First appearance datum (FAD) is a term used by geologists and paleontologists to designate the first appearance of a species in the geologic record. FADs are determined by identifying the geologically oldest fossil discovered, to date, of a particular species.[1] A related term is last appearance datum (LAD), the last appearance of a species in the geologic record.[2]
FADs are frequently used to designate segments in the geologic time scale. A given FAD can be used to define a Global Boundary Stratotype Section and Point (GSSP).[1] For example, the beginning of the Tremadocian Stage of the Ordovician Period is marked by the first appearance of the conodontIapetognathus fluctivagus in the geologic record. This occurs in bed 23 of the rock formation known as the Green Point section, located in western Newfoundland, as well as in geologically correlated strata in many parts of the world.[3] However, diachronous FADs can be problematic for correlating chronostratigraphic units, particularly over longer distances.[1][4] Use of other data, such as radiometric data, may be ultimately necessary in order to establish more reliable correlations of chronostratigraphic units.[5]
^ abcLanding, Ed; Geyer, Gerd; Brasier, Martin D.; Bowring, Samuel A. (August 2013). "Cambrian Evolutionary Radiation: Context, correlation, and chronostratigraphy—Overcoming deficiencies of the first appearance datum (FAD) concept". Earth-Science Reviews. 123: 135. Bibcode:2013ESRv..123..133L. doi:10.1016/j.earscirev.2013.03.008 – via Astrophysics Data System.
first, appearance, datum, term, used, geologists, paleontologists, designate, first, appearance, species, geologic, record, fads, determined, identifying, geologically, oldest, fossil, discovered, date, particular, species, related, term, last, appearance, dat. First appearance datum FAD is a term used by geologists and paleontologists to designate the first appearance of a species in the geologic record FADs are determined by identifying the geologically oldest fossil discovered to date of a particular species 1 A related term is last appearance datum LAD the last appearance of a species in the geologic record 2 FADs are frequently used to designate segments in the geologic time scale A given FAD can be used to define a Global Boundary Stratotype Section and Point GSSP 1 For example the beginning of the Tremadocian Stage of the Ordovician Period is marked by the first appearance of the conodont Iapetognathus fluctivagus in the geologic record This occurs in bed 23 of the rock formation known as the Green Point section located in western Newfoundland as well as in geologically correlated strata in many parts of the world 3 However diachronous FADs can be problematic for correlating chronostratigraphic units particularly over longer distances 1 4 Use of other data such as radiometric data may be ultimately necessary in order to establish more reliable correlations of chronostratigraphic units 5 See also EditBiostratigraphyReferences Edit a b c Landing Ed Geyer Gerd Brasier Martin D Bowring Samuel A August 2013 Cambrian Evolutionary Radiation Context correlation and chronostratigraphy Overcoming deficiencies of the first appearance datum FAD concept Earth Science Reviews 123 135 Bibcode 2013ESRv 123 133L doi 10 1016 j earscirev 2013 03 008 via Astrophysics Data System Last appearance datum Oxford Reference Retrieved 2021 04 22 a href Template Cite web html title Template Cite web cite web a CS1 maint url status link International Commission on Stratigraphy stratigraphy org Retrieved 2021 04 05 Servais Thomas Molyneux Stewart G Li Jun Nowak Hendrik Rubinstein Claudia V Vecoli Marco Wang Wen Hui Yan Kui 2018 First Appearance Datums FADs of selected acritarch taxa and correlation between Lower and Middle Ordovician stages Lethaia 51 2 248 doi 10 1111 let 12248 ISSN 1502 3931 Pasquo Mercedes di Grader George W Isaacson Peter Souza Paulo A Iannuzzi Roberto Diaz Martinez Enrique 2015 10 03 Global biostratigraphic comparison and correlation of an early Cisuralian palynoflora from Bolivia Historical Biology 27 7 891 doi 10 1080 08912963 2014 910204 ISSN 0891 2963 S2CID 129872538 External links EditBiostratigrahic Zonation Global Boundary Stratotype Sections and Points lists FADs associated with GSSPs This paleontology article is a stub You can help Wikipedia by expanding it vte This geology article is a stub You can help Wikipedia by expanding it vte Retrieved from https en wikipedia org w index php title First appearance datum amp oldid 1116599691, wikipedia, wiki, book, books, library,
