fossil (offline format)

8/12/2019 Fossil (Offline Format)

1/20

Fossil

Fossils(from ClassicalLatinfossilis, literally "obtained by digging[1]

") are the preservedremains ortracesof animals, plants, and other organisms from the remote past. The totality of

fossils, both discovered and undiscovered, and their placement infossiliferous(fossil-containing)

rockformations andsedimentarylayers (strata)is known as thefossil record.

The study of fossils acrossgeological time,how they were formed, and theevolutionary

relationships betweentaxa(phylogeny)are some of the most important functions of the scienceofpaleontology.Such a preserved specimen is called a "fossil" if it is older than some minimum

age, most often the arbitrary date of 10,000 years.[2]

Hence, fossils range in age from the

youngest at the start of theHoloceneEpoch to the oldest from theArchaeanEon, up to3.48billionyears old.

[3][4][5]The observation that certain fossils were associated with certain rock

strataled early geologists to recognize a geological timescale in the 19th century. The

development ofradiometric datingtechniques in the early 20th century allowed geologists to

determine the numerical or "absolute" ageof the various strata and thereby the included fossils.

Likeextantorganisms, fossils vary in size frommicroscopic,even single bacterial cells[6]

one

micrometerin diameter, to gigantic, such asdinosaursand trees many meters long and weighingmany tons. A fossil normally preserves only a portion of the deceased organism, usually that

portion that was partiallymineralizedduring life, such as thebonesand teeth ofvertebrates,or

thechitinousorcalcareousexoskeletonsofinvertebrates.Fossils may also consist of the marksleft behind by the organism while it was alive, such asanimal tracksorfeces(coprolites). These

types of fossil are calledtrace fossils(or ichnofossils), as opposed to body fossils. Finally,past

lifeleaves some markers that cannot be seen but can be detected in the form ofbiochemical

Fossilization processes
http://en.wikipedia.org/wiki/Latinhttp://en.wikipedia.org/wiki/Latinhttp://en.wikipedia.org/wiki/Latinhttp://en.wikipedia.org/wiki/Fossil#cite_note-1http://en.wikipedia.org/wiki/Fossil#cite_note-1http://en.wikipedia.org/wiki/Trace_fossilhttp://en.wikipedia.org/wiki/Trace_fossilhttp://en.wikipedia.org/wiki/Trace_fossilhttp://en.wikipedia.org/wiki/Rock_%28geology%29http://en.wikipedia.org/wiki/Rock_%28geology%29http://en.wikipedia.org/wiki/Sedimentary_rockhttp://en.wikipedia.org/wiki/Sedimentary_rockhttp://en.wikipedia.org/wiki/Sedimentary_rockhttp://en.wikipedia.org/wiki/Stratumhttp://en.wikipedia.org/wiki/Stratumhttp://en.wikipedia.org/wiki/Stratumhttp://en.wikipedia.org/wiki/Geologic_time_scalehttp://en.wikipedia.org/wiki/Geologic_time_scalehttp://en.wikipedia.org/wiki/Geologic_time_scalehttp://en.wikipedia.org/wiki/Evolutionhttp://en.wikipedia.org/wiki/Evolutionhttp://en.wikipedia.org/wiki/Evolutionhttp://en.wikipedia.org/wiki/Taxonhttp://en.wikipedia.org/wiki/Taxonhttp://en.wikipedia.org/wiki/Taxonhttp://en.wikipedia.org/wiki/Phylogeneticshttp://en.wikipedia.org/wiki/Phylogeneticshttp://en.wikipedia.org/wiki/Phylogeneticshttp://en.wikipedia.org/wiki/Paleontologyhttp://en.wikipedia.org/wiki/Paleontologyhttp://en.wikipedia.org/wiki/Paleontologyhttp://en.wikipedia.org/wiki/Fossil#cite_note-2http://en.wikipedia.org/wiki/Fossil#cite_note-2http://en.wikipedia.org/wiki/Fossil#cite_note-2http://en.wikipedia.org/wiki/Holocenehttp://en.wikipedia.org/wiki/Holocenehttp://en.wikipedia.org/wiki/Holocenehttp://en.wikipedia.org/wiki/Archeanhttp://en.wikipedia.org/wiki/Archeanhttp://en.wikipedia.org/wiki/Archeanhttp://en.wikipedia.org/wiki/1000000000_%28number%29http://en.wikipedia.org/wiki/1000000000_%28number%29http://en.wikipedia.org/wiki/1000000000_%28number%29http://en.wikipedia.org/wiki/Fossil#cite_note-AP-20131113-3http://en.wikipedia.org/wiki/Fossil#cite_note-AP-20131113-3http://en.wikipedia.org/wiki/Fossil#cite_note-5http://en.wikipedia.org/wiki/Fossil#cite_note-5http://en.wikipedia.org/wiki/Stratumhttp://en.wikipedia.org/wiki/Stratumhttp://en.wikipedia.org/wiki/Radiometric_datinghttp://en.wikipedia.org/wiki/Radiometric_datinghttp://en.wikipedia.org/wiki/Radiometric_datinghttp://en.wikipedia.org/wiki/Extant_taxonhttp://en.wikipedia.org/wiki/Extant_taxonhttp://en.wikipedia.org/wiki/Extant_taxonhttp://en.wikipedia.org/wiki/Microscopehttp://en.wikipedia.org/wiki/Microscopehttp://en.wikipedia.org/wiki/Microscopehttp://en.wikipedia.org/wiki/Fossil#cite_note-6http://en.wikipedia.org/wiki/Fossil#cite_note-6http://en.wikipedia.org/wiki/Fossil#cite_note-6http://en.wikipedia.org/wiki/Micrometrehttp://en.wikipedia.org/wiki/Micrometrehttp://en.wikipedia.org/wiki/Dinosaurhttp://en.wikipedia.org/wiki/Dinosaurhttp://en.wikipedia.org/wiki/Dinosaurhttp://en.wikipedia.org/wiki/Mineralization_%28biology%29http://en.wikipedia.org/wiki/Mineralization_%28biology%29http://en.wikipedia.org/wiki/Mineralization_%28biology%29http://en.wikipedia.org/wiki/Bonehttp://en.wikipedia.org/wiki/Bonehttp://en.wikipedia.org/wiki/Bonehttp://en.wikipedia.org/wiki/Vertebratehttp://en.wikipedia.org/wiki/Vertebratehttp://en.wikipedia.org/wiki/Vertebratehttp://en.wikipedia.org/wiki/Chitinhttp://en.wikipedia.org/wiki/Chitinhttp://en.wikipedia.org/wiki/Chitinhttp://en.wikipedia.org/wiki/Calcareoushttp://en.wikipedia.org/wiki/Calcareoushttp://en.wikipedia.org/wiki/Exoskeletonhttp://en.wikipedia.org/wiki/Exoskeletonhttp://en.wikipedia.org/wiki/Exoskeletonhttp://en.wikipedia.org/wiki/Invertebratehttp://en.wikipedia.org/wiki/Invertebratehttp://en.wikipedia.org/wiki/Invertebratehttp://en.wikipedia.org/wiki/Animal_trackshttp://en.wikipedia.org/wiki/Animal_trackshttp://en.wikipedia.org/wiki/Animal_trackshttp://en.wikipedia.org/wiki/Feceshttp://en.wikipedia.org/wiki/Feceshttp://en.wikipedia.org/wiki/Feceshttp://en.wikipedia.org/wiki/Coprolitehttp://en.wikipedia.org/wiki/Coprolitehttp://en.wikipedia.org/wiki/Coprolitehttp://en.wikipedia.org/wiki/Trace_fossilhttp://en.wikipedia.org/wiki/Trace_fossilhttp://en.wikipedia.org/wiki/Trace_fossilhttp://en.wikipedia.org/wiki/Evolutionary_history_of_lifehttp://en.wikipedia.org/wiki/Evolutionary_history_of_lifehttp://en.wikipedia.org/wiki/Evolutionary_history_of_lifehttp://en.wikipedia.org/wiki/Evolutionary_history_of_lifehttp://en.wikipedia.org/wiki/Biochemistryhttp://en.wikipedia.org/wiki/Biochemistryhttp://en.wikipedia.org/wiki/Biochemistryhttp://en.wikipedia.org/wiki/File:Palais_de_la_Decouverte_Tyrannosaurus_rex_p1050042.jpghttp://en.wikipedia.org/wiki/Biochemistryhttp://en.wikipedia.org/wiki/Evolutionary_history_of_lifehttp://en.wikipedia.org/wiki/Evolutionary_history_of_lifehttp://en.wikipedia.org/wiki/Trace_fossilhttp://en.wikipedia.org/wiki/Coprolitehttp://en.wikipedia.org/wiki/Feceshttp://en.wikipedia.org/wiki/Animal_trackshttp://en.wikipedia.org/wiki/Invertebratehttp://en.wikipedia.org/wiki/Exoskeletonhttp://en.wikipedia.org/wiki/Calcareoushttp://en.wikipedia.org/wiki/Chitinhttp://en.wikipedia.org/wiki/Vertebratehttp://en.wikipedia.org/wiki/Bonehttp://en.wikipedia.org/wiki/Mineralization_%28biology%29http://en.wikipedia.org/wiki/Dinosaurhttp://en.wikipedia.org/wiki/Micrometrehttp://en.wikipedia.org/wiki/Fossil#cite_note-6http://en.wikipedia.org/wiki/Microscopehttp://en.wikipedia.org/wiki/Extant_taxonhttp://en.wikipedia.org/wiki/Radiometric_datinghttp://en.wikipedia.org/wiki/Stratumhttp://en.wikipedia.org/wiki/Fossil#cite_note-5http://en.wikipedia.org/wiki/Fossil#cite_note-AP-20131113-3http://en.wikipedia.org/wiki/Fossil#cite_note-AP-20131113-3http://en.wikipedia.org/wiki/1000000000_%28number%29http://en.wikipedia.org/wiki/Archeanhttp://en.wikipedia.org/wiki/Holocenehttp://en.wikipedia.org/wiki/Fossil#cite_note-2http://en.wikipedia.org/wiki/Paleontologyhttp://en.wikipedia.org/wiki/Phylogeneticshttp://en.wikipedia.org/wiki/Taxonhttp://en.wikipedia.org/wiki/Evolutionhttp://en.wikipedia.org/wiki/Geologic_time_scalehttp://en.wikipedia.org/wiki/Stratumhttp://en.wikipedia.org/wiki/Sedimentary_rockhttp://en.wikipedia.org/wiki/Rock_%28geology%29http://en.wikipedia.org/wiki/Trace_fossilhttp://en.wikipedia.org/wiki/Fossil#cite_note-1http://en.wikipedia.org/wiki/Latin


2/20

External mold of abivalvefrom theLogan Formation,LowerCarboniferous,Ohio

Silicified (replaced with silica) fossils from the Road Canyon Formation (Middle Permian of

Texas).

Recrystallizedscleractiniancoral (aragonite to calcite) from theJurassicof southern Israel
http://en.wikipedia.org/wiki/Bivalviahttp://en.wikipedia.org/wiki/Bivalviahttp://en.wikipedia.org/wiki/Bivalviahttp://en.wikipedia.org/wiki/Logan_Formationhttp://en.wikipedia.org/wiki/Logan_Formationhttp://en.wikipedia.org/wiki/Logan_Formationhttp://en.wikipedia.org/wiki/Carboniferoushttp://en.wikipedia.org/wiki/Carboniferoushttp://en.wikipedia.org/wiki/Carboniferoushttp://en.wikipedia.org/wiki/Scleractiniahttp://en.wikipedia.org/wiki/Scleractiniahttp://en.wikipedia.org/wiki/Scleractiniahttp://en.wikipedia.org/wiki/Jurassichttp://en.wikipedia.org/wiki/Jurassichttp://en.wikipedia.org/wiki/Jurassichttp://en.wikipedia.org/wiki/File:MatmorScleractinian.JPGhttp://en.wikipedia.org/wiki/File:MatmorScleractinian.JPGhttp://en.wikipedia.org/wiki/File:Permian_Silicified_Sclerobionts.JPGhttp://en.wikipedia.org/wiki/File:Permian_Silicified_Sclerobionts.JPGhttp://en.wikipedia.org/wiki/File:Aviculopecten_subcardiformis01.JPGhttp://en.wikipedia.org/wiki/File:Aviculopecten_subcardiformis01.JPGhttp://en.wikipedia.org/wiki/File:MatmorScleractinian.JPGhttp://en.wikipedia.org/wiki/File:MatmorScleractinian.JPGhttp://en.wikipedia.org/wiki/File:Permian_Silicified_Sclerobionts.JPGhttp://en.wikipedia.org/wiki/File:Permian_Silicified_Sclerobionts.JPGhttp://en.wikipedia.org/wiki/File:Aviculopecten_subcardiformis01.JPGhttp://en.wikipedia.org/wiki/File:Aviculopecten_subcardiformis01.JPGhttp://en.wikipedia.org/wiki/File:MatmorScleractinian.JPGhttp://en.wikipedia.org/wiki/File:MatmorScleractinian.JPGhttp://en.wikipedia.org/wiki/File:Permian_Silicified_Sclerobionts.JPGhttp://en.wikipedia.org/wiki/File:Permian_Silicified_Sclerobionts.JPGhttp://en.wikipedia.org/wiki/File:Aviculopecten_subcardiformis01.JPGhttp://en.wikipedia.org/wiki/File:Aviculopecten_subcardiformis01.JPGhttp://en.wikipedia.org/wiki/File:MatmorScleractinian.JPGhttp://en.wikipedia.org/wiki/File:MatmorScleractinian.JPGhttp://en.wikipedia.org/wiki/File:Permian_Silicified_Sclerobionts.JPGhttp://en.wikipedia.org/wiki/File:Permian_Silicified_Sclerobionts.JPGhttp://en.wikipedia.org/wiki/File:Aviculopecten_subcardiformis01.JPGhttp://en.wikipedia.org/wiki/File:Aviculopecten_subcardiformis01.JPGhttp://en.wikipedia.org/wiki/File:MatmorScleractinian.JPGhttp://en.wikipedia.org/wiki/File:MatmorScleractinian.JPGhttp://en.wikipedia.org/wiki/File:Permian_Silicified_Sclerobionts.JPGhttp://en.wikipedia.org/wiki/File:Permian_Silicified_Sclerobionts.JPGhttp://en.wikipedia.org/wiki/File:Aviculopecten_subcardiformis01.JPGhttp://en.wikipedia.org/wiki/File:Aviculopecten_subcardiformis01.JPGhttp://en.wikipedia.org/wiki/File:MatmorScleractinian.JPGhttp://en.wikipedia.org/wiki/File:MatmorScleractinian.JPGhttp://en.wikipedia.org/wiki/File:Permian_Silicified_Sclerobionts.JPGhttp://en.wikipedia.org/wiki/File:Permian_Silicified_Sclerobionts.JPGhttp://en.wikipedia.org/wiki/File:Aviculopecten_subcardiformis01.JPGhttp://en.wikipedia.org/wiki/File:Aviculopecten_subcardiformis01.JPGhttp://en.wikipedia.org/wiki/Jurassichttp://en.wikipedia.org/wiki/Scleractiniahttp://en.wikipedia.org/wiki/Carboniferoushttp://en.wikipedia.org/wiki/Logan_Formationhttp://en.wikipedia.org/wiki/Bivalvia


3/20

The star-shaped holes (Catellocaula vallata) in this Upper Ordovician bryozoan represent a soft-

bodied organism preserved by bioimmuration in the bryozoan skeleton.[7]

This section needs additional citations forverification.Please helpimprove thisarticlebyadding citations to reliable sources.Unsourced material may be challenged

and removed. (August 2012)

The process of fossilization varies according to tissue type and external conditions.

Permineralization

Permineralizationis a process of fossilization that occurs when an organism is buried. The empty

spaces within an organism (spaces filled with liquid or gas during life) become filled withmineral-rich groundwater. Minerals precipitate from the groundwater, occupying the empty

spaces. This process can occur in very small spaces, such as within thecell wallof aplant cell.

Small scale permineralization can produce very detailed fossils. For permineralization to occur,the organism must become covered by sediment soon after death or soon after the initial decay

process. The degree to which the remains are decayed when covered determines the later details

of the fossil. Some fossils consist only of skeletal remains or teeth; other fossils contain traces of

skin,feathersor even soft tissues. This is a form ofdiagenesis.

Casts and molds

In some cases the original remains of the organism completely dissolve or are otherwise

destroyed. The remaining organism-shaped hole in the rock is called an external mold. If this

hole is later filled with other minerals, it is a cast. Anendocastor internal moldis formed when

sediments or minerals fill the internal cavity of an organism, such as the inside of abivalveorsnailor the hollow of askull.

Authigenic mineralisation

This is a special form of cast and mold formation. If the chemistry is right, the organism (or

fragment of organism) can act as a nucleus for the precipitation of minerals such as siderite,resulting in a nodule forming around it. If this happens rapidly before significant decay to the
http://en.wikipedia.org/wiki/Fossil#cite_note-7http://en.wikipedia.org/wiki/Fossil#cite_note-7http://en.wikipedia.org/wiki/Fossil#cite_note-7http://en.wikipedia.org/wiki/Wikipedia:Verifiabilityhttp://en.wikipedia.org/wiki/Wikipedia:Verifiabilityhttp://en.wikipedia.org/wiki/Wikipedia:Verifiabilityhttp://en.wikipedia.org/w/index.php?title=Fossil&action=edithttp://en.wikipedia.org/w/index.php?title=Fossil&action=edithttp://en.wikipedia.org/w/index.php?title=Fossil&action=edithttp://en.wikipedia.org/w/index.php?title=Fossil&action=edithttp://en.wikipedia.org/wiki/Help:Introduction_to_referencing/1http://en.wikipedia.org/wiki/Help:Introduction_to_referencing/1http://en.wikipedia.org/wiki/Help:Introduction_to_referencing/1http://en.wikipedia.org/wiki/Permineralizationhttp://en.wikipedia.org/wiki/Permineralizationhttp://en.wikipedia.org/wiki/Cell_wallhttp://en.wikipedia.org/wiki/Cell_wallhttp://en.wikipedia.org/wiki/Cell_wallhttp://en.wikipedia.org/wiki/Plant_cellhttp://en.wikipedia.org/wiki/Plant_cellhttp://en.wikipedia.org/wiki/Plant_cellhttp://en.wikipedia.org/wiki/Skinhttp://en.wikipedia.org/wiki/Skinhttp://en.wikipedia.org/wiki/Featherhttp://en.wikipedia.org/wiki/Featherhttp://en.wikipedia.org/wiki/Featherhttp://en.wikipedia.org/wiki/Diagenesishttp://en.wikipedia.org/wiki/Diagenesishttp://en.wikipedia.org/wiki/Diagenesishttp://en.wikipedia.org/wiki/Endocasthttp://en.wikipedia.org/wiki/Endocasthttp://en.wikipedia.org/wiki/Endocasthttp://en.wikipedia.org/wiki/Bivalvehttp://en.wikipedia.org/wiki/Bivalvehttp://en.wikipedia.org/wiki/Bivalvehttp://en.wikipedia.org/wiki/Snailhttp://en.wikipedia.org/wiki/Snailhttp://en.wikipedia.org/wiki/Skullhttp://en.wikipedia.org/wiki/Skullhttp://en.wikipedia.org/wiki/Skullhttp://en.wikipedia.org/wiki/File:Question_book-new.svghttp://en.wikipedia.org/wiki/File:Catellocaula.jpghttp://en.wikipedia.org/wiki/File:Catellocaula.jpghttp://en.wikipedia.org/wiki/File:Question_book-new.svghttp://en.wikipedia.org/wiki/File:Catellocaula.jpghttp://en.wikipedia.org/wiki/File:Catellocaula.jpghttp://en.wikipedia.org/wiki/File:Question_book-new.svghttp://en.wikipedia.org/wiki/File:Catellocaula.jpghttp://en.wikipedia.org/wiki/File:Catellocaula.jpghttp://en.wikipedia.org/wiki/Skullhttp://en.wikipedia.org/wiki/Snailhttp://en.wikipedia.org/wiki/Bivalvehttp://en.wikipedia.org/wiki/Endocasthttp://en.wikipedia.org/wiki/Diagenesishttp://en.wikipedia.org/wiki/Featherhttp://en.wikipedia.org/wiki/Skinhttp://en.wikipedia.org/wiki/Plant_cellhttp://en.wikipedia.org/wiki/Cell_wallhttp://en.wikipedia.org/wiki/Permineralizationhttp://en.wikipedia.org/wiki/Help:Introduction_to_referencing/1http://en.wikipedia.org/w/index.php?title=Fossil&action=edithttp://en.wikipedia.org/w/index.php?title=Fossil&action=edithttp://en.wikipedia.org/wiki/Wikipedia:Verifiabilityhttp://en.wikipedia.org/wiki/Fossil#cite_note-7


4/20

organic tissue, very fine three-dimensional morphological detail can be preserved. Nodules from

the CarboniferousMazon Creek fossil bedsof Illinois, USA, are among the best documented

examples of such mineralisation.

Replacement and recrystallization

Replacement occurs when the shell, bone or other tissue is replaced with another mineral. In

some cases mineral replacement of the original shell occurs so gradually and at such fine scales

that microstructural features are preserved despite the total loss of original material. A shell is

said to be recrystallizedwhen the original skeletal compounds are still present but in a differentcrystal form, as fromaragonitetocalcite.

Adpression (compression-impression)

Compression fossils,such as those of fossil ferns, are the result of chemical reduction of the

complex organic molecules composing the organism's tissues. In this case the fossil consists of

original material, albeit in a geochemically altered state. This chemical change is an expressionofdiagenesis.Often what remains is acarbonaceous filmknown as a phytoleim, in which case

the fossil is known as a compression. Often, however, the phytoleim is lost and all that remains is

an impression of the organism in the rockan impression fossil. In many cases, however,compressions and impressions occur together. For instance, when the rock is broken open, the

phytoleim will often be attached to one part (compression), whereas the counterpart will just be

an impression. For this reason, one term covers the two modes of preservation: adpression.[8]

Carbon films

Carbonaceous filmsare thin coatings which consist predominantly of the chemical element

carbon.Thesoft tissuesof organisms are made largely oforganic carboncompounds and duringdiagenesis under reducing conditions only a thin film of carbon residue is left which forms a

silhouette of the original organism.

Bioimmuration

Bioimmuration occurs when a skeletal organism overgrows or otherwise subsumes anotherorganism, preserving the latter, or an impression of it, within the skeleton.

[9]Usually it is a

sessileskeletal organism, such as abryozoanor anoyster,which grows along asubstrate,

covering other sessilesclerobionts.Sometimes the bioimmured organism is soft-bodied and is

then preserved in negative relief as a kind of external mold. There are also cases where an

organism settles on top of a living skeletal organism and grows upwards, preserving the settler inits skeleton. Bioimmuration is known in the fossil record from theOrdovician

[10]to the Recent.

[9]

Fossil record

Estimating dates
http://en.wikipedia.org/wiki/Mazon_Creek_fossil_bedshttp://en.wikipedia.org/wiki/Mazon_Creek_fossil_bedshttp://en.wikipedia.org/wiki/Mazon_Creek_fossil_bedshttp://en.wikipedia.org/wiki/Aragonitehttp://en.wikipedia.org/wiki/Aragonitehttp://en.wikipedia.org/wiki/Aragonitehttp://en.wikipedia.org/wiki/Calcitehttp://en.wikipedia.org/wiki/Calcitehttp://en.wikipedia.org/wiki/Calcitehttp://en.wikipedia.org/wiki/Compression_fossilhttp://en.wikipedia.org/wiki/Compression_fossilhttp://en.wikipedia.org/wiki/Diagenesishttp://en.wikipedia.org/wiki/Diagenesishttp://en.wikipedia.org/wiki/Diagenesishttp://en.wikipedia.org/wiki/Carbonaceous_filmhttp://en.wikipedia.org/wiki/Carbonaceous_filmhttp://en.wikipedia.org/wiki/Carbonaceous_filmhttp://en.wikipedia.org/wiki/Fossil#cite_note-ShuteCleal_1986-8http://en.wikipedia.org/wiki/Fossil#cite_note-ShuteCleal_1986-8http://en.wikipedia.org/wiki/Fossil#cite_note-ShuteCleal_1986-8http://en.wikipedia.org/wiki/Carbonaceous_filmhttp://en.wikipedia.org/wiki/Carbonaceous_filmhttp://en.wikipedia.org/wiki/Carbonhttp://en.wikipedia.org/wiki/Carbonhttp://en.wikipedia.org/wiki/Soft_tissuehttp://en.wikipedia.org/wiki/Soft_tissuehttp://en.wikipedia.org/wiki/Soft_tissuehttp://en.wikipedia.org/wiki/Organic_carbonhttp://en.wikipedia.org/wiki/Organic_carbonhttp://en.wikipedia.org/wiki/Organic_carbonhttp://en.wikipedia.org/wiki/Fossil#cite_note-Taylor.2C_PD._1990-9http://en.wikipedia.org/wiki/Fossil#cite_note-Taylor.2C_PD._1990-9http://en.wikipedia.org/wiki/Fossil#cite_note-Taylor.2C_PD._1990-9http://en.wikipedia.org/wiki/Sessility_%28zoology%29http://en.wikipedia.org/wiki/Sessility_%28zoology%29http://en.wikipedia.org/wiki/Bryozoanhttp://en.wikipedia.org/wiki/Bryozoanhttp://en.wikipedia.org/wiki/Bryozoanhttp://en.wikipedia.org/wiki/Oysterhttp://en.wikipedia.org/wiki/Oysterhttp://en.wikipedia.org/wiki/Oysterhttp://en.wikipedia.org/wiki/Substrate_%28biology%29http://en.wikipedia.org/wiki/Substrate_%28biology%29http://en.wikipedia.org/wiki/Substrate_%28biology%29http://en.wikipedia.org/wiki/Sclerobionthttp://en.wikipedia.org/wiki/Sclerobionthttp://en.wikipedia.org/wiki/Sclerobionthttp://en.wikipedia.org/wiki/Ordovicianhttp://en.wikipedia.org/wiki/Ordovicianhttp://en.wikipedia.org/wiki/Ordovicianhttp://en.wikipedia.org/wiki/Ordovicianhttp://en.wikipedia.org/wiki/Fossil#cite_note-Taylor.2C_PD._1990-9http://en.wikipedia.org/wiki/Fossil#cite_note-Taylor.2C_PD._1990-9http://en.wikipedia.org/wiki/Fossil#cite_note-Taylor.2C_PD._1990-9http://en.wikipedia.org/wiki/Fossil#cite_note-Taylor.2C_PD._1990-9http://en.wikipedia.org/wiki/Ordovicianhttp://en.wikipedia.org/wiki/Ordovicianhttp://en.wikipedia.org/wiki/Sclerobionthttp://en.wikipedia.org/wiki/Substrate_%28biology%29http://en.wikipedia.org/wiki/Oysterhttp://en.wikipedia.org/wiki/Bryozoanhttp://en.wikipedia.org/wiki/Sessility_%28zoology%29http://en.wikipedia.org/wiki/Fossil#cite_note-Taylor.2C_PD._1990-9http://en.wikipedia.org/wiki/Organic_carbonhttp://en.wikipedia.org/wiki/Soft_tissuehttp://en.wikipedia.org/wiki/Carbonhttp://en.wikipedia.org/wiki/Carbonaceous_filmhttp://en.wikipedia.org/wiki/Fossil#cite_note-ShuteCleal_1986-8http://en.wikipedia.org/wiki/Carbonaceous_filmhttp://en.wikipedia.org/wiki/Diagenesishttp://en.wikipedia.org/wiki/Compression_fossilhttp://en.wikipedia.org/wiki/Calcitehttp://en.wikipedia.org/wiki/Aragonitehttp://en.wikipedia.org/wiki/Mazon_Creek_fossil_beds


5/20

Commonindex fossilsused to date rocks in North-East USA

Paleontology seeks to map out how life evolved across geologic time. A substantial hurdle is thedifficulty of working out fossil ages. Beds that preserve fossils typically lack the radioactive

elements needed forradiometric dating.This technique is our only means of giving rocks greater

than about 50 million years old an absolute age, and can be accurate to within 0.5% or better.[11]

Although radiometric dating requires careful laboratory work, its basic principle is simple: the

rates at which various radioactive elementsdecayare known, and so the ratio of the radioactive

element to its decay products shows how long ago the radioactive element was incorporated into

the rock. Radioactive elements are common only in rocks with a volcanic origin, and so the onlyfossil-bearing rocks that can be dated radiometrically are volcanic ash layers.[11]

Stratigraphy

Consequently, palaeontologists rely onstratigraphyto date fossils. Stratigraphy is the science ofdeciphering the "layer-cake" that is thesedimentaryrecord.

[12]Rocks normally form relatively

horizontal layers, with each layer younger than the one underneath it. If a fossil is found between
http://en.wikipedia.org/wiki/Index_fossilhttp://en.wikipedia.org/wiki/Index_fossilhttp://en.wikipedia.org/wiki/Index_fossilhttp://en.wikipedia.org/wiki/Radiometric_datinghttp://en.wikipedia.org/wiki/Radiometric_datinghttp://en.wikipedia.org/wiki/Radiometric_datinghttp://en.wikipedia.org/wiki/Fossil#cite_note-Martin2000-11http://en.wikipedia.org/wiki/Fossil#cite_note-Martin2000-11http://en.wikipedia.org/wiki/Fossil#cite_note-Martin2000-11http://en.wikipedia.org/wiki/Radioactive_decayhttp://en.wikipedia.org/wiki/Radioactive_decayhttp://en.wikipedia.org/wiki/Radioactive_decayhttp://en.wikipedia.org/wiki/Fossil#cite_note-Martin2000-11http://en.wikipedia.org/wiki/Fossil#cite_note-Martin2000-11http://en.wikipedia.org/wiki/Fossil#cite_note-Martin2000-11http://en.wikipedia.org/wiki/Stratigraphyhttp://en.wikipedia.org/wiki/Stratigraphyhttp://en.wikipedia.org/wiki/Stratigraphyhttp://en.wikipedia.org/wiki/Sedimenthttp://en.wikipedia.org/wiki/Sedimenthttp://en.wikipedia.org/wiki/Sedimenthttp://en.wikipedia.org/wiki/Fossil#cite_note-12http://en.wikipedia.org/wiki/Fossil#cite_note-12http://en.wikipedia.org/wiki/Fossil#cite_note-12http://en.wikipedia.org/wiki/File:Index_fossils_blank_01.pnghttp://en.wikipedia.org/wiki/File:Index_fossils_blank_01.pnghttp://en.wikipedia.org/wiki/File:Index_fossils_blank_01.pnghttp://en.wikipedia.org/wiki/File:Index_fossils_blank_01.pnghttp://en.wikipedia.org/wiki/Fossil#cite_note-12http://en.wikipedia.org/wiki/Sedimenthttp://en.wikipedia.org/wiki/Stratigraphyhttp://en.wikipedia.org/wiki/Fossil#cite_note-Martin2000-11http://en.wikipedia.org/wiki/Radioactive_decayhttp://en.wikipedia.org/wiki/Fossil#cite_note-Martin2000-11http://en.wikipedia.org/wiki/Radiometric_datinghttp://en.wikipedia.org/wiki/Index_fossil


6/20

two layers whose ages are known, the fossil's age is claimed to lie between the two known

ages.[13]

Because rock sequences are not continuous, but may be broken up byfaultsor periods of

erosion,it is very difficult to match up rock beds that are not directly adjacent. However, fossilsof species that survived for a relatively short time can be used to match isolated rocks: this

technique is called biostratigraphy. For instance, the conodontEoplacognathus pseudoplanus

has a short range in the Middle Ordovician period.

[14]

If rocks of unknown age have traces of E.pseudoplanus, they have a mid-Ordovician age. Suchindex fossilsmust be distinctive, beglobally distributed and occupy a short time range to be useful. Misleading results are produced

if the index fossils are incorrectly dated.[15]

Stratigraphy and biostratigraphy can in general

provide only relative dating (Awas beforeB), which is often sufficient for studying evolution.However, this is difficult for some time periods, because of the problems involved in matching

rocks of the same age acrosscontinents.[16]

Family-tree relationships also help to narrow down

the date when lineages first appeared. For instance, if fossils of B or C date to X million years

ago and the calculated "family tree" says A was an ancestor of B and C, then A must haveevolved earlier.

It is also possible to estimate how long ago two living clades divergedi.e. approximately howlong ago their last common ancestor must have lived by assuming that DNAmutations

accumulate at a constant rate. These "molecular clocks", however, are fallible, and provide onlyapproximate timing: for example, they are not sufficiently precise and reliable for estimatingwhen the groups that feature in theCambrian explosionfirst evolved,

[17]and estimates produced

by different techniques may vary by a factor of two.[18]

Limitations

Further information:Biostratigraphy

Some of the most remarkable gaps in the fossil record (as of October 2013) show slanting toward

organisms with hard parts

Organisms are only rarely preserved as fossils in the best of circumstances, and only a fraction ofsuch fossils have been discovered. This is illustrated by the fact that the number of species

known through the fossil record is less than 5% of the number of known living species,

suggesting that the number of species known through fossils must be far less than 1% of all thespecies that have ever lived.

[19]Because of the specialized and rare circumstances required for a

biological structure to fossilize, only a small percentage of life-forms can be expected to be

represented in discoveries, and each discovery represents only a snapshot of the process of
http://en.wikipedia.org/wiki/Fossil#cite_note-13http://en.wikipedia.org/wiki/Fossil#cite_note-13http://en.wikipedia.org/wiki/Fossil#cite_note-13http://en.wikipedia.org/wiki/Fault_%28geology%29http://en.wikipedia.org/wiki/Fault_%28geology%29http://en.wikipedia.org/wiki/Fault_%28geology%29http://en.wikipedia.org/wiki/Erosionhttp://en.wikipedia.org/wiki/Erosionhttp://en.wikipedia.org/wiki/Fossil#cite_note-14http://en.wikipedia.org/wiki/Fossil#cite_note-14http://en.wikipedia.org/wiki/Fossil#cite_note-14http://en.wikipedia.org/wiki/Index_fossilhttp://en.wikipedia.org/wiki/Index_fossilhttp://en.wikipedia.org/wiki/Index_fossilhttp://en.wikipedia.org/wiki/Fossil#cite_note-15http://en.wikipedia.org/wiki/Fossil#cite_note-15http://en.wikipedia.org/wiki/Fossil#cite_note-15http://en.wikipedia.org/wiki/Continenthttp://en.wikipedia.org/wiki/Continenthttp://en.wikipedia.org/wiki/Fossil#cite_note-Gehling2001-16http://en.wikipedia.org/wiki/Fossil#cite_note-Gehling2001-16http://en.wikipedia.org/wiki/Fossil#cite_note-Gehling2001-16http://en.wikipedia.org/wiki/Mutationhttp://en.wikipedia.org/wiki/Mutationhttp://en.wikipedia.org/wiki/Mutationhttp://en.wikipedia.org/wiki/Molecular_clockhttp://en.wikipedia.org/wiki/Molecular_clockhttp://en.wikipedia.org/wiki/Molecular_clockhttp://en.wikipedia.org/wiki/Cambrian_explosionhttp://en.wikipedia.org/wiki/Cambrian_explosionhttp://en.wikipedia.org/wiki/Cambrian_explosionhttp://en.wikipedia.org/wiki/Fossil#cite_note-17http://en.wikipedia.org/wiki/Fossil#cite_note-17http://en.wikipedia.org/wiki/Fossil#cite_note-17http://en.wikipedia.org/wiki/Fossil#cite_note-PetersonEtAl2005-18http://en.wikipedia.org/wiki/Fossil#cite_note-PetersonEtAl2005-18http://en.wikipedia.org/wiki/Fossil#cite_note-PetersonEtAl2005-18http://en.wikipedia.org/wiki/Biostratigraphyhttp://en.wikipedia.org/wiki/Biostratigraphyhttp://en.wikipedia.org/wiki/Biostratigraphyhttp://en.wikipedia.org/wiki/Fossil#cite_note-Prothero2007pp5053-19http://en.wikipedia.org/wiki/Fossil#cite_note-Prothero2007pp5053-19http://en.wikipedia.org/wiki/Fossil#cite_note-Prothero2007pp5053-19http://en.wikipedia.org/wiki/File:Fossil_record_gaps_20131028.pdfhttp://en.wikipedia.org/wiki/File:Fossil_record_gaps_20131028.pdfhttp://en.wikipedia.org/wiki/File:Fossil_record_gaps_20131028.pdfhttp://en.wikipedia.org/wiki/File:Fossil_record_gaps_20131028.pdfhttp://en.wikipedia.org/wiki/Fossil#cite_note-Prothero2007pp5053-19http://en.wikipedia.org/wiki/Biostratigraphyhttp://en.wikipedia.org/wiki/Fossil#cite_note-PetersonEtAl2005-18http://en.wikipedia.org/wiki/Fossil#cite_note-17http://en.wikipedia.org/wiki/Cambrian_explosionhttp://en.wikipedia.org/wiki/Molecular_clockhttp://en.wikipedia.org/wiki/Mutationhttp://en.wikipedia.org/wiki/Fossil#cite_note-Gehling2001-16http://en.wikipedia.org/wiki/Continenthttp://en.wikipedia.org/wiki/Fossil#cite_note-15http://en.wikipedia.org/wiki/Index_fossilhttp://en.wikipedia.org/wiki/Fossil#cite_note-14http://en.wikipedia.org/wiki/Erosionhttp://en.wikipedia.org/wiki/Fault_%28geology%29http://en.wikipedia.org/wiki/Fossil#cite_note-13


7/20

evolution. The transition itself can only be illustrated and corroborated by transitional fossils,

which will never demonstrate an exact half-way point.[20]

The fossil record is heavily slanted toward organisms with hard parts, leaving most groups of

soft-bodied organismswith little to no role.[19]

It is replete with themollusks,thevertebrates,the

echinoderms,thebrachiopodsand some groups ofarthropods.

[21]

Lagerstatten

Main article:Lagerstatten

Further information:List of fossil sites

Fossil sites with exceptional preservationsometimes including preserved soft tissuesare

known asLagersttten.These formations may have resulted from carcass burial in ananoxic

environment with minimal bacteria, thus slowing decomposition. Lagersttten spangeological

time from theCambrianperiod to thepresent.Worldwide, some of the best examples of near-

perfect fossilization are theCambrianMaotianshan shalesandBurgess Shale,theDevonianHunsrck Slates,theJurassicSolnhofen limestone,and theCarboniferousMazon Creek

localities.

Stromatolites

Main article:Stromatolites

Lower ProterozoicStromatolitesfromBolivia,South America

Stromatolites are layeredaccretionarystructuresformed in shallow water by the trapping,binding and cementation of sedimentary grains bybiofilmsofmicroorganisms,especially

cyanobacteria.[22]

Stromatolites provide some of the most ancient fossil records of life on Earth,dating back more than 3.5 billion years ago.

[23]
http://en.wikipedia.org/wiki/Fossil#cite_note-CC200-20http://en.wikipedia.org/wiki/Fossil#cite_note-CC200-20http://en.wikipedia.org/wiki/Fossil#cite_note-CC200-20http://en.wikipedia.org/wiki/Soft-bodied_organismshttp://en.wikipedia.org/wiki/Soft-bodied_organismshttp://en.wikipedia.org/wiki/Fossil#cite_note-Prothero2007pp5053-19http://en.wikipedia.org/wiki/Fossil#cite_note-Prothero2007pp5053-19http://en.wikipedia.org/wiki/Fossil#cite_note-Prothero2007pp5053-19http://en.wikipedia.org/wiki/Molluskshttp://en.wikipedia.org/wiki/Molluskshttp://en.wikipedia.org/wiki/Molluskshttp://en.wikipedia.org/wiki/Vertebratehttp://en.wikipedia.org/wiki/Vertebratehttp://en.wikipedia.org/wiki/Vertebratehttp://en.wikipedia.org/wiki/Echinodermhttp://en.wikipedia.org/wiki/Echinodermhttp://en.wikipedia.org/wiki/Brachiopodhttp://en.wikipedia.org/wiki/Brachiopodhttp://en.wikipedia.org/wiki/Brachiopodhttp://en.wikipedia.org/wiki/Arthropodhttp://en.wikipedia.org/wiki/Arthropodhttp://en.wikipedia.org/wiki/Fossil#cite_note-21http://en.wikipedia.org/wiki/Fossil#cite_note-21http://en.wikipedia.org/wiki/Fossil#cite_note-21http://en.wikipedia.org/wiki/Lagerstattenhttp://en.wikipedia.org/wiki/Lagerstattenhttp://en.wikipedia.org/wiki/Lagerstattenhttp://en.wikipedia.org/wiki/List_of_fossil_siteshttp://en.wikipedia.org/wiki/List_of_fossil_siteshttp://en.wikipedia.org/wiki/List_of_fossil_siteshttp://en.wikipedia.org/wiki/Lagerst%C3%A4ttehttp://en.wikipedia.org/wiki/Lagerst%C3%A4ttehttp://en.wikipedia.org/wiki/Lagerst%C3%A4ttehttp://en.wikipedia.org/wiki/Hypoxia_%28environmental%29http://en.wikipedia.org/wiki/Hypoxia_%28environmental%29http://en.wikipedia.org/wiki/Hypoxia_%28environmental%29http://en.wikipedia.org/wiki/Geologyhttp://en.wikipedia.org/wiki/Geologyhttp://en.wikipedia.org/wiki/Geologyhttp://en.wikipedia.org/wiki/Cambrianhttp://en.wikipedia.org/wiki/Cambrianhttp://en.wikipedia.org/wiki/Cambrianhttp://en.wikipedia.org/wiki/Holocenehttp://en.wikipedia.org/wiki/Holocenehttp://en.wikipedia.org/wiki/Holocenehttp://en.wikipedia.org/wiki/Cambrianhttp://en.wikipedia.org/wiki/Cambrianhttp://en.wikipedia.org/wiki/Maotianshan_shaleshttp://en.wikipedia.org/wiki/Maotianshan_shaleshttp://en.wikipedia.org/wiki/Maotianshan_shaleshttp://en.wikipedia.org/wiki/Burgess_Shalehttp://en.wikipedia.org/wiki/Burgess_Shalehttp://en.wikipedia.org/wiki/Burgess_Shalehttp://en.wikipedia.org/wiki/Devonianhttp://en.wikipedia.org/wiki/Devonianhttp://en.wikipedia.org/wiki/Devonianhttp://en.wikipedia.org/wiki/Hunsr%C3%BCck_Slateshttp://en.wikipedia.org/wiki/Hunsr%C3%BCck_Slateshttp://en.wikipedia.org/wiki/Jurassichttp://en.wikipedia.org/wiki/Jurassichttp://en.wikipedia.org/wiki/Solnhofen_limestonehttp://en.wikipedia.org/wiki/Solnhofen_limestonehttp://en.wikipedia.org/wiki/Solnhofen_limestonehttp://en.wikipedia.org/wiki/Carboniferoushttp://en.wikipedia.org/wiki/Carboniferoushttp://en.wikipedia.org/wiki/Mazon_Creekhttp://en.wikipedia.org/wiki/Mazon_Creekhttp://en.wikipedia.org/wiki/Mazon_Creekhttp://en.wikipedia.org/wiki/Stromatoliteshttp://en.wikipedia.org/wiki/Stromatoliteshttp://en.wikipedia.org/wiki/Stromatoliteshttp://en.wikipedia.org/wiki/Stromatolitehttp://en.wikipedia.org/wiki/Stromatolitehttp://en.wikipedia.org/wiki/Stromatolitehttp://en.wikipedia.org/wiki/Boliviahttp://en.wikipedia.org/wiki/Boliviahttp://en.wikipedia.org/wiki/Boliviahttp://en.wikipedia.org/wiki/Accretion_%28geology%29http://en.wikipedia.org/wiki/Accretion_%28geology%29http://en.wikipedia.org/wiki/Structurehttp://en.wikipedia.org/wiki/Structurehttp://en.wikipedia.org/wiki/Structurehttp://en.wikipedia.org/wiki/Biofilmhttp://en.wikipedia.org/wiki/Biofilmhttp://en.wikipedia.org/wiki/Biofilmhttp://en.wikipedia.org/wiki/Microorganismhttp://en.wikipedia.org/wiki/Microorganismhttp://en.wikipedia.org/wiki/Microorganismhttp://en.wikipedia.org/wiki/Cyanobacteriahttp://en.wikipedia.org/wiki/Fossil#cite_note-22http://en.wikipedia.org/wiki/Fossil#cite_note-22http://en.wikipedia.org/wiki/Fossil#cite_note-22http://en.wikipedia.org/wiki/Fossil#cite_note-23http://en.wikipedia.org/wiki/Fossil#cite_note-23http://en.wikipedia.org/wiki/Fossil#cite_note-23http://en.wikipedia.org/wiki/File:Stromatolites_Cochabamba.jpghttp://en.wikipedia.org/wiki/File:Stromatolites_Cochabamba.jpghttp://en.wikipedia.org/wiki/File:Stromatolites_Cochabamba.jpghttp://en.wikipedia.org/wiki/File:Stromatolites_Cochabamba.jpghttp://en.wikipedia.org/wiki/Fossil#cite_note-23http://en.wikipedia.org/wiki/Fossil#cite_note-22http://en.wikipedia.org/wiki/Cyanobacteriahttp://en.wikipedia.org/wiki/Microorganismhttp://en.wikipedia.org/wiki/Biofilmhttp://en.wikipedia.org/wiki/Structurehttp://en.wikipedia.org/wiki/Accretion_%28geology%29http://en.wikipedia.org/wiki/Boliviahttp://en.wikipedia.org/wiki/Stromatolitehttp://en.wikipedia.org/wiki/Stromatoliteshttp://en.wikipedia.org/wiki/Mazon_Creekhttp://en.wikipedia.org/wiki/Carboniferoushttp://en.wikipedia.org/wiki/Solnhofen_limestonehttp://en.wikipedia.org/wiki/Jurassichttp://en.wikipedia.org/wiki/Hunsr%C3%BCck_Slateshttp://en.wikipedia.org/wiki/Devonianhttp://en.wikipedia.org/wiki/Burgess_Shalehttp://en.wikipedia.org/wiki/Maotianshan_shaleshttp://en.wikipedia.org/wiki/Cambrianhttp://en.wikipedia.org/wiki/Holocenehttp://en.wikipedia.org/wiki/Cambrianhttp://en.wikipedia.org/wiki/Geologyhttp://en.wikipedia.org/wiki/Hypoxia_%28environmental%29http://en.wikipedia.org/wiki/Lagerst%C3%A4ttehttp://en.wikipedia.org/wiki/List_of_fossil_siteshttp://en.wikipedia.org/wiki/Lagerstattenhttp://en.wikipedia.org/wiki/Fossil#cite_note-21http://en.wikipedia.org/wiki/Arthropodhttp://en.wikipedia.org/wiki/Brachiopodhttp://en.wikipedia.org/wiki/Echinodermhttp://en.wikipedia.org/wiki/Vertebratehttp://en.wikipedia.org/wiki/Molluskshttp://en.wikipedia.org/wiki/Fossil#cite_note-Prothero2007pp5053-19http://en.wikipedia.org/wiki/Soft-bodied_organismshttp://en.wikipedia.org/wiki/Fossil#cite_note-CC200-20


8/20

Stromatolites were much more abundant in Precambrian times. While older,Archeanfossil

remains are presumed to becoloniesofcyanobacteria,younger (that is,Proterozoic)fossils may

beprimordialforms of theeukaryotechlorophytes(that is,green algae). Onegenusofstromatolite very common in thegeologic recordisCollenia.The earliest stromatolite of

confirmed microbial origin dates to 2.724 billion years ago.[24]

A 2009 discovery provides strong evidence of microbial stromatolites extending as far back as

3.45 billion years ago.[25]

Stromatolites are a major constituent of the fossil record for life's first 3.5 billion years, peaking

about 1.25 billion years ago.[25]

They subsequently declined in abundance and diversity,[26]

which

by the start of the Cambrian had fallen to 20% of their peak. The most widely supportedexplanation is that stromatolite builders fell victims to grazing creatures (theCambrian substrate

revolution), implying that sufficiently complex organisms were common over 1 billion years

ago.[27][28][29]

The connection between grazer and stromatolite abundance is well documented in the youngerOrdovicianevolutionary radiation;stromatolite abundance also increased after theend-

Ordovicianandend-Permianextinctions decimated marine animals, falling back to earlier levelsas marine animals recovered.

[30]Fluctuations in metazoan population and diversity may not have

been the only factor in the reduction in stromatolite abundance. Factors such as the chemistry of

the environment may have been responsible for changes.[31]

Whileprokaryoticcyanobacteria themselves reproduce asexually through cell division, they

were instrumental in priming the environment for theevolutionary developmentof morecomplexeukaryoticorganisms. Cyanobacteria (as well asextremophileGammaproteobacteria)

are thought to be largely responsible for increasing the amount ofoxygenin the primeval earth's

atmospherethrough their continuingphotosynthesis.Cyanobacteria usewater,carbon dioxideandsunlightto create their food. A layer ofmucusoften forms over mats of cyanobacterial cells.In modern microbial mats, debris from the surrounding habitat can become trapped within the

mucus, which can be cemented by the calcium carbonate to grow thin laminations oflimestone.

These laminations can accrete over time, resulting in the banded pattern common tostromatolites. The domal morphology of biological stromatolites is the result of the vertical

growth necessary for the continued infiltration of sunlight to the organisms for photosynthesis.

Layered spherical growth structures termedoncolitesare similar to stromatolites and are alsoknown from thefossil record.Thrombolitesare poorly laminated or non-laminated clotted

structures formed by cyanobacteria common in the fossil record and in modern sediments.[24]

The Zebra River Canyon area of the Kubis platform in the deeply dissected Zaris Mountains of

south westernNamibiaprovides an extremely well exposed example of the thrombolite-

stromatolite-metazoan reefs that developed during the Proterozoic period, the stromatolites here

being better developed in updip locations under conditions of higher current velocities andgreater sediment influx.

[32]

Types
http://en.wikipedia.org/wiki/Archeanhttp://en.wikipedia.org/wiki/Archeanhttp://en.wikipedia.org/wiki/Archeanhttp://en.wikipedia.org/wiki/Colony_%28biology%29http://en.wikipedia.org/wiki/Colony_%28biology%29http://en.wikipedia.org/wiki/Colony_%28biology%29http://en.wikipedia.org/wiki/Cyanobacteriahttp://en.wikipedia.org/wiki/Cyanobacteriahttp://en.wikipedia.org/wiki/Cyanobacteriahttp://en.wikipedia.org/wiki/Proterozoichttp://en.wikipedia.org/wiki/Proterozoichttp://en.wikipedia.org/wiki/Proterozoichttp://en.wikipedia.org/wiki/Prehistorichttp://en.wikipedia.org/wiki/Prehistorichttp://en.wikipedia.org/wiki/Prehistorichttp://en.wikipedia.org/wiki/Eukaryotahttp://en.wikipedia.org/wiki/Eukaryotahttp://en.wikipedia.org/wiki/Chlorophytahttp://en.wikipedia.org/wiki/Chlorophytahttp://en.wikipedia.org/wiki/Chlorophytahttp://en.wikipedia.org/wiki/Green_algaehttp://en.wikipedia.org/wiki/Green_algaehttp://en.wikipedia.org/wiki/Green_algaehttp://en.wikipedia.org/wiki/Genushttp://en.wikipedia.org/wiki/Genushttp://en.wikipedia.org/wiki/Genushttp://en.wikipedia.org/wiki/Geologic_time_scalehttp://en.wikipedia.org/wiki/Geologic_time_scalehttp://en.wikipedia.org/wiki/Geologic_time_scalehttp://en.wikipedia.org/wiki/Colleniahttp://en.wikipedia.org/wiki/Colleniahttp://en.wikipedia.org/wiki/Colleniahttp://en.wikipedia.org/wiki/Fossil#cite_note-Lepot2008-24http://en.wikipedia.org/wiki/Fossil#cite_note-Lepot2008-24http://en.wikipedia.org/wiki/Fossil#cite_note-Lepot2008-24http://en.wikipedia.org/wiki/Fossil#cite_note-Allwood2009-25http://en.wikipedia.org/wiki/Fossil#cite_note-Allwood2009-25http://en.wikipedia.org/wiki/Fossil#cite_note-Allwood2009-25http://en.wikipedia.org/wiki/Fossil#cite_note-Allwood2009-25http://en.wikipedia.org/wiki/Fossil#cite_note-Allwood2009-25http://en.wikipedia.org/wiki/Fossil#cite_note-Allwood2009-25http://en.wikipedia.org/wiki/Fossil#cite_note-26http://en.wikipedia.org/wiki/Fossil#cite_note-26http://en.wikipedia.org/wiki/Fossil#cite_note-26http://en.wikipedia.org/wiki/Cambrian_substrate_revolutionhttp://en.wikipedia.org/wiki/Cambrian_substrate_revolutionhttp://en.wikipedia.org/wiki/Cambrian_substrate_revolutionhttp://en.wikipedia.org/wiki/Cambrian_substrate_revolutionhttp://en.wikipedia.org/wiki/Fossil#cite_note-McNamara1996DatingOriginAnimals-27http://en.wikipedia.org/wiki/Fossil#cite_note-McNamara1996DatingOriginAnimals-27http://en.wikipedia.org/wiki/Fossil#cite_note-Bengtson2002OriginsOfPredation-29http://en.wikipedia.org/wiki/Fossil#cite_note-Bengtson2002OriginsOfPredation-29http://en.wikipedia.org/wiki/Ordovicianhttp://en.wikipedia.org/wiki/Evolutionary_radiationhttp://en.wikipedia.org/wiki/Evolutionary_radiationhttp://en.wikipedia.org/wiki/Evolutionary_radiationhttp://en.wikipedia.org/wiki/Ordovician-Silurian_extinction_eventshttp://en.wikipedia.org/wiki/Ordovician-Silurian_extinction_eventshttp://en.wikipedia.org/wiki/Ordovician-Silurian_extinction_eventshttp://en.wikipedia.org/wiki/Ordovician-Silurian_extinction_eventshttp://en.wikipedia.org/wiki/Permian_extinctionhttp://en.wikipedia.org/wiki/Permian_extinctionhttp://en.wikipedia.org/wiki/Permian_extinctionhttp://en.wikipedia.org/wiki/Fossil#cite_note-SheehanHarris2004ResurgenceAfterOrdovicianExtinction-30http://en.wikipedia.org/wiki/Fossil#cite_note-SheehanHarris2004ResurgenceAfterOrdovicianExtinction-30http://en.wikipedia.org/wiki/Fossil#cite_note-SheehanHarris2004ResurgenceAfterOrdovicianExtinction-30http://en.wikipedia.org/wiki/Fossil#cite_note-Riding2006-31http://en.wikipedia.org/wiki/Fossil#cite_note-Riding2006-31http://en.wikipedia.org/wiki/Fossil#cite_note-Riding2006-31http://en.wikipedia.org/wiki/Prokaryotehttp://en.wikipedia.org/wiki/Prokaryotehttp://en.wikipedia.org/wiki/Prokaryotehttp://en.wikipedia.org/wiki/Timeline_of_evolutionhttp://en.wikipedia.org/wiki/Timeline_of_evolutionhttp://en.wikipedia.org/wiki/Timeline_of_evolutionhttp://en.wikipedia.org/wiki/Eukaryotehttp://en.wikipedia.org/wiki/Eukaryotehttp://en.wikipedia.org/wiki/Eukaryotehttp://en.wikipedia.org/wiki/Extremophilehttp://en.wikipedia.org/wiki/Extremophilehttp://en.wikipedia.org/wiki/Gammaproteobacteriahttp://en.wikipedia.org/wiki/Gammaproteobacteriahttp://en.wikipedia.org/wiki/Gammaproteobacteriahttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Atmospherehttp://en.wikipedia.org/wiki/Atmospherehttp://en.wikipedia.org/wiki/Photosynthesishttp://en.wikipedia.org/wiki/Photosynthesishttp://en.wikipedia.org/wiki/Photosynthesishttp://en.wikipedia.org/wiki/Waterhttp://en.wikipedia.org/wiki/Waterhttp://en.wikipedia.org/wiki/Waterhttp://en.wikipedia.org/wiki/Carbon_dioxidehttp://en.wikipedia.org/wiki/Carbon_dioxidehttp://en.wikipedia.org/wiki/Carbon_dioxidehttp://en.wikipedia.org/wiki/Sunlighthttp://en.wikipedia.org/wiki/Sunlighthttp://en.wikipedia.org/wiki/Sunlighthttp://en.wikipedia.org/wiki/Mucushttp://en.wikipedia.org/wiki/Mucushttp://en.wikipedia.org/wiki/Mucushttp://en.wikipedia.org/wiki/Limestonehttp://en.wikipedia.org/wiki/Limestonehttp://en.wikipedia.org/wiki/Limestonehttp://en.wikipedia.org/wiki/Oncolitehttp://en.wikipedia.org/wiki/Oncolitehttp://en.wikipedia.org/wiki/Oncolitehttp://en.wikipedia.org/wiki/Fossil_recordhttp://en.wikipedia.org/wiki/Fossil_recordhttp://en.wikipedia.org/wiki/Fossil_recordhttp://en.wikipedia.org/wiki/Thrombolitehttp://en.wikipedia.org/wiki/Thrombolitehttp://en.wikipedia.org/wiki/Thrombolitehttp://en.wikipedia.org/wiki/Fossil#cite_note-Lepot2008-24http://en.wikipedia.org/wiki/Fossil#cite_note-Lepot2008-24http://en.wikipedia.org/wiki/Fossil#cite_note-Lepot2008-24http://en.wikipedia.org/wiki/Namibiahttp://en.wikipedia.org/wiki/Namibiahttp://en.wikipedia.org/wiki/Namibiahttp://en.wikipedia.org/wiki/Fossil#cite_note-32http://en.wikipedia.org/wiki/Fossil#cite_note-32http://en.wikipedia.org/wiki/Fossil#cite_note-32http://en.wikipedia.org/wiki/Fossil#cite_note-32http://en.wikipedia.org/wiki/Namibiahttp://en.wikipedia.org/wiki/Fossil#cite_note-Lepot2008-24http://en.wikipedia.org/wiki/Thrombolitehttp://en.wikipedia.org/wiki/Fossil_recordhttp://en.wikipedia.org/wiki/Oncolitehttp://en.wikipedia.org/wiki/Limestonehttp://en.wikipedia.org/wiki/Mucushttp://en.wikipedia.org/wiki/Sunlighthttp://en.wikipedia.org/wiki/Carbon_dioxidehttp://en.wikipedia.org/wiki/Waterhttp://en.wikipedia.org/wiki/Photosynthesishttp://en.wikipedia.org/wiki/Atmospherehttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Gammaproteobacteriahttp://en.wikipedia.org/wiki/Extremophilehttp://en.wikipedia.org/wiki/Eukaryotehttp://en.wikipedia.org/wiki/Timeline_of_evolutionhttp://en.wikipedia.org/wiki/Prokaryotehttp://en.wikipedia.org/wiki/Fossil#cite_note-Riding2006-31http://en.wikipedia.org/wiki/Fossil#cite_note-SheehanHarris2004ResurgenceAfterOrdovicianExtinction-30http://en.wikipedia.org/wiki/Permian_extinctionhttp://en.wikipedia.org/wiki/Ordovician-Silurian_extinction_eventshttp://en.wikipedia.org/wiki/Ordovician-Silurian_extinction_eventshttp://en.wikipedia.org/wiki/Evolutionary_radiationhttp://en.wikipedia.org/wiki/Ordovicianhttp://en.wikipedia.org/wiki/Fossil#cite_note-Bengtson2002OriginsOfPredation-29http://en.wikipedia.org/wiki/Fossil#cite_note-McNamara1996DatingOriginAnimals-27http://en.wikipedia.org/wiki/Fossil#cite_note-McNamara1996DatingOriginAnimals-27http://en.wikipedia.org/wiki/Cambrian_substrate_revolutionhttp://en.wikipedia.org/wiki/Cambrian_substrate_revolutionhttp://en.wikipedia.org/wiki/Fossil#cite_note-26http://en.wikipedia.org/wiki/Fossil#cite_note-Allwood2009-25http://en.wikipedia.org/wiki/Fossil#cite_note-Allwood2009-25http://en.wikipedia.org/wiki/Fossil#cite_note-Lepot2008-24http://en.wikipedia.org/wiki/Colleniahttp://en.wikipedia.org/wiki/Geologic_time_scalehttp://en.wikipedia.org/wiki/Genushttp://en.wikipedia.org/wiki/Green_algaehttp://en.wikipedia.org/wiki/Chlorophytahttp://en.wikipedia.org/wiki/Eukaryotahttp://en.wikipedia.org/wiki/Prehistorichttp://en.wikipedia.org/wiki/Proterozoichttp://en.wikipedia.org/wiki/Cyanobacteriahttp://en.wikipedia.org/wiki/Colony_%28biology%29http://en.wikipedia.org/wiki/Archean


9/20

Index

Main article:Index fossil

Examples of index fossils

Index fossils (also known as guide fossils, indicator fossils or zone fossils) are fossils used to

define and identifygeologic periods(or faunal stages). They work on the premise that, althoughdifferentsedimentsmay look different depending on the conditions under which they were

deposited, they may include the remains of the samespeciesof fossil. The shorter the species'

time range, the more precisely different sediments can be correlated, and so rapidly evolving

species' fossils are particularly valuable. The best index fossils are common, easy-to-identify atspecies level and have a broad distributionotherwise the likelihood of finding and recognizing

one in the two sediments is poor

Trace

Main article:Trace fossil

Cambriantrace fossilsincludingRusophycus,made by atrilobite
http://en.wikipedia.org/wiki/Index_fossilhttp://en.wikipedia.org/wiki/Index_fossilhttp://en.wikipedia.org/wiki/Index_fossilhttp://en.wikipedia.org/wiki/Geologic_columnhttp://en.wikipedia.org/wiki/Geologic_columnhttp://en.wikipedia.org/wiki/Geologic_columnhttp://en.wikipedia.org/wiki/Sedimenthttp://en.wikipedia.org/wiki/Sedimenthttp://en.wikipedia.org/wiki/Sedimenthttp://en.wikipedia.org/wiki/Specieshttp://en.wikipedia.org/wiki/Specieshttp://en.wikipedia.org/wiki/Specieshttp://en.wikipedia.org/wiki/Trace_fossilhttp://en.wikipedia.org/wiki/Trace_fossilhttp://en.wikipedia.org/wiki/Trace_fossilhttp://en.wikipedia.org/wiki/Cambrianhttp://en.wikipedia.org/wiki/Trace_fossilhttp://en.wikipedia.org/wiki/Trace_fossilhttp://en.wikipedia.org/wiki/Trace_fossilhttp://en.wikipedia.org/wiki/Rusophycushttp://en.wikipedia.org/wiki/Rusophycushttp://en.wikipedia.org/wiki/Rusophycushttp://en.wikipedia.org/wiki/Trilobitehttp://en.wikipedia.org/wiki/Trilobitehttp://en.wikipedia.org/wiki/Trilobitehttp://en.wikipedia.org/wiki/File:Coprolite.jpghttp://en.wikipedia.org/wiki/File:Coprolite.jpghttp://en.wikipedia.org/wiki/File:CambrianRusophycus.jpghttp://en.wikipedia.org/wiki/File:CambrianRusophycus.jpghttp://en.wikipedia.org/wiki/File:Index_fossils.gifhttp://en.wikipedia.org/wiki/File:Index_fossils.gifhttp://en.wikipedia.org/wiki/File:Coprolite.jpghttp://en.wikipedia.org/wiki/File:Coprolite.jpghttp://en.wikipedia.org/wiki/File:CambrianRusophycus.jpghttp://en.wikipedia.org/wiki/File:CambrianRusophycus.jpghttp://en.wikipedia.org/wiki/File:Index_fossils.gifhttp://en.wikipedia.org/wiki/File:Index_fossils.gifhttp://en.wikipedia.org/wiki/File:Coprolite.jpghttp://en.wikipedia.org/wiki/File:Coprolite.jpghttp://en.wikipedia.org/wiki/File:CambrianRusophycus.jpghttp://en.wikipedia.org/wiki/File:CambrianRusophycus.jpghttp://en.wikipedia.org/wiki/File:Index_fossils.gifhttp://en.wikipedia.org/wiki/File:Index_fossils.gifhttp://en.wikipedia.org/wiki/File:Coprolite.jpghttp://en.wikipedia.org/wiki/File:Coprolite.jpghttp://en.wikipedia.org/wiki/File:CambrianRusophycus.jpghttp://en.wikipedia.org/wiki/File:CambrianRusophycus.jpghttp://en.wikipedia.org/wiki/File:Index_fossils.gifhttp://en.wikipedia.org/wiki/File:Index_fossils.gifhttp://en.wikipedia.org/wiki/File:Coprolite.jpghttp://en.wikipedia.org/wiki/File:Coprolite.jpghttp://en.wikipedia.org/wiki/File:CambrianRusophycus.jpghttp://en.wikipedia.org/wiki/File:CambrianRusophycus.jpghttp://en.wikipedia.org/wiki/File:Index_fossils.gifhttp://en.wikipedia.org/wiki/File:Index_fossils.gifhttp://en.wikipedia.org/wiki/File:Coprolite.jpghttp://en.wikipedia.org/wiki/File:Coprolite.jpghttp://en.wikipedia.org/wiki/File:CambrianRusophycus.jpghttp://en.wikipedia.org/wiki/File:CambrianRusophycus.jpghttp://en.wikipedia.org/wiki/File:Index_fossils.gifhttp://en.wikipedia.org/wiki/File:Index_fossils.gifhttp://en.wikipedia.org/wiki/Trilobitehttp://en.wikipedia.org/wiki/Rusophycushttp://en.wikipedia.org/wiki/Trace_fossilhttp://en.wikipedia.org/wiki/Cambrianhttp://en.wikipedia.org/wiki/Trace_fossilhttp://en.wikipedia.org/wiki/Specieshttp://en.wikipedia.org/wiki/Sedimenthttp://en.wikipedia.org/wiki/Geologic_columnhttp://en.wikipedia.org/wiki/Index_fossil


10/20

A coprolite of a carnivorous dinosaur found in southwesternSaskatchewan.

Trace fossils consist mainly of tracks and burrows, but also includecoprolites(fossilfeces)andmarks left by feeding.

[33][34]Trace fossils are particularly significant because they represent a

data source that is not limited to animals with easily fossilized hard parts, and they reflect animal

behaviours. Many traces date from significantly earlier than the body fossils of animals that arethought to have been capable of making them.[35]

Whilst exact assignment of trace fossils to their

makers is generally impossible, traces may for example provide the earliest physical evidence of

the appearance of moderately complex animals (comparable toearthworms).[34]

Coprolites are classified astrace fossilsas opposed to body fossils, as they give evidence for the

animal's behaviour (in this case, diet) rather than morphology. They were first described byWilliam Bucklandin 1829. Prior to this they were known as "fossilfir cones" and "bezoar

stones." They serve a valuable purpose in paleontology because they provide direct evidence of

the predation and diet of extinct organisms.[36]

Coprolites may range in size from a few

millimetres to over 60 centimetres.

Transitional

Main article:Transitional fossil

Further information:List of transitional fossils

A transitional fossilis any fossilized remains of a life form that exhibits traits common to both

an ancestral group and its derived descendant group.[37]

This is especially important where the

descendant group is sharply differentiated by gross anatomy and mode of living from theancestral group. Because of the incompleteness of the fossil record, there is usually no way to

know exactly how close a transitional fossil is to the point of divergence. These fossils serve as a

reminder that taxonomic divisions are human constructs that have been imposed in hindsight ona continuum of variation.

Microfossils

Microfossils about 1 mm

Main article:Micropaleontology
http://en.wikipedia.org/wiki/Saskatchewanhttp://en.wikipedia.org/wiki/Saskatchewanhttp://en.wikipedia.org/wiki/Saskatchewanhttp://en.wikipedia.org/wiki/Coprolitehttp://en.wikipedia.org/wiki/Coprolitehttp://en.wikipedia.org/wiki/Coprolitehttp://en.wikipedia.org/wiki/Feceshttp://en.wikipedia.org/wiki/Feceshttp://en.wikipedia.org/wiki/Feceshttp://en.wikipedia.org/wiki/Fossil#cite_note-UCMPWhatIsPaleo-33http://en.wikipedia.org/wiki/Fossil#cite_note-UCMPWhatIsPaleo-33http://en.wikipedia.org/wiki/Fossil#cite_note-UCMPWhatIsPaleo-33http://en.wikipedia.org/wiki/Fossil#cite_note-Seilacher1994-35http://en.wikipedia.org/wiki/Fossil#cite_note-Seilacher1994-35http://en.wikipedia.org/wiki/Fossil#cite_note-Seilacher1994-35http://en.wikipedia.org/wiki/Earthwormhttp://en.wikipedia.org/wiki/Earthwormhttp://en.wikipedia.org/wiki/Earthwormhttp://en.wikipedia.org/wiki/Fossil#cite_note-FedonkinGehlingEtAl2007RiseOfAnimals-34http://en.wikipedia.org/wiki/Fossil#cite_note-FedonkinGehlingEtAl2007RiseOfAnimals-34http://en.wikipedia.org/wiki/Fossil#cite_note-FedonkinGehlingEtAl2007RiseOfAnimals-34http://en.wikipedia.org/wiki/Trace_fossilhttp://en.wikipedia.org/wiki/Trace_fossilhttp://en.wikipedia.org/wiki/Trace_fossilhttp://en.wikipedia.org/wiki/William_Bucklandhttp://en.wikipedia.org/wiki/William_Bucklandhttp://en.wikipedia.org/wiki/Conifer_cone#Pinaceae_coneshttp://en.wikipedia.org/wiki/Conifer_cone#Pinaceae_coneshttp://en.wikipedia.org/wiki/Bezoarhttp://en.wikipedia.org/wiki/Bezoarhttp://en.wikipedia.org/wiki/Bezoarhttp://en.wikipedia.org/wiki/Fossil#cite_note-36http://en.wikipedia.org/wiki/Fossil#cite_note-36http://en.wikipedia.org/wiki/Fossil#cite_note-36http://en.wikipedia.org/wiki/Transitional_fossilhttp://en.wikipedia.org/wiki/Transitional_fossilhttp://en.wikipedia.org/wiki/Transitional_fossilhttp://en.wikipedia.org/wiki/List_of_transitional_fossilshttp://en.wikipedia.org/wiki/List_of_transitional_fossilshttp://en.wikipedia.org/wiki/List_of_transitional_fossilshttp://en.wikipedia.org/wiki/Fossil#cite_note-37http://en.wikipedia.org/wiki/Fossil#cite_note-37http://en.wikipedia.org/wiki/Fossil#cite_note-37http://en.wikipedia.org/wiki/Micropaleontologyhttp://en.wikipedia.org/wiki/Micropaleontologyhttp://en.wikipedia.org/wiki/Micropaleontologyhttp://en.wikipedia.org/wiki/File:Microfossils.JPGhttp://en.wikipedia.org/wiki/File:Microfossils.JPGhttp://en.wikipedia.org/wiki/File:Microfossils.JPGhttp://en.wikipedia.org/wiki/File:Microfossils.JPGhttp://en.wikipedia.org/wiki/Micropaleontologyhttp://en.wikipedia.org/wiki/Fossil#cite_note-37http://en.wikipedia.org/wiki/List_of_transitional_fossilshttp://en.wikipedia.org/wiki/Transitional_fossilhttp://en.wikipedia.org/wiki/Fossil#cite_note-36http://en.wikipedia.org/wiki/Bezoarhttp://en.wikipedia.org/wiki/Conifer_cone#Pinaceae_coneshttp://en.wikipedia.org/wiki/William_Bucklandhttp://en.wikipedia.org/wiki/Trace_fossilhttp://en.wikipedia.org/wiki/Fossil#cite_note-FedonkinGehlingEtAl2007RiseOfAnimals-34http://en.wikipedia.org/wiki/Earthwormhttp://en.wikipedia.org/wiki/Fossil#cite_note-Seilacher1994-35http://en.wikipedia.org/wiki/Fossil#cite_note-UCMPWhatIsPaleo-33http://en.wikipedia.org/wiki/Fossil#cite_note-UCMPWhatIsPaleo-33http://en.wikipedia.org/wiki/Feceshttp://en.wikipedia.org/wiki/Coprolitehttp://en.wikipedia.org/wiki/Saskatchewan


11/20

Microfossil is a descriptive term applied to fossilized plants and animals whose size is just at or

below the level at which the fossil can be analyzed by the naked eye. A commonly applied cutoff

point between "micro" and"macro" fossilsis 1 mm. Microfossils may either be complete (ornear-complete) organisms in themselves (such as the marine planktersforaminiferaand

coccolithophores)or component parts (such as small teeth orspores)of larger animals or plants.

Microfossils are of critical importance as a reservoir ofpaleoclimateinformation, and are alsocommonly used bybiostratigraphersto assist in the correlation of rock units.

Resin

Main article:Amber

Leptofoenus pittfieldaetrapped inDominican amber,from 20 to 16 million years ago

Fossil resin (colloquially calledamber)is a naturalpolymerfound in many types of stratathroughout the world, even theArctic.The oldest fossil resin dates to theTriassic,though mostdates to theCenozoic.The excretion of the resin by certain plants is thought to be an

evolutionaryadaptationfor protection from insects and to seal wounds. Fossil resin often

contains other fossils called inclusions that were captured by the sticky resin. These include

bacteria, fungi, other plants, and animals. Animal inclusions are usually smallinvertebrates,predominantlyarthropodssuch as insects and spiders, and only extremely rarely avertebrate

such as a small lizard. Preservation of inclusions can be exquisite, including small fragments of

DNA.

Derived

See also:Zombie taxon
http://en.wikipedia.org/wiki/Macrofossilhttp://en.wikipedia.org/wiki/Macrofossilhttp://en.wikipedia.org/wiki/Macrofossilhttp://en.wikipedia.org/wiki/Foraminiferahttp://en.wikipedia.org/wiki/Foraminiferahttp://en.wikipedia.org/wiki/Foraminiferahttp://en.wikipedia.org/wiki/Coccolithophorehttp://en.wikipedia.org/wiki/Coccolithophorehttp://en.wikipedia.org/wiki/Palynologyhttp://en.wikipedia.org/wiki/Palynologyhttp://en.wikipedia.org/wiki/Palynologyhttp://en.wikipedia.org/wiki/Paleoclimatologyhttp://en.wikipedia.org/wiki/Paleoclimatologyhttp://en.wikipedia.org/wiki/Paleoclimatologyhttp://en.wikipedia.org/wiki/Biostratigraphyhttp://en.wikipedia.org/wiki/Biostratigraphyhttp://en.wikipedia.org/wiki/Biostratigraphyhttp://en.wikipedia.org/wiki/Amberhttp://en.wikipedia.org/wiki/Amberhttp://en.wikipedia.org/wiki/Amberhttp://en.wikipedia.org/wiki/Leptofoenus_pittfieldaehttp://en.wikipedia.org/wiki/Leptofoenus_pittfieldaehttp://en.wikipedia.org/wiki/Dominican_amberhttp://en.wikipedia.org/wiki/Dominican_amberhttp://en.wikipedia.org/wiki/Dominican_amberhttp://en.wikipedia.org/wiki/Amberhttp://en.wikipedia.org/wiki/Amberhttp://en.wikipedia.org/wiki/Amberhttp://en.wikipedia.org/wiki/Polymerhttp://en.wikipedia.org/wiki/Polymerhttp://en.wikipedia.org/wiki/Polymerhttp://en.wikipedia.org/wiki/Arctichttp://en.wikipedia.org/wiki/Arctichttp://en.wikipedia.org/wiki/Arctichttp://en.wikipedia.org/wiki/Triassichttp://en.wikipedia.org/wiki/Triassichttp://en.wikipedia.org/wiki/Triassichttp://en.wikipedia.org/wiki/Cenozoichttp://en.wikipedia.org/wiki/Cenozoichttp://en.wikipedia.org/wiki/Cenozoichttp://en.wikipedia.org/wiki/Adaptationhttp://en.wikipedia.org/wiki/Adaptationhttp://en.wikipedia.org/wiki/Adaptationhttp://en.wikipedia.org/wiki/Invertebrateshttp://en.wikipedia.org/wiki/Invertebrateshttp://en.wikipedia.org/wiki/Invertebrateshttp://en.wikipedia.org/wiki/Arthropodhttp://en.wikipedia.org/wiki/Arthropodhttp://en.wikipedia.org/wiki/Arthropodhttp://en.wikipedia.org/wiki/Vertebratehttp://en.wikipedia.org/wiki/Vertebratehttp://en.wikipedia.org/wiki/Vertebratehttp://en.wikipedia.org/wiki/DNAhttp://en.wikipedia.org/wiki/DNAhttp://en.wikipedia.org/wiki/Zombie_taxonhttp://en.wikipedia.org/wiki/Zombie_taxonhttp://en.wikipedia.org/wiki/Zombie_taxonhttp://en.wikipedia.org/wiki/File:CentrumSideView.jpghttp://en.wikipedia.org/wiki/File:Leptofoenus_pittfieldae_(male)_rotated.JPGhttp://en.wikipedia.org/wiki/File:Leptofoenus_pittfieldae_(male)_rotated.JPGhttp://en.wikipedia.org/wiki/File:CentrumSideView.jpghttp://en.wikipedia.org/wiki/File:Leptofoenus_pittfieldae_(male)_rotated.JPGhttp://en.wikipedia.org/wiki/File:Leptofoenus_pittfieldae_(male)_rotated.JPGhttp://en.wikipedia.org/wiki/File:CentrumSideView.jpghttp://en.wikipedia.org/wiki/File:Leptofoenus_pittfieldae_(male)_rotated.JPGhttp://en.wikipedia.org/wiki/File:Leptofoenus_pittfieldae_(male)_rotated.JPGhttp://en.wikipedia.org/wiki/Zombie_taxonhttp://en.wikipedia.org/wiki/DNAhttp://en.wikipedia.org/wiki/Vertebratehttp://en.wikipedia.org/wiki/Arthropodhttp://en.wikipedia.org/wiki/Invertebrateshttp://en.wikipedia.org/wiki/Adaptationhttp://en.wikipedia.org/wiki/Cenozoichttp://en.wikipedia.org/wiki/Triassichttp://en.wikipedia.org/wiki/Arctichttp://en.wikipedia.org/wiki/Polymerhttp://en.wikipedia.org/wiki/Amberhttp://en.wikipedia.org/wiki/Dominican_amberhttp://en.wikipedia.org/wiki/Leptofoenus_pittfieldaehttp://en.wikipedia.org/wiki/Amberhttp://en.wikipedia.org/wiki/Biostratigraphyhttp://en.wikipedia.org/wiki/Paleoclimatologyhttp://en.wikipedia.org/wiki/Palynologyhttp://en.wikipedia.org/wiki/Coccolithophorehttp://en.wikipedia.org/wiki/Foraminiferahttp://en.wikipedia.org/wiki/Macrofossil


12/20

ErodedJurassicplesiosaurvertebral centrum found in the LowerCretaceousFaringdon Sponge

Gravels in Faringdon, England. An example of a remanifossil.

A derived, reworkedor remani fossilis a fossil found in rock made significantly later than when

the fossilized animal or plant died:

[38]

it happens when a hard fossil is freed from a soft rockformation byerosionand redeposited in a currently forming sedimentary deposit.

Wood

Main article:Fossil wood

Petrified wood.The internal structure of the tree and bark are maintained in the

permineralizationprocess.

Fossil wood is wood that is preserved in the fossil record. Wood is usually the part of a plant that

is best preserved (and most easily found). Fossil wood may or may not bepetrified.The fossilwood may be the only part of the plant that has been preserved:[39]

therefore such wood may get

a special kind ofbotanical name.This will usually include "xylon" and a term indicating its

presumed affinity, such asAraucarioxylon(wood ofAraucariaor some related genus),

Palmoxylon(wood of an indeterminatepalm), or Castanoxylon(wood of an indeterminatechinkapin).

[40]

Subfossil

Main article:Subfossil
http://en.wikipedia.org/wiki/Jurassichttp://en.wikipedia.org/wiki/Jurassichttp://en.wikipedia.org/wiki/Plesiosaurhttp://en.wikipedia.org/wiki/Plesiosaurhttp://en.wikipedia.org/wiki/Plesiosaurhttp://en.wikipedia.org/wiki/Cretaceoushttp://en.wikipedia.org/wiki/Cretaceoushttp://en.wikipedia.org/wiki/Cretaceoushttp://en.wikipedia.org/wiki/Fossil#cite_note-38http://en.wikipedia.org/wiki/Fossil#cite_note-38http://en.wikipedia.org/wiki/Fossil#cite_note-38http://en.wikipedia.org/wiki/Erosionhttp://en.wikipedia.org/wiki/Erosionhttp://en.wikipedia.org/wiki/Erosionhttp://en.wikipedia.org/wiki/Fossil_woodhttp://en.wikipedia.org/wiki/Fossil_woodhttp://en.wikipedia.org/wiki/Fossil_woodhttp://en.wikipedia.org/wiki/Petrified_woodhttp://en.wikipedia.org/wiki/Petrified_woodhttp://en.wikipedia.org/wiki/Fossil#Permineralizationhttp://en.wikipedia.org/wiki/Fossil#Permineralizationhttp://en.wikipedia.org/wiki/Petrified_woodhttp://en.wikipedia.org/wiki/Petrified_woodhttp://en.wikipedia.org/wiki/Petrified_woodhttp://en.wikipedia.org/wiki/Fossil#cite_note-strauss-39http://en.wikipedia.org/wiki/Fossil#cite_note-strauss-39http://en.wikipedia.org/wiki/Fossil#cite_note-strauss-39http://en.wikipedia.org/wiki/Botanical_namehttp://en.wikipedia.org/wiki/Botanical_namehttp://en.wikipedia.org/wiki/Botanical_namehttp://en.wikipedia.org/wiki/Araucarioxylon_arizonicumhttp://en.wikipedia.org/wiki/Araucarioxylon_arizonicumhttp://en.wikipedia.org/wiki/Araucarioxylon_arizonicumhttp://en.wikipedia.org/wiki/Araucariahttp://en.wikipedia.org/wiki/Araucariahttp://en.wikipedia.org/wiki/Araucariahttp://en.wikipedia.org/wiki/Palmoxylonhttp://en.wikipedia.org/wiki/Palmoxylonhttp://en.wikipedia.org/wiki/Arecaceaehttp://en.wikipedia.org/wiki/Arecaceaehttp://en.wikipedia.org/wiki/Arecaceaehttp://en.wikipedia.org/wiki/Castanopsishttp://en.wikipedia.org/wiki/Castanopsishttp://en.wikipedia.org/wiki/Fossil#cite_note-stewart-40http://en.wikipedia.org/wiki/Fossil#cite_note-stewart-40http://en.wikipedia.org/wiki/Fossil#cite_note-stewart-40http://en.wikipedia.org/wiki/Subfossilhttp://en.wikipedia.org/wiki/Subfossilhttp://en.wikipedia.org/wiki/Subfossilhttp://en.wikipedia.org/wiki/File:Petrified_forest_log_2_md.jpghttp://en.wikipedia.org/wiki/File:Petrified_forest_log_2_md.jpghttp://en.wikipedia.org/wiki/File:CentrumSideView.jpghttp://en.wikipedia.org/wiki/File:Petrified_forest_log_2_md.jpghttp://en.wikipedia.org/wiki/File:Petrified_forest_log_2_md.jpghttp://en.wikipedia.org/wiki/File:CentrumSideView.jpghttp://en.wikipedia.org/wiki/File:Petrified_forest_log_2_md.jpghttp://en.wikipedia.org/wiki/File:Petrified_forest_log_2_md.jpghttp://en.wikipedia.org/wiki/File:CentrumSideView.jpghttp://en.wikipedia.org/wiki/Subfossilhttp://en.wikipedia.org/wiki/Fossil#cite_note-stewart-40http://en.wikipedia.org/wiki/Castanopsishttp://en.wikipedia.org/wiki/Arecaceaehttp://en.wikipedia.org/wiki/Palmoxylonhttp://en.wikipedia.org/wiki/Araucariahttp://en.wikipedia.org/wiki/Araucarioxylon_arizonicumhttp://en.wikipedia.org/wiki/Botanical_namehttp://en.wikipedia.org/wiki/Fossil#cite_note-strauss-39http://en.wikipedia.org/wiki/Petrified_woodhttp://en.wikipedia.org/wiki/Fossil#Permineralizationhttp://en.wikipedia.org/wiki/Petrified_woodhttp://en.wikipedia.org/wiki/Fossil_woodhttp://en.wikipedia.org/wiki/Erosionhttp://en.wikipedia.org/wiki/Fossil#cite_note-38http://en.wikipedia.org/wiki/Cretaceoushttp://en.wikipedia.org/wiki/Plesiosaurhttp://en.wikipedia.org/wiki/Jurassic


13/20

A subfossildodoskeleton

The term subfossil can be used to refer to remains, such as bones, nests, or defecations, whose

fossilizationprocess is not complete, either because the length of time since the animal involvedwas living is too short (less than 10,000 years) or because the conditions in which the remainswere buried were not optimal for fossilization. Subfossils are often found in caves or other

shelters where they can be preserved for thousands of years.[41]

The main importance of subfossil

vs. fossil remains is that the former contain organic material, which can be used forradiocarbondatingor extraction and sequencing ofDNA,protein,or other biomolecules. Additionally,

isotoperatios can provide much information about the ecological conditions under which extinct

animals lived. Subfossils are useful for studying the evolutionary history of an environment andcan be important to studies inpaleoclimatology.

Subfossils are often found in depositionary environments, such as lake sediments, oceanic

sediments, and soils. Once deposited, physical and chemicalweatheringcan alter the state ofpreservation.

Chemical fossils

Chemical fossils are chemicals found in rocks and fossil fuels (petroleum, coal, and natural gas)that provide an organic signature for ancient life. Molecular fossils and isotope ratios represent

two types of chemical fossils.[42]

Pseudofossils
http://en.wikipedia.org/wiki/Dodohttp://en.wikipedia.org/wiki/Dodohttp://en.wikipedia.org/wiki/Dodohttp://en.wikipedia.org/wiki/Fossilizationhttp://en.wikipedia.org/wiki/Fossilizationhttp://en.wikipedia.org/wiki/Fossil#cite_note-41http://en.wikipedia.org/wiki/Fossil#cite_note-41http://en.wikipedia.org/wiki/Fossil#cite_note-41http://en.wikipedia.org/wiki/Radiocarbon_datinghttp://en.wikipedia.org/wiki/Radiocarbon_datinghttp://en.wikipedia.org/wiki/Radiocarbon_datinghttp://en.wikipedia.org/wiki/Radiocarbon_datinghttp://en.wikipedia.org/wiki/DNA_sequencinghttp://en.wikipedia.org/wiki/DNA_sequencinghttp://en.wikipedia.org/wiki/DNA_sequencinghttp://en.wikipedia.org/wiki/Protein_sequencinghttp://en.wikipedia.org/wiki/Protein_sequencinghttp://en.wikipedia.org/wiki/Protein_sequencinghttp://en.wikipedia.org/wiki/Isotopehttp://en.wikipedia.org/wiki/Isotopehttp://en.wikipedia.org/wiki/Paleoclimatologyhttp://en.wikipedia.org/wiki/Paleoclimatologyhttp://en.wikipedia.org/wiki/Paleoclimatologyhttp://en.wikipedia.org/wiki/Weatheringhttp://en.wikipedia.org/wiki/Weatheringhttp://en.wikipedia.org/wiki/Weatheringhttp://en.wikipedia.org/wiki/Fossil#cite_note-42http://en.wikipedia.org/wiki/Fossil#cite_note-42http://en.wikipedia.org/wiki/Fossil#cite_note-42http://en.wikipedia.org/wiki/File:Dendrites01.jpghttp://en.wikipedia.org/wiki/File:Dodo-Skeleton_Natural_History_Museum_London_England.jpghttp://en.wikipedia.org/wiki/File:Dodo-Skeleton_Natural_History_Museum_London_England.jpghttp://en.wikipedia.org/wiki/File:Dendrites01.jpghttp://en.wikipedia.org/wiki/File:Dodo-Skeleton_Natural_History_Museum_London_England.jpghttp://en.wikipedia.org/wiki/File:Dodo-Skeleton_Natural_History_Museum_London_England.jpghttp://en.wikipedia.org/wiki/File:Dendrites01.jpghttp://en.wikipedia.org/wiki/File:Dodo-Skeleton_Natural_History_Museum_London_England.jpghttp://en.wikipedia.org/wiki/File:Dodo-Skeleton_Natural_History_Museum_London_England.jpghttp://en.wikipedia.org/wiki/Fossil#cite_note-42http://en.wikipedia.org/wiki/Weatheringhttp://en.wikipedia.org/wiki/Paleoclimatologyhttp://en.wikipedia.org/wiki/Isotopehttp://en.wikipedia.org/wiki/Protein_sequencinghttp://en.wikipedia.org/wiki/DNA_sequencinghttp://en.wikipedia.org/wiki/Radiocarbon_datinghttp://en.wikipedia.org/wiki/Radiocarbon_datinghttp://en.wikipedia.org/wiki/Fossil#cite_note-41http://en.wikipedia.org/wiki/Fossilizationhttp://en.wikipedia.org/wiki/Dodo


14/20

An example of a pseudofossil: Manganese dendrites on a limestone bedding plane from

Solnhofen,Germany; scale in mmMain article:Pseudofossils

Pseudofossilsare visual patterns in rocks that are produced by geologic processes rather thanbiologic processes. They can easily be mistaken for real fossils. Some pseudofossils, such as

dendrites,are formed by naturally occurring fissures in the rock that get filled up by percolating

minerals. Other types of pseudofossils are kidney ore (round shapes in iron ore) andmoss agates,which look like moss or plant leaves.Concretions,spherical or ovoid-shaped nodules found in

some sedimentary strata, were once thought to bedinosaureggs, and are often mistaken for

fossils as well.

History of the study of fossils

Main article:History of paleontology

See also:Timeline of paleontology

Gathering fossils dates at least to the beginning of recorded history. The fossils themselves arereferred to as the fossil record. The fossil record was one of the early sources of data underlying

the study ofevolutionand continues to be relevant to thehistory of life on Earth.Paleontologists

examine the fossil record to understand the process of evolution and the way particularspecies

have evolved.

Explanations

Before Darwin

Many early explanations relied on folktales or mythologies. In China the fossil bones of ancient

mammals includingHomo erectuswere often mistaken for dragonbones and used as medicineandaphrodisiacs.In the West fossilized sea creatures on mountainsides were seen as proof of the

biblical deluge.

In 1027, thePersianAvicennaexplained fossils' stoniness inThe Book of Healing:

If what is said concerning the petrifaction of animals and plants is true, the cause of this

(phenomenon) is a powerful mineralizing and petrifying virtue which arises in certain stony

spots, or emanates suddenly from the earth during earthquake and subsidences, and petrifies

whatever comes into contact with it. As a matter of fact, the petrifaction of the bodies of plantsand animals is not more extraordinary than the transformation of waters.

[43]

GreekscholarAristotlerealized that fossil seashells from rocks were similar to those found onthe beach, indicating the fossils were once living animals.Aristotlepreviously explained it in

terms ofvaporousexhalations,which Avicenna modified into the theory ofpetrifyingfluids

(succus lapidificatus), later elaborated byAlbert of Saxonyin the 14th century and accepted insome form by mostnaturalistsby the 16th century.

[44]
http://en.wikipedia.org/wiki/Solnhofenhttp://en.wikipedia.org/wiki/Solnhofenhttp://en.wikipedia.org/wiki/Pseudofossilshttp://en.wikipedia.org/wiki/Pseudofossilshttp://en.wikipedia.org/wiki/Pseudofossilshttp://en.wikipedia.org/wiki/Dendrite_%28crystal%29http://en.wikipedia.org/wiki/Dendrite_%28crystal%29http://en.wikipedia.org/wiki/Agatehttp://en.wikipedia.org/wiki/Agatehttp://en.wikipedia.org/wiki/Agatehttp://en.wikipedia.org/wiki/Concretionhttp://en.wikipedia.org/wiki/Concretionhttp://en.wikipedia.org/wiki/Concretionhttp://en.wikipedia.org/wiki/Dinosaurhttp://en.wikipedia.org/wiki/Dinosaurhttp://en.wikipedia.org/wiki/Dinosaurhttp://en.wikipedia.org/wiki/History_of_paleontologyhttp://en.wikipedia.org/wiki/History_of_paleontologyhttp://en.wikipedia.org/wiki/History_of_paleontologyhttp://en.wikipedia.org/wiki/Timeline_of_paleontologyhttp://en.wikipedia.org/wiki/Timeline_of_paleontologyhttp://en.wikipedia.org/wiki/Timeline_of_paleontologyhttp://en.wikipedia.org/wiki/Evolutionhttp://en.wikipedia.org/wiki/Evolutionhttp://en.wikipedia.org/wiki/Evolutionhttp://en.wikipedia.org/wiki/Timeline_of_evolutionhttp://en.wikipedia.org/wiki/Timeline_of_evolutionhttp://en.wikipedia.org/wiki/Timeline_of_evolutionhttp://en.wikipedia.org/wiki/Paleontologisthttp://en.wikipedia.org/wiki/Paleontologisthttp://en.wikipedia.org/wiki/Paleontologisthttp://en.wikipedia.org/wiki/Specieshttp://en.wikipedia.org/wiki/Specieshttp://en.wikipedia.org/wiki/Specieshttp://en.wikipedia.org/wiki/Homo_erectushttp://en.wikipedia.org/wiki/Homo_erectushttp://en.wikipedia.org/wiki/Homo_erectushttp://en.wikipedia.org/wiki/Dragonhttp://en.wikipedia.org/wiki/Dragonhttp://en.wikipedia.org/wiki/Aphrodisiachttp://en.wikipedia.org/wiki/Aphrodisiachttp://en.wikipedia.org/wiki/Aphrodisiachttp://en.wikipedia.org/wiki/Noah%27s_Arkhttp://en.wikipedia.org/wiki/Noah%27s_Arkhttp://en.wikipedia.org/wiki/Persian_peoplehttp://en.wikipedia.org/wiki/Persian_peoplehttp://en.wikipedia.org/wiki/Avicennahttp://en.wikipedia.org/wiki/Avicennahttp://en.wikipedia.org/wiki/Avicennahttp://en.wikipedia.org/wiki/The_Book_of_Healinghttp://en.wikipedia.org/wiki/The_Book_of_Healinghttp://en.wikipedia.org/wiki/The_Book_of_Healinghttp://en.wikipedia.org/wiki/Fossil#cite_note-43http://en.wikipedia.org/wiki/Fossil#cite_note-43http://en.wikipedia.org/wiki/Fossil#cite_note-43http://en.wikipedia.org/wiki/Ancient_Greecehttp://en.wikipedia.org/wiki/Ancient_Greecehttp://en.wikipedia.org/wiki/Aristotlehttp://en.wikipedia.org/wiki/Aristotlehttp://en.wikipedia.org/wiki/Aristotlehttp://en.wikipedia.org/wiki/Aristotlehttp://en.wikipedia.org/wiki/Aristotlehttp://en.wikipedia.org/wiki/Aristotlehttp://en.wikipedia.org/wiki/Vaporhttp://en.wikipedia.org/wiki/Vaporhttp://en.wikipedia.org/wiki/Exhalationhttp://en.wikipedia.org/wiki/Exhalationhttp://en.wikipedia.org/wiki/Exhalationhttp://en.wikipedia.org/wiki/Petrifactionhttp://en.wikipedia.org/wiki/Petrifactionhttp://en.wikipedia.org/wiki/Fluidhttp://en.wikipedia.org/wiki/Fluidhttp://en.wikipedia.org/wiki/Fluidhttp://en.wikipedia.org/wiki/Albert_of_Saxony_%28philosopher%29http://en.wikipedia.org/wiki/Albert_of_Saxony_%28philosopher%29http://en.wikipedia.org/wiki/Albert_of_Saxony_%28philosopher%29http://en.wikipedia.org/wiki/Naturalisthttp://en.wikipedia.org/wiki/Naturalisthttp://en.wikipedia.org/wiki/Naturalisthttp://en.wikipedia.org/wiki/Fossil#cite_note-44http://en.wikipedia.org/wiki/Fossil#cite_note-44http://en.wikipedia.org/wiki/Fossil#cite_note-44http://en.wikipedia.org/wiki/File:Dendrites01.jpghttp://en.wikipedia.org/wiki/Fossil#cite_note-44http://en.wikipedia.org/wiki/Naturalisthttp://en.wikipedia.org/wiki/Albert_of_Saxony_%28philosopher%29http://en.wikipedia.org/wiki/Fluidhttp://en.wikipedia.org/wiki/Petrifactionhttp://en.wikipedia.org/wiki/Exhalationhttp://en.wikipedia.org/wiki/Vaporhttp://en.wikipedia.org/wiki/Aristotlehttp://en.wikipedia.org/wiki/Aristotlehttp://en.wikipedia.org/wiki/Ancient_Greecehttp://en.wikipedia.org/wiki/Fossil#cite_note-43http://en.wikipedia.org/wiki/The_Book_of_Healinghttp://en.wikipedia.org/wiki/Avicennahttp://en.wikipedia.org/wiki/Persian_peoplehttp://en.wikipedia.org/wiki/Noah%27s_Arkhttp://en.wikipedia.org/wiki/Aphrodisiachttp://en.wikipedia.org/wiki/Dragonhttp://en.wikipedia.org/wiki/Homo_erectushttp://en.wikipedia.org/wiki/Specieshttp://en.wikipedia.org/wiki/Paleontologisthttp://en.wikipedia.org/wiki/Timeline_of_evolutionhttp://en.wikipedia.org/wiki/Evolutionhttp://en.wikipedia.org/wiki/Timeline_of_paleontologyhttp://en.wikipedia.org/wiki/History_of_paleontologyhttp://en.wikipedia.org/wiki/Dinosaurhttp://en.wikipedia.org/wiki/Concretionhttp://en.wikipedia.org/wiki/Agatehttp://en.wikipedia.org/wiki/Dendrite_%28crystal%29http://en.wikipedia.org/wiki/Pseudofossilshttp://en.wikipedia.org/wiki/Solnhofen


15/20

More scientific views of fossils emerged during theRenaissance.Leonardo da Vinciconcurred

with Aristotle's view that fossils were the remains of ancient life.[45]

For example, da Vinci

noticed discrepancies with the biblical flood narrative as an explanation for fossil origins:

"If the Deluge had carried the shells for distances of three and four hundred miles from the sea it

would have carried them mixed with various other natural objects all heaped up together; buteven at such distances from the sea we see the oysters all together and also the shellfish and the

cuttlefish and all the other shells which congregate together, found all together dead; and the

solitary shells are found apart from one another as we see them every day on the sea-shores.

And we find oysters together in very large families, among which some may be seen with their

shells still joined together, indicating that they were left there by the sea and that they were stillliving when the strait of Gibraltar was cut through. In the mountains of Parma and Piacenza

multitudes of shells and corals with holes may be seen still sticking to the rocks...."[46]

IchthyosaurusandPlesiosaurusfrom the 1834 Czech edition ofCuvier'sDiscours sur les

revolutions de la surface du globe.

William Smith (17691839),an English canal engineer, observed that rocks of different ages(based on thelaw of superposition)preserved different assemblages of fossils, and that these

assemblages succeeded one another in a regular and determinable order. He observed that rocksfrom distant locations could be correlated based on the fossils they contained. He termed this theprinciple offaunal succession. This principle became one of Darwin's chief pieces of evidence

that biological evolution was real.

Georges Cuviercame to believe that most if not all the animal fossils he examined were remains

of extinct species. This led Cuvier to become an active proponent of the geological school ofthought calledcatastrophism.Near the end of his 1796 paper on living and fossil elephants he

said:

All of these facts, consistent among themselves, and not opposed by any report, seem to

me to prove the existence of a world previous to ours, destroyed by some kind ofcatastrophe.

[47]

Linnaeus and Darwin

Earlynaturalistswell understood the similarities and differences of living species leadingLinnaeusto develop a hierarchical classification system still in use today. Darwin and his

contemporaries first linked the hierarchical structure of the tree of life with the then very sparse
http://en.wikipedia.org/wiki/Renaissancehttp://en.wikipedia.org/wiki/Renaissancehttp://en.wikipedia.org/wiki/Renaissancehttp://en.wikipedia.org/wiki/Leonardo_da_Vincihttp://en.wikipedia.org/wiki/Leonardo_da_Vincihttp://en.wikipedia.org/wiki/Leonardo_da_Vincihttp://en.wikipedia.org/wiki/Fossil#cite_note-45http://en.wikipedia.org/wiki/Fossil#cite_note-45http://en.wikipedia.org/wiki/Fossil#cite_note-45http://en.wikipedia.org/wiki/Fossil#cite_note-46http://en.wikipedia.org/wiki/Fossil#cite_note-46http://en.wikipedia.org/wiki/Fossil#cite_note-46http://en.wikipedia.org/wiki/Ichthyosaurushttp://en.wikipedia.org/wiki/Ichthyosaurushttp://en.wikipedia.org/wiki/Plesiosaurushttp://en.wikipedia.org/wiki/Plesiosaurushttp://en.wikipedia.org/wiki/Plesiosaurushttp://en.wikipedia.org/wiki/Georges_Cuvierhttp://en.wikipedia.org/wiki/Georges_Cuvierhttp://en.wikipedia.org/wiki/Georges_Cuvierhttp://en.wikipedia.org/wiki/William_Smith_%28geologist%29http://en.wikipedia.org/wiki/William_Smith_%28geologist%29http://en.wikipedia.org/wiki/William_Smith_%28geologist%29http://en.wikipedia.org/wiki/William_Smith_%28geologist%29http://en.wikipedia.org/wiki/Law_of_superpositionhttp://en.wikipedia.org/wiki/Law_of_superpositionhttp://en.wikipedia.org/wiki/Law_of_superpositionhttp://en.wikipedia.org/wiki/Georges_Cuvierhttp://en.wikipedia.org/wiki/Georges_Cuvierhttp://en.wikipedia.org/wiki/Catastrophismhttp://en.wikipedia.org/wiki/Catastrophismhttp://en.wikipedia.org/wiki/Catastrophismhttp://en.wikipedia.org/wiki/Fossil#cite_note-47http://en.wikipedia.org/wiki/Fossil#cite_note-47http://en.wikipedia.org/wiki/Fossil#cite_note-47http://en.wikipedia.org/wiki/Natural_sciencehttp://en.wikipedia.org/wiki/Natural_sciencehttp://en.wikipedia.org/wiki/Natural_sciencehttp://en.wikipedia.org/wiki/Carolus_Linnaeushttp://en.wikipedia.org/wiki/Carolus_Linnaeushttp://en.wikipedia.org/wiki/File:Rozprawa_o_p%C5%99ewratech_k%C5%AFry_zemnj,_Ichthyosaurus_and_Plesiosaurus.jpghttp://en.wikipedia.org/wiki/File:Rozprawa_o_p%C5%99ewratech_k%C5%AFry_zemnj,_Ichthyosaurus_and_Plesiosaurus.jpghttp://en.wikipedia.org/wiki/File:Rozprawa_o_p%C5%99ewratech_k%C5%AFry_zemnj,_Ichthyosaurus_and_Plesiosaurus.jpghttp://en.wikipedia.org/wiki/File:Rozprawa_o_p%C5%99ewratech_k%C5%AFry_zemnj,_Ichthyosaurus_and_Plesiosaurus.jpghttp://en.wikipedia.org/wiki/Carolus_Linnaeushttp://en.wikipedia.org/wiki/Natural_sciencehttp://en.wikipedia.org/wiki/Fossil#cite_note-47http://en.wikipedia.org/wiki/Catastrophismhttp://en.wikipedia.org/wiki/Georges_Cuvierhttp://en.wikipedia.org/wiki/Law_of_superpositionhttp://en.wikipedia.org/wiki/William_Smith_%28geologist%29http://en.wikipedia.org/wiki/Georges_Cuvierhttp://en.wikipedia.org/wiki/Plesiosaurushttp://en.wikipedia.org/wiki/Ichthyosaurushttp://en.wikipedia.org/wiki/Fossil#cite_note-46http://en.wikipedia.org/wiki/Fossil#cite_note-45http://en.wikipedia.org/wiki/Leonardo_da_Vincihttp://en.wikipedia.org/wiki/Renaissance


16/20

fossil record. Darwin eloquently described a process of descent with modification, or evolution,

whereby organisms either adapt to natural and changing environmental pressures, or they perish.

When Darwin wroteOn the Origin of Species by Means of Natural Selection, or the Preservation

of Favoured Races in the Struggle for Life,the oldest animal fossils were those from the

CambrianPeriod, now known to be about 540 million years old. He worried about the absence ofolder fossils because of the implications on the validity of his theories, but he expressed hope

that such fossils would be found, noting that: "only a small portion of the world is known with

accuracy." Darwin also pondered the sudden appearance of many groups (i.e.phyla)in the oldestknown Cambrian fossiliferous strata.

[48]

Further discoveries

Since Darwin's time, the fossil record has been extended to between 2.3 and 3.5 billion years.[49]

Most of these Precambrian fossils are microscopic bacteria ormicrofossils.However,

macroscopic fossils are now known from the late Proterozoic. TheEdiacara biota(also called

Vendian biota) dating from 575 million years ago collectively constitutes a richly diverseassembly of early multicellulareukaryotes.

The fossil record and faunal succession form the basis of the science ofbiostratigraphyor

determining the age of rocks based on embedded fossils. For the first 150 years ofgeology,

biostratigraphy and superposition were the only means for determining therelative ageof rocks.Thegeologic time scalewas developed based on the relative ages of rock strata as determined by

the early paleontologists andstratigraphers.

Since the early years of the twentieth century,absolute datingmet

fossil (offline format)

Documents