VIZUALIZING EARTH HISTORY By Loren E. Babcock Chapter 4 Life on Earth and Its Fossil Record.

VIZUALIZING EARTH HISTORYBy Loren E. Babcock

Chapter 4

Life on Earth and Its Fossil Record

Classification of Life on EarthUnderstand 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.


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 EarthDifferentiate 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 EarthDifferentiate 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 EarthExplain the differences between prokaryotes and

eukaryotes.

CELLULAR ORGANIZATIONLiving 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 EarthExplain the differences between prokaryotes and

eukaryotes.


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).


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 EarthARCHAEA

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.


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 EarthBACTERIA

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).


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.


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 EarthPROTOCTISTS

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 EarthPROTOCTISTS

Classification of Life on EarthFUNGI

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 EarthFUNGI

Classification of Life on EarthPLANTS

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 EarthPLANTS

Classification of Life on EarthANIMALS

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.


ANIMALSAnimals 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 FormsFactors 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 FormsFactors governing the distribution and abundance of

life forms.

Types of Fossils and How They FormDefine 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 FormDistinguish the three types of fossils.

Fossils are of three basic forms:

body fossils, trace fossils, and biomarkers.

Types of Fossils and How They FormHOW 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 FormHOW BODY FOSSILS ARE FORMED

Major Groups in the Fossil RecordExplain 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.


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.


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 RecordExplain 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.

VIZUALIZING EARTH HISTORY By Loren E. Babcock Chapter 4 Life on Earth and Its Fossil Record.

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Transcript of VIZUALIZING EARTH HISTORY By Loren E. Babcock Chapter 4 Life on Earth and Its Fossil Record.