Late Jurassic
Third epoch of the Jurassic Period
From Wikipedia, the free encyclopedia
The Late Jurassic is the third epoch of the Jurassic period, and it spans the geologic time from 161.5 ± 1.0 to 143.1 ± 0.6 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 | |||||||||
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| 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) |
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| Upper boundary definition | Not formally defined | ||||||||
| Upper boundary definition candidates |
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| 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
The Late Jurassic is divided into three ages, which correspond with the three faunal stages of Upper Jurassic rock:[4]
| Name | Lower boundary (Ma) |
|---|---|
| Tithonian | 149.2 ± 0.7 |
| Kimmeridgian | 154.8 ± 0.8 |
| Oxfordian | 161.5 ± 1.0 |
Paleogeography
By the Late Jurassic, Pangaea had broken apart into Laurasia (Eurasia and North America) to the north and Gondwana to the south, divided by the wide Tethys Ocean. During the Late Jurassic, narrow ocean basins formed separating Eastern Gondwana (Antarctica, Australia, India and Madagascar), Western Gondwana (Africa, Arabia and South America) and Laurasia. These nascent oceans – including the young Atlantic Ocean – brought increased moisture to the formerly highly arid subtropical interior of Pangaea.
Climate
Deep ocean basins covered the poles, inhibiting the formation of polar ice caps. Polar summers were ice-free. The circulation of ocean currents between the high and low latitudes contributed to a generally warmer climate than today.[5] Europe became progressively more arid over the Late Jurassic.[6]
Life forms
This 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:
| Name | Description | Where found |
|---|---|---|
| Allosaurus | The most common Late Jurassic theropod | North America, also present in Europe |
| Anurognathus | One of the smallest pterosaurs | Europe |
| Apatosaurus | A large herbivorous sauropod dinosaur | North America |
| Archaeopteryx | A bird-like maniraptoran | Europe |
| Barosaurus | An exceptionally long herbivorous sauropod dinosaur | North America |
| Brachiosaurus | A massive herbivorous sauropod dinosaur | North America |
| Brachytrachelopan | A small herbivorous sauropod dinosaur | South America |
| Brontosaurus | A large herbivorous sauropod dinosaur | North America |
| Camarasaurus | A large herbivorous sauropod dinosaur | North America |
| Camptosaurus | An ornithopod | North America and possibly Europe |
| Ceratosaurus | A medium-sized Jurassic carnivore | North America, Europe, and possibly Africa |
| Chaoyangsaurus | An early marginocephalian dinosaur | Asia |
| Compsognathus | A small theropod | Europe |
| Dakosaurus | A medium-sized sea-going crocodylomorph | Europe |
| Dicraeosaurus | A large herbivorous sauropod dinosaur | Africa |
| Diplodocus | An exceptionally long herbivorous sauropod dinosaur | North America |
| Dryosaurus | An ornithopod | North America |
| Elaphrosaurus | A medium-sized Jurassic carnivore | Africa |
| Epanterias | A massive carnivore (possibly just Allosaurus) | North America |
| Europasaurus | A small herbivorous sauropod dinosaur | Europe |
| Gargoyleosaurus | A thyreophoran | North America |
| Giraffatitan | A large sauropod (formerly recognized as a species of Brachiosaurus) | Africa |
| Juramaia | A basal mammal | Asia |
| Kentrosaurus | A thyreophoran | Africa |
| Liopleurodon | A medium-sized sea-going pliosaur | Europe |
| Maraapunisaurus | Possibly among the largest sauropod dinosaurs ever known | |
| Ophthalmosaurus | A very common sea-going ichthyosaur | Europe and North America |
| Ornitholestes | A small theropod | North America |
| Perisphinctes | An ammonite | |
| Pterodactylus | A short-tailed pterosaur | Europe |
| Rhamphorhynchus | A long-tailed pterosaur | Europe |
| Saurophaganax | A giant carnivore; possibly the largest land predator of the Jurassic (possibly a synonym of Allosaurus) | North America |
| Stegosaurus | A thyreophoran | North America and Europe |
| Supersaurus | Possibly the longest sauropod dinosaur of them all | |
| Torvosaurus | A large Jurassic carnivore | North America and Europe |
| Tuojiangosaurus | A thyreophoran | Asia |
| Yangchuanosaurus | A large theropod | Asia |
| Yinlong | An early marginocephalian dinosaur | Asia |
