fossil basics

• Fossils are the remains of one living organisms or their actions. They must be older than 10,000 years, any younger than that then they are known as sub fossils.
• Body fossils are the remains of teeth, bones, hair, scales, shells, and vegetation. 
• Trace fossils are evidence of the activity of an organism. The preservation of burrows, tracks, footprints, trails, toothmarks, stone implements and gastroliths. 
• Coprolites are fossilised droppings, excreta or faecal pellets.  Distinctive shapes or markings can provide info regarding the structure of the animals alimentary canal.
• Vertebrate fossil material is skeletons (mainly bone or collagen), teeth (coated in enamel) and to a lesser extent hair and nails. 
• Invertebrate fossil material are shells and exoskeletons often made of calcium carbonate and calcium phosphate. 
• Plant fossils are plants made of cellulose and lignin which can resist decay. 
• Moulds are imprints left by the shell on the rock that surrounded it. External moulds are imprints of the outside of the shell. An internal mould is when the inside of the shell is preserved by sediment inside the shell. 
• Casts are made when groundwater dissolves the original shell, new minerals can be precipitated in its place. 
• Benthonic organisms live on or in the sediment on the sea floor. 
• Infuanal organisms live in the sediment in burrows. 
• Epifaunal organisms live on the sediment. 
• Vagrant organisms move around, either scavengers or predators. 
• Sessile organisms do not move around. 
• Pelagic organisms live in the water column. 
• Planktonic organisms float around, moving where ocean currents transport them. 
• Nektonic organisms actively swim in the water column.