Transcript fossil record

VIZUALIZING EARTH HISTORY
By Loren E. Babcock
Chapter 4
Life on Earth and Its Fossil Record
Classification of Life on Earth
Understand how living things are classified.
In 1789, the Swedish biologist Carl von Linné (who latinized
his name to Carolus Linnaeus) introduced the
Linnaean classification system, is based on similarities
and differences among organisms and recognizes the species
as the fundamental unit of classification.
Species are grouped in categories of ever-increasing size called
genera, families, orders, classes, phyla,
kingdoms, and domains.
Classification of Life on Earth
Understand how living things are classified.
Species - A group of organisms that can
interbreed and produce fertile offspring.
Species are referred to using a two-part Latin name consisting
of a genus name followed by a species name. This is called
binominal nomenclature.
Binominal nomenclature - A technique of identifying organisms
using a two-part Latin name, a genus name followed by a species
name. The Latin names are set off from ordinary text using italics
or underlining.
Classification of Life on Earth
Understand how living things are classified.
Classification of Life on Earth
Differentiate between a biological species
and a paleontological species.
Paleontological species concept - The concept that the
limits of ancient species may be inferred from their
preserved physical traits.
For fossils, applying the reproductive criterion is
impossible, so we use proxy evidence that individuals
found which indicates that fossils could have interbred
and produced fertile offspring.
Classification of Life on Earth
Differentiate between a biological species
and a paleontological species.
Biological species concept - The concept that
members of a species can interbreed and
produce fertile offspring and that members
of a single species are distinguished from
other species by reproductive isolation.
Classification of Life on Earth
Explain the differences between prokaryotes and
eukaryotes.
CELLULAR ORGANIZATION
Living things fall into two fundamental categories
based on the structure and biochemistry
of their cell types: prokaryotes and eukaryotes.
Prokaryote - (typically 1–10 μm) An organism that lacks a
nucleated cell type and certain organelles.
Eukaryote - (typically 10–100 μm) An organism that has a
nucleated cell type, more complex and incorporate heritable
organelles.
Classification of Life on Earth
Explain the differences between prokaryotes and
eukaryotes.
Classification of Life on Earth
Understand how living things are classified.
Cellular organisms are usually organized
into three domains and six kingdoms
The three domains are:
Eukarya (Eukaryotes),
Archaea (Archaebacteria - (Prokaryotes),), and
Bacteria (Eubacteria (Prokaryotes), (also sometimes
called Monera).
Classification of Life on Earth
Understand how living things are classified.
Cellular organisms are usually organized
into three domains and six kingdoms
The six kingdoms are:
Protoctista, Fungi, Plantae, and Animalia.
(Eukaryotes (domain Eukarya).
Archaebacteria(domain Archaea)
Eubacteria, also sometimes called Monera (domain Bacteria)
Classification of Life on Earth
ARCHAEA
Archaebacteria (or archeans) are the methanogenic, or
methane-producing; halophilic, or salt-loving; and
thermoacidophilic, or heat- and acid-loving prokaryotes
Archaebacteria are among the most primitive life forms.
They are perhaps best known in extreme environments:
oxygen-depleted muds and soils, hot salt flats,
salty sea shores, hot springs, boiling volcanic
environments, and deep-sea hydrothermal vents.
Classification of Life on Earth
ARCHAEA
Classification of Life on Earth
ARCHAEA
Archaebacteria metabolize by means of chemosynthesis,
which involves conversion of chemical energy into biologically
useful organic compounds. The ability of some archaebacteria
to withstand, grow, and reproduce in hot, oxygen-deficient
environments, including tectonically active areas, suggests
that they may have been the first organisms to evolve on Earth.
Chemosynthesis - Synthesis of organic molecules
using chemical energy released through oxidation
of inorganic compounds.
Classification of Life on Earth
BACTERIA
Bacteria (or eubacteria) are all the prokaryotes except
for those classified as archeans (archaebacteria). This
group is exceedingly diverse in structure and metabolism.
Eubacteria range from simple, solitary unicells to
more complex stalked, budding, and aggregated forms.
Eubacteria usually form organic compounds such as
sugars, starches, phosphorous compounds, and
proteins in one of two ways: through chemosynthesis
(similar to archaebacteria) or through
photosynthesis (similar to plants).
Classification of Life on Earth
BACTERIA
Photosynthesis involves using sunlight to convert
carbon dioxide in the atmosphere into organic compounds.
In eubacteria, photosynthesis is essentially an anaerobic
process occurring in dysoxic water. Conversion of light
energy requires chlorophyll or some other pigment
molecule such as rhodopsin.
The chemical energy produced, called adenosine
triphosphate (ATP), is a nucleotide used in the
transformation reactions of all cells.
Classification of Life on Earth
BACTERIA
Chemosynthetic and photosynthetic nutrition are referred
to as autotrophy, which is the self-production of food and
derivation of energy from inorganic sources. Eubacterial
cycling of elements and compounds is essential for all life
forms on Earth.
Autotrophy - The process of “self-feeding” by
means of either harvesting light energy from
the Sun or from oxidation of inorganic
compounds to make organic molecules.
Classification of Life on Earth
PROTOCTISTS
Symbiosis - A condition in which two or more dissimilar
organisms live together in close association.
Protoctists are eukaryotic microorganisms and their
descendants other than fungi, plants, and animals.
The best-known protoctists are algae, oomycotes (water molds,
slime molds, and slime nets), and protozoans (the protists such
as amoebas, ciliates, and diatoms).
Protoctists have a good fossil record dating to the
Proterozoic. Protoctists are unicellular
and multicellular eukaryotes.
Classification of Life on Earth
PROTOCTISTS
Classification of Life on Earth
FUNGI
Fungi are eukaryotic organisms that develop from chitinous
fungal spores (propagules), have chitinous cell walls,
and lack undulipodia at all stages of the life cycle.
Most fungi are multicellular. They all acquire
nutrients by digesting living or dead tissue through a
process known as absorptive heterotrophy. Fungal cells
can have more than one nucleus per cell.
Reproduction occurs asexually, through mitosis, or
sexually, in which meiosis produces haploid propagules.
Classification of Life on Earth
FUNGI
Classification of Life on Earth
PLANTS
Plants can be divided into two major groups:
nonvascular plants and vascular plants.
Nonvascular plants include mosses, liverworts, and hornworts.
Nonvascular lack the true stems, leaves, and roots
that characterize vascular plants.
Vascular plants include club mosses, psilophytes, horsetails,
ferns, gymnosperms (cycads, ginkgos, conifers, and
gnetophytes), and the angiosperms (flowering plants).
Classification of Life on Earth
PLANTS
Classification of Life on Earth
ANIMALS
Heterotrophy - A means of obtaining nutrients
by ingesting or breaking down organic matter.
Animals acquire nutrients through heterotrophy, and most
ingest food through an oral opening. Some animals are
parasitic and lack a digestive system. Rarely, animals
take in photosynthesizing symbionts that help them
acquire essential nutrients.
Animals normally have cells specialized for functions such
as respiration, digestion, and protection, and these cells
are grouped into tissues and organs.
Classification of Life on Earth
Understand how living things are classified.
ANIMALS
Animals can be divided in a couple different ways. One way is to
distinguish animals that lack backbones (the invertebrates) from
those that have backbones (the vertebrates).
Another way is to distinguish the animals that lack tissues
organized into organs (the parazoans) from those that have
tissues organized into organs and organ systems
(the metazoans).
Ecology of Life Forms
Factors governing the distribution and abundance of life forms.
Paleoecology - Study of the factors controlling
the distribution and abundance of species.
Habitats are settings on or close to the Earth’s surface inhabited
by life forms. The distribution of organisms is largely controlled
by access to water, so habitats can be broadly divided
into terrestrial (land) and aquatic (water) settings.
Hypsometric curve - A graph indicating the proportions
of the Earth’s surface above and below sea level.
Ecology of Life Forms
Factors governing the distribution and abundance of life forms.
Types of Fossils and How They Form
Define the meaning of fossil.
A fossil is any evidence of ancient life.
To a geologist, the term ancient usually implies something
that is pre-Holocene in age. We can use a figure of
10,000 years as a rough estimate for the
Pleistocene–Holocene boundary, even though the
position and age of the boundary have not yet been
fixed. Evidence of past life that is younger than
the Pleistocene is referred to as subfossil.
Types of Fossils and How They Form
Distinguish the three types of fossils.
Fossils are of three basic forms:
body fossils, trace fossils, and biomarkers.
Types of Fossils and How They Form
HOW BODY FOSSILS ARE FORMED
Durable and inedible hard parts (bones, teeth, shells,
tests, or wood), are a prerequisite for fossilization.
The fossil record is strongly biased in favor of biomineralized
remains such as calcite or aragonite shells and
phosphatic teeth and bones.
The fossil record is biased against nonbiomineralized
insects, spiders, and plant leaves.
Types of Fossils and How They Form
HOW BODY FOSSILS ARE FORMED
Major Groups in the Fossil Record
Explain what organisms are represented in the fossil record.
Eubacteria, whose remains have been reported from strata as
old as 3.4 billion years, are the oldest known body fossils.
They may have a greater antiquity, however, because chemical
breakdown products (biomarkers) attributed by some to
eubacteria have been reported from even older rocks.
Most of the known record of eubacteria comes from
stromatolites, thrombolites, and other structures
they constructed. These structures are the primary
physical evidence of life through the Archean Eon
and most of the Proterozoic Eon.
Major Groups in the Fossil Record
Explain what organisms are represented in the fossil record.
Protoctists are well represented as fossils. Some red
algae make calcareous structures important in the
construction of Phanerozoic reefs, and green algae
have been a major source of minute calcareous
needles forming Phanerozoic carbonate muds.
More than 40,000 species of foraminifera, a
protozoan group, have been described from
fossils dating back to the Cambrian Period.
Most are small in size.
Major Groups in the Fossil Record
Explain what organisms are represented in the fossil record.
Ancient fungi are known mostly from fossilized
hyphae, although their presence has also been
inferred from some types of borings in wood and shell.
Hyphal remains are known from both nonmarine
and marine deposits.
Plants have left a good fossil record of leaves, stems, bark,
and seeds or spores. Spores of terrestrial plants first appear in
Cambrian strata. The first clear evidence of other tissues, mostly
stalks and reproductive organs, comes from Silurian strata. Vascular
tissues, stems, roots, and leaves are important components of
many terrestrial sedimentary deposits.
Major Groups in the Fossil Record
Explain what organisms are represented in the fossil
record.
Animals, principally those having hard skeletal parts, have
perhaps the most diverse fossil record of any group.
Animal fossils extend back more than 550 million years to the
late Proterozoic. Some scientists have argued that animals
appeared before that time, perhaps as much as
600 to 1,500 million years ago, but did not leave fossils
until much later in their history.
Mollusks, brachiopods, bryozoans, corals, sponges,
echinoderms, some arthropods, and vertebrates are well
represented in the fossil record. In addition to a body fossil
record, animals have also left an excellent trace fossil record.