Mesozoic geochronology/ is the science of applying dates in the past to rocks of the Mesozoic.
- ALMA represent the Asian Land Mammal Age,
- b2k represent before AD 2000,
- BP represent before present, as the chart is for 2008, this may require an added -8 for b2k,
- ELMMZ represent the European Land Mammal Mega Zone,
- FAD represent first appearance datum,
- FO represent first occurrence,
- Ga represent Gegaannum, billion years ago, or -109 b2k,
- GICC05 represent Greenland Ice Core Chronology 2005,
- GRIP represent Greenland Ice Core Project,
- GSSP represent Global Stratotype Section and Point,
- HO represent highest occurrence,
- ICS represent the International Commission on Stratigraphy,
- IUGS represent the International Union of Geological Sciences,
- LAD represent last appearance datum,
- LO represent lowest occurrence,
- Ma represent Megaannum, million years ago, or -106 b2k,
- NALMA represent the North American Land Mammal Age,
- NGRIP represent North Greenland Ice Core Project, and
- SALMA represent South American Land Mammal Age.
"The term b2 k [b2k] refers to the ice-core zero age of AD 2000; note that this is 50 years different from the zero yr for radiocarbon, which is AD 1950 [...]."
Mesozoic time frames
|Name (English)||base/start (Ma)||top/end (Ma)||status||subdivision of||usage||named after||author, year|
|Aalenian||175.6 ± 2.0||171.6 ± 3.0||age||Jurassic||ICS||Aalen (Germany)|
|Aegean||245 ± 1.5||244||age||Middle Triassic||Europe||Aegean Sea|
|Albian||112.0 ± 1.0||99.6 ± 0.9||age||Cretaceous||ICS||Albia, Latin name of the river Aube (France)||d'Orbigny, 1842|
|Anisian||245.0 ± 1.5||237.0 ± 2.0?||age/Stage||Middle Triassic||ICS||Anisus, Latin name for the river Enns (Austria)|
|Aptian||125.0 ± 1.0||112.0 ± 1.0||age||Cretaceous||ICS||Apt (France)||d'Orbigny, 1840|
|Austinian||age||Cretaceous||south and east of the US||Austin, Texas||Murray, 1961|
|Bajocian||171.6 ± 3.0||167.7 ± 3.5||age||Jurassic||ICS||Bayeux (France)||d'Orbigny|
|Barremian||130.0 ± 1.5||125.0 ± 1.0||age||Cretaceous||ICS||Barrême (France)||Coquand, 1873|
|Bathonian||167.7 ± 3.5||164.7 ± 4.0||age||Jurassic||ICS||Bath (England)|
|Berriasian||145.5 ± 4.0||140.2 ± 3.0||age||Cretaceous||ICS||Berrias (France)|
|Brahmanian||252.6||251||Stage||Lower Triassic||India, Germany|
|Buntsandstein||251.0 ± 0.4||246.6||epoch/subperiod||Triassic||Europe||German: bunte Sandstein = coloured sandstone||Von Alberti, 1834|
|Callovian||164.7 ± 4.0||161.2 ± 4.0||age||Jurassic||ICS||Kellaways (England)||d'Orbigny|
|Campanian||83.5 ± 0.7||70.6 ± 0.6||age||Cretaceous||ICS||Champagne (France)||Coquand, 1857|
|Carixian||189.6 ± 1.5||sub-age||Jurassic||regional|
|Carnian||228.0 ± 2.0||216.5 ± 2.0||age||Late Triassic||ICS||Carnic Alps (Austria)||Mojsisovics, 1869|
|Cenomanian||99.6 ± 0.9||93.5 ± 0.8||age||Cretaceous||ICS||Latin: Cenomanium = Le Mans (France)||d'Orbigny, 1847|
|Coniacian||89.3 ± 1.0||85.8 ± 0.7||age||Cretaceous||ICS||Cognac (France)||Coquand, 1857|
|Cretaceous||145.5 ± 4.0||65.5 ± 0.3||period||Mesozoic||ICS||Crete; Latin creta=chalk||d'Omalius d'Halloy, 1822|
|Dogger||175.6 ± 2.0||161.2 ± 4.0||epoch||Jurassic||Northern Europe||dogger=ironrich sediment type|
|Domerian||183.0 ± 1.5||sub-age||Jurassic||regional|
|Eaglefordian||age||Cretaceous||Gulf and Atlantic coast of the US||Eagle Ford, Dallas, Texas||Murray, 1961|
|Fassanian||237 ± 2.0?||233?||sub-age/substage||Middle Triassic||Europe|
|Gallic||130.0 ± 1.5||89.3 ± 1.0||epoch||Cretaceous||obsolete|
|Gandarian||251.6||251||Substage||Lower Triassic||India, Germany|
|Gangetian||252.6||251.6||Substage||Lower Triassic||India, Germany|
|Gulf(-ian)||epoch||Cretaceous||south and east of the US||the Mexican Gulf|
|Hauterivian||136.4 ± 2.0||130.0 ± 1.5||age||Cretaceous||ICS||Hauterive (Switzerland)||Renevier, 1873|
|Hettangian||199.6 ± 0.6||196.5 ± 1.0||age||Jurassic||ICS||Hettange-Grande (France)||Renevier, 1864|
|Illyrian||240 ± 2.0||237 ± 2.0?||sub-age/Substage||Middle Triassic||Europe|
|Induan||251.0 ± 0.4||249.7 ± 0.7||age||Triassic||ICS||river Indus||Kiparisova & Popov, 1956|
|Julian||229.6 ± 2.0||222.5||sub-age||Late Triassic||Europe|
|Jurassic||199.6 ± 0.6||145.5 ± 4.0||period||Mesozoic||ICS||Jura mountains||Brongniart|
|Karoo Ice Age||~360||~260||ice age||Phanerozoic||Karoo (South Africa)|
|Keuper||±230||199.6||epoch||Triassic||Europe||Von Alberti, 1834|
|Kimmeridgian||155.7 ± 4.0||150.8 ± 4.0||age||Jurassic||ICS||Kimmeridge (England)||d'Orbigny|
|Lacian||217.4 ± 2.0||211||sub-age||Upper Triassic||Europe|
|Ladinian||237.0 ± 2.0||228.0 ± 2.0||age||Middle Triassic||ICS||Ladini, people in northern Italy||Bittner, 1892|
|Lias||199.6 ± 0.6||175.6 ± 2.0||epoch||Jurassic||Northern Europe||unclear|
|Longobardian||233?||229.6 ± 2.0?||sub-age/substage||Middle Triassic||Europe|
|Lotharingian||193.3 ± 0.7||189.6 ± 0.7||substage||Jurassic|
|Maastrichtian||70.6 ± 0.6||65.5 ± 0.3||age||Cretaceous||ICS||Maastricht (Netherlands)||Dumont, 1849|
|Malm||161.2 ± 4.0||145.5 ± 4.0||epoch||Jurassic||Europe||Old English: malm = calcareous soil|
|Mesozoic||251.0 ± 0.7||65.5 ± 0.3||era||ICS||middle life|
|Muschelkalk||243 ± 2||235 ± 2||epoch||Triassic||Europe||German: limestone with mussels||Füchsel, 1761|
|Navarroan||age||Cretaceous-Paleocene||south and east of the US||Navarro, Texas||Murray, 1961|
|Neocomian||145.5||125.0/130.0||epoch||obsolete||Neocomium, Latin name for Neuchâtel|
|Norian||216.5 ± 2.0||203.6 ± 1.5||age||Upper Triassic||ICS||Noric Alps (Austria)|
|Olenekian||249.5||245.9||age||Triassic||ICS||river Olenyok (Siberia)|
|Oxfordian||161.2 ± 4.0||155.0 ± 4.0||age||Jurassic||ICS||Oxford (England)||d’Orbigny|
|Paleozoic||542.0 ± 1.0||251.0 ± 0.7||era||Phanerozoic||ICS||old life|
|Phanerozoic||542.0 ± 1.0||present||eon||ICS||visible life|
|Pliensbachian||189.6 ± 1.5||183.0 ± 1.5||age||Jurassic||ICS||Pliensbach (Germany)||Oppel, 1858|
|Portlandian||age||Jurassic||British Isles||Isle of Portland (England)|
|Purbeckian||age||Cretaceous-Jurassic||England (obsolete)||Isle of Purbeck (England)|
|Rhaetian||203.6 ± 1.5||199.6 ± 0.6||age||Triassic||ICS||Rhaetian Alps (Switzerland, Austria, Italy)|
|Santonian||85.8 ± 0.7||83.5 ± 0.7||age||Cretaceous||ICS||Saintes (France)||Coquand, 1873|
|Scythian||251 ± 0.2||245 ± 1.5||Epoch||Early Triassic||Europe||Scythia|
|Sevatian||206||202.3 ± 1.5||sub-age||Upper Triassic||Europe|
|Sinemurian||196.5 ± 1.0||189.6 ± 1.5||age||Jurassic||ICS||Semur-en-Auxois (France)||d'Orbigny, 1842|
|Tayloran||age||Cretaceous||south and west of the US||Taylor, Texas||Murray, 1961|
|Tithonian||150.8 ± 4.0||145.5 ± 4.0||age||Jurassic||ICS||Tithon (Greek mythology)||Oppel, 1865|
|Toarcian||183.0 ± 1.5||175.6 ± 2.0||age||Jurassic||ICS||Thouars (France)||d'Orbigny, 1849|
|Triassic||251.0 ± 0.4||199.6 ± 0.6||period||Mesozoic||ICS||threefold||Von Alberti, 1834|
|Turonian||93.5 ± 0.8||89.3 ± 1.0||age||Cretaceous||ICS||Tours (France)||d'Orbigny, 1842|
|Tuvalian||222.5||217.4 ± 2.0||sub-age||Upper Triassic||Europe|
|Valanginian||140.2 ± 3.0||136.4 ± 2.0||age||Cretaceous||ICS||Valangin (Switzerland)||Desor, 1853|
|Woodbinian||age||Cretaceous||Gulf and Atlantic coast of the US||Murray, 1961|
The Cretaceous/Cenozoic boundary occurs at 65.0 ± 0.1 Ma (million years ago).
The aerial image on the right shows the quarry pit in Mantua Township in central New Jersey has been owned by the Inversand Company for nearly a century.
"When an asteroid hit the Earth around 66 million years ago, it wiped out almost 75 percent of the plants and animals on the planet. All dinosaurs, except those that would eventually give rise to modern birds, were killed following the impact. Yet despite such a vast die-off, no bone bed containing a concentration of fossils as a result of this event has been found."
“We don’t know yet [if it dates from the mass extinction], but we are testing this hypothesis by examining the fossils, the sediments and the chemistry.”
"At the end of the Cretaceous, when the dinosaurs met their maker, the region was a shallow tropical sea full of fish, sea turtles, crocodiles, and even mosasaurs. But at some point around 66 million years ago, whether it was due to the asteroid impact or some other cause, many of the inhabitants of the sea died and were preserved in a large bone bed."
On the left is a specimen of Catapleura repanda from the Rowan quarry found in the Cretaceous marl.
"Three Antarctic Ocean K/T boundary sequences from ODP Site 738C on the Kerguelen Plateau, ODP Site, 752B on Broken Ridge and ODP Site 690C on Maud Rise, Weddell Sea, have been analyzed for stratigraphic completeness and faunal turnover based on quantitative planktic foraminiferal studies. Results show that Site 738C, which has a laminated clay layer spanning the K/T boundary, is biostratigraphically complete with the earliest Tertiary Zones P0 and P1a present, but with short intrazonal hiatuses. Site 752B may be biostratigraphically complete and Site 690C has a hiatus at the K/T boundary with Zones P0 and P1a missing."
"The cosmopolitan nature of the dominant fauna began during the last 200,000 to 300,000 years of the Cretaceous and continued at least 300,000 years into the Tertiary. This indicates a long-term environmental crisis that led to gradual elimination of specialized forms and takeover by generalists tolerant of wide ranging temperature, oxygen, salinity and nutrient conditions. A few thousand years before the K/T boundary these generalists gradually declined in abundance and species became generally dwarfed due to increased environmental stress. There is no evidence of a sudden mass killing of the Cretaceous fauna associated with a bolide impact at the K/T boundary. Instead, the already declining Cretaceous taxa gradually disappear in the early Danian and the opportunistic survivor taxa (Ch. waiparaensis and Guembelitria cretacea) increase in relative abundance coincident with the evolution of the first new Tertiary species."
"The Chicxulub impact is commonly believed to have crashed into Yucatan precisely at the KT boundary and caused the mass extinction. However, the stratigraphically oldest impact glass spherule ejecta documented from NE Mexico and Texas predate the mass extinction by 100-150 ky. Elsewhere in the North Atlantic, Caribbean, Belize, Guatemala and southern Mexico, there is a consistent pattern of impact spherules reworked in early Danian sediments and overlying a major KTB unconformity. This indicates that the Chicxulub impact predates the KT boundary and did not cause the mass extinction (Keller et al., 2009, 2013)."
In the top center is a 2.7 cm section of a polished shell with 6 sutures. It is from the extinct cephalopod Baculites compressus; Cretaceous, 100 million years old, Bearpaw Formation, Montana, USA.
The middle center photo is of Baculites ovatus, at the Naturalis Museum, Leiden.
The lower center is a fossil cast of a Baculites grandis shell taken at the North American Museum of Ancient Life.
On the right is an example of Plesiacanthoceras wyomingense from the late Cretaceous in Wyoming, USA. It is exhibited in Smithsonian National Museum of Natural History: Hall of Fossils.
Discoscaphites iris on the right is an ammonite from the Owl Creek Formation (Upper Cretaceous), Owl Creek, Ripley, Mississippi USA.
The specimen on the left is Jeletzkytes spedeni from the Maastrichtian (Upper-Cretaceous) Fox Hills Formation, locality - South Dakota, USA. Matrix free specimen is 7.5 cm (3") in diameter, displaying pearly aragonite preservation of the shell.
"Paleogeographically, the sub-alpine terrain of southeastern France [...] was located on the proximal part of the South-European Tethys margin. It includes the Vocontian Basin, which experienced relatively high rates of subsidence during Jurassic and Early Cretaceous times, bordered by carbonate platforms limited by a net of extensional or strike–slip faults (Graciansky et al., 1999)."
This phraseology connects "Early Cretaceous" with "times".
The Jurassic/Cretaceous boundary occurs at 144.2±2.6 Ma (million years ago).
The Jurassic/Cretaceous boundary occurs at 144.2±2.6 Ma (million years ago).
Paleontologists appear to prefer "Late Jurassic", "Middle Jurassic", and "Early Jurassic".
Time frame references such as "We applied the method of frequency ratios (Huang et al., 1992; Mayer and Appel, 1999) to compare the observed spectral frequencies with orbital frequencies estimated for Late Jurassic time (Berger and Loutre, 1994) (Tables 1A and B)." use "Late Jurassic" as a time frame, but "Upper Jurassic" as a stratigraphic frame.
On the right is an example of Kosmoceras cromptoni from the Late Jurassic, Chippenham, England.
The International Commission on Stratigraphy (ICS) uses only "Upper Jurassic", "Middle Jurassic", and "Lower Jurassic" in its Global Boundary Stratotype Section and Point (GSSP) Table for all periods.
On the right is an image of Peltoceras solidum, an ammonite from the Matmor Formation (Jurassic, Callovian), Makhtesh Gadol, Israel.
On the left is an example of Kosmoceras medea.
Another species of Kosmoceras is on the lower right, specifically Kosmoceras proniae.
"The Global Boundary Stratotype Section and Point (GSSP) for the Aalenian Stage, formally defined at the base of bed FZ107 in the Fuentelsaz section, Castilian Branch of the Iberian Range (Spain), has been ratified by the IUGS."
"The position of the boundary coincides with the first occurrence of the ammonite assemblage characterized by Leioceras opalinum and Leioceras lineatum and corresponds with a normal polarity interval correlated with the up-to-date Jurassic magnetic polarity time scale (Gradstein and others, 1994; Ogg, 1995)."
The "first occurrence of the species of the genus Leioceras, evolved from Pleydellia, has been widely accepted as being the biochronological event which best enables the recognition of the basal boundary of the Aalenian Stage."
On the right is a chart which indicates the ammonite zones that serve as geochrons for the Aalenian.
The second image down on the right displays the type strata for the Aalenian.
An example of Leioceras opalinum is shown on the left.
Uptonia jamesoni from the lower Jurassic is in the family Polymorphitidae, superfamily Eoderocerataceae, order Ammonitida, subclass Ammonoidea, class Cephalopoda.
Pleuroceras spinatum (Bruguière 1789) is of the family Amaltheidae. It is a pyritic specimen. The biozone index is to the end of Pliensbachian.
"Since the 1960’s, the LO (lowest occurrence) of the ammonite Psiloceras (usually the species P. planorbis [first image on the right]) has provided the working definition of the TJB (e.g., Lloyd, 1964; Maubeuge, 1964; Cope et al., 1980; Warrington et al., 1994; Gradstein et al., 2004)."
"The Global Stratotype Section and Point (GSSP) defining the base of the Jurassic System Lower Jurassic Epoch and Hettangian Stage is situated at the Kuhjoch pass, Karwendel Mountains, Northern Calcareous Alps, Austria (47°29'02"N/11°31'50"E). The Triassic-Jurassic (T-J) boundary is exposed at Kuhjoch West and at Kuhjoch East [in the second image on the right], and corresponds to the first occurrence (FO) of the ammonite Psiloceras spelae tirolicum [at the top of this section]."
Another FO is that of "the aragonitic foraminifer Praegubkinella turgescens"
The Triassic/Jurassic boundary occurs at 205.7±4.0 Ma (million years ago).
"What must underlie discussion of the definition of the TJB is the well accepted concept that global correlateability should be the main emphasis in the selection of a GSSP (e.g., Cowie et al., 1986; Remane et al., 1996; Gradstein et al., 2004; Walsh et al., 2004). As Remane et al. (1996: 79) expressed it, “the boundary definition will normally start from the identification of a level which can be characterised by a marker event of optimal correlation potential.” Thus, our goal here is to evaluate the possible marker events that could be used to define the TJB and to argue that an ammonite-based marker event has optimal correlation potential. This marker event is the LO of Psiloceras tilmanni in the New York Canyon section of Nevada."
"During the Late Triassic, the Newark rift basin of Eastern North America was in the interior of tropical (2.5–9.5° N) Pangaea. Strikingly cyclical lacustrine rocks comprise most of the 6770 m of continuous core recovered from this basin by the Newark Basin Coring Project."
"A consistent hierarchy in frequencies of the lake level cycles is present throughout the Late Triassic (and earliest Jurassic) portions of the cores, an interval of about 22 m.y.. Calibration of the sediment accumulation rate by a variety of methods shows that these thickness periodicities are consistent with an origin in changes in precipitation governed by celestial mechanics. The full range of precession-related periods of lake level change are present, including the two peaks of the ∼20,000 year cycle of climatic precession, the two peaks of the ∼100,000 year eccentricity cycle, the single peak of the 412,900 year eccentricity cycle, and the ∼2,000,000 year eccentricity cycle."
The chart in the Norian section describes the chronology of Upper Triassic time frames.
The "extinction of Conodonta has long been seen as a terminal Triassic event, and the presence/absence of conodonts thus is routinely used to distinguish Triassic from Jurassic strata. Rhaetian conodont assemblages are of low diversity and abundance, and conodonts can be easily reworked. Therefore, the HO of Conodonta is not a reliable criterion for TJB definition. However, it is very useful to know that the presence of autochthonous Conodonta is a pre-Jurassic indicator, and this micropaleontological criterion has been widely used and accepted."
The chart above shows the chronological positions of Upper Triassic Stages and Substages, including the Norian.
The chart in the Norian section describes the chronology of Upper Triassic time frames, including the Sevatian.
The chart in the Norian section describes the chronology of Upper Triassic time frames, including the Alaunian.
The chart in the Norian section describes the chronology of Upper Triassic time frames, including the Lacian or Early Norian.
The chart in the Anisian section places the Carnian in the Late, or Upper, Triassic.
The chart in the Norian section describes the chronology of Upper Triassic time frames, including the Tuvalian.
The chart in the Anisian section places the Julian in the Carnian.
The chart in the Anisian section places the Cordevolian in the Carnian.
The chart in the Anisian section places the Middle Triassic below the Late Triassic.
The chart in the Anisian section places the Ladinian above the Asinian.
The chart in the Anisian section places the Longobardian above the Fassanian.
The chart in the Anisian section places the Fassanian at the base of the Ladinian.
The chart above indicates the time frames at and above the Anisian.
An example of Ussuriphyllites amurensis (Kiparisova) is on the right. It is from the Lower-most Anisian, Atlasov Cape area.
The chart in the Anisian section places the Illyrian at the top of the Anisian.
The chart in the Anisian section places the Pelsonian below the Illyrian.
The chart in the Anisian section places the Bithynian below the Pelsonian.
The chart above shows the Aegean as the lowest time frame of the Anisian.
The magnetostratigraphy in the farthest right column of the above chart has black as normal polarity, white as reversed polarity, and gray for no reliable data.
The chart in the Aegean section shows the Scythian to be equivalent to the Lower Triassic.
"Global warming is widely regarded to have played a contributing role in numerous past biotic crises. Here, we show that the end-Permian mass extinction coincided with a rapid temperature rise to exceptionally high values in the Early Triassic that were inimical to life in equatorial latitudes and suppressed ecosystem recovery."
The chart in the Aegean section shows the Scythian to be equivalent to the Lower Triassic.
The chart in the Aegean section indicates that the Scythian is divided into the Olenekian above and Induan below.
The Spathian is sometimes referred to as the Late Olenekian.
As indicated in the above stratigraphy, the Sinbad Formation is entirely within the Smithian, or Early Olenekian.
The Smithian is sometimes referred to as the Early Olenekian.
The chart in the Aegean section indicates that the Brahmanian is equivalent to the Induan.
In the diagram on the right, the Permian-Triassic boundary is at the base of the Induan limestone that occurs within the Yinkeng Formation.
"The Global Stratotype Section and Point (GSSP) of the Permian-Triassic boundary [...] is defined at the base of Hindeodus parvus horizon, i.e. the base of Bed 27c of Meishan section D, Changxing County, Zhejiang Province, South China."
"Hindeodus parvus is now recognized as the index fossil" occurring in the Zone above the P-T boundary.
The chart in the Aegean section indicates that the Dienerian is equivalent to the Gandarian.
The chart in the Aegean section indicates that the Gandarian is in the Brahmanian.
The chart in the Aegean section indicates that the Gangetian is in the Brahmanian.
The Permian/Triassic boundary occurs at 248.2 ± 4.8 Ma (million years ago).
Locations on Earth
At the Inversand quarry, imaged on the right, "Located in South Jersey, the cradle of dinosaur paleontology, the quarry in Mantua Township, N.J., contains thousands of fossils dating back 65 million years."
But asteroid impacts, though rare, occur once in a while, over very large areas, at aperiodic intervals such as the Chicxulub crater, diagrammed on the left. Most scientists agree that this impact is the cause of the Cretatious-Tertiary Extinction, 65 million years ago (Ma), that marked the sudden extinction of the dinosaurs and the majority of life then on Earth. This shaded relief image of Mexico's Yucatan Peninsula shows a subtle, but unmistakable, indication of the Chicxulub impact crater.
- Each time frame or span of time in geochronology has at least one dating technique.
- Late Jurassic and Upper Jurassic are different time frames.
- Mike Walker, Sigfus Johnsen, Sune Olander Rasmussen, Trevor Popp, Jørgen-Peder Steffensen, Phil Gibbard, Wim Hoek, John Lowe, John Andrews, Svante Björck, Les C. Cwynar, Konrad Hughen, Peter Kershaw, Bernd Kromer, Thomas Litt, David J. Lowe, Takeshi Nakagawa, Rewi Newnham and Jakob Schwander (2009). "Formal definition and dating of the GSSP (Global Stratotype Section and Point) for the base of the Holocene using the Greenland NGRIP ice core, and selected auxiliary records". Journal of Quaternary Science 24 (1): 3-17. doi:10.1002/jqs.1227. http://www.stratigraphy.org/GSSP/Holocene.pdf. Retrieved 2015-01-18.
- Names from local versions of the geologic timescale can often be found in the local language. The English name is usually found by replacing the suffix in the local language for -an or -ian. Examples for "local" suffices are -en (French), -ano (Spanish), -ium (German), -aidd (Welsh) or -aan (Flemish Dutch). The English name "Norian", for example, becomes Noriano in Spanish, Norium in German, Noraidd in Welsh or Norien in French.
- Time is given in Megaannum (million years BP, unless other units are given in the table. BP stands for "years before present". For ICS-units the absolute ages are taken from Gradstein et al. (2004).
- This name is often still used in a chronostratigraphic or geochronologic sense, although it is now officially a lithostratigraphic unit.
- Menning et al. 2005
- Felix M. Gradstein, Frits P. Agterberg, James G. Ogg, Jan Hardenbol, Paul Van Veen, Jacques Thierry, and Zehui Huang (1995). A Triassic, Jurassic and Cretaceous Time Scale, In: Geochronology Time Scales and Global Stratigraphic Correlation. Society for Sedimentary Geology. doi:1-56576-024-7. http://archives.datapages.com/data/sepm_sp/SP54/A_Triassic_Jurassic_and_Cretaceous_Time_Scale.htm. Retrieved 2016-10-24.
- Josh L Davis (12 January 2016). "Paleontologists Believe They Have Discovered The First Fossil Bed From The Dinosaur Extinction Event Itself". iflscience. Retrieved 2016-01-16.
- Kenneth Lacovara (12 January 2016). "Paleontologists Believe They Have Discovered The First Fossil Bed From The Dinosaur Extinction Event Itself". iflscience. Retrieved 2016-01-16.
- Gerta Keller (4 January 1993). "The Cretaceous-Tertiary boundary transition in the Antarctic Ocean and its global implications". Marine Micropaleontology 21 (1-3): 1 - 45. doi:10.1016/0377-8398(93)90010-U. http://linkinghub.elsevier.com/retrieve/pii/037783989390010U. Retrieved 2016-10-24.
- Gerta Keller (2014). "RESEARCH TOPICS". Princeton, New Jersey USA: Princeton University. Retrieved 2016-10-24.
- Slah Boulila, Bruno Galbrun, Linda A. Hinnov, Pierre-Yves Collin (January 2008). "High-resolution cyclostratigraphic analysis from magnetic susceptibility in a Lower Kimmeridgian (Upper Jurassic) marl–limestone succession (La Méouge, Vocontian Basin, France)". Sedimentary Geology 203 (1-2): 54-63. http://www.sciencedirect.com/science/article/pii/S0037073807002928. Retrieved 2015-01-27.
- Guillermo W. Rougier, John R. Wible, and James A. Hopson (22 November 1996). "Basicranial Anatomy of Priacodon fruitaensis (Triconodontidae, Mammalia) from the Late Jurassic of Colorado, and a Reappraisal of Mammaliaform Interrelationships". Novitates (3183): 38. http://digitallibrary.amnh.org/dspace/handle/2246/3639. Retrieved 2015-01-27.
- International Commission on Stratigraphy (27 January 2015). "GSSP Table - All Periods". ICS. Retrieved 2015-01-27.
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