Jurassic

From EvoWiki

Painting of a late Jurassic Scene on one of the large island in the Lower Saxony basin in northern Germany. It shows an adult and a juvenile specimen of the sauropod Europasaurus holgeri and Iguanodons passing by. There are two Compsognathus in the foreground and an Archaeopteryx at the right.

The Jurassic was the period of time from 213-144 million years ago. It is the middle period of the Mesozoic Era.

[edit] Life and Evolution

Major events include the appearance of birds, crabs, frogs and salamanders. The Jurassic is often referred to as the "Age of the Dinosaurs" and the Dinosauria were a dominant life form. The herbivores included the gigantic sauropods - Diplodocus, Brachiosaurus, and Apatosaurus along with the stegosaurs. Predators included carnosaurs, coelurosaurs and ceratosaurs. The pterosaurs learned to fly. The Jurassic also saw the evolution of the first birds, including the well-known Archaeopteryx (although Protoavis which lived in the Triassic may be an older bird). Ichthyosaurs, plesiosaurs, giant marine crocodiles, modern-looking sharks and rays roamed the seas. The ammonites and belemnites were prominent invertebrates. Microscopic dinoflagellates and coccolithophorids diversified. On land plants abounded with ferns, ginkgoes, true cycads and conifers flourishing. Small early rat-sized mammals evolved.

[edit] Geologic and Paleotectonic Environment

In the early Jurassic (200mya) the Cimmerian and Cathayasian orogenies continued across southern Eurasia. Pangea continued to split apart along the proto-Atlantic and an incipient split between India and E. Africa was forming. By 160mya the Atlantic and Gulf of Mexico were opening and India, Madagascar and Antarctica were separating from Africa. The Nevadan orogeny was developing in SW North America.

See also: Geological Timescale.

[edit] External Links

• Berkeley - Jurassic Life