History of the Earth and Life[The History of the Earth and Life～The Paleozoic Era]

Soon after life appeared on Earth 3.8 billion years ago, numerous species appeared, evolved, and then disappeared. Here, in the hall of “History of the Earth and Life,” some of the typical species of this period of Earth’s history are displayed. At the entrance to the hall are explanations of the processes and materials of Earth’s formation, and next to this are Paleozoic fossils showing early life on Earth.

The Campo-del-Cielo Ferrous Meteorite	Druse In Granite	Opal	Trilobite

In 1576, while invading South America, the Spanish army seized a large iron meteorite referred to as “Field of the Sky” in local legend. The discovery of fragments of the meteorite continues.	Vapor pockets sometimes form in cooling granite magma; crystals grow inside these hollows, forming what are called druses.	Opal’s beautiful color is not the material color of its crystals. The color you see arises from light refracting in delicately arranged crystal particles. The mineral is relatively soft because of the presence of water molecules.	Geologists often use “index fossils” to determine the age of stratum. Uncovering a species whose time period is known, scientists can identify when the surrounding stratum formed. Because of their morphologic distinctiveness, common occurrence, a broad, worldwide geographic range, and a narrow or restricted stratigraphic range, trilobite species are very useful as index fossils.

Dunkleosteus terelli	Orthacanthus senckenbergianus	Screlocephalus	Dimetrodon

The largest animal of the Paleozoic Era, the Dunkleostus terelli reached nine meters in length. Serrations on its hatchet-like lower jaw show that it was a carnivore.	A large, thick spine behind the head characterizes this Paleozoic shark. At 2.45 meters, this is the world’s largest specimen of this species.	In the Paleozoic, many gigantic amphibians lived in freshwaters. Sclerocephalus is one of those gigantic “salamanders” and it had similar life to recent crocodiles.	Dimetrodon is a member of the mammal-like reptiles flourished in the end of the Paleozoic Era. The “sail” on the back of Dimetrodon is a structure for the control of warmness of its body.