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The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 161.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.[2]
| Late/Upper Jurassic | |||||||||
|---|---|---|---|---|---|---|---|---|---|
.png) A map of Earth as it appeared 155 million years ago during the Late Jurassic Epoch, Oxfordian Age | |||||||||
| Chronology | |||||||||
| |||||||||
| Etymology | |||||||||
| Chronostratigraphic name | Upper Jurassic | ||||||||
| Geochronological name | Late Jurassic | ||||||||
| Name formality | Formal | ||||||||
| Usage information | |||||||||
| Celestial body | Earth | ||||||||
| Regional usage | Global (ICS) | ||||||||
| Time scale(s) used | ICS Time Scale | ||||||||
| Definition | |||||||||
| Chronological unit | Epoch | ||||||||
| Stratigraphic unit | Series | ||||||||
| Time span formality | Formal | ||||||||
| Lower boundary definition | Not formally defined | ||||||||
| Lower boundary definition candidates | Horizon of the Ammonite Cardioceras redcliffense. | ||||||||
| Lower boundary GSSP candidate section(s) | |||||||||
| Upper boundary definition | Not formally defined | ||||||||
| Upper boundary definition candidates |
| ||||||||
| Upper boundary GSSP candidate section(s) | None | ||||||||
In European lithostratigraphy, the name "Malm" indicates rocks of Late Jurassic age.[3] In the past, Malm was also used to indicate the unit of geological time, but this usage is now discouraged to make a clear distinction between lithostratigraphic and geochronologic/chronostratigraphic units.
Subdivisions
editThe Late Jurassic is divided into three ages, which correspond with the three (faunal) stages of Upper Jurassic rock:[citation needed]
| Tithonian | (149.2 ±0.7 – 145.0 ± 0.8 Ma) |
| Kimmeridgian | (154.8 ±0.8 – 149.2 ±0.7 Ma) |
| Oxfordian | (161.5 ± 1.0 – 154.8 ±0.8 Ma) |
Paleogeography
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During the Late Jurassic Epoch, Pangaea broke up into two supercontinents, Laurasia to the north, and Gondwana to the south. The result of this break-up was the spawning of the Atlantic Ocean. However, at this time, the Atlantic Ocean was relatively narrow.[citation needed]
Life forms of the epoch
editThis epoch is well known for many famous types of dinosaurs, such as the sauropods, the theropods, the thyreophorans, and the ornithopods. Other animals, such as some crocodylomorphs and the first birds, appeared in the Jurassic. Listed here are only a few of the many Jurassic animals:
- Camarasaurus, a large herbivorous sauropod dinosaur from North America
- Apatosaurus, a large herbivorous sauropod dinosaur from North America
- Brachiosaurus, a massive herbivorous sauropod dinosaur from North America
- Brontosaurus, a large herbivorous sauropod dinosaur from North America
- Diplodocus, an exceptionally long herbivorous sauropod dinosaur from North America
- Barosaurus, an exceptionally long herbivorous sauropod dinosaur from North America
- Europasaurus, a small herbivorous sauropod dinosaur from Europe
- Brachytrachelopan, a small herbivorous sauropod dinosaur from South America
- Supersaurus, possibly the longest sauropod dinosaur of them all
- Maraapunisaurus, possibly among the largest sauropod dinosaurs ever known
- Dicraeosaurus, a large herbivorous sauropod dinosaur from Africa
- Giraffatitan, another large sauropod from Africa (usually recognized as a species of Brachiosaurus)
- Allosaurus, the most common Late Jurassic theropod of North America, also present in Europe
- Epanterias, a massive carnivore from North America (possibly just Allosaurus)
- Saurophaganax, a giant carnivore from North America and possibly the largest land predator of the Jurassic (possibly a synonym of Allosaurus)
- Yangchuanosaurus, a large theropod from Asia
- Torvosaurus, a large Jurassic carnivore, from North America and Europe
- Ceratosaurus, a medium-sized Jurassic carnivore from North America, Europe, and possibly Africa
- Elaphrosaurus, a medium-sized Jurassic carnivore from Africa
- Ornitholestes, a small theropod from North America
- Compsognathus, a small theropod from Europe
- Tuojiangosaurus, a thyreophoran from Asia
- Stegosaurus, a thyreophoran from North America and Europe
- Kentrosaurus, a thyreophoran from Africa
- Gargoyleosaurus, a thyreophoran from North America
- Dryosaurus, a North American ornithopod
- Camptosaurus, an ornithopod from North America and possibly Europe
- Yinlong, an early marginocephalian dinosaur from Asia
- Chaoyangsaurus, an early marginocephalian dinosaur from Asia
- Juramaia, a basal mammal from Asia
- Archaeopteryx, a bird-like maniraptoran from Europe
- Rhamphorhynchus a long-tailed pterosaur from Europe
- Pterodactylus, a short-tailed pterosaur from Europe
- Anurognathus, one of the smallest pterosaurs from Europe
- Ophthalmosaurus, a very common sea-going ichthyosaur from Europe and North America
- Liopleurodon, a medium-sized sea-going pliosaur from Europe
- Dakosaurus, a medium-sized sea-going crocodylomorph from Europe
- Perisphinctes, an ammonite
- [citation needed]
References
edit
- ^ "International Chronostratigraphic Chart" (PDF). International Commission on Stratigraphy.
- ^ Owen 1987.
- ^ Gradstein, F.M.; Ogg, J.G.; Schmitz, M.D.; Ogg, G.M., eds. (2012). The Geologic Timescale 2012 (volume 1). Elsevier. p. 744. ISBN 978-0-44-459390-0.
- Owen, Donald E. (March 1987). "Commentary: Usage of Stratigraphic Terminology in Papers, Illustrations, and Talks". Journal of Sedimentary Petrology. 57 (2): 363–372.
- Kazlev, M. Alan (2002-06-28). "Late Jurassic — The Malm Epoch: The Acme of the Dinosaurs". Palæos. Retrieved 2014-10-23.