Fossils

By Mady Smith

How is a fossil made?

After an organism dies its body is exposed to a variety of factors that destroy it. The remains are buried by layers of sand and silt. Over time layers harden into sedimentary rocks. Over millions of years the remains can become fossilized as materials within the bon are dissolved by water and replaced by minerals from the ground.

Types of fossils.

Mold fossils- a fossilized impression made in the substrate

Cast fossils- formed when a mold is filled in

Trace fossils- ichnofossils

True form fossils- fossils of the actual animal or animal part

Guaranteed to Give You Knowledge About Fossils

Ages of Fossils

Precambrian- Dated between 590 and 700 million years ago. Some fossils were the Banded Iron, Archaea Cells, and Hox Genes


Cambria- Dated back to a few tens of millions of years ago. Some fossils were Marella Splendens, Emeraldella, Kuamaia Lata


Ordovican- Dated between 443.7 and 1.5 million years ago. Some fossils were Stromatolites, Cupulocrines, an Porocrines Crinoids


Silurian- Sea creatures, Euryptenus Remipes, Spirograptus Graptolite


Devonian- Dated to about 365 million years ago. Some fossils were Palaeospondylus Gunni, Fovosites Turinatus, and Coral Fossils.


Carboniferous- Dated between 360 and 286 million years ago. Some fossils were Rayonnoceras Solidiforme and Lepidodendron Mannabachense.


Permian- Dated between 440 and 410 million years ago. Some fossils were Glossopteris sp and Eryeps Megaacephalus.


Triassic- Dated between 245 and 208 million years ago. Some fossils were Ichthyosaur and Keichousaurus Hui.


Jurrassic- Dated between 208 and 146 million years ago. Some fossils were Agathis Jurrassica Plant and Craspedites Nodiger Ammonite.


Cretaceous- Dated between 146 and 65 million years ago. Some fossils are the Tyrannosaurus Rex and Dragon Fly.


Teritary- Dated between 65 and 1.8 million years ago. Some fossils were Baltic Fossil Amber Dipterans and Ginko Aduantoides Plant.