Concept of population
Concept of gene pool
Speciation is origin of species
Concept of reproductive or geographic barriers
Adaptive radiation
Gradual versus punctuated equilibrium
a. phyletic gradualism
b. punctuated equilibrium
8. Phylogeny and phylogenetic trees
a. phylogenetic tree
b. cladogram
9. Evidence of evolution
a. paleontologic
b. biologic (homologous structures, vestigial organs)
c. DNA sequences
V. Fossils and Stratigraphy: establishing age equivalence of strata using
fossils
A. Key Findings
1.
2.
3.
4.
5.
Principle of fossil succession
Life has changed through time
Principle of superposition
Extinction: permanent loss of a species
Similar fossils in similar environments of same age
B. Correlation by Fossils
1. Key fossils – correlative value based on geologic range
a. first occurrence (oldest)
b. last occurrence (youngest)
2. Assemblages of fossils – also have correlative value
3. Index (guide) fossils – abundant, widely dispersed, lived short time
4. Reworked fossils – fossils from a older interval
5. Biostratigraphic zones (biozones)
a. range zone
b. concurrent range zone
c. assemblage zone
VI.
Ancient Environments and Fossils (Paleoecology)
A. Marine Realms
1. Pelagic (Neritic and Oceanic)
a. floaters (plankton and phytoplankton)
b. swimmers (nekton – such as crustaceans, cephalopods, and
vertebrates)
2. Benthic: supratidal, littoral, sublittoral, bathyal, abyssal, hadal
a. bioturbation – animal-sediment interaction on seafloor
b. oozes – siliceous and calcareous bioclastic material on seafloor
c. carbonate compensation depth – depth at which carbonate dissolves
on seafloor (about 4-5 km)
B. Environmental Reconstruction (Paleogeography)
1. Land bridges, isolation, and migration
2. Species diversity and geography
3. Biofacies analysis
C.
Ancient Climatic Reconstruction (Paleoclimatology)
1. Distribution of key plants and animals
2. Oxygen-16/Oxygen-18 isotopic ratios
VII.
Overview of History of Life
A. Precambrian
1. First one billion years — no fossil record
2. More than 3.5 billion to 700 million years ago—bacteria, algae,
cyannobacteria (stromatolites)
3. 700 million years ago—fossil metazoans (worms, arthropods, and
relatives of the corals and jellyfish) first appear
B. Phanerozoic
1. Evolution of plants
a. Late Ordovician – land plants appeared
b. Earliest Cretaceous – flowering plants appeared
2. Evolution of animals
a. Paleozoic: marine invertebrates, first vertebrates
b. Mesozoic: more marine invertebrates, land vertebrates
c. Cenozoic: more marine invertebrates and vertebrates; modern
mammals
C. Mass Extinctions
1.
2.
3.
4.
5.
End of Ordovician
Late Devonian
End of Permian
Late Triassic
End of Cretaceous
VIII. Life on Other Planets
A. Life as We Know It: places to look
1. Mars
2. Jupiter’s satellites (Europa and Io)
3. Saturn’s satellite (Titan)
B. Life on other planets: there may be as many as 1000 or more planets in
the numerous other solar systems of the universe where there may be
life as we define it.
Answers to Discussion Questions
1. Factors in determining whether a fossil will be valuable and not as an indicator of
age and for correlation include: cosmopolitan distribution of the fossil, good
preservation, and having a relatively short span of existence.
2. a) Ordovician through Permian. b) Ordovician. c) Fossil A has the narrower age
range, and is therefore the better guide fossil.
3. The different, coeval fossil assemblages can be accounted for by different,
coeval environments and fossil assemblages of organisms sensitive to those
environmental differences.
4. These older fossils (conodonts) may have been reworked by erosion of a
Devonian unit, thus contributing fossil—containing detrital to the Permian unit.
5. During Paleozoic, vascular land plants such as psilopsida, lycopsida (scale
trees), sphenopsida, pteropsida (tree ferns), pteridospermophyta (seed ferns),
ginkophyta (ginkgoes), and coniferophyta (conifers) existed on land. This list
includes all main groups of vascular land plants except angiosperms and cycads
and cycadeoids.
6. a) Mitosis is the reproduction of exact copies of cells as in asexual reproduction
and production of somatic cells in sexually reproducing organisms. Meiosis is
reproduction unicellular or sexually reproducing multi-cellular organisms where
in two divisions produce four haploid (daughter) cells without paired
chromosomes. The haploid cells are sexual gametes which fuse during sexual
reproduction. b) Cells without paired chromosomes are haploid; cells with
paired homologous chromosomes are diploid. c) Gymnosperms are nonflowering plants that produce pollen or seeds; angiosperms are flowering plants
that produce pollen or seeds. d) Cladograms like phylogentic trees show
relationships between organisms, but the cladogram is completely objective and
ignores the age relationships among organisms involved.
7. Adaptation is acquisition of heritable characteristics that are advantageous to an
individual and a population. The honey creepers of Hawaii, displaying various
adaptations of beak sizes and shapes, are a good example.
8. The theory of biologic evolution has been supported by the fossil succession
record and extinction evidence. The paleontologic evidence is at least as
important to reconstruction of past geographies as physical (sedimentologic
evidence). The paleontologic evidence can be a detailed record of past climate
change as in isotopic shell studies and coiling patterns of foraminifers, for
example. Paleontologic evidence helps reconstruct ancient environments by
using fossils as clues (e.g., the mode of life of a trace or body fossil suggests
characteristics of ancient environments).
9. Darwin established natural selection as the driving force in macroevolution.
Mendel discovered the fact that unknown but heritable factors (genes) were the
cause of the variation Darwin observed.
10. The ranges of fossils are carefully documented in global correlation that has
been studied for many decades.
11. Phyletic gradualism and punctuated equilibrium are opposite in that the former
stresses slow, gradual change and the latter abrupt change, then stasis. A
continuous core from the ocean would intuitively yield better samples for study of
gradual versus punctuated events.
12. The sublittoral zone is continuously covered by sea water, but is shallow enough
for light to penetrate readily to the seafloor. Light promotes the growth of algae
and other marine plants, which are important parts of the food chain. Soft,
oxygenated bottom sediments are good habitats for marine organisms that
engage in bioturbation.
13. Heterotropic means that the organism has to consume something to make
energy and it does not make energy from the Sun. Prokaryotic means that the
cell lacks a nucleus. And, anerobic means that it does not require oxygen to
survive.
14.
e
15.
b
CHAPTER ACTIVITIES
Student activities for in-depth learning:
1. There are many different types of trace fossils and these are made by
various organisms interacting with the sediment during the time they lived.
Take a look at the various types of trace fossils and make a list of all of
them by looking that the Nova Scotia Museum page at
http://museum.gov.ns.ca/mnh/nature/tracefossils/english/.
Visit
the
“Whodunnit” section of this page and make a sketch of three different trace
fossils and explain how the organism in question made each trace fossil.
2. Using your computer’s search engine, conduct a search for
“stromatolites.” Take a look at images of both modern and ancient
stromatolites. How and where do stromatolites form today and how and
where did they form in the distant past? Just how far back in the geological
record do we find stromatolites? Based on the field photographs you find
on the web showing stromatolites, how would you recognize one yourself?
Why do you suppose stromatolites have been alive so long on Earth? Use
web resources and your textbook for answers.
Chapter 6—Life on Earth: What do Fossils Reveal?
CHAPTER OVERVIEW
This chapter discusses what fossils are and how they are preserved. It also
reflects some of the earliest findings and history providing support for
organic evolution by laying the foundation for paleontology, i.e. Lamark’s
theory, Darwin’s theory of natural selection, Mendelian principles of
inheritance, while providing newer views on mutations and their
importance. A clear case supporting evolution is made using
paleontological evidence. The final sections of the chapter illustrate how
fossils are used to correlate rock units and establish index fossils. In
addition, there is detailed discussion regarding how fossils are used to
indicate paleogeography, past climates, and give us some clues to the
history of life on Earth.
LEARNING OBJECTIVES
By reading and completing information within this chapter, you should gain an
understanding of the following concepts:




Explain the processes by which fossils are preserved, for
example, permineralization, replacement carbonization, etc.
Discuss the purpose and use of biological classification in
understanding the concept of organic evolution.
Discuss how natural selection, inheritance, and mutation can be
used in explaining organic evolution.
Discuss how fossils may be used to define and correlate
paleoecological zones, and as indicators of past environmental
conditions.
CHAPTER OUTLINE
I.
Fossils: Surviving Records of Past Life
A. How Does Life of the Past Become Preserved
1. Three Common Preservation Processes
2. Molds and Casts
B. Sometimes Only Traces Remain
C. Why Are Some Fossils Rare, Yet Others Abundant
II.
Figuring Out How Life Is Organized
A. Linnaeus Leads the Way
B. What Is a Species?
C. What Is Taxonomy?
III.
Evolution: Continuous Changes in Life
A. Lamark’s Flawed Hypothesis
B. Darwin’s Theory of Natural Selection
C. Inheritance, Genes, and DNA
D. Cell Division and Reproduction: Bringing Variety to Offspring
E. Mutation: Source of Variations
F. Species, Population, and Gene Pool
G. How New Species Arise and Adaptively Radiate
H. Gradual or Sporadic Evolution
I. Phylogeny: Depicting How Ancestors Relate to Their Descendants
The Case for Evolution
J. Evidence from Paleontology
K. Evidence from Biology
IV.
Fossils and Stratigraphy
A. How Do Fossils Reveal the Age of Strata?
B. The Geologic Range of Fossils: From First Appearance to Last
C. Using Fossils to Correlate Rock Units
D. Pitfalls of Correlating With Fossils
E. Index Fossils Especially Useful
V.
Fossils Indicate Past Environments
A. Ecology of the Past: Paleoecology
B. The Marine Ecosystem: Diverse Habitats for Diverse Organisms
1. Pelagic Realm (Ocean Water)
2. Benthic Realm (Seafloor)
3. Benthic Life and Oozes in Deeper Water
4. Carbonate Compensation Depth
VI.
How Fossils Indicate Paleogeography
A. Paleogeographic Mapping
B. Land Bridges, Isolation, and Migration
C. Species Diversity and Geography
VII.
How Fossils Indicate Past Climates
A. How the Oxygen-16/Oxygen-18 Isotope Ratio Indicates Ancient
Seawater Temperature
VIII.
An Overview of the History of Life
A. The Earliest Traces
B. The History of Plants
C. The History of Animals
D. Mass Extinctions
IX.
Life on Other Planets: Are We Alone?
A. Life in Our Solar System
B. Life in the Universe
KEY TERMS (pages given in parentheses)
abyssal marine environment (153): Environment located below 4000 meters
in the oceans. There are low temperatures, little or no light, and high pressures.
adaptation (137): A modification of an organism that better fits it for existence
in its present environment or enables it to live in a somewhat different
environment.
adaptive radiation (137): The diversity that develops among species as each
adapts to a different set of environmental conditions.
Animalia (132): One of the five kingdoms in the classification system. Includes
heterotrophs.
Archaea (domain) (132): The domain of life that includes microscopic life that
thrives in extreme enviroments
assemblage zone (150): Biostratigraphic zones which can be identified due to
the occurrence of particular fossils or genera known to exist within that certain
zone.
Bacteria (domain) (133): Unicellular, prokaryotic microorganisms belonging to
the Kingdom Monera. One of the three great domains of organisms that include
also the domains Archaea and Eukarya.
bathyal marine environment (153): Oceanic environment encountered from
the edge of the continental shelves to a depth of about 4000 meters. It is
subjected to low temperature, little or no light, and high pressures.
benthic marine realm (151): A bottom-dwelling organism.
bioturbation (152): The process of churning and mixing sediment.
biozone (150): A body of rock that is identified strictly on the basis of its
contained fossils.
calcareous ooze (154): A fine-grained pelagic sediment containing
undissolved sand or silt-sized calcareous skeletal remains of small marine
organisms mixed with amorphous clay-sized material.
carbonate compensation depth (CCD) (155): The water depth at which
calcium carbonate is dissolved as fast as it falls from the upper water levels.
carbonization (127): The concentration of carbon during fossilization.
cast (128): A replica of an organic object, such as a fossil shell, formed when
sediment fills a mold of that object.
chromosome (135): Genes are linked together to form larger units termed
chromosomes, the central axis of which consists of a very long DNA molecule
comprising hundreds of genes.
clade (140): A group of organisms in a cladogram that begin with the first
appearance of a significant new evolutionary characteristic; the base of a clade
in a cladogram is a node.
cladogram (140): A diagram that illustrates common characteristics and
relationships of different groups of living plants or animals by their closeness of
relationships to each other.
class (taxonomic) (132): A group of related orders.
concurrent range zone (150): A biostratigraphic zone recognized by the
overlapping ranges of two or more taxa (sing. taxon).
crossing over (genetic) (136): During initial chromosome division while
chromosomes are still paired, they may break at corresponding places and
exchange their severed segments in a process called crossing over. It results in
additional mixing of genes.
deoxyribonucleic acid (DNA) (135): Chemical units or segments of a nucleic
acid. The DNA molecule is conceived as two parallel strands twisted somewhat
like the handrails of a spiral staircase. The strands are made up of phosphate
and sugar compounds and are linked with cross-members composed of
specific nitrogenous bases. It indirectly controls the production of proteins, the
essential components of many basic structures and organs.
diploid cell (135): Cells having two sets of chromosomes that form pairs, as in
somatic cells.
domain (132): A major taxonomic division ranking higher than a kingdom. The
three domains are the Archaea, Bacteria, and Eukarya.
ecology (151): The study of the present relationships between organisms and
their environments.
ecosystem (151): Any selected part of the physical environment together with
the animals and plants in it.
epifaunal (152): Organisms living on, as distinct from in, a particular body of
sediment or another organism. They live on top of the sediment that carpets the
sea floor.
Eukarya (domain) (133): Single or multi-celled organisms that have a distinct
cell nucleus and cell membrane. Includes Animalia, Plantae, Fungi, and
Protista.
family (taxonomic) (132): A group of related genera.
fungi (133): A kingdom of multicellular eukaryotic organisms that feed on dead
or decaying organic material.
gamete (136): Either of two cells (male or female) that must unite in sexual
reproduction to initiate the development of a new individual.
gene (135): The part of the DNA molecule that is active in the transmission of
hereditary traits. The unit of heredity transmitted in the chromosome.
gene pool (137): The sum of all genes available within a breeding population.
geologic range (e.g., of fossil species) (145): The geologic time span
between the first and last appearance of an organism.
genus (taxonomic) (131, 132): The major subdivision of a taxonomic family or
subfamily of plants or animals, usually consisting of more than one species.
hadal marine environment (153): Refers to the oceanic environment which is
found at extreme depths in oceanic trenches.
haploid cell (136): One having a single set of chromosomes, as in gametes
(see diploid).
homologous structures (144): Organs having structural and developmental
similarities due to genetic relationship. Basically similar structures in
superficially dissimilar organisms are referred to as homologous.
index fossil (=guide fossil) (150): Fossil with a wide geographical distribution
but narrow stratigraphic range and thus useful in correlating strata and for age
determination.
infaunal (152): Organisms that live and feed within bottom sediments. They
burrow into soft sediment for food and protection.
kingdom (taxonomic) (132): A large group of related phyla.
littoral zone (152): Seaward of the supralittoral zone is the area between high
and low tide known as the
littoral zone.
mass extinction (163): Marked by times of sudden worldwide extinctions of
large numbers of animal and some plant populations.
meiosis (136): That kind of nuclear division, usually involving tow successive
cell divisions, that result in daughter cells having one-half the number of
chromosomes that were in the original cell.
mitosis (135): The method of cell division by which each of the two daughter
nuclei receives exactly the same complement of chromosomes as had existed
in the parent nucleus. This process of cell division produces new diploid cells
with exact replicas of the chromosomal components of the parent cells.
mold (127): An impression, or imprint, of an organism or part of an organism in
the enclosing sediment.
mutation (137): A stable and inheritable change in a gene.
natural selection (135): A mechanism for evolution proposed by Charles
Darwin. Competition for food, shelter, living space, and sexual partners among
species with individual variations and surplus reproductive capacity will
inevitably result in elimination of the less well fitted and survival of those that
are better fitted to their environments.
nekton (151): True swimming animals. They are able to travel where they
choose under their own power.
neritic (151): A division of the pelagic realm (water mass above the ocean
floor) which extends seaward from the continental shelves.
node (140): The base of a clade in a cladogram is at a node.
oceanic zone (151): A division of the pelagic realm (water mass above the
ocean floor), which extends seaward from the continental shelves.
order (taxonomic) (132): A group of related families.
paleoecology (151): The study of the relationship of ancient organisms to their
environment.
pelagic marine realm (151): Consists of the water mass lying above the ocean
floor. It is divided into the neritic zone, which overlies the continental shelves,
and the oceanic zone, which extends seaward from the shelves.
permineralization (126): A manner of fossilization in which voids in an organic
structure (such as bone) are filled with mineral matter.
petrifaction (126): A fossilization process whereby inorganic matter dissolved
in water replaces the original organic materials, converting them to a stony
substance.
phyletic gradualism (139): Gradual progressive change. Phyletic refers to
evolutionary pathways. Proponents believe that change occurs by slow degrees
along the evolutionary pathway of a lineage.
phylogenetic tree (140): A model for depicting styles of evolution. Various
taxa are traced from outermost branches (representing lower taxonomic
division such as species, genera, or families) through a succession of junctures
downward (and backward in time) to the major trunks of the higher taxa.
phylogeny (140): The historical development of groups of organisms by
phylum that can be shown by a phyogentic tree or cladogram.
phylum (taxonomic) (132): A group of related classes.
phytoplankton (151): Microscopic marine planktonic plants, most of which are
various forms of algae.
plankton (151): Minute, free-floating aquatic organisms (includes small animals
and plants that float, drift, or feebly swim).
Plantae (133): Multicellular eukaryotes that typically live on land and make their
own food by the process of photosynthesis. They are autotrophs.
population (genetic) (137): A group of individuals that live close enough
together so that each individual has an equal chance to mate with all members
of the opposite sex within the group.
Protista (133): A varied group of mostly unicellular organisms that, unlike the
Monera, have a cell structure that includes a nucleus and organelles. They are
eukaryotes. Include heterotrophs, autotrophs, and saprophytes.
punctuated equilibrium (139): Term suggested for evolution that consists of
fitful sudden advances that punctuate long episodes of little evolutionary
progress.
range zone (150): The rock body representing the total geologic life span of a
distinct group of organisms.
replacement (127): A fossilization process in which the original skeletal
substance is replaced after burial by inorganically precipitated mineral matter.
reworked fossils (149): Fossils that have been freed from their host rock by
weathering and erosion and then reworked into younger beds. Younger strata
might be mistakenly assigned to an older geologic time.
siliceous ooze (153): An ooze composed of siliceous skeletal remains of
organisms, such as radiolatians.
speciation (137): The process by which new species originate.
species (132):
sublitorral zone (152): Extends from low-tide levels to the edge of the
continental shelf (about 200 meters deep). Benthic animals and plants are most
abundant in the continuously submerged sublittoral zone.
supratidal zone (151): Pertaining to the shore area immediately marginal to
and above the high-tide level.
taxonomy (132): The science of naming, describing, and classifying
organisms.
trace fossil (130): Tracks, trails, burrows, and other markings made in now
lithified sediments by ancient animals.
vestigial organ or structure (144): An organ that is useless, small, or
degenerate but representing a structure that was more fully developed or
functional in an ancestral organism.
zooplankton (151): Planktonic animals constitute zooplankton and include
protests such as radiolaria, foraminifers, certain tiny mollusks, small
crustaceans, and the motile larva of many different families of invertebrates that
live the adult stage of their life cycles on the sea floor.
CHAPTER 6
Life on Earth: What do Fossils Reveal?
FOSSILS
Fossils are the remains or traces of ancient life which have been preserved by natural
causes in the Earth's crust.
Fossils include both the remains of organisms (such as bones or shells), and the traces
of organisms (such as tracks, trails, and burrows—called trace fossils). 3
FOSSIL PRESERVATION
Organisms do not all have an equal chance of being preserved.
The organism must live in a suitable environment.
Marine and transitional environments are more favorable for fossil preservation.
Higher rate of sediment deposition.
To become preserved as a fossil, an organism should:
Have preservable parts. Bones, shells, teeth, wood are more readily preserved than
soft parts.
Be buried by sediment to protect the organism from scavengers and decay.
Escape physical, chemical, and biological destruction after burial (bioturbation,
dissolution, metamorphism, or erosion).
4
TYPES OF FOSSIL PRESERVATION
1.Chemical Alteration of Hard Parts
2.Imprints of Hard Parts in Sediment
3.Preservation of Unaltered Soft Parts
4.Trace fossils or Ichnofossils
5.Preservation of Unaltered Hard Parts
Hard Parts—mineralized material such as shells
Soft Parts—soft tissue
5
. PRESERVATION OF UNALTERED HARD PARTS
The shells of invertebrates and single-celled organisms, vertebrate bones and teeth:
a.Calcite (echinoderms and forams)
b.Aragonite (clams, snails, modern corals)
c.Phosphate (bones, teeth, conodonts, fish scales)
d.Silica (diatoms, radiolarians, some sponges)
e.Organic matter (insects, pollen, spores, wood, fur)
6
CHEMICAL ALTERATION OF HARD PARTS
a.Permineralization—filling of tiny pores
b.Replacement—molecule-by-molecule substitution of one mineral for another (silica or
pyrite replacing calcite)
c.Recrystallization—aragonite alters to calcite
d.Carbonization—soft tissues preserved as a thin carbon film (ferns in shale)
7 All photos by Harold Levin
IMPRINTS OF HARD PARTS IN SEDIMENT
Impressions
External molds
Internal molds
Cast
8
PRESERVATION OF UNALTERED SOFT PARTS
Freezing
Desiccation
Preservation in amber
Preservation in tar
Preservation in peat bogs
9
RESERVED. TRACE FOSSILS OR ICHNOFOSSILS
Tracks
Trails
Burrows—in soft sediment
Borings—in hard material
Root marks
Nests
Eggs
Coprolites
Bite marks
Markings in the sediment made by the activities of organisms
TRACE FOSSILS OR ICHNOFOSSILS
Trace fossils provide information about ancient water depths, paleocurrents, availability
of food, and sediment deposition rates.
Tracks can provide information on foot structure, number of legs, leg length, speed,
herding behavior,
and interactions. 11
RESERVED. TAXONOMY
Organisms are grouped based on their similarities into taxonomic groups or taxa.
Domain
Kingdom Phylum (plural = phyla) Class Order Family Genus (plural = genera) Species
(singular and plural)
Broad grouping Narrow grouping
12
RESERVED. BIOLOGICAL CLASSIFICATION
A system of binomial nomenclature (i.e., two names) is used to name organisms.
The first of the two names is the genus and the second name is the species.
Genus and species names are underlined or italicized.
Genus is capitalized, but species is not. 13 RESERVED.
THE SPECIES
A group of organisms that have structural, functional, and developmental similarities,
and that are able to interbreed and produce fertile offspring.
The species is the fundamental unit of biological classification.
Paleontology relies on physical traits of fossils and the range in the appearance to
identify species. 14 RESERVED.
CLASSIFICATION OF THE HUMAN
Domain Eukarya Kingdom Animalia Phylum Chordata Class Mammalia Order Primates
Family Hominidae Genus Homo Species sapiens
15 RESERVED. DOMAINS
1. Domain Eukarya
2. Domain Bacteria
3. Domain Archaea
There are six Kingdoms distributed into three Domains 16
CELLS
All organisms are composed of cells.
Eukaryotic cells have a nucleus (or nuclei) and organelles.
Organisms with this type of cell are called eukaryotes (Domain Eukarya).
Prokaryotic cells have no nucleus or organelles.
Organisms with this type of cell are called prokaryotes (Domain Archaea and Domain
Bacteria).
17 RESERVED. DOMAIN EUKARYA
Organisms with eukaryotic cells (cells with a nucleus)
•Kingdom Animalia (animals)
•Kingdom Plantae (plants)
•Kingdom Fungi (mushrooms, fungus)
•Kingdom Protista (single-celled organisms)
18 RESERVED. DOMAIN BACTERIA
Organisms with prokaryotic cells (cells without a nucleus)
•Kindgom Eubacteria (bacteria and cyanobacteria or blue-green algae)
RESERVED.
DOMAIN ARCHAEA
Organisms with prokaryotic cells, but which are very unusual and quite different from
bacteria. Archaea tend to live under extreme conditions of heat, salinity, acidity.
•Kingdom Archaebacteria
20
RESERVED.
EVOLUTION = CHANGE
Organic evolution refers to changes in populations
In biology, evolution is the "great unifying theory" for understanding the history of life.
Plants and animals living today are different from their ancestors because of evolution.
They differ in appearance, genetic characteristics, body chemistry, and in the way they
function. These differences appear to be a response to changes in the environment and
competition for food. 21
RESERVED.
LAMARCK'S HYPOTHESIS OF EVOLUTION
Jean Baptiste Lamarck (1744–1829) observed lines of descent from older fossils to
more recent ones, and to living forms.
He correctly concluded that all species are descended from other species. 22
RESERVED.
LAMARCK'S HYPOTHESIS OF EVOLUTION
Lamarck assumed that new structures in an organism appear because of the needs or "
inner want " of the organism.
Structures acquired in this way were thought to be somehow inherited by later
generations - inheritance of acquired traits.
The idea was challenged because there was no way to test for the presence of an "inner
want." 23
LAMARCK'S HYPOTHESIS OF EVOLUTION
Lamarck also suggested that unused body parts would not be inherited by succeeding
generations.
The hypothesis was tested and rejected after an experiment in which the tails were cut
from mice for twenty generations. The offspring still had tails.
Similarly, circumcision has been practiced for more than 4000 years with no change
among newborn males.
DARWIN'S NATURAL SELECTION
Charles Darwin and Alfred Wallace were the first scientists to assemble a large body of
convincing observational evidence in support of evolution.
They proposed a mechanism for evolution which Darwin called natural selection.
DARWIN'S NATURAL SELECTION
Natural selection is based on the following observations:
1.More offspring are produced than can survive to maturity.
2.Variations exist among the offspring.
3.Offspring must compete with one another for food, habitat, and mates.
4.Offspring with the most favorable characteristics are more likely to survive to
reproduce.
5.Beneficial traits are passed on to the next generation.
DARWIN'S NATURAL SELECTION
Darwin's theory was unable to explain WHY offspring exhibited variability.
This was to come many years later, when scientists determined that genetics is the
cause of these variations.
This principle can be stated as:
" the survival of the fittest."
27
INHERITANCE, GENES, AND DNA
Gregor Mendel (1822–1884) demonstrated the mechanism by which traits are passed
to offspring through his experiments with garden peas. His findings were published in an
obscure journal and not recognized by the scientific community until 1900. Mendel
discovered that heredity in plants is determined by what we now call genes. Genes are
recombined during fertilization. Genes are linked together to form chromosomes
CHROMOSOMES AND DNA
Within the nucleus of each of our cells are chromosomes.
Chromosomes consist of long DNA molecules (deoxyribonucleic acid).
Genes are the parts of the DNA molecule that transmit hereditary traits.
29
The DNA molecule consists of two parallel strands, which resemble a twisted ladder.
The twisted strands are phosphate and sugar compounds, linked with nitrogenous
bases (adenine, thimine, guanine, and cytosine).
CHROMOSOMES AND DNA 30
DNA
The structure of the DNA molecule was discovered by Watson and Crick in 1953.
DNA carries chemically coded information from generation to generation, providing
instructions for growth, development, and functioning. 31
REPRODUCTION AND CELL DIVISION
Reproduction in organisms may be:
Sexual
Asexual
Alternation of sexual and asexual generations
All reproductive methods involve cell division.
32
GENETIC RECOMBINATION
New combinations of chromosomes result through sexual reproduction. One of each
pair of chromosomes is inherited from each parent.
This sexual genetic recombination leads to variability within the species.
ASEXUAL REPRODUCTION
Binary fission—single-celled organisms that divide to form two organisms
Budding—a bud forms on the parent that may:
Separate to grow into an isolated individual, or
Remain attached to the parent (colonial organisms).
Budding occurs in some unicellular and some multicellular organisms.
Spores shed by the parent (as in a seedless plant like moss or ferns) that germinate
and produce male and female sex cells (leading to alternation of sexual and asexual
generations).
DIPLOID AND HAPLOID CELLS
In a human cell there are 23 pairs of chromosomes. One of these pairs determines the
sex of the individual.
Diploid cells—cells with paired chromosomes.
Haploid cells—sex cells (or gametes) with only one half of a pair of chromosomes.
Example: egg cells or sperm cells
35
CELL DIVISION
Mitosis—Division of body cells of sexual organisms. Produces new diploid cells with
identical chromosomes to the parent cells.
Meiosis—Division of cells to form gametes or sex cells (haploid cells), with half of
chromosomal set of the parent cell; occurs in a two-step process, producing four haploid
gametes.
36
RECOMBINATION OF GENES
Fertilized egg forms when two gametes (egg and sperm) combine. Fertilized egg has
paired chromosomes (diploid cell).
Variation occurs because of the sexual recombination of genes.
Genes are recombined in each successive generation.
37
MUTATIONS
Mutations are chemical changes to the DNA molecule.
Mutations can be caused by:
Chemicals (including certain drugs),
Radiation (including cosmic radiation, ultraviolet light, and gamma rays).
Mutations may also occur spontaneously without a specific causative agent.
38
MUTATIONS
Mutations may occur in any cell, but mutations in sex cells will be passed on to
succeeding generations.
Mutations produce much of the variability on which natural selection operates. 39
CAUSES OF EVOLUTION
Evolution may involve change from three different sources:
Mutations
Gene recombination as a result of sexual reproduction
Natural selection
40
EVOLUTION IN POPULATIONS
Evolution is a process of biologic change that occurs in populations.
Population—A group of interbreeding organisms that occupy a given area at a given
time.
Gene pool—The sum of all of the genetic components of the individuals in a
population.
41
RESERVED. EVOLUTION IN POPULATIONS
There is no exchange of genes between different populations because they are
reproductively isolated.
Barriers keep their gene pools separate (distance, geographic barriers, reproductive
barriers, etc.) 42
RESERVED. GEOGRAPHIC BARRIERS
Isthmus of Panama, is a barrier between oceans and populations of marine
organisms.
Islands with isolated populations of land animals.
Galapagos Island finches
Galapagos Island tortoises
Hawaiian Island honeycreepers (birds)
Grand Canyon separates different species of animals living on opposite sides of the
canyon.
43
RESERVED.
REPRODUCTIVE BARRIERS
Ecological isolation—Populations inhabiting the same geographic area, but living in
different habitats
Temporal isolation—Populations that reproduce at different times (such as plants that
flower in different seasons)
Mechanical isolation—Incompatible reproductive organs due to differences in size,
shape, or structure
Gametic isolation—Fertilization is prevented by incompatible gametes
44
RESERVED. SPECIATION
Speciation = The process through which new species arise.
When a population is split by a barrier each population becomes isolated. Over many
generations, the genetic differences may accumulate to the point that the different
populations are no longer able to interbreed.
At this point, the different populations would be considered separate species.
45
RESERVED. SPECIATION
Once a new species is established, segments of the population around the fringes of the
population may undergo additional speciation.
With successive speciations, diverse organisms arise with diverse living strategies. 46
RESERVED.
ADAPTIVE RADIATION
Defined as the branching of a population to produce descendants adapted to particular
environments and living strategies. Bill shapes are adaptations to different means of
gathering food. 47 FIGURE 6-17 The honeycreepers of Hawaii are a fine example
of adaptive radiation.
RESERVED.
MODELING HOW EVOLUTION OCCURS
The question is not whether evolution occurs, but rather, exactly how it occurs. What is
the mechanism of evolution?
Phyletic gradualism—gradual progressive change by means of many small steps (old
idea).
Punctuated equilibrium—sudden changes interrupting long periods of little change
(stasis). Most change occurs over a short period of time.
48
RESERVED.
Phyletic gradualism
vs.
Punctuated equilibrium FIGURE 6-21 Evolutionary models: (A) punctuated
equilibrium, (B) phyletic gradualism. MODELING HOW EVOLUTION OCCURS
49
RESERVED.
SPECIATION
Punctuated equilibrium model suggests that evolution occurs in isolated areas around
the periphery of the population (peripheral isolates).
Speciation may occur rapidly in these isolated areas.
When the new species expands or migrates from the isolated area into new areas, it
looks like a sudden appearance in the fossil record.
PHYLOGENY—THE TREE OF LIFE
Phylogeny = the sequence of organisms placed in evolutionary order.
Diagrams called phylogenetic trees are used to display ancestor-descendant
relationships.
Branches on the tree are called clades. FIGURE 6-22 The phylogenetic tree of
horses.
CLADOGRAMS
Diagrams drawn to show ancestor-descendant relationships based on characteristics
shared by organisms.
They show how organisms are related but do not include information about time or
geologic ranges.
52
LINES OF EVIDENCE FOR EVOLUTION CITED BY DARWIN
Fossils provide direct evidence for changes in life in rocks of different ages.
Homologous structures—Certain organs or structures are present in a variety of
species, but they are modified to function differently.
Modern organisms contain vestigial organs that appear to have little or no use. These
structures had a useful function in ancestral species.
Animals that are very different, had similar-looking embryos.
53
1.Genetics—DNA molecule
2.Biochemistry—similar in closely-related organisms, but very different in more distantly
related organisms.
3.Molecular biology—sequences of amino acids in proteins
OTHER LINES OF EVIDENCE FOR EVOLUTION
EVIDENCE FOR EVOLUTION FROM PALEONTOLOGY
1.Horses
2.Cephalopods and other molluscs
3.Foraminifera and other microfossils
Many examples of gradual or sequential evolution in the fossil record, including:
FIGURE 6-25 Evolutionary change in Permian ammonoid cephalopods.
EVIDENCE FOR EVOLUTION FROM BIOLOGY
Homologous structures—body parts with similar origin, history and structure, but
different functions.
56 FIGURE 6-26 Bones of the right forelimb from several vertebrates reveal
similarity of structure.
EVIDENCE FOR EVOLUTION FROM BIOLOGY
Vestigial organs suggest a common ancestry. Vestigial organs serve no apparent
purpose, but resemble functioning organs in other animals.
57
FIGURE 6-27 The pelvis and femur (upper leg bone) of a whale are vestigial
organs.
EVIDENCE FOR EVOLUTION FROM BIOLOGY
Similarity of embryos of all vertebrates suggests a common ancestry. 58 FIGURE 6-28
Embryos of different vertebrates.
EVIDENCE FOR EVOLUTION FROM BIOLOGY
Biochemistry - Chemicals (such as proteins, antigen reactions of blood, digestive
enzymes, and hormone secretions) are more similar in related organisms.
59
EVIDENCE FOR EVOLUTION FROM BIOLOGY
DNA sequencing —If organisms appear to be similar on the basis of form, embryonic
development, or fossil record, we can predict that they would have a greater percentage
of DNA sequences in common, compared with less similar organisms.
This is proven to be correct in hundreds of analyses. 60
FOSSILS AND STRATIGRAPHY
The Geologic Time Scale is based on the appearance and disappearance of fossil
species in the stratigraphic record.
Fossils can be used to recognize the approximate age of a unit and its place in the
stratigraphic column.
Fossils can also be used to correlate strata from place to place.
GEOLOGIC RANGE
Geologic range = The interval between the first and last occurrence of a fossil species in
the geologic record.
The geologic range is determined by recording the occurrence of the fossils in numerous
stratigraphic sequences from hundreds of locations.
62
USING FOSSILS TO CORRELATE ROCK UNITS
Geologic range for fossil “X”, “Y”, and ‘z’
63
FIGURE 6-29 Use of geologic ranges of fossils to identify time-rock units.
USE OF COSMOPOLITAN AND ENDEMIC SPECIES IN CORRELATION
Cosmopolitan species have a widespread distribution.
Endemic species are restricted to a specific area or environment.
Cosmopolitan species are most useful in correlation
64
PITFALLS OF CORRELATING WITH FOSSILS
Appearances and disappearances of fossils may indicate:


Changing environmental conditions that cause organisms to migrate into or out of an
area
INDEX FOSSILS
Index fossils (or guide fossils) are useful in identifying time-rock units and in correlation.
Characteristics of an index fossil:
1.Abundant
2.Widely distributed (cosmopolitan)
3.Short geologic time range (rapid evolution)
BIOSTRATIGRAPHIC ZONES
Biozone = A body of rock deposited during the time when a particular fossil organism
existed.
A biozone is identified only on the basis of the fossils it contains.
Biozones are the basic unit for biostratigraphic classification and correlation.
67
RESERVED.
FOSSILS AND PAST ENVIRONMENTS
1.Ecology = Interrelationship between organisms and their environment.
2.Paleoecology = Ancient ecology; interaction of ancient organisms with their
environment. Depends on comparisons of ancient and living organisms (modern
analogs).
3.Ecosystem = Organisms and their environment—the entire system of physical,
chemical, and biological factors influencing organisms.
68
RESERVED.
FOSSILS AND PAST ENVIRONMENTS
4.Habitat = Environment in which an organism lives.
5.Niche = Way in which the organism lives; its role or lifestyle.
6.Community = Association of several species of organisms in a particular habitat (living
part of ecosystem).
7.Paleocommunity = An ancient community.
69
RESERVED.
MARINE ECOSYSTEM
The ocean may be divided into two realms:
Pelagic realm = The water mass lying above the ocean floor.
Benthic realm = The bottom of the sea
70
RESERVED. MARINE ECOSYSTEM
Pelagic realm
Neritic zone = The water overlying the continental shelves.
Oceanic zone = The water seaward of the continental shelves.
71
RESERVED.
MARINE ECOSYSTEM
Benthic realm
Supratidal zone = Above high tide line
Littoral zone (or intertidal zone) = Between high and low tide lines
Sublittoral zone (or subtidal zone) = Low tide line to edge of continental shelf (~200 m
deep)
Bathyal zone—200–4000 m deep
Abyssal zone—4000–6000 m deep
Hadal zone — >6000 m deep; deep sea trenches.
72
RESERVED. MARINE ECOSYSTEM 73 FIGURE 6-35 Classification of marine
environments. RESERVED. MODES OF LIFE OF MARINE ANIMALS
Plankton—Small plants and animals that float, drift, or swim weakly.
•Phytoplankton—Plants and plant-like plankton, such as diatoms and coccolithophores
•Zooplankton—Animals and animal-like plankton, such as foraminifera and radiolaria
74
RESERVED. MODES OF LIFE OF MARINE ANIMALS
Nekton—Swimming animals that live within the water column
Benthic organisms or benthos—Bottom dwellers, which may be either:
•Infaunal: Living beneath the sediment surface; they burrow and churn and mix the
sediment, a process called bioturbation
•Epifaunal: Living on top of the sediment surface
75
RESERVED. MARINE SEDIMENTS
Terrigenous sediment—from weathered rocks
Biogenous sediment—of biological origin
Calcareous oozes: foraminifera, pteropods, and coccolithophores
Siliceous oozes: radiolarians and diatoms
Phosphatic material: fish bones, teeth and scales
Hydrogenous sediment: precipitated from sea water manganese nodules
76
RESERVED. CARBONATE COMPENSATION DEPTH
A depth in the oceans (about 4000-5000 m), which affects where calcareous oozes can
accumulate.
Above the CCD (shallower than 4000-5000 m), the water is warmer, and CaCO3 is
precipitated. Calcareous sediments (chalk or limestone) are deposited. 77 FIGURE 644 Carbonate compensation depth (CCD).
RESERVED. CARBONATE COMPENSATION DEPTH
Below the CCD (below about 4000–5000 m), water is colder, and CaCO3 dissolves. Clay
or siliceous sediments are deposited. 78 FIGURE 6-44 Carbonate compensation
depth (CCD).
RESERVED.
USE OF FOSSILS IN RECONSTRUCTING ANCIENT GEOGRAPHY
Environmental limitations control the distribution of modern plants and animals.
Note locations of fossil species of the same age on a map
Interpret paleoenvironment for each region using rock types, sedimentary structures,
and fossils.
Plot the environments to produce a paleogeographic map for that time interval.
79
RESERVED. LAND BRIDGES, ISOLATION AND MIGRATION
Migration and dispersal patterns of land animals can indicate the existence of:
•Former land bridge
•(Bering Strait)
•Mountain barriers
•Former ocean barriers between continents
80
FIGURE 6-46 Intercontinental migrations of camel family members
RESERVED. SPECIES DIVERSITY AND GEOGRAPHY
High latitudes have low species diversity
Low latitudes have high species diversity.
Species diversity is related to geographic location, particularly latitude.
As a general rule, species diversity increases toward the equator. 81 FIGURE 6-47
Species diversity ranges from low at polar latitudes to high at equatorial latitudes.
RESERVED.
USE OF FOSSILS IN THE INTERPRETATION OF ANCIENT CLIMATIC CONDITIONS
Fossils can be used to interpret paleoclimates (ancient climates):
1.Fossil spore and pollen grains can tell about the types of plants that lived, which is an
indication of the paleoclimate.
2.Plant fossils showing aerial roots, lack of yearly rings, and large wood cell structure
indicate tropical climates
3.Presence of corals indicates tropical climates
82
RESERVED. USE OF FOSSILS IN THE INTERPRETATION OF ANCIENT CLIMATIC
CONDITIONS
4.Marine molluscs with spines and thick shells inhabit warm seas
5.Planktonic foraminifera vary in size and coiling direction with temperature
6.Shells in warmer waters have higher Mg contents
7.Oxygen isotope ratios in shells.
83
. OVERVIEW OF THE HISTORY OF LIFE OLDEST EVIDENCE OF LIFE
Remains of prokaryotic cells (blue-green algae or cyanobacteria) more than 3.5 billion
years old. Found in algal mats and stromatolites. 85
EARLIEST METAZOAN ORGANISMS
Metazoans = multicellular organisms
Trace fossils of metazoans about 1 billion years ago
First body fossils of soft-bodied metazoans (worms, jellyfish, and arthropods) about
0.7 billion years ago
Invertebrates with hard parts appeared during Late Proterozoic or Early Paleozoic.
86
RESERVED.
GEOLOGIC RANGES AND RELATIVE ABUNDANCES OF FOSSIL ORGANISMS 87
FIGURE 6-54 Geologic ranges and relative abundances of frequently fossilized
categories of invertebrate animals.
RESERVED. EARLY PALEOZOIC—CAMBRIAN PERIOD
Most animals were deposit and suspension feeders
Trilobites
Brachiopods without hinged shells (inarticulates)
Small cap-shaped molluscs
Soft-bodied worms
Chitin-shelled arthropods
Reef-building archaeocyathids
LATER DURING PALEOZOIC
Trilobites
Articulate (hinged) brachiopods
Nautiloids
Crinoids
Rugose (horn) corals
Tabulate corals
Branching twig-like bryozoans (moss animals)
Vertebrates
Fishes
Amphibians
Reptiles
89 RESERVED. MESOZOIC ERA
Modern scleractinian corals
Bivalves
Sea urchins
Ammonoids
Vertebrates
Dinosaurs
Primitive mammals
Birds
RESERVED. CENOZOIC ERA
Molluscs of many types (but no ammonoids)
Planktonic foraminifera
Sea urchins
Encrusting bryozoans
Barnacles
Vertebrates
Age of mammals
Appearance of humans
Many other vertebrate groups
. EXTINCTIONS
Mass extinctions occurred at the ends of the following periods:
Permian—the greatest extinction. More than 90% of marine species disappeared or
nearly went extinct of marine invertebrates extinct
Cretaceous—affected dinosaurs, other land animals, and marine organisms; about
25% of all known animal families extinct
. EVOLUTIONARY HISTORY OF PLANTS 93 FIGURE 6-53 Geologic ranges, relative
abundances, and evolutionary relationships of vascular land plants.
EVOLUTIONARY HISTORY OF PLANTS
1.Earliest photosynthetic organisms were single-celled organisms during Precambrian.
2.Green algae or chlorophytes may be the ancestors of vascular land plants.
3.Plants invaded the land during Ordovician, reproducing with spores.
HISTORY OF PLANTS
4.First plants with seeds appeared during Devonian. Gymnosperms (such as conifers).
Had pollen.
5.Carboniferous coal swamps dominated by seedless, spore-bearing scale trees.
6.Flowering plants appeared during Cretaceous. Angiosperms. Dominant plants today.
•FIGURE 6-17 The honeycreepers of Hawaii are a fine example of adaptive
radiation. Source: Harold Levin.
• FIGURE 6-21 Evolutionary models: (A) punctuated equilibrium, (B) phyletic
gradualism. Source: Harold Levin.
• FIGURE 6-22 The phylogenetic tree of horses. Source: Based on Macfaddan, B.J.
1992. Fossil Horses: Systematics, Paleobiology, and Evolution of the Family
Equidae. Cambridge: Cambridge University Press.
• FIGURE 6-25 Evolutionary change in Permian ammonoid cephalopods. Source:
Harold Levin.
• FIGURE 6-26 Bones of the right forelimb from several vertebrates reveal similarity
of structure. Source: Harold Levin.
• FIGURE 6-27 The pelvis and femur (upper leg bone) of a whale are vestigial
organs. Source: Harold Levin.
• FIGURE 6-28 Embryos of different vertebrates. Source: Harold Levin.
• FIGURE 6-29 Use of geologic ranges of fossils to identify time-rock units. Source:
Harold Levin.
•FIGURE 6-35 Classification of marine environments. Source: Harold Levin.
•FIGURE 6-44 Carbonate compensation depth (CCD). Source: Harold Levin.
• FIGURE 6-46 Intercontinental migrations of camel family members. Source: After
Ross, C., 1967, Development of fusulinid (Foraminiferida) faunal realms. J Paleo
41: 1341-1354.
• FIGURE 6-47 Species diversity ranges from low at polar latitudes to high at
equatorial latitudes. Source: Harold Levin.
• FIGURE 6-54 Geologic ranges and relative abundances of frequently fossilized
categories of invertebrate animals. Source: Harold Levin.
•FIGURE 6-53 Geologic ranges, relative abundances, and evolutionary
relationships of vascular land plants. Source: Harold Levin.