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The Jurassic Portal

Introduction

The Jurassic (/dʒʊˈræsɪk/ juurr-ASS-ik) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period 201.4 million years ago (Mya) to the beginning of the Cretaceous Period, approximately 145 Mya. The Jurassic constitutes the middle period of the Mesozoic Era and is named after the Jura Mountains, where limestone strata from the period were first identified.

The start of the Jurassic was marked by the major Triassic–Jurassic extinction event, associated with the eruption of the Central Atlantic Magmatic Province (CAMP). The beginning of the Toarcian Stage started around 183 million years ago and is marked by the Toarcian Oceanic Anoxic Event, a global episode of oceanic anoxia, ocean acidification, and elevated global temperatures associated with extinctions, likely caused by the eruption of the Karoo-Ferrar large igneous provinces. The end of the Jurassic, however, has no clear, definitive boundary with the Cretaceous and is the only boundary between geological periods to remain formally undefined.

By the beginning of the Jurassic, the supercontinent Pangaea had begun rifting into two landmasses: Laurasia to the north and Gondwana to the south. The climate of the Jurassic was warmer than the present, and there were no ice caps. Forests grew close to the poles, with large arid expanses in the lower latitudes. (Full article...) (Full article...)

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Selected article on the Jurassic world and its legacies

Artist's restoration of Leedsichthys. — Artist's restoration of *Leedsichthys*.

A fish is any member of a paraphyletic group of organisms that consist of all gill-bearing aquatic craniate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups. Most fish are ectothermic ("cold-blooded"), allowing their body temperatures to vary as ambient temperatures change. Fish are abundant in most bodies of water. They can be found in nearly all aquatic environments, from high mountain streams to even hadal depths of the deepest oceans. At 32,000 species, fish exhibit greater species diversity than any other group of vertebrates. Because the term "fish" is defined negatively, and excludes the tetrapods (i.e., the amphibians, reptiles, birds and mammals) which descend from within the same ancestry, it is paraphyletic, and is not considered a proper grouping in systematic biology.

The earliest organisms that can be classified as fish were soft-bodied chordates that first appeared during the Cambrian period. Although they lacked a true spine, they possessednotochords which allowed them to be more agile than their invertebrate counterparts. Fish would continue to evolve through the Paleozoic era, diversifying into a wide variety of forms. Many fish of the Paleozoic developed external armor that protected them from predators. The first fish with jaws appeared in the Silurian period, after which many (such as sharks) became formidable marine predators rather than just the prey of arthropods. (see more...)

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Selected article on the Jurassic in human science, culture and economics

Edward Drinker Cope (July 28, 1840 – April 12, 1897) was an American paleontologist and comparative anatomist, as well as a noted herpetologist and ichthyologist. Cope distinguished himself as a child prodigy, publishing his first scientific paper at the age of nineteen. Cope later married and moved from Philadelphia to Haddonfield, New Jersey, although Cope would maintain a residence and museum in Philadelphia in his later years.

Cope had little formal scientific training, and he eschewed a teaching position for field work. He made regular trips to the American West prospecting in the 1870s and 1880s, often as a member of United States Geological Survey teams. A personal feud between Cope and paleontologist Othniel Charles Marsh led to a period of intense fossil-finding competition now known as the Bone Wars. Cope's financial fortunes soured after failed mining ventures in the 1880s. He experienced a resurgence in his career toward the end of his life before dying in 1897.

Cope's scientific pursuits nearly bankrupted him, but his contributions helped to define the field of American paleontology. He was a prodigious writer, with 1,400 papers published over his lifetime, although his rivals would debate the accuracy of his rapidly published works. He discovered, described, and named more than 1,000 vertebrate species including hundreds of fishes and dozens of dinosaurs. His proposals on the origin of mammalian molars and for the gradual enlargement of mammalian species over geologic time ("Cope's Law") are notable among his theoretical contributions. (see more...)

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A skeleton of Steneosaurus, an extinct genus of teleosaurid crocodyliform from the Toarcian Lower Jurassic of Holzmaden, Germany.
Photo credit: Didier Descouens

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Did you know?

... that the 150-million-year-old ink of the extinct, squid-like Belemnotheutis (artist's rendition pictured) was used to draw a picture that paleontologists called "the ultimate self portrait"?
... that Ororaphidia and Styporaphidia are the oldest snakeflies known from China, dating from the Middle Jurassic?
... that the extinct snakefly genus Proraphidia is known from fossils found in Spain, England, and Kazakhstan?
... that a single spoon-shaped lower jaw belonging to the goniopholidid crocodyliform Sunosuchus is the most well preserved fossil found from the Phu Kradung Formation in Thailand?
... that fossils of extinct giant cicadas (pictured) were once misidentified as the oldest known butterflies?