Study of fossils linking concepts of geology and biology.
Paleontology
So to produce a fossil, two conditions must be observed:
The organism must possess hard parts (bones, teeth, etc.), and
Rapid burial of the remains increases the chance of preservation.
Different Ways a Fossil Can Be Preserved:
Permineralization
Molds and Cast
Amber
Carbonization
Freezing
Trace Fossils
This occurs when pores and open spaces in tissue (such as bone and wood) are filled with minerals precipitated from mineral-rich solutions such as groundwater.
Permineralization
When organisms buried in sediment dissolve or decay away, it leaves behind a hollow space called mold in the organism’s shape. If minerals eventually fill in this hollow space, a cast is made.
Organisms in amber are exceptionally preserved well, often still containing their soft parts. These organisms are preserved when they fall into a viscous tree sap which hardens into amber.
This happens when these organisms are buried in sediment and eventually dissolve, leaving behind a thin layer of carbon outlining the organism’s shape.
Carbonization
A fossil can be preserved records of its activities such as tracks, burrows, coprolites (fossilized poop), and gastroliths (stomach stones).
Tool geologists use to classify and date rocks and fossils. Instead of numerical ages, time is divided into eons, eras, periods, epochs, and ages (in descending order of duration).
Geologic time scale (GTS)
Maintains the GTS. It aims to create unified terminologies for geologists worldwide to use in stratigraphy.
International Commission on Stratigraphy (ICS)
Based on the radiometric dating of the oldest rocks on Earth, the age of Earth is believed to be?
4.534 billion years old
Hadean Eon
The formation of the Earth; magma ocean; intense bombardment of space bodies ("Late Heavy Bombardment")
Archean Eon
Life begins as prokaryotic bacteria; Blue-green algae start to produce oxygen in the atmosphere
Proterozoic Eon
Multicellular life emerges
Cambrian Period
Multicellular life flourishes and diversifies ("Cambrian Explosion")
Ordovician Period
"Age of Invertebrates"
Silurian Period
Emergence of plants on land
Devonian Period
"Age of Fishes"; Towards the end, true amphibians emerged
Carboniferous Period
"Age of Amphibians"
Mississippian
Amphibians diversified; large coal swamps formed
Pennsylvanian
Emergence of reptiles
Permian Period
Existence of Pangaea; the largest mass extinction in Earth's history occurred towards the end ("The Great Paleozoic Extinction")
Triassic Period
Dinosaurs emerged; start of the Age of Reptiles; first true mammals (therapsids) emerged as well
Jurassic Period
Dinosaurs dominated the Earth; the first birds emerged
Cretaceous Period
First flowering plants emerged (angiosperms); marked the end of the Age of Reptiles with the Cretaceous-Tertiary Extinction ("K-T Extinction")
Paleogene Period
Start of the Age of Mammals
Neogene Period
Mammals and birds evolved into modern forms; hominids, the ancestors of humans, appeared towards the end
Quaternary Period
Current period; a cycle of glacial and interglacial periods