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Museum of Ancient Wonders: The Jurassic Period


from 195 million to

140 million years ago

The Jurassic period, with its lush rainforests, derives its name from an abundantly fossiliferous sequence of chalky deposits discovered in the Jura Mountains bordering Switzerland and France.

For the 55 million year duration of the Jurassic period, the supercontinent of Pangaea was gradually being wrenched into 2 separate masses, Gondwanaland (Africa, South America, Australia, India, Arabia, and Antarctica) and Laurasia (Europe, Asia, Greenland, and North America). Among the survivors of the Triassic extinction, tiny primitive mammals began to diversify during the Early Jurassic. By the dawning of the Late Jurassic (150 million years ago), the Atlantic Ocean had formed and the drifting continents had barely begun to resemble their present shapes. Gigantic dinosaurs that cared for their young had evolved from their smaller Late Triassic ancestors. Land bridges between the continents allowed the thriving herds of dinosaurs to migrate across great distances. Palm-like plants appeared and flourished throughout the warm, swampy landscapes of the period, nourishing the largest creatures that ever walked the Earth.

Class Aves,

Subclass Archaeornithes

Archaeopteryx lithographica

Late Jurassic, Germany

Meaning “Ancient Wing,” Archaeopteryx was a small, feathered dinosaur inhabiting the Late Jurassic forests of Central Europe 150 million years ago. Insectivores adapted for gliding and presumably for limited flight, these primitive ancestral birds still retained efficient, grasping claws on each wing, as well as a long bony tail and jaws lined with sharp archosaurian teeth. Perhaps the most famous fossil in the world, the spectacular “Berlin specimen” was found in 1877. Owing to the faint preservation of its flight feathers (overlooked for many years), the juvenile specimen, known as the “Eichstatt specimen,” was long misidentified as a Compsognathus. This rare specimen is spectacular evidence of an intermediate stage between Reptiles and birds.

Suborder Theropoda,

Infraorder Coelurosauria 

Compsognathus longipes

Late Jurassic, Germany

Of all the known fossils of adult dinosaurs, Compsognathus (“Elegant Jaw”) has the distinction of being the smallest. Running upright on its strong hind legs and stalking the underbrush for smaller Reptiles along the forested seashores of Jurassic Germany and France, Compsognathus was a swift and capable hunter, armed with sharp claws and teeth. This tiny coelurosaur was a relative of such giant creatures as the Tyrannosaurus rex of a later age. More closely related to Archaeopteryx (the bird-dinosaur), this skeleton shows that they shared a very recent common ancestor, suggesting that birds may have inherited their warm-blooded metabolism from their dinosaur forebears.

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