geol162 fossils

7/31/2019 GEOL162 Fossils

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FossilsFossils


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Fossils Fossils

are any evidence of past life.

Body fossils

>

parts of the body of an organism

-

e.g. --> pollen, leaves, stems, flowers,

seeds, bones, fur, teeth, and shells.

Trace fossils

>

indicators of past activity of organisms

-

e.g.--> tracks, trails, burrows, and wastes.

are any evidence of past life.

Body fossils

>

parts of the body of an organism

-

e.g. --> pollen, leaves, stems, flowers,

seeds, bones, fur, teeth, and shells.

Trace fossils

>

indicators of past activity of organisms

-

e.g.--> tracks, trails, burrows, and wastes.


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Fossil RecordFossil RecordGenerally incomplete>due to

-poor presevation

-poor observation & recovery-poor fossilzation potential

Generally incomplete>due to

-poor presevation

-poor observation & recovery-poor fossilzation potential


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To Be or Not to Be...a Fossil

To Be or Not to Be...a Fossil

chances are better that youcould become a fossil if:>A) You have hard parts

-like teeth, bones, or shell>B) You are buried rapidly

-prevents recycling of organic materials by beingeaten by something

>C) You are prolific-there is a lot of your type around

chances are better that youcould become a fossil if:>A) You have hard parts

-like teeth, bones, or shell>B) You are buried rapidly

-prevents recycling of organic materials by beingeaten by something

>C) You are prolific-there is a lot of your type around


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This fossil fly and fern werecompressed by sediment.

This is a type of body fossilIn addition, it has, along with theferns, also undergone a processcalled Carbonization

This fossil fly and fern werecompressed by sediment.

This is a type of body fossilIn addition, it has, along with theferns, also undergone a processcalled Carbonization


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Types of FossilizationTypes of Fossilization

Iron Sulfide ReplacementIron Sulfide Replacement

These fossils have undergone a process calledReplacement

original mineral components where replaced with an equivalent amount

The feature on the far left is a pyrite sun (a psuedo-fossil) whereasthose on the right are pyritized ammonites.

These fossils have undergone a process calledReplacement, where the

original mineral components where replaced with an equivalent amountof a new mineral.The feature on the far left is a pyrite sun (a psuedo-fossil) whereasthose on the right are pyritized ammonites.


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Petrification by PermineralizationPetrification by Permineralizationis the literal "turning to stone" by infilling of pore spaces and supplementationorganic matter with silica or other minerals.

Petrified wood forms by this process.


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Molds and CastsMolds and Casts

Internal mold aka SteinkernInternal mold aka Steinkern External mold and cast of a trilobiteExternal mold and cast of a trilobite


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Body FossilsBody Fossils

Trilobite

CrinoidCrinoid

Horseshoe crabHorseshoe crab


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Fossil BonesFossil Bones

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This fossil

Rhino wasexcavated

at Ashfall

Historic Park,

Nebraska.The bones in

this case are

only slightly

modifiedfrom their

original

composition

This fossil

Rhino wasexcavated

at Ashfall

Historic Park,

Nebraska.The bones in

this case are

only slightly

modifiedfrom their

original

composition


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Other TypesOther Types Entombing

> organisms preserved in amber or other resin

Mummification> organism is dehydrated without bacteriologic

or fungal decay> Can occur in extremely cold regions

- Arctic and Glacial settings,

>

extremely dry- Deserts (warm or cold)

> or in areas with "built in" preservatives

- Tar Pits

Entombing

> organisms preserved in amber or other resin

Mummification> organism is dehydrated without bacteriologicor fungal decay

> Can occur in extremely cold regions

- Arctic and Glacial settings,

>

extremely dry- Deserts (warm or cold)

> or in areas with "built in" preservatives

- Tar Pits


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Actual Critters- Insects and other animals trapped in

amber or mummified organisms like this mammoth


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Trace FossilsTrace Fossils

Interpretation of trace fossils and their

relationship to paleo-environmental setting istermed Ichnology

Interpretation of trace fossils and their

relationship to paleo-environmental setting istermed Ichnology

Evidence of biologic activity>Tracks>Feeding traces>Dwellings

specific traces (e.g. tracks made by knownspecies )are called Ichnofacies

Evidence of biologic activity

>Tracks>Feeding traces>Dwellings

specific traces (e.g. tracks made by knownspecies )are called Ichnofacies


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Common Categorical Ichnofacies (Fossil Behavior) Cubichnia

- resting traces caused as the animal stopped its motion to take rest

refuge> Often found on the surfaces of beds

Domichnia- dwelling traces excavated by some living thing for the purposes ofestablishing a home

> Often penetrates into specific lithologies, disrupting beds Fugichnia

- fleeing or escape traces caused as an organism "bolted" from theirburrow to escape some threat

Repichnia- crawling traces, appearing on the surface of beds

Pasichnia- grazing traces caused as the organism systematically combed thesediment in the horizontal plane for food


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Common Categorical Ichnofacies (Fossil Behaviour) Agrichnia

- "farming" traces caused as they burrowed into the surroundingsediment then returned to a dwelling structure

> Often found on the surfaces of beds (or on the sole of the overlying bed Fodichnia

- deposit feeding traces excavated by some living thing as it ate thesediment, removed the nutrients, and then passed the remains out ofthe organism into the chamber

> a three dimensional structure, that can be either branching or single limbed, horizontal, vertical, or at some inclined angle


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Common Ichnofacies


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Ichnofacies the standard tool used to further define the nature of

trace fossils

Skolithos- sandy shoreline facies- vertical tube-like burrows with a vareity of shapes and dimensions

- charactistic of organisms that lived in environments with rapidly

shifting sands>

implying rapidly moving water- trace maker may be extinct since the Cretaceous

- no living means of seeing this being made

Specific examples of this ichnofacies include- Ophiomorphia- a bumpy walled short burrow made by ghost shrimp

- Diplocraterion- a U-shaped burrow which either gets increasinglydeeper or increasing shallower


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QuickTime and aPhoto - JPEG decompressor

are needed t o see this picture.

These are burrows

made by organismsburrowing into

sandy sediment

These are burrows

made by organismsburrowing into

sandy sediment

Trace FossilsTrace Fossils

T F il


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Trace Fossil

These are the tracks of a bipedal dinosaur left in sandy

sediments along an ancient shoreline


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Uses of FossilsUses of FossilsFossils are used for:>Determining EOD's,>Correlation of rocks,>Jewelry & Collectables,

phylogenetic studies of living and

fossil organisms.Many organisms are known onlyfrom fossils.>e.g. Trilobites, Dinosaurs, Mammoths

Fossils are used for:>Determining EOD's,>Correlation of rocks,>Jewelry & Collectables,

phylogenetic studies of living andfossil organisms.

Many organisms are known onlyfrom fossils.>e.g. Trilobites, Dinosaurs, Mammoths

S t ti


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Systematics Taxonomic Classification of Living (and once living) things

Linnean Classification scheme

Based on morphology and structure of parts

- e.g., four legs would be form, with one upper bone and two lowerbones would be structure

used in taxonomic classification- must be latin or latinized- must use binomial classification at the fundamental level

> Genus and species- must be printed and italicized with the Genus capitalized and thespecies in lower case> Homo sapiens is our taxonomic classification at the Genus and species level

Fi Ki d


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Five Kingdoms these are divided in turn

- Kingdom> Ken

- Phylum> Patton

- Class> Came

- Order>

Over- Family

> For

- Genus> Greasy

-species> Seafood


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Development of Evolutionary Theory Not a new idea

- Lamarckism>

an inherited need to develop something would provoke certain developmentresponses

E.G., lizards who preferred to crawl rather than run would

develop smaller and less functional legs, while also developi

long, thin bodies to facilitate crawling- implies some level of control over the process

Darwinproposed that decendants would inherit traits that would

facilitate their survival

weaknesses- didn't know about genetics

- was using extremely limited observations> fossil record and living organisms might have transitional forms

Phylo eny


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Phylogeny illustrates the historical development of a species over time

shown by the use of a tree-like diagram or a candelabra-lik

diagram- which depends on method of phylogenetic grouping

Stratophenic Phylogeny branches based on timing of appearance of new species of

organisms- branches at the top are "newer" than those at the bottom

> implies transitional forms again and relies heavily on linkage via fossil recor

Cladistic Phylogeny based on shared traits between organisms


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Cladogram of mammals

St t f h


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Stratogram of horses


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Use of fossils for correlation need relative age of rocks before they could be

used to correlate Must determine the Geologic Range of the organism

in the rocks- only accomplished by examining many locations with fossils

in them Once accomplished, identify chronostratigraphic

units using the fossils

Can then create a composite Geologic column


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Geologic Range of several organisms that lived in

the late Creatceous


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Index Fossil (aka Guide

Fosssils)prolific (lots of them)

widespread (large geographiarea)

short lived in the geologic

record- can be used to identify what

chronostratigraphic unit you

are looking at in the field or

lab.


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Interpretation of the RecordInterpretation of the RecordEvidence for Large Scale Extinctions

> Ordovician/Silurian Extinction- related to global cooling & glaciation

>Devonian/Mississippian Extinction

- related to global cooling & glaciation

> Permian/Triassic Extinction- 90% of all known species became extinct

> Cretaceous/Tertiary Extinction- Dinosaurs 130 million year dominance ended

> Pleistocene/Holocene Extinction-

Many large land mammals became extinct

Evidence for Large Scale Extinctions> Ordovician/Silurian Extinction

- related to global cooling & glaciation>

Devonian/Mississippian Extinction

- related to global cooling & glaciation> Permian/Triassic Extinction

- 90% of all known species became extinct> Cretaceous/Tertiary Extinction

- Dinosaurs 130 million year dominance ended> Pleistocene/Holocene Extinction

-Many large land mammals became extinct


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TrilobiteTrilobite

existed from Cambrian

(600my) to the late

Permian (230my)

existed from Cambrian

(600my) to the late

Permian (230my)

Name means "ThreeSections or lobes"Name means "ThreeSections or lobes"

Dominant Species in

the Cambrian

Dominant Species in

the Cambrian


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Age of the DinosaursAge of the DinosaursThe Mesozoic era

> Triassic, Jurassic, Cretaceous> Existed and dominant species for 170

my or so

The Mesozoic era> Triassic, Jurassic, Cretaceous> Existed and dominant species for 170

my or soBecame extinct 65 mya

> Meteorite impact(?)-Yuctan area in Gulf of Mexico

> Climate Change (?)> Volcanic activity (?)> Disease (?)

Became extinct 65 mya> Meteorite impact(?)

-Yuctan area in Gulf of Mexico> Climate Change (?)> Volcanic activity (?)> Disease (?)

AlbAlb t


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AlbertasaurusAlbertasaurus

QuickTime and aPhoto - JPEG decompressor

are needed t o see this picture.

AA t


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ApatosaurusApatosaurus

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DimetrodonDimetrodon


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DimetrodonDimetrodon

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Not a dinosaur!


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